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Microscopical aspects of hardwood refiner pulps Cisneros, Hector A. 1991

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MICROSCOPICAL  ASPECTS  OF  HARDWOOD R E F I N E R  PULPS  by HECTOR A . B. Sc.  CISNEROS  F . , U n i v e r s i d a d Nacional A g r a r i a , Lima, M. Sc.. F. ,' U n i v e r s i t y o f T o r o n t o , 1983  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR T H E DEGREE OF DOCTOR OF PHILOSOPHY  in THE FACULTY OF GRADUATE STUDIES FORESTRY  We a c c e p t t h i s t h e s i s as to  the  conforming  required standard  THE UNIVERSITY OF BRITISH COLUMBIA January, (c)  1991  H e c t o r A . C i s n e r o s , COPYRIGHT  1991  1981  In presenting this thesis in partial fulfilment  of the requirements for an advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department  or  by his or  her  representatives.  It  is understood that  copying or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of  Forestr  The University of British Columbia Vancouver, Canada Date  DE-6 (2/88)  ABSTRACT  In  order  taking  to  gain  place  mechanical using  during  pulps,  several  Marsh.)  wood  (TMP), (CMP)  fibres  due  each  chips  fibres  used  to  species  the  sections  and  detailed  f o r each  as  the  evaluated. produced  was  fibres  pretreatment the  remained  of  was  the  middle  extent  It  optical  (Populus  (Betula  papyrifera  thermomechanical  and  chemimechanical that  the- surface  were  detail  Aspen  hypothesis  were  into  and  there  state  conditions,  analyzed.  obtained  a n a l y s i s of  300  of  four  Trends  within  are the pulps  in  fibre  each  group,  fibre  cross-  pulp.  quality  Retention  (CTMP)  process  hardwoods  produce  processing  development  surface  study.  and  changes  were s t u d i e d i n  birch to  the in  of  techniques.  white  were  differences  species  on  well  and  Following  characteristic  Fibre  pulp  chemithermomechanical  fundamental  nor  refiner  ultrastructural  conversion  microscopical  pulps.  based  into  the  Michx.)  tremuloides  for  insights  of  found  most  lamella exposure  that  TMP  improve the  extent  of  stiff,  producing  of  of  the  of  the  extent  fibrillation. pulp  and  aspect  the  S2  of  S2  However, sheets  of  of  this  layer,  S2  processing  w i t h more e x p o s u r e  d i d not  important  of  layer  as were  wood  chips  layer.  Chemical  layer  exposure  the low  TMP  fibres  density  and  strength. Birch at  fibres  or  exposure  near of  showed the S2  a  marked  S1/S2  layers  tendency  boundary. in  TMP  to  This  fibres,  but  produce  separation  resulted  in  produced  a  high sheath  iii  of  S]_ a n d ML  This  around  from  s h e a t h was sometimes r o l l e d  layer. with  Aspen  TMP  showed  t o aspen  chips  o f S 2 exposure than  levels this  exposing the f i b r e S 2  back, high  proportions  species,  but only  resulted  those  Fibres  wood  achieved  fibres  chemical  of similar  by TMP  processing  freeness  levels of  that  showed  radial  failure  fibres  (G-fibres)  were  frequent  The breakdown p a t t e r n  was  also  studied.  showed p r e f e r e n t i a l breakdown o f G - f i b r e s , layers from  were  freed.  This  was  chemically-treated  generally discussed  remained  chips,  inside  i n the analysis delamination  the  fibres  d i s t o r t e d due t o c h e m i c a l of  c o m p a r i n g VE s i z e whole  small  VE  vessel  former.  due  included of  impregnation. (VE)  refining.  virtually  was  i n CTMP  t o be d e s t r o y e d  to the i n t e r v e s s e l  TMP  studied  reduced  no whole  VE  aspen,  categories  and p r o p o r t i o n  high  from b i r c h tend  Other  G-layer  layer  pretreatment  o f whole  the  sections  s o f t e n i n g due t o c h e m i c a l proportion  i n the G-fibres  by  d i s t r i b u t i o n s and t h e p r o p o r t i o n  survived  showing  2  processing  cross  elements  frequency  that  fragments  of the S  of tension  TMP  which-  fibres.  of fibre  with  breakdown  in  i n TMP b u t  f r o m w h i c h t h e G-  not t h e case  fibres  of  of  i n fibres  a f t e r reaching  i n CTMP n o r CMP p u l p s .  The  chips.  1 0 0 mL CSF.  about  not  pulps  chemically-treated  e x p o s e d S 2 l a y e r . The a p p l i c a t i o n o f  partially  pretreatments  of  fibres  VE,  VE  into  while  wood  was r e s p o n s i b l e and CMP  more e a s i l y pitting  pulps.  than  for a The VE  those  arrangement  from  of the  iv  It  is  TMP  the into  concluded  fibres  due  that  despite  superior  l a r g e S2 e x p o s u r e i n f i b r e s on a t o r n e a r t h e S^/52 boundary,  -  increased  -  longer  -  r e l e a s e and from t e n s i o n  low  of  of  fibrils  of  separation  in fines,  and  exposure of h i g h l y c e l l u l o s i c wood i n t h e c a s e o f a s p e n ,  density,  o t h e r w i s e w o u l d be  account  fibrillation,  conformability  sheet  potential  to:  -  lack  bonding  of  negates  obtained.  TMP the  fibres,  which  promising  G-layers  translates  benefits  that  V  TABLE OF CONTENTS Page ABSTRACT  ....  i  TABLE OF CONTENTS  v  L I S T OF TABLES L I S T OF FIGURES  i  viii ,.  ....x  ACKNOWLEDGEMENTS  xv  INTRODUCTION  1  LITERATURE REVIEW  9  2.1.  I m p o r t a n c e o f Hardwoods  2.2. R e f i n e r M e c h a n i c a l  ....9  Pulping....  2.3. C h a r a c t e r i z a t i o n o f M e c h a n i c a l  11 Pulps  15  2.4. E f f e c t o f Wood a n d F i b r e C h a r a c t e r i s t i c s i n Mechanical Pulping 2.5. M e c h a n i c a l  P u l p i n g o f Hardwoods  ...20 24  2.6. T e n s i o n Wood i n P u l p  29  2.7. The R o l e o f V e s s e l E l e m e n t s i n P u l p  32  METHODOLOGY  36  3.1. Wood P r o c u r e m e n t  36  3.2. P r o d u c t i o n a n d C h a r a c t e r i z a t i o n o f C h i p s  38  3.3. P r e p a r a t i o n o f P u l p s  40  3.3.1. P r o d u c t i o n o f T h e r m o m e c h a n i c a l  Pulps  41  3.3.2. P r o d u c t i o n o f C h e m i t h e r m o m e c h a n i c a l  Pulps..43  3.3.3. P r o d u c t i o n o f C h e m i m e c h a n i c a l P u l p s  44  3.3.4. P r o d u c t i o n o f K r a f t P u l p s  45  3.4. P u l p p r o c e s s i n g  47  3.5. P u l p T e s t i n g .  48  vi  3.6.  Microscopy  49  3.6.1.  Pulp S l i d e s  3.6.2.  Study, of  49  Fibre  Cross Sections  3.6.2.1.  Preparation of  3.6.2.2.  Definition  3.6.2.3.  Repeatability  of  Fibre  50  Cross  Categories  S e c t i o n s . . . 52  Studied  55 64  3.7.  Scanning E l e c t r o n Microscopy  64  3.8.  Transmission E l e c t r o n Microscopy  65  3.9.  Vessel  66  Element  Breakdown  RESULTS  69  4.1.  Analysis  4.1.1.  of  Fibre  Retention  Cross Sections  of  69  Compound M i d d l e L a m e l l a  and S]_ L a y e r  69  4.1.2.  Exposure of  the  4.1.3.  Cell  Wall  Damage  70  4.1.4.  Distorted  Fibres  71  4.1.5.  T e n s i o n Wood F i b r e s  4.2.  Pulp P r o p e r t i e s . . .  4.3.  Breakdown o f V e s s e l  4.4.  Fibre  S  2  layer  -.70  71 71  Elements  L e n g t h and Wood S p e c i f i c  73 Gravity.  DISCUSSION 5.1.  74 93  Analysis  of  Fibre  5.1.1.  Retention  5.1.2.  and S-L L a y e r E x p o s u r e and D e l a m i n a t i o n S  2  of  Cross Sections  93  Compound M i d d l e L a m e l l a 93 of  the  layer  119  5.1.3.  Distorted  Fibres  5.1.4. 5.1.5.  Radial Failure Breakdown o f T e n s i o n Wood F i b r e s  126 130 134  vii 5.2.  Breakdown o f V e s s e l  5.3.  Pulp Properties  5.4.  Significance  of  Elements  144 .156  Findings  160  SUMMARY  170  CONCLUSIONS  174  SUGGESTIONS FOR FURTHER RESEARCH  178  LITERATURE CITED  182  APPENDICES  193  A p p e n d i x A . Hardwood f i b r e s t r u c t u r e t o Jayme and A z z o l a (1965)  according 193  Appendix B. Chart used f o r r e c o r d i n g c a t e g o r i e s of f i b r e s i n cross s e c t i o n  194  A p p e n d i x C . R e s u l t s and d i s c u s s i o n r e p e a t a b i l i t y of the a n a l y s i s cross sections  195  on of  fibre  A p p e n d i x D. V a r i a t i o n o f wood s p e c i f i c g r a v i t y from p i t h t o b a r k a t d i f f e r e n t h e i g h t s o f t h e t r e e stem  202  Appendix E . C a l c u l a t i o n s i n v o l v e d i n e s t i m a t i o n of the o r i g i n of the i n t h e P100 f r a c t i o n  205  Appendix F . A b b r e v i a t i o n s  the material 207  viii  LIST OF TABLES  3.1.  Accept chip thickness  4.1.  Percentage of f i b r e s d e f i n e d f o r ML and  4.2.  4.3. 4.4.  classification  39  under the c a t e g o r i e s retention  Dependancy o f M L r , and S-^r o r S e , on e n e r g y i n p u t . C h i - s q u a r e v a l u e s compared t o a c r i t i c a l v a l u e o f 16.92 ( d=0.05, 9 d . f )  76  Percentage separation  77  2  o f f i b r e s showing mode of the outer l a y e r  of  Percentage of f i b r e s under c a t e g o r i e s f o r the exposure of the S l a y e r  defined 78  2  4.5. 4.6. 4.7. 4.8. 4.9.  Percentage damage  of  fibres  showing  cell  wall 79  Percentage of d i s t o r t e d f i b r e s i n r e f i n e r p u l p s from c h e m i c a l l y - t r e a t e d wood c h i p s  80  P e r c e n t a g e o f t e n s i o n wood f i b r e s i n a s p e n by a n a l y s i s of cross s e c t i o n s of k r a f t pulp f i b r e s  81  P e r c e n t a g e o f t e n s i o n wood f i b r e s r e f i n e r R48 p u l p f r a c t i o n s  82  A s p e n and b i r c h and f i b r e  size  r e f i n e r pulp  in  aspen  characteristics  classification  4.10.  Physical properties  4.11.  Surface  83  of p u l p handsheets  and o p t i c a l p r o p e r t i e s  of  Size  4.13.  Aspen v e s s e l element s i z e frequency a n a l y s i s (N=50) B i r c h v e s s e l element s i z e frequency a n a l y s i s (N=50) C h i - s q u a r e t e s t s on v e s s e l e l e m e n t s i z e d i s t r i b u t i o n ( d = 0.05)  4.16.  vessel  85  4.12.  4.15.  of  84  pulp  handsheets  4.14.  75  elements  S u r v i v a l o f whole refiner pulps..  vessel  from k r a f t p u l p s  elements  86  87 .88 89  in 90  ix 4.17. 5.1.  A s p e n and b i r c h  fibre  l e n g t h measurements  Percentage of f i b r e s with t o t a l S l a y e r exposure f r o m among t h e f i b r e s s h o w i n g d e l a m i n a t i o n  91  2  124  X  LIST OF FIGURES 2.1. 2.2. 2.3.  Mechanical pulping processes t o F r a n z e n (1986) Schematic r e p r e s e n t a t i o n in pure mechanical pulps  according 14  of the p a r t i c l e s ( M o h l i n 1982a)  present  Influence of d i f f e r e n t mechanical pulp p a r t i c l e s on some i m p o r t a n t p u l p p r o p e r t i e s ( M o h l i n 1982b)  3.1.. General o u t l i n e of experimental procedures. V E : v e s s e l e l e m e n t s ; TW: t e n s i o n wood f i b r e s ; SEM: s c a n n i n g e l e c t r o n m i c r o s c o p e ; TEM: t r a n s m i s s i o n e l e c t r o n microscope 3.2.  3.3.  3.4. 3.5. 3.6.  3.7.  3.8. 3.9.  3.10.  4.1.  16 17  37  R e l a t i o n s h i p between s p e c i f i c e n e r g y c o n s u m p t i o n and u n s c r e e n e d f r e e n e s s f o r t h e hardwood r e f i n e r pulps produced  41  C r o s s s e c t i o n o f a s p e n t e n s i o n wood. A H e r z b e r g reagent s t a i n e d p u r p l e the G - l a y e r s , while the l i g n i f i e d material turned yellow  46  Aspen k r a f t p u l p f i b r e s s t a i n e d w i t h T o l u i d i n e B l u e 0, s h o w i n g . G - l a y e r s i n c r o s s s e c t i o n  46  R e l a t i o n s h i p between f r e e n e s s and t h e p e r c e n t o f f i b r e s r e t a i n e d on a 48 mesh s c r e e n  51  Hardwood r e f i n e r p u l p f i b r e s i n c r o s s section s h o w i n g : (a) ML r e t a i n e d , (b) d e l a m i n a t i o n o f t h e S2 layer, (c) r a d i a l f a i l u r e , and (d) s e p a r a t i o n of the outer c e l l w a l l or " o u t / i n " e f f e c t  58  R e t e n t i o n o f S^ l a y e r s around f i b r e s i n cross light  59  (a)  Peeling  of  the  shown as b r i g h t l i n e s s e c t i o n under p o l a r i z e d  ML  A s p e n p u l p f i b r e s showing (a) from t h e l i g n i f i e d c e l l w a l l , the f i b r e  59 G-layer stripped (b) G - l a y e r i n s i d e 59  P u l p p r o d u c e d from c h e m i c a l l y - t r e a t e d c h i p s s h o w i n g (a) N o n - d i s t o r t e d f i b r e , and (b) distorted fibre Wood s p e c i f i c g r a v i t y v a r i a t i o n a t the t r e e s used i n t h i s study  59  DBH f o r 92  xi 5.1.  B a u e r McNett f r a c t i o n a t i o n p a t t e r n s f o r a l l hardwood r e f i n e r p u l p s u n d e r s t u d y . S o l i d l i n e s : h i g h f r e e n e s s p u l p s ; d a s h e d l i n e s : low f r e e n e s s ; dotted l i n e s : intermediate freeness  96  5.2.  Plot  98  5.3.  P l o t o f p e r c e n t a g e o f f i b r e s w i t h t o t a l ML r e t e n t i o n against pulp freeness  .98  SEM p h o t o g r a p h o f a s p e n TMP f i b r e s h o w i n g uneven e x p o s u r e o f c e l l w a l l l a y e r s ( p u l p A-TMP4)  102  C r o s s s e c t i o n o f a s p e n TMP f i b r e s s h o w i n g p a r t i a l r e t e n t i o n o f ML ( p u l p A-TMP3)  102  TEM p h o t o g r a p h o f b i r c h TMP f i b r e i n s e c t i o n o f showing s e p a r a t i o n o f t h e ( p u l p B-TMP1)  104  5.4. 5.5. 5.6.  5.7.  5.8.  5.9.  o f ML r e t e n t i o n  index  against  pulp freeness  cross layer  TEM p h o t o g r a p h , o f aspen TMP f i b r e b u n d l e i n c r o s s s e c t i o n showing s e p a r a t i o n o f t h e S^ l a y e r n e a r t h e S-L/S2 b o u n d a r y ( p u l p A-TMP1)  104  D i s t r i b u t i o n p a t t e r n o f ML and S^ l a y e r r e t e n t i o n i n a s p e n and b i r c h TMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-TMP3 and B-TMP3)  106  TEM p h o t o g r a p h o f aspen TMP f i b r e i n c r o s s s e c t i o n showing d e t a i l o f r e t e n t i o n and e x p o s u r e o f t h e S-L l a y e r ( p u l p A-TMP1)  106  5.10.  D i s t r i b u t i o n p a t t e r n o f ML and S^ r e t e n t i o n f o r a s p e n and b i r c h CTMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-CTMP2 and B-CTMP4)  107  5.11.  D i s t r i b u t i o n p a t t e r n o f ML and S^ r e t e n t i o n f o r a s p e n and b i r c h CMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-CMP3 and B-CMP3) ......107  5.12a.  Unbeaten b i r c h k r a f t p u l p f i b r e s i n c r o s s s e c t i o n showing gaps between t h e S^ and S layers in bright f i e l d illumination 2  5.12b. 5.13.  Same f i e l d  under p a r t i a l p o l a r i z e d l i g h t  TEM p h o t o g r a p h showing d e t a i l o f t h e gap p r o d u c e d between t h e S and S l a y e r s . The S± l a y e r had s e p a r a t e d but remained s u r r o u n d i n g t h e f i b r e ( p u l p B-CMP4) 1  5.14.  109 109  2  Ill  B i r c h CMP p u l p f i b r e s i n c r o s s s e c t i o n . Note t h e f i b r e s i n w h i c h t h e S^ l a y e r has c o m p l e t e l y s e p a r a t e d but s u r r o u n d s t h e f i b r e ( p u l p B-CMP4) . . . . 111  xii 5.15. 5.16.  5.17.  5.18. 5.19.  5.20.  B i r c h CMP f i b r e s s h o w i n g r o l l i n g " ( p u l p B-CMP3)  "skinning" or "sleeve114  B i r c h CMP f i b r e s e c t i o n e d a t t h e p o i n t where s k i n n i n g o c c u r r e d a l o n g t h e Si l a y e r . Photograph taken under p a r t i a l p o l a r i z e d l i g h t ( p u l p B-CMP4)  114  Whole a s p e n TMP p u l p s h o w i n g e x t e n t of f i b r i l l a t i o n under phase c o n t r a s t i l l u m i n a t i o n ( p u l p A-TMP1)  117  Whole a s p e n CTMP p u l p . N o t e l e s s e r f i b r i l l a t i o n compared t o TMP p u l p ( p u l p A-CTMP1)  117  SEM p h o t o g r a p h o f f r e e z e - d r i e d a s p e n TMP (R48 f r a c t i o n ) . The f i b r e s a r e s t r a i g h t , and f i b r i l l a t e d ( p u l p A-TMP4)  fibres stiff 118  A s p e n CTMP R48 f r a c t i o n .  t o be  more f l e x i b l e  than  i n TMP  o f S2 e x p o s u r e i n d e x  F i b r e s appeared ( p u l p A-CTMP4)  5.21.  Plot  5.22.  P l o t o f p e r c e n t a g e o f f i b r e s w i t h t o t a l S2 l a y e r exposure a g a i n s t pulp f r e e n e s s P e r c e n t a g e o f f i b r e s showing d e l a m i n a t i o n i n aspen r e f i n e r p u l p s  5.23. 5.24. 5.25.  5.26.  Percentage of f i b r e s b i r c h r e f i n e r pulps  against pulp  freeness....120  5.28. 5.29.  5.30.  120 122  showing d e l a m i n a t i o n i n 122  TEM p h o t o g r a p h o f b i r c h CMP f i b r e i n c r o s s s e c t i o n s h o w i n g d e l a m i n a t i o n o f t h e S2 l a y e r ( p u l p B-CMP4)  . 125  TEM p h o t o g r a p h o f b i r c h CMP f i b r e i n c r o s s s e c t i o n showing d e t a i l o f d e l a m i n a t i o n o f t h e S l a y e r ( p u l p B-CMP4)  .127  x  5.27.  118  A n o t h e r example o f S-j_ l a y e r ( p u l p B-CMP4)  delamination 127  Percentage o f f i b r e s showing d i s t o r t i o n i n a s p e n CTMP a n d CMP p u l p s  129  P e r c e n t a g e o f f i b r e s showing d i s t o r t i o n i n b i r c h CTMP and CMP p u l p s  129  Percentage o f f i b r e s showing r a d i a l i n aspen r e f i n e r p u l p s  132  failure  xiii  5.31. 5.32.  5.33. 5.34.  5.35.  P e r c e n t a g e o f f i b r e s showing in b i r c h r e f i n e r pulps  radial  failure 132  SEM p h o t o g r a p h o f G - f i b r e s i n a s p e n s e c t i o n showing t h i n G - l a y e r s  wood  cross 136  SEM p h o t o g r a p h o f G - f i b r e s i n a s p e n wood s e c t i o n showing t h i c k G - l a y e r s Percentage of aspen r e f i n e r  G - f i b r e s i n the pulps  cross 136  R48 f r a c t i o n  of 137  SEM p h o t o g r a p h o f G - f i b r e s h o w i n g p a r t i a l u n r a v e l l i n g of the c e l l w a l l to expose the G - l a y e r i n s i d e ( p u l p A-TMP4)  138  5.36.  SEM p h o t o g r a p h i n w h i c h t h e f i b r e w a l l has b e e n r i p p e d , l e a v i n g an e x p o s e d G - l a y e r ( p u l p A - T M P 4 ) . . . 1 3 8  5.37.  P r e s e n c e o f G - l a y e r s t h a t were d e t a c h e d t h e i r p a r e n t f i b r e s i n t h e R48 f r a c t i o n p u l p A-TMP3  5.38.  5.39. 5.40. 5.41.  5.42.  5.43. 5.44. 5.45.  5.46. 5.47.  from of 140  I s o l a t e d G - l a y e r showing f i n e cellulosic f i l a m e n t s d e t a c h i n g from t h e s u r f a c e . F r a c t i o n 48/100 of p u l p A-TMP3.  140  G - l a y e r fragments p u l p A-TMP3  i n the  141  G-layer filaments A-TMP3  i n the  100/150 P200  fraction  fraction  of  of pulp 141  G - l a y e r i n aspen CTMP R48 f r a c t i o n . N o t e t h e t h i n - w a l l e d s k i n l e f t b e h i n d ( p u l p A-CTMP4)  143  G - l a y e r exposed at the c e n t r e c o v e r e d by t h e f i b r e w a l l s a t ( p u l p A-CTMP4)  143  of a f i b r e while the extremes  F r e q u e n c y p o l y g o n s f o r VE s i z e pulps of s i m i l a r freenesses  i n aspen  F r e q u e n c y p o l y g o n s f o r VE s i z e pulps of s i m i l a r freenesses  in birch  refiner 146 refiner •  P e r c e n t a g e o f whole VE t h a t t h e r e f i n i n g o f aspen c h i p s  survived during  P e r c e n t a g e o f whole VE t h a t the r e f i n i n g of b i r c h chips  survived during  146  148  B i r c h VE f r a g m e n t s h o w i n g s p i t t i n g a l o n g t h e l i n e o f i n t e r v e s s e l p i t t i n g ( p u l p B-CTMP3)  148 155  xiv 5.48.  5.49. 5.50.  5.51. 5.52.  5.53 5.54. 5.55. 5.56.  5.57. 5.58. 5.59. 5.60. 5.61.  5.62.  S i n g l e - w a l l e d VE f r a g m e n t s h o w i n g s e p a r a t i o n i n the d i r e c t i o n of i n t e r v e s s e l p i t t i n g ( p u l p B-CTMP3)  155  R e l a t i o n s h i p between t e n s i l e s t r e n g t h and s h e e t d e n s i t y f o r a l l hardwood r e f i n e r p u l p s s t u d i e d  158  R e l a t i o n s h i p between t e n s i l e i n d e x and d e g r e e o f e x p o s u r e o f t h e S2 l a y e r f o r a l l hardwood r e f i n e r pulps studied  161  SEM p h o t o g r a p h o f p u l p A-TMP1  a handsheet  162  SEM p h o t o g r a p h o f p u l p A-CTMP1  a handsheet  SEM p h o t o g r a p h o f p u l p A-TMP4  a handsheet  SEM p h o t o g r a p h o f p u l p A-CTMP4  a handsheet  SEM p h o t o g r a p h o f O f p u l p A-TMP4  a handsheet  surface surface  for for 162  surface  for 163  surface  for 163  in cross  section 164  SEM p h o t o g r a p h o f a h a n d s h e e t i n c r o s s section o f p u l p A - C T M P 4 . Note t h e d i f f e r e n c e i n f i b r e c o l l a p s i b i l i t y and b u l k compared t o TMP  164  P200 f r a c t i o n o f a s p e n TMP p u l p u n d e r c o n t r a s t i l l u m i n a t i o n ( p u l p A-TMP3)  166  phase  P200 f r a c t i o n o f a s p e n CMP p u l p o f s i m i l a r f r e e n e s s t h a n t h a t i n F i g . 5.57 ( p u l p A-CMP3)  166  P200 f r a c t i o n o f b i r c h TMP p u l p u n d e r c o n t r a s t i l l u m i n a t i o n ( p u l p B-TMP3)  167  phase  P200 f r a c t i o n o f b i r c h CMP p u l p o f s i m i l a r f r e e n e s s t h a n t h a t i n F i g . 5 . 5 9 ( p u l p B-CMP3)  167  E s t i m a t e d c o m p o s i t i o n o f t h e P100 f r a c t i o n f o r aspen r e f i n e r p u l p s a c c o r d i n g t o the o r i g i n of the f i n e m a t e r i a l  169  E s t i m a t e d c o m p o s i t i o n o f t h e P100 f r a c t i o n for b i r c h r e f i n e r pulps a c c o r d i n g to the o r i g i n of the f i n e m a t e r i a l  169  XV  ACKNOWLEDGEMENTS I  am  indebted  PAPRICAN, Science,  the  the  R.  J . Kerekes  for  of  particularly advice, Johal  help,  study.  to  to  their  G.  regards  patience  work  advice,  I am a l s o  very  grateful  Drs.  R. W. K e n n e d y , criticism.  providing  Williams,  I  access  want  Head  of  to  at  assisted  are  to  express  Microscopy,  broad t e c h n i c a l  microscopical  and many o t h e r s or  guidance  for  and f r i e n d s h i p  Wood  and  facilities.  to  Hatton,  Paszner,  constructive  PAPRICAN and  L.  J.V.  support  committe.e,  for  Dr.  Dr.  interest,  s h a r i n g w i t h me h i s with  time,  advisor,  this  services  and W. Gee,  kind  due  gratitude for  supervisor,  supervisory  are  technical  PAPRICAN,  of  and A . Kozak  thanks  special  their  course  members  their  research  my a c a d e m i c  U.B.C.,  to  Special  my  and t o  throughout  my  to  knowledge,  techniques.  His  appreciated.  To S.  PAPRICAN who w i t h  their  me  in  completing  this  study. I  am a l s o  for  indebted  access Alex  their  to  are  due  their  Fraser  extend  Research  my g r a t i t u d e help  to  aspen  electron  B . C . Forest stands  and t o  Forest, to  Biological  for  L . Jozsa,  gratitude  to  all  financial  International  others course  support Development  of  for  Ken D a y ,  forest  this  received Agency  via in  allowing  tree  me  manager,  samples.  and h i s  X-ray one  U.B.C.,  services.  Products  FORINTEK,  which  Sciences,  microscopy  supplying  i n m e a s u r i n g wood d e n s i t y  h e l p e d me d u r i n g t h e The  M. Weis,  providing transmission  - Many t h a n k s  My  to  team  I for  densitometry.  way  or  another  investigation. from (CIDA)  the is  Canadian thankfully  xvi  acknowledged. I want t o her as  love, a  t h a n k my f a m i l y , encouragement,  student.  in particular and endurance  my w i f e  Marcela  throughout  my  for  years  1  I.  The  use  of  hardwoods  INTRODUCTION  f o r pulp  and  paper  products  increased considerably i n recent years, p r i m a r i l y the  decreasing  coniferous  raw  developments for  pulps  paperboard metric 1988.  million  furnish  the s u i t a b i l i t y and  of  recent  o f hardwoods  writing  conversion  papers.  i n 1982  t o 39.3  by 1993  paper  million  million  For  and  air-dry  adt/year i n  the capacity w i l l  (Anon. 1983,  are often  into  32.6  has i n c r e a s e d from  the proper Hardwood  offered  pulping  systems,  family  of  Due  because  grow t o  1989a).  manufactured  with  a  high-yield  p u l p as t h e m a j o r p u l p component. T h i s p r o v i d e s a  with  anticipated  also  old-growth  c a p a c i t y f o r t h e manufacture of  their  adt/year  properties.  of  total  per year  papers  furnishes  and  because of  traditional  printing  I t i s estimated that  mechanical  The  of  for  products  tonnes  Printing  of  i n demonstrating  the world's  hardwood  and  materials,  the manufacture  example,  47.4  availability  has  of  mechanical  by are  mechanical that  balance  their  a  pulps,  plethora  becoming pulps use w i l l  optical  of  and  and  strength  alternative  refiner  mechanical  important  members  available  today.  continue  t o grow  of the It  is  i n Canada  elsewhere. manufacture of h i g h - y i e l d pulps mechanical  energy  t o the nature  variety  of particle  to separate  the fibres  of the process, sizes  requires the application  these  and s h a p e s .  from pulps  These  t h e wood. contain  particles  a  can  2  range  from f i b r e  wall.  The p a t t e r n  in  turn,  the  into  bundles of  small  standpoint  of  to  fragments  the  that  p o r t i o n of  the  The q u a l i t y  of  determined in  turn,  by t h e  component the  Almost the  then,  of  any t r e e  strength generally unless  some t y p e  of  of  Hardwood f i b r e s  appear  thought  to  fibrillation mechanical flexibility  the  wood  is  S  pulping. of  2  of  of  layer  are  in  layer  a mild  softened,  the  (Law  chemical fibres  the low  al  and a  This  layer  al  1979)  treatment more  to  is and  during  to  1985) .  the  1979) .  structure  the  not  papers,  al  considered  become  and  tracheids.  et  et  p u l p by  resulting  Marton et  of  is  the  applied during  rigid  of  pulp.  printing  is  (Marton  of  mechanical  pulps  a more  fibres  the  is  fibre only  quality  In g e n e r a l ,  It  long not  is  which,  pulping.  of  so  originate  fractions  the  the  1982,  Fibres  themselves  quality  peeling-off  The  hardwood  upon a p p l i c a t i o n the  the  will  fibre  l a y e r than softwood  prevent of  of  treatment  have  pulp.  from  wood m a t e r i a l  of  inclusion  ( A t a c k and H e i t n e r to  important  the  fibres  hardwoods  chemical  thicker  of  reduced to  1967).  for  is  an i n d i c a t i o n ,  pulping process  relatively  and,  i n the  also  c a n be  satisfactory  fibres  into  conditions  overall  (Sugden  properties  wood  fractions  the  provide  and t h e  process  cell  different  of  but  species  the  examination  pattern,  fractions,  refiner  that  a pulp w i l l  breakdown  smaller  structure  of  quality  smaller the  fragments  fines,  m a j o r component  may be m o d i f i e d by t h e  anticipated,  the  and  ultimate  are the  from t h e s e .  fine  breakdown o f  or t r a c h e i d s a large  very  impede However,  the  chips,  flexible,  and  3  the  primary  similar  to  1977) .  The  layer  in  wall what  of  to  desirable  the  pulp  content it  potential.  This  hardwoods,  in  However, without  the the  exposure  of  quantitative fibres  after  specific  of  the  to  the  the  the  ratio  layers  highest  (Giertz the  fibrillation  layer  is  appears  be  S  to  the  of  cellulose  layer  2  to  to  interfibre  relative  it.  bonding  the  case  of  concentration  is  2  and  of  in  S  treatment  external  true  wall  manner  access  chemical  higher  the  of  retention  compound the  S  manner  middle  higher  for  has  a large  separation are  the  species of  the  not  than  layer  and  and been  number o f from  effects  removal  c a n be b e s t  of  lamella--,  layer  2  their  of  in  the  refining of  studied  the  the  studied  wood  outer  in  a  hardwood  matrix.  mechanical energy  or  resulting  isolated  the of  --with  Of  pulping  consumption  layers  by e x a m i n a t i o n  of  of  the  fibres  section.  One  technique  for  was  developed  to  certain  its  a  (Rydholm 1 9 6 5 ) .  pattern  cross  a  secondary  levels  in  promote  particularly  extent  This  to  The e x p o s u r e  wood  wall.  order  strength.  alternatives,  cell  to  in  TMP f i b r e s  of  which  interest  on t h e  in  off  retention  is  softwoods  peeled  spruce  fines,  possesses  in  in  and  compared  Therefore,  are  that,  fibres  because  carbohydrates  is  fibrillar  Thus,  detrimental  case of  observed  hardwood  necessary.  lignin  is  layer  implication  production  is  and  pulping  assessing study  the  lignin  treatment.  surface  quality  distribution  The  process  of  patterns uses  a  fibre  after  a  ultra-violet  4  light  microscopy  1961,  Kerr  Lindroos also  been  Williams fibre this  done pulp  A  the  of  fibres  1980a,  define The  the  has  technique  could  hardwood  surface useful  pulping.  The  in  in  extent and  development,  which  the  outer  o f damage t o  radial  used  failure;  can  For the  (Iwamida use  of  surface  to  although the  answers of  use  to  by fibre  of  this of  fundamental  hardwood  the  an  questions  other of  not  quantitative  The  refiner  examination  quality  and  of  fibre  exploring.  regarding  i n a d d i t i o n to elucidation  information  separate  from  fibres,  including cell  on  proportion  the  and  makes  fibre  pulps.  of  provide  layers  exposed  limited  for  in cross-section,  mentioned  1983,  layer.  also  terms  softwood  the  method  the  offered  worth  Examination of f i b r e s  in  is  e l u c i d a t i n g aspects  possibilities  already  on  p o t e n t i a l l y provide  breakdown a p p e a r t o be  surface  been  for  i s laborious,  cross-sections,  and  has  examines  . The  mechanical  cross-sections  features  1961)  not  retention  (Kibblewhite  analyzed  al and  e l e c t r o n microscope.  exposed  quality,  features  fibre  al  of the  tool,  of  be  microfibrils  fibre  analysis  fibre  of  et  of  new  section  et  Bruum  techniques  technique  can  1981,  lamella  sample p r e p a r a t i o n  identity  entirely  cross  (Wardrop  al  et  middle  a transmission  Wardrop  analysis  in  which  orientation  Gadda  of  second  technique  sections  staining  fibres  under  al  the  using  1989).  cross  1976,  Analysis  surface  number  fibre  Goring  1983).  mechanical  et  and  of  of  the  on  of  the  fibre;  wall  those fibre manner on  the  delamination  chemically-treated  5  fibres wood and  in  a  refiner  chips, on  as  the  fibres  well  pulp as  presence  commonly  features,  produced  the  extent  present  in  with  techniques,  should  provide  behavior  hardwoods  for  process  these  in  the  of  treatment of  hardwood  use  of  reliable  wood  species.  and  better  These  microscopy  explanations  to  itself;  tension  other  pulping  leading  microscopical  expected  to  of  shear  properties  of  Another hardwoods  is  of  the  'to  for  set  the  the basis  utilization  of  fibres  of  the  conducive serious  to  interest  in of  generally parent  bonding  problems  particularly the  Thus,  strength  and  Previously,  within  troublesome  surface.  fast  of  the  intense  determine  mechanical  vessel  elements  characteristic  the  in  Thus, a  their  paper  1979,  offset  50% o f  good  the  whole  the  sheet  and by  Vessel  than  the  is  not  can  cause  picking  C o l l e y 1973).  This  in is  which' c o n s i s t s  inks  to of  resistance vessel  of  wood o f  shape  printing  high-viscosity  and  (VE) .  of  p r i n t i n g process al  pulping  and much w i d e r  p r i n t i n g requires papers  integrity,  about  study  of  under  the  wood.  (Marton et  application  fibres  ultimately,  shorter  d u r i n g the  p r i n t i n g press  a  fibres.  breakdown  trees,  such  understanding  pulp  which,  elements are conducting c e l l s , angiosperm  p r o v i d e d by  the  mechanical  stresses  these  aspect  detail  contribute  hardwood  mechanical  of  the  species.  behavior  the  chemically-treated  pattern  some  refiner  improvements  The amount is  of  and breakdown  combined  of  from  the  high to  elements  paper surface  picking. present  6  in  the  wood  pulping Since are  despite  the  fibres  more  c a n be  rigid  been  refining  and,  presumably,  in  i n the  nature  different  survival  as  of  components element important  With  these  questions  established  a)  To  in this  investigate  American  in  of  made o f  of  pulps,  VE  pulps  papers. mechanical  pulps  and  their  can p r o v i d e  problems  pulps  are  mechanical  following  basic  when  used.  large Vessel  pulping  p i c k i n g problem  the  .  pulps  these  hardwood m e c h a n i c a l  i n mind,  1979)  al  conditions,  picking  the  et  chemical  upon r e f i n i n g ,  after  mechanical  high y i e l d  hardwood  pulping  in eliminating  with p r i n t i n g papers  VE o f  proportions  mechanical  modification  task  the  printing  potential  hardwood  size  VE  entities  the  of  of  survive (Marton  those  of  mechanical  entire  information  than  manufacture  to  action  increasing  size-distribution  under  estimated  the  a p r o b l e m when  are used The  have  is  an  associated pulps.  objectives  were  thesis:  the  hardwoods  response to  of  refiner  two  important  mechanical  North pulping  conditions, b)  c)  To c h a r a c t e r i z e by  detailed  to  the  state  To s t u d y  the  such  hardwood  examination of  their  of  cell  breakdown o f  refiner  the  fibre  mechanical  pulps  cross-sections  as  walls, vessel  e l e m e n t s upon  refining.  7  In  order  to  achieve  h y p o t h e s e s were t e s t e d  a)  Different  these  objectives,  in this  hardwoods  the  following  to  mechanical  study:  respond  differently  defiberization. b)  The o p t i c a l  analysis  fundamental  species'  differences  on  differences processes of  the  well fibre  on  chip  but  proportion  of  the  range  data  particular,  of  d)  of  the  whole  features  with  vessel  result  Surface  properties  may  on s p e c i e s Other  be  explored  fibre  and These  damage,  affected  as  relevant  observations.  to,  of  different  conditions.  breakdown  collected  the  a of  be d e p e n d e n t  optical  reveal  by  the  liquor  characteristics  of  (G-fibres). could and is  be  the  recorded  surface to  by  statistical  expected  properties  expected  of  to  analysis  uncover  the  properties  relate  fibre  to  some  pulp. observed the  In for  strength  pulp.  The breakdown p a t t e r n of  levels.  can  quantitative  as  application  chemically  analysis,  are  changes  limited  quantitative  fibres  properties  the  not  wood f i b r e s  relationships  the  on  and  and p r o v i d e  categories  fibres  cross-sectional of  processing  are  penetration,  wide  and  should prove to  based  include,  A  species  and r e f i n i n g e n e r g y  developed  c)  cross-sections  structural  cross-sectional  tension  fibre  responses,  fibre  in  fibres  as  of  of  elements  vessel that  elements survive  and the  the  number  refining  of  8  wood  chips  is  largely  conditions.  However, due  dimensions  and  species  structure  e f f e c t may  dependent  on  to species of  the  chip  processing  differences vessel  a l s o be important.  i n the  elements,  a  9  II.  2.1.  Importance  Canada's  pulp  of  market  hardwoods  is  only  in  paper  true  Canada  economy  pulps  only  particularly  REVIEW  Hardwoods  and  softwood  LITERATURE  on  and a  relatively  other  primarily  newsprint.  f o r medium t o  and  is  small  high  zones  on  Utilization  of  scale.  is  density  temperate  based  This  hardwoods,  but  also  not  in  the  tropics. Today,  however,  opportunities  with the abound  increasing  for  the  Hardwoods i n Canada c o m p r i s e timber Aspen  (Anon. (Populus  growing 1979). of  of  the  Birch  with  a  is  northern Alberta,  projects  that  resource losses from is  (Sims  of  foreseen of  there  account  In  fibre  of  the  pulp  of  most  merchantable comprise  major  of  for  a total  over  (Hosie  net  virtually  56%.  species,  Canada  abundant  of  resource.  volume  untapped  hardwood  one  in  b i l l i o n m^  Canada. much c u r r e n t a c t i v i t y  of  the  eastern have  and  large  available  Canada,  resulted  budworm i n f e s t a t i o n , for  the  still  volume  is  make use  1989) .  softwood  spruce  harvest  will  most  is areas  a resource  merchantable  d i s t r i b u t e d throughout In  forested  the , second  3  hardwoods,  this  species  Populus  forests  m i l l i o n m^,  1989).  Canada,  which  of  of  billion m  Michx.)  In B . C . , a s p e n 220  utilization 5.32  tremuloides  throughout  over  (Zak  1989b)  acceptance  a  where in  the  industry  s o u n d o l d - g r o w t h t i m b e r and t h a t  of  new  hardwood  substantial 70s  raw m a t e r i a l  paper  with  and  80s  supply  gap  between  the  second-growth  10  timber  (Bird  this  1985).  supply  gap  satisfactorily. incentive  Hardwoods provided  These  in  the  have  factors  the  they are  production  potential can  be  stimulating  of  to  fill  processed interest  mechanical  and  pulps  from  hardwoods. The  successful  mechanical  pulp  conditions suitable for  for  of  will  the  adt/year pulps  formation  in  annum.  from  somewhat  is  100.9  in  future. the  impart finish  Specifically of  it  was  reported  hardwoods,  mechanical hardwood papers  is  pulp  adding  likely  to  the  an  that  the  in  are  papers  approximate total  1988  the  the  world papers  to  112.5  pulps  to  adt/day  has  pulping  four  of  new of  continue  the to  been (Leask  will  mechanical  the  the  increase  surveys.  the  of  be  pulps  world's  production  manufacture  increase  an  in  already  to  It  hardwoods  systems  pulp  Furthermore,  of  increase  pulps  pulps  good  paper product.  mechanical  manufacture  for  provide  utilization  continue  that  2120  and  final  mechanical  capacity.  mechanical  at  adt/year  hardwood  1989,  from  to  for  last  for  grow  opacity,  will  the  i n Canada  Hardwood p u l p s  p r i n t i n g and w r i t i n g  good  In  installed  processing  (Anon. 1 9 8 9 a ) . .  manifested. 1990)  to  estimated  anticipated that  utilization  into  p r i n t i n g and w r i t i n g  million  p u l p and p a p e r p r o d u c t s  near  of  species  different  softwoods.  and o t h e r  and s u r f a c e  therefore,  for  It  by 1992 can  hardwood  continues  f o r newsprint  Hardwood  of  manufacture  demand  increase  million  is,  the  3% p e r  capacity  requires  than those used  which  rate  conversion  of  printing  (Wood and  Karnis  11  1989,  M o l d e n i u s and J a c k s o n  2.2. In  Refiner Mechanical Pulping the  the in  1930's,  Asplund,  p r o d u c t i o n of the  The  method  170  followed  °C,  rotating  by  and t o  treat  stone  grinding.  refine  wood  chips  1950's  and,  in  mechanical produce pulping with  at  steaming about  Then,  and  process, least  action  as  located  the the  middle  the  first  was  installed  few  seconds  in  prior  i n the used  was  for  1940's,  a  few of  single-  atmospheric  produce  semichemical  zone  eye  and the  the  as  the  refining  disc early  refiner  commercially  refiner  metal  refiner.  by  large  The  coarse  it  passes  the  plate  as of  disks  occurs  b r o k e n by t h e  zone  to  mechanical  Defibration  first of  the  today  further refined  refiner. pressurized  Canada.  being  used  in  f e d between two  are  manner i s  r e q u i r e d to  taken  known  rotating.  chips  step  was  In  are  commercial  to  to  first  pulps.  near the  eastern  use  1985) .  a pressurized  late  system,  them  p e r i p h e r y of  in  residuals  the  chips  for  kPa and a t e m p e r a t u r e  additional  this  of  wood  for  from m e c h a n i c a l p u l p s p r o d u c e d by  wood c h i p s  one  of  800  were  (RMP),  pulp produced i n t h i s  1964,  (Atack  newsprint-grade  breaker bars  towards  hardboard  small  pulping  mechanical  through  resin-bonded  rejects  1962,  method  pulp  defiberization  The  a  mechanical  refiners  pulps  developed  of  of  refiner.  disc  Sweden,  grades  the  a pressure  disc  discharge  of  involved  at  in  coarse  manufacture  minutes  In  1989).  fed  Chips  into  refining  were  system  steamed  a pressurised  for  a  refiner.  After in of  1968,  Sweden and t h e the  type  Asplund  of  300  Defibrator  kPa.  for  is  is  many  stage  pulps  stone g r i n d i n g The disc  Pulps  were  refining  original  produced  a)  at  refined  this  (TMP).  This  pressure  refining.  its  in  between  a  between  The  final  the  prior  systems  casing 200  state  process,  to  so  refining.  now s u r p a s s e d  have  that  and  in  an  the  added  an  chips  are  The o v e r a l l p r o d u c t i o n  that  by t h e  of  some  the  Atack  of  have  the  resulted  production et  al  important  conventional  of  in  variables  the  refiner  the  current  major  mechanical  pulps  r e f i n i n g of  untreated  atmospheric chips,  TMP: t h e r m o m e c h a n i c a l p u l p i n g ; p r e s t e a m i n g  CTMP:  in  (1980):  RMP: r e f i n e r m e c h a n i c a l p u l p i n g ;  and d)  to  in  temperature  a pressure  p r e s s u r i z e d r e f i n i n g of c)  a  by p r e s s u r i z e d  pulping  to  has  discharge b)  under  design  refiner.  system  for  according to  at  installed  process.  modification  processes  chips  minutes,  refiner  chemically treated refiner  wood-  then  discharge  impregnation  of  systems  system.  maintained  The p u l p  atmospheric  1-3  followed  refiner  Today,  steaming  vessel  and 1 3 0 ° C , the  pressurised  U n i t e d S t a t e s b a s e d on t h e  involves  steaming 105  new  s y s t e m were named t h e r m o m e c h a n i c a l p u l p s  system  of  several  untreated  chips,  chemithermomechanical p u l p i n g ;  p r e s s u r i z e d r e f i n i n g of  treated  CMP: c h e m i m e c h a n i c a l p u l p i n g ;  and  presteaming chips,  atmospheric  and  13  discharge  There  are,  refining stage. to  however, can  Mild  the  and  first-stage  1987),  (Mackie  Reasons  of  in  pulp  of  from  chips,  chips  shavings  lower  (Leask  pulp;  quality  control;  chemical  treatments  strength  of  and  the  to  chemical  produce  pulps  high,  consumption  however,  energy  several  s u c h as  the  chips,  chip  ways  application  of  detailed  stone  grinding  wood w a s t e ,  of  a  like  using  which  such  of as  sawdust  substantially  refiner  of  pulps  can  and  pulp  low-level  approach  the  has  been  its  relatively  (White  1969).  energy  usage  in  refining  chemical pretreatment  to  the  reducing  destructuring,  a more  pulps  1969).  refining  of  specific  "alphabet"  effective  (White  disk  the  raw m a t e r i a l  pulps  The main c r i t i c i s m o f specific  to  processes.  to  potential  et  There  mechanical  production  and more  Prusas  1987) .  of  using  quality  1977);  simpler  of  Thus,  (Leask  pulping  opposed  possibility  and  stronger  as  pulp.  post-  shows  expansion  chips,  1980),  related  2.1  the  one  al  so-called  Figure  since  than  1988,  et  rejects  these  1988).  manufactured  the  more  (Jackson  (Barnet  o f most m e c h a n i c a l  include  in  the  existence  rapid  and  to  treatment  the  residual  or  chip treatment  for  bolts,  done  methods  finished  conditions  classification  these  pulp,  patents  and T a y l o r  is,  of  applied to  and r e f i n i n g  processing  variations  chips.  t r e a t m e n t s c a n be  include  several  treated  usually  inter-stage  treatment, are  be,  many  chemical  alternatives al  r e f i n i n g of  uniform  refining  There  are,  wood  consistency,  14 SGW PGW RMP TRMP PRMP TMP  cu  o z  M H  z  ECHANICAL TME C  CO  ,J P-.  P-(  JPUR URE  o z o s:  H Z  LFCMP CTLF  HEAVY FRACnONALl  TCMP CRMP CTMP  LIGHT  CHEMICALLY MODIFIED  w U  lO  OPCO SCMP BCMP IJHYBS  O PM  P<S - J  O b  S5  D Pi  M  W  HEAVY  UHYS  MONO  PULP:  Pulp that, because of i t s combination of o p t i c a l and strength p r o p e r t i e s , can c o n s t i t u t e 100% of a newsprint furnish.  PRINTING PULP:  Pulp t h a t c o n s t i t u t e s the bulk o f a newsprint r e q u i r e s a strong pulp f o r reinforcement.  f u r n i s h but  REINFORCEMENT PULP:  Strong h i g h - y i e l d pulp t h a t can replace chemical pulps i n a newsprint f u r n i s h .  SGW PGW RMP TRMP PRMP TMP LFCMP CTFL TCMP CRMP CTMP OPCO SCMP BCMP UHYBS UHYS  STONE GR0UNDW00D  PRESSURIZED GR0UNDW00D REFINER MECHANICAL PULP THERMO REFINER MECHANICAL PULP PRESSURIZED REFINER MECHANICAL PULP THERMO MECHANICAL PULP LONG FIBRE CHEMIMECHANICAL PULP CHEMICAL TREATMENT LONG FIBRE THERMO CHEMI MECHANICAL PULP CHEMIMECHANICAL PULP (ALSO AS CMP) CHEMI THERMO MECHANICAL PULP ONTARIO PAPER COMPANY PROCESS SULFONATED CMP (CIP PROCESS) BISULPHITE CMP ULTRA HIGH YIELD BISULPHITE ULTRA HIGH YIELD SULPHITE  F i g u r e 2.1. Mechanical p u l p i n g processes a c c o r d i n g t o Franzen (1986).  15  improved  plate  (Allan  al 1968,  The  et  most  by  (Gavelin  most  newsprint  the  offset when  mechanical  amounts  papers  large  energy  refining  pulps  systems 1980).  consumption under  is  pressure  of  pulps  including  coated  used  products  and t o w e l l i n g ,  wallpaper,  (Leask  produced are  variety  mechanical  tissues  boards,  specialty  a  of  w r i t i n g papers,  packaging  contain printing  diapers, paper  in  liquid-  and  other  1982).  C h a r a c t e r i z a t i o n of Mechanical Pulps  model  of  Appendix of  of  manufacture,  substantial  A  to  recovery  control  G a v e l i n 1982b, H a r t l e r  1980,  means  heat  computerized  1982b).  Although  2.3.  and  Atack  important  probably  and  design,  a  the  layered  A for  wood  structure  a better  chip  into  of  a  understanding  fibres  and  of  fibre  during r e f i n e r mechanical p u l p i n g .  When  wood  resulting and  pulp  sizes.  five  subjected is  The  composed  different  categories  to  as  shown  of  mechanical particles  particles in  the  is  of  can  be  Figure 2.2,  given  in  tranformation  particles  place  is  fibre  that  takes  attrition, different  the shapes  classified  according to  into Mohlin  (1982a). Today's  fractionation  completely a  the  particles  Bauer-McNett  bundles fibre  are  techniques  fragments  according to  Classifier,  found  in and  the  are  for  unable  Figure 2.2.  example,  coarse  ribbon-like  fibre  to  shives  fraction  lamellae  separate When u s i n g and  (R50  mainly  fibre mesh),  in  the  16  Shives  Fibres Fibre fragments  Ribbon-like particles Fines  Figure  2.2. S c h e m a t i c r e p r e s e n t a t i o n o f t h e p a r t i c l e s p r e s e n t i n pure m e c h a n i c a l p u l p s ( M o h l i n 1982a). j  middle fine of  fraction  fraction  the different  used the  index  particle  o f handsheets Each  different  particles  summarized  (Mohlin on  type  a r e t h e most  ability  The  important  particles,  fractions  pulp  influence pulp  has been  contributes to  o f a mechanical  in a  of the  properties i s  i n F i g u r e 2.3.  In  g e n e r a l , t h e r e a r e two f u n d a m e n t a l l y  to  mechanical  papermaking  important  of these  of particle  1982a).  some  i n the  amounts and q u a l i t y  of separate  p r o p e r t i e s and performance way  particles  pulps.  o f t h e bonding  as a c r i t e r i o n .  non-additive  and f i n e  types  o f mechanical  an i n d i c a t i o n  tensile  mesh),  (P200 mesh). T h e r e l a t i v e  characteristics As  (50/200  pulp process  characterization  different  approaches  . One i s t o i m i t a t e t h e  i n t h e l a b o r a t o r y and, based  on  test  17  Strength Properties (Tensile Index)  Optical Properties (Light scatt. Coefficient)  Surface Properties (Smoothness)  -  S hives  (Drainage)  -  +  Fibres .  Runnability  -  -  +  +  +  -  ++  +  -  Reinforcing bars  -  Fibre fragments  +  Ribbons  Bonding  +  Fines  Bonding  Figure  2.3. I n f l u e n c e o f d i f f e r e n t m e c h a n i c a l p u l p p a r t i c l e s on some important pulp properties. (Mohlin 1982b).  results for  obtained  a certain  basic  pulp  results and  into  t h e pulp  of  experience,  the pulp  (Mohlin  1982a).  probably  particularly  render  when  alternatives to predict  tested A  t h e most  for pulp  which quality.  new  a few  translate  these  quality  f o r certain  combination  assessing  quality  i s t o measure  r e l e v a n t i n f o r m a t i o n about t h e expected  approaches w i l l  insufficient  evaluate  The o t h e r  p r o p e r t i e s a n d , from  applications  process  handsheets,  application.  suitability  pulp,  from  paper  o f these  two  i n f o r m a t i o n about a raw  materials  experience  might  or be  18  Among t h e specific to  methods surface  determine  extent  of  fibre  of  a pulp or of  development.  other  the  hand,  property degree  dimensional  fractions  as of  to  fibre  a  the  of  under  an  index  of  extent  of  and  after  drying  used  of  as  it  (Jackson  the  the  of  measure  complex  also  the  density  consolidate a  used  measures  a useful  measure fibres  it  the  been  packing  fibres  authors  has  Apparent  represents  the  These  swelling  web  of  1979).  since  provides  wet-formed  b o n d i n g between  of  fractions  surface  This  Williams  its  potential,  flexibility,  volume  c h a r a c t e r i z e mechanical pulps,  bonding  on t h e  load.  interfibre and  the  ability  applied  of  fibre  handsheets, the  used to  swollen  degree  related  to  of fibre  flexibility. The  fines,  long  with  fibre  paper  a large  fraction,  with  good  printability.  These  like  fraction  bonding and  Pulp  fines  the  (Honkasalo to  direct  as  compared t o  role  optical could  in  properties  and  divided  into  be  (slimy,  and a l i g n i n - c o n t a i n i n g non-swelling et  al  1983).  prepare  fines It  with  is  handsheets  permeability  the  producing  w i t h good b o n d i n g a b i l i t y  of  however,  surface  important  particles  consisting  potential  and  an  and l a m e l l a e )  laborious,  material for  fibrils  have  strength,  cellulose-containing swollen  specific  method  flourpoor  difficult from  this  not  work  does  fines. freeness  characterize widespread  is  perhaps  mechanical  use  in  spite  the  most  pulps. of  important  Freeness  criticism  test  measurement of  this  used  to  enjoys  t e s t • as  an  19  indication assess  of pulp q u a l i t y .  dewatering  estimate  the  For a given pulp  the  mill,  strength,  calculate  produced  but  than  effect pulp  on may  species A  full  never  whereas f i b r e Thus,  not  the  mean  complete  each  quality  of  unravelling, provides  an  determine  and  the  the  frequency  fibres,  especially  1983).  Furthermore,  samples  and t o  of in  to  various the  bonded paper  of  much  freeness  more little  for  one  particularly  pulp  will  study.  if  fibre  whole the  structural  can to  surface and  It  also  techniques  modifications  fraction be  pulp  cutting  fibrillation.' counting  probably  Microscopy  the  determine  of  sheets  can  pulp  comparatively  long-fibre  microscopy  Pulps  different  examine  to  apply  a  changed.  visually  of  in  freeness  freeness  has  are  extent  of to  used  uniform.  the  another,  and  1982a).  alone  best  is  microscopic  degree  opportunity  for  1987).  value  for  fraction,  fibres,  However,  indicator  same  a mechanical a  to  the  by  length  conditions of  is  affect  a test  without  individual  at  (Fahey  same  opportunity  to  freeness  test  to  and  (Gavelin  wood s u p p l y  instance,  freeness.  an  The  differently  for  pulp  made.  ideal  use  processes  characterization be  cannot  properties  or processing  provides or  Fines,  done b o t h  the  be  than  is  c a n be a v e r y u s e f u l  where t h e  affected  strength,  less  one  different  is  fractions.  is  of  paper to  accurately.  show v e r y d i f f e r e n t Freeness  the  freeness  situation  by  of  test  strength  restricted  testing  characteristics  strength  both purposes,  Freeness  applied  visually  to on  (Laamanen to  pulp  assess  their  20  papermaking sections  potential.  of  fibres,  With  regard  microscopy  different  p u l p i n g or pretreatment  al- 1961,  Bruun  Goring  1976).  techniques fibre  2.4.  The  on c r o s s  sections  of  influence  of  wood  of  depends  upon  thickness  numerous  of  number o f  (Panshin between  and  of middle  the  both  within  of pulps  walls,  relationships  fibres  from  1980).  In the  of  general  species  in  been  the  terms,  SG  and  of  (1)  relationships properties  pulps,  softwood  has  relationship  and p u l p  variability  considered),  evaluate  and m o r p h o l o g y  cells  the  The  chemical  number  staining  to  in general,  of  and  (SG)  v a r i o u s k i n d s i n terms  and between  are  used  and  lamellae.  gravity  diameter  Zeeuw  greater  chemical  of  Kerr  C h a r a c t e r i s t i c s in Mechanical  characteristics  small  hand,  Specific  cell  mostly  relatively  hardwoods  the  de  wood  derived  the  violet  alternatives  1983,  has  investigations.  (1)  cells  Lindroos  softwood  specific  physical properties  cross  l i g n i n d i s t r i b u t i o n on  (1983)  E f f e c t o f Wood and F i b r e Pulping  subject  for  and  Kibblewhite  damage and r e t e n t i o n  on t h e  the  assess  on  ultra  fibres  et  to  with  has  (Wardrop  used  coupled  studies  illumination after  been  to  and  species.  morphology  (2)  between and  (2)  obtained have  often  been on  On t h e for  the  a  other  hardwoods,  ( p a r t i c u l a r l y when t r o p i c a l  makes  it  between wood p a r a m e t e r s  difficult  to  develop  and p u l p q u a l i t y ,  even  pulps.  gravity  has  probably  been  the  wood  property  most  21  widely  used  to  it  been  considered  has  with  explain  or p r e d i c t that  low b o n d i n g a b i l i t y .  indication  of  not  as  serve  provides  For  a  and  make up t h e  predictor  clue  as  1979) .  pulp  per  strength  that  apply  mechanical  De  tensile  example,  black  produced  (SG=0.472) of  that to  Marton  produce  lower  (De  of  density  much  strength, a l  than  the  Similarly, red  former.  yield  than  should  acceptable  oak  bonding  sugar  the  lower  mechanical  1965).  but  fir.  white  For  birch  mechanical pulp  even  higher  pulp  For  strength,  that  maple  in  fir  d i d balsam  statement for  may n o t  r a n k i n g low  Eucalyptus  (SG=0.548)  Thus, be  did  a l  et  than balsam  greater  refiner  strength  strength  resulting  Montmorency  a higher  pulps  direct  pulp  some woods  p r o d u c e d a much b e t t e r  p u l p than  pulp  and  showed  (SG=0.465).  of  fact,  that  Marton  can y i e l d c h e m i c a l p u l p s  with  et  SG  no  pulp  1965,  (1979)  tensile  stronger values  of  1976).  and  it  form,  (Scurfield is  may  since  for chemical pulps,  strength  spruce  pulps  hardwoods,  Labill.  burst  mechanical  chemical  terms  and  In  it  types  Montmorency  pulps.  general  cell  SG  wood  pulps  numbers,  there  wood  a p p e a r t o be c l e a r  quality  various  species  a  raw m a t e r i a l ,  relative  the  between  strong mechanical pulps in  of  between  1978,  SG, p r o d u c e  pulp  properties,  se  (Bueno  of  the  different  Relationships  to  to  distribution  mechanical  properties  high  Generally,  A l t h o u g h SG may p r o v i d e  good  wood o f  relationship  woods o f  p u l p a b i l i t y for a certain  little  structure  pulp strength.  in  v i m i n a l i s  (SG=0.607) at by  gave  higher Giertz  density  strength,  yield (1977)  species does  not  22  universally Since  a great  during  deal  mechanical  material factor  has  fibre  and  1977,  and  fibres  strength  For  8  twice  added l e n g t h individual  of  fibres  (1981)  without  unnecessarily  pulping  is be  to  good  In  fact,  the  bonding  fine  material  acts  like  however, surface the  (fines  bridges at  the  layers  fines  level and  same t i m e are  content  that  with  the  without  pulp,  the  of  properties pulp,  Mohlin  surface  R14  not  on t h e  the  task  fibrillar  the  length  of  quantitatively On t h e in  other  mechanical capable  rather than largely  particles) fibres.  indicating  on  mechanical  fines  a p u l p depends  also  in  produced  stiff  long  1982b).  fibres.  fines  most  the  depend  layers  become more  removed,  long  100/200  of  size  consolidation,  the  TMP the  strength  ribbon-like  between  than the  softwood  a paramount  of  middle  and  i.e.  i m p r o v i n g b o n d i n g and s h e e t  the  stresses,  the  quality,  limiting  distribute  shortening that  wood  However,  1963,  the  the  fraction.  i n the  that  place  48/100  strength  remove  essential of  the  to  (Forgacs  indicated be  In f a c t ,  a  tensile  of  important  reported  of  fibres  must  it  the  pulp  pulping  hand,  (1979)  correlate  the  an  for  takes  length  al 1 9 6 5 ) .  example,  important  i.e.,  fibre  considered  that  properties  fraction  initial  higher bonding a b i l i t y  times  are  and f r a g m e n t a t i o n  Marton et  Williams  had  fraction,  Giertz  been  f r a c t i o n have  fraction  fibre  cutting  pulping,  fraction.  Jackson  of  not  (Giertz  and f i n e s  long  apply.  flexible that  one  influencing  chop. on  the  because  These as  it  fibres,  the  cannot the  of  fibre vary fibre  23  characteristics  (Gavelin  fibres  are  and f i n e s  The q u a l i t y which the  the  loses  more  fibres  is  higher  proportion  the  layer.  to  2  be  other  significance (1963)  promote  the  or  surface  prime  of  be  Simmonds  and  of  on  appears  to  be  the  morphology,  length,  affects  mechanical  of  to  the  fines.  the  The  S  relative  it  thicknesses  of  a  from seems  pulping.  pulp.  is  of  Forgacs  pulping  the  Because  ability  a to  development turned of  into  the  large  particularly  when  ability. for  mechanical  fibres  to  seems t h a t  specific  fibre  the  have  wall  layer  2  and b o n d i n g  internal  fibre  with  bonding  Thus,  strength  of  originating  He showed how  their  than  Hyttinen  also  mechanically  ribbons,  of  will  i n mechanical  raw m a t e r i a l s  rather  the  pulps.  of  ability  produce good q u a l i t y fibre  these  improve  layer  2  a mechanical  fibres.  cracks  S  the  associated  t h e y had i n c r e a s e d  limitation  In  ribbon-like particles  success  the  of  during refining. will  u n r a v e l l i n g and r i b b o n f o r m a t i o n .  fibrillated,  only  the  might  splits  of  quality. in  fines  consideration  both  way  fraction  layer  quality  u n r a v e l l i n g of  specific  The  this  formation  species  initial  fibre  to  suggested that  particular  of  for  fines  pulp  fractions  1977,  fibrillar-type  important hand,  both  that  d e p e n d on t h e  cellulose-rich  and t h e  Access  clear  mechanical  layers  of  (Giertz  of  is  largely  surface  the  It  for  will  ability  of  exposed,  a very  On t h e  its  proceeds  since  S  fines  bonding  refining  1964)  important  these  fibre  general, as  of  1982a) .  unravel the  gravity  and  internal or  fibre  characteristics  morphology the  pulps  cell  refers  wall  of not  layers,  24  particularly layer,  2.5.  but to  than  their  structure  hardwoods have  softwoods.  hardwoods.  may r e s t r i c t and c h e m i c a l  (vessels)  of  species,,  species  being or  no  except  for  short  rays.  series  pores  with  radial  1983) .  in  crowd  rays  are  Further,  North  chains bend  other  having multiseriate  it  present pulps  its  not  S  2  acceptable  often  application  of  this  of  the  out  section.  considerably ring-porous  Hardwoods  fibres  or  in  the  joined  structures  and  vessels  group  and a r e  vary  a  have  vessels,  few  pores, of  in  species  and  line.  large  Also,  in  width,  with  rays  or  without  uniseriate  with  usually of  contain  more  most  strand  arrangements.  that  their  quality.  many  hardwood  conversion  into  Consequently, and n o t  in p r i n t i n g papers.  a chemical  found  in  low i n s t r e n g t h  inclusion  of  anatomy  variable  surprising in  of  America.  cells  hardwoods  difficulties of  is  is  is  wood c r o s s  can  around  parenchyma w i t h a l a r g e v a r i e t y Thus,  on t h e  diffuse-porous  in  more  types  form t u b e - l i k e  wood  alignment  rays  cell  nonfibrous  to  the  both  radial  The  elements  hardwoods,  for  the  composition.  characteristic  are s h o r t ,  represented  little  species  are  w h i c h a r e s e e n as p o r e s  between  vessel  cells  in a vertical  arrangement  (Parham  number o f  elements  These  end-to-end  pulp  access to  a more h e t e r o g e n e o u s wood  A greater  Vessel  species.  The  layer that  M e c h a n i c a l P u l p i n g o f Hardwoods  Tn g e n e r a l ,  of  the  pretreatment  F o r most is  mechanical  the  generally  species  resulting  satisfactory species,  essential  for  the the  25  successful without 1982).  refining  serious  improvement  in  combinations of  related  for  et  al  brightness,  the  fibre  enhances  the  another  ability  d u r i n g sheet  c a n be  Hardwood  fibres  softwood  tracheids,  the  resulting They  (Marton  layer in  of  difficult associated  it  to  c a n be  for  et  al  that  conform et  al  swelling  of  1981) .  many  a  level  mechanical  pulp,  upgraded to  rigid off  structure of  the  difficult, also  been  fibrillation  it.  the  upon  layer,  The t h i n n e r  w i t h good f i b r i l l a t i o n upon r e f i n i n g .  than layer  if  disproportionally  remove  to  In  is  w o u l d be t o  that  and b o n d  hardwoods  thicker  is  on  has  the  as  effect  It  to  a  brightness  1979).  response  of  in p r i n t i n g papers.  layer  2  use  plasticization  softwood  peeling  S  The  NaOH a d d i t i o n  increases  to  also  effective  a negative  making t h e the  and  has  a more  of  The  improves  (Katz  pulps  density  different  Na2S03  fibres  making  Leask  1982) .  with  While the  have  many  poor  suggested  common  chemical pulps  appear  fibrillation  impossible  is  substituted  p a r t i a l l y replace  and  substantial.  the  hardwood m e c h a n i c a l they  is  accompanying  of  1979,  Heitner  consumption  with  bundles  for higher  brightness  Although i t  alkali  al  and  pulp strength,  walls  et  fibre  c o l o u r e d s p e c i e s may  . and  Na2SC>3  1977) .  pulp  light  hardwood c h i p s .  to  and  (Marton  (Atack  and  fibres  p a r t i c u l a r l y true  chemicals  NaOH  mainly  (Higgins  or  is  strength  of  pretreatment  where  damage  pretreatment  mixture  into  e v e n low d e n s i t y ,  require  cases,  wood  fibre  Although t h i s  hardwoods,  one  of  found  not that  thick,  refining. the layer  more was  26  However, is  when  softened  wall  layer  to  what  For these  was  possible  and,  upon  back. to  give  TMP  fibres  birch  high  and  the  of  be  experiment  mentioned were  had  different  for  spruce  freeness in  the  that  freeness  and  44  fines  bonding  Levina  which (Marton  quality  al  strength  (removed  from  a  account  reported.  et  al  1979) ,  A different They  cotton pulp  of  sulphite 26  be  an  of  the  quality  of  125  and in  fact  vessel  of  of this  a r r i v e d at  aspen 400  This  terms  improvement  about  mL C S F  the  cause  was  which  difference  hand,  the  it the  birch) .  the  fines  that  in  pulps  cells  p u l p when  °SR or  of  hold,  about  conclusion  reported  s p r u c e TMP  still  birch  ray  spruce  to  other  quality may  from  involved  part  On t h e  poor  fibrillated  the  mL CSF f o r  for  produce  rolled  inferior  may  and  there  layer  with  was  °SR or  200  abundant  (1987). of  over  (57  contain  difference. et  may  quality  hardwoods  values  S  properties  fines  spruce  (Giertz  layers  fines  pulps  conclusion  from  ° S R or  difference  elements,  pulp  removed  manner  2  c r a c k e d and  pulps  the  a  and  concluded that  that  in  and  strength  this  primary  TMP f i b r e s  By m i x i n g  hardwood m e c h a n i c a l Although  off  the  bisulphite  Giertz  the  wood  proposed that  wall  layer  the  sheets,  softwoods.  should  yield  peeled  between  and the  fibres,  Giertz  layer.  2  applied  spruce  primary  measuring  pulp  with  the. S  be  fibres,  the  the  are  flexible  to  bonding  same t i m e  resulting  of  weak  to  fines  said  softwood  access  and  more  observed  refining,  At the  in  are  was  1977). a  treatments  resulting  and  similar  chemical  in  CTMP  mL CSF)  by the  fines were  27  added. It  is  clear  the  role  the  quality  that  of  fines of  alternatives  work  the  if  bonding  needs  to  be  fines  the  S  layer  2  is  exposed,  because  i n l i g n i n and r e l a t i v e l y Cellulose,  least  3  (Rydholm  1965).  lignin  in  the  effect  of  terms order  times  in  access  the  S  external  to  layer  removed and a t  is  1977) .  In  remove  the  Eucalyptus wall cold  layer, species,  separated  as  it a  the  of of  be the  softwoods. fibre  It  be  more  of  removed.  In it  treatment  for  and  the  morphological  a  lower  more  and  wood, lignin of  and  the  beneficial  in  fibres.  in  In  layers the  Sj_  (Giertz order  required.  to For  and p r i m a r y complex  under  a l 1961).  common  production in  is  that  (Wardrop et  is  of  fibrillates  alkaline  lignified  in  softwoods,  that  of  (CML),  lignin-rich  seems  reported  lamella  softwood  the  same t i m e  was  percentage  softwoods,  even  case  have  concentrations  it  results  fraction  pulping  will  potential  however,  lignin chips  example,  carbohydrate  lower  layer,  2  fibres  high  compared t o  soda p u l p i n g c o n d i t i o n s  pretreatment  long  to  hardwoods,  Sulphonation  from  have  main  have  should  than  it  For  poor i n c e l l u l o s e  bonding  wall  bonding  to  the  Hardwoods  secondary  the  compound m i d d l e  the  CML r e m o v a l  of  understand  mechanical  their  which i s  at  the  of  compared t o  has  pulps.  from d i f f e r e n t  carbohydrates  hemicelluloses.  to  study.  potential  rich  done  i n hardwood m e c h a n i c a l  requires  Presumably, more  more  of  practice  in  mechanical  shive  content,  flexible  fibers,  a  the pulps  larger thereby  28  indirectly  increasing  sulphonation  of  for  conifers  (Beatson  The  basic  chemical  phenylpropane the of  phenol two  all  et  The  and s y r i n g y l  Evidence  has  been  pulping  of  aspen,  distribution found  that  vessel  are  applies On  of  of  It  is  of  the  the  hand,  observed treatment strength  in  a  for  of  that  methoxyl  lamella rich,  is  all  a  lignin  cell  Almost  hardwoods  copolymer  sulphur  wall.  1986).  al  aspen  This  (Fergus (1985)  lignin  sulfite  units  corner  do  not  followed It  region the  the  was  also  and  statement  reported only  50  the  syringyl  and G o r i n g  was  of  Zeeuw 1980) .  whereas most o f  wood et  of  (Beatson  fibre  birch  of  and  to  addition  unit.  syringyl  of  group  the  ( P a n s h i n and de  units  the  consists  also 1970).  that  the  per  cent  lignin.  generally fibre  than  d u r i n g chemimechanical  Beatson  sulphonation  extent  lower  while  which  distribution  middle  of  a  syringyl  guaiacyl  case  spruce  results  the  in  one  lignin,  lignin,  residues  the  the  lignin  of  in  guaiacyl  were g u a i a c y l  other  degree that  results  found t h a t  located  in  the  of the  wall  units  addition  contain  guaiacyl  of  a guaiacyl u n i t ,  groups  Thus,  generally  structure  guaiacyl-syringyl  sulphonate.  is  However,  al 1 9 8 5 ) .  r i n g produces  methoxyl  a  strength.  hardwood l i g n i n  units.  gymnosperms  have  pulp  accepted  wall lower  lignin  is  of  It  largely  the  low d e g r e e o f  hardwood  strength  softwoods.  which  that  gain  is  responsible  f o r hardwood m e c h a n i c a l  chemimechanical  relative  actually  pulps.  sulphonation  the for  to  that  alkalinity the  pulps usually of  increase  the in  29  2.6.  T e n s i o n Wood i n P u l p  T e n s i o n wood It  (TW)  i s thought  leaning for  tree  i s a f o r m o f r e a c t i o n wood i n a n g i o s p e r m s .  t o be  formed  of  a  branches  (Panshin  typically  on t h e u p p e r i t may  cross-section, eccentricity, Tension type  as  and  occur o r be  angular  orientation  de  1980).  of the c e l l  side  normal  layer  wood  pentosans  in  secondary  t o normal  labeled  gelatinous, in  microfibril has a walls  the  o f normal  has  a  the  inner  layer,  known  and i s l o o s e l y  Thus,  is  contrary  low  in  to the  lignin  but has u s u a l l y  highly parallel  Despite no  I t has a l s o with  and  higher  i t being  pectins.  The  crystalline;  the  to the fibre  axis  microcapillary  structure  These  1966)  G-layer  lamellar  singular  i s composed o f  contains  wood.  stem  which  of G-fibres.  is  of  of a  i n that  the G-layer  developed  evidence  of a unique  wood,  i n t h e stem  (or G - f i b r e ) .  fibres  TW  orientation i s nearly better  fibre  wall.  forms  Populus.  of  and M e i r  i t  of  or branches,  arrangement  (or G - l a y e r ) ,  due t o t h e p r e s e n c e  cellulose  trunks  by t h e p r e s e n c e  softwoods,  compared  Thus,  little  consists  density  G-layer  with  wood  (Norberg  to the inner  reaction  cell  of leaning  in a diffuse  wall  98% c e l l u l o s e  attached  and  Zeeuw  present  from  the gelatinous  over  preferred  known as g e l a t i n o u s  differ  f o r restoring orientation, or  p a r t i c u l a r l y i n species  of f i b r e  portion  mechanism vertical  wood i s c h a r a c t e r i z e d  G-fibres  a  stems t o t h e i r n o r m a l  maintenance  although  as  system  been weak  than the  shown t h a t t h e lateral  bonds  30  (Cote of  a n d Day  this  and  1965,  N o r b e r g and M e i e r  G-layer varies  degree  of  considerably  development  of  tips  at  the  (Okumura e t  depending Parham  on  species  more  (Rao e t  presence  fibres were  specific  also  the and  in  TW compared  Woolly the  surface  (1965)  the  the  to  related  and  rotation for  to  the  More  and  cell  other  specific  other that  wall  of  Fibre  normal  thickness  VE d e c r e a s e d ,  length  wood,  for  remained  although  l u m b e r and  buckling  much  T h i s has b e e n  1968). veneer  problems  lower  and  strength  a t t r i b u t e d to  TW f i b r e s ,  beating  wood  c a u s e d by TW.'  TW have  of  wood non-G-  ( S c a r a m u z z i and V e c c h i  recently,  minimal  wood of  diameter  are a l l  from  content  swelling  only  indicated  appearance,  f r o m n o r m a l wood.  and C l e r m o n t 1 9 6 1 ) . •been  in short  number  increased.  tools  prepared  hemicellulose  adversely  the  variable  Isebrands  indicated  not  TW a r e u n d e s i r a b l e  cutting  pulps  than those  also  de  much  than toward  TW i s  and i n c r e a s e d  in  of  and  G-layer is  length  been  and  g r a v i t y had i n c r e a s e d  Chemical  lower  Boyce  TW, and t h a t  High p r o p o r t i o n s of  dulling  % has  size  frequency  products.  the  %G-fibres  species  (Panshin  conditions.  affects  their  unchanged  fibre  40  70  reduced diameter  present  fibre,  growth  G-fibres  Kaeiser  of  although  than  wood  The amount o f  and  thickness  al 1983) .  of  but  elements.  1977).  r e p o r t e d up t o  and  gravity,  al  along the  species  (1974)  Populus,  The  centre  The  d e p e n d i n g on t h e  tension  Zeeuw 1980) . Even w i t h i n a s i n g l e thicker  1966) .  thus  affecting  characteristics  weak  sheets  conformability  of  the  (Perem  f r o m TW have the  G-fibres  31  and  their  Parham  the  same  For  the  freeness same  (Clermont  level  lower  and  tear  bulk  Isebrands  values  times,  tensile  Bender  of  fibre  index  (NSSC) p u l p i n g o f  compared t o  those  however, strength  1958).  length  f r o m n o r m a l wood.  higher  higher  1977,  f r o m TW r e q u i r e d more  beating  preservation  by  semichemical  produced  density,  those  shown  (Robinson  and  and cross  handsheets.  sulphite  pulps  collapse  as  of pulp  Neutral  lower  of  1974),  sections  that  lack  However,  indicate  a lower  showed  to  reach  f r o m n o r m a l wood. exhibited  and h i g h e r  tear  index  suggests  TW NSSC the  beating  TW p u l p s  This  in  aspen  lower  pulps  better  compared  sheet density  degree of  collapse  to and  of  the  G-fibres. Little wood  information  on  found  mechanical  that  highest  the  chips  separation  on  chip  than  for  a  of  TW c o n t e n t s  was  Populus  freeness  n o r m a l wood.  The  Eucalyptus  of  tension  a l  et  to of  ease  the  with  G-fibres.  of  presented  and V e c c h i  in  density  and  r i b b o n - s h a p e d and Evidence  done  showed tension  f r o m TW RMP  individualized  1968).  lignin  wood  prepared  E.  fibre  Work  o c c u r e d more q u i c k l y f o r Handsheets  the  and  lower  tension  deltoides  (1957)  nitens  The  attributed  a c c o m p a n i e d by abundant (Scaramuzzi  Dadswell  conditions.  increase  pulp  effect  were a s s o c i a t e d  "rubbery" nature  of  the  properties.  RMP  significant  properties.  on  when r e f i n i n g  under  refining  wood  material  highest  and a more  reduction  elements  pulp  reported  that  showed  available  pulp strength  regnans  content  is  of  strength and  long  fibrillar exposure  32  of  G-layers  presented  separated  for this  predominantly  is  the  of  of  low  interesting  fibres  to  note  On  other  hand,  than  those  of  these pulps  of  the  inside  mechanical pattern  fibres  can  mechanical  p u l p i n g and o t h e r  chemimechanical  2.7.  These  present  fibres  manufacture  their  with  only  in  conduction  shorter  difficulty since  Elements  strength.  from  TW  for  the  out  stronger breakdown  details  tension  on  density  G-layers  cause of  are  of  the  wood  on  pure  modifications  of  this  the  effect  of  TW i n  in Pulp  cells  associated  the  a  pulps.  individual  diameter,  of  The i n c r e a s e d  of  reported  of  for  pulps  chemical  structures  cells,  and  processes  fundamental  tube-like  specialized  In t h e  be  are  composed  material,  s t r i p p i n g of  effects  been  The R o l e o f V e s s e l  Vessels  also  presented  on TW p u l p  Assessment  provide  detrimental  has  the  TW.  or  Nothing  effects  might  beneficial  process.  pulping  mechanical  that  from  G-fibres  was  wood  chippy  from n o r m a l wood.  the  pulps  of  pure  indicates of  adjacent  and  that  n a t u r e had d e t r i m e n t a l  stronger  fibres  strength.  chemical the  parent  pulp. Conversely,  bundles  produced pulps It  from  in length  called wood  and a r e  undetermined vessel  of  and have  elements  deciduous  generally thinner  length, (VE) .  trees,  are  much l a r g e r walls  than  in the  (Haygreen and Bowyer 1982) . of  p r i n t i n g paper p r o d u c t s ,  respect  shape  of  is  not  to  the  surface  conducive  to  quality  VE can  cause  of  paper  development  the of  strong  33  bonds between p u l p e l e m e n t s . The  chemical  fibres. rich  i n the  syringyl  units,  that  type  bonding  gave  ability  strength  potential  to  adverse  not  1965) .  their on  presence  the  i n the  surface  surface  of  resistance.  printing  hardwood  of  offset  occur,  causing  This  can  tests,  sheet  cause  printing, the  surface.  vessel  the  fibres  present  in they  pulps.  The  therefore as  but because  elements may  problems  deposition  This  will  picking of  printing  1982).  blankets  picking  (Smook  has  including  been  studied  tropical  the  of  present  reduce  its  during  the  quality press  for  a  number  woods,  but  c a r r i e d out  Colley  1975  and  Ward  elements  the  From e x p e r i m e n t s Colley  lift-off  of  pulps.  and  or  these  reduce  shutdowns  species,  of  pulps  nature,  kraft  Vessel  paper  and can l e a d t o p e r i o d i c  Vessel  that  b o n d i n g between e l e m e n t s ,  pulp strength  printing  the  kraft  VE a r e in  of  al 1 9 8 0 ) .  than  of  is  process.  During  printing  of  those  the  fibres  et  VE o f  found  of  mostly  lower  when  paper s u r f a c e .  a  of  o f VE i n a p a p e r s h e e t  from a r e d u c t i o n  m e a s u r e d by c o n v e n t i o n a l  to  those  influence  wall  Hardell  generally  However,  strength  that  VE i s  1970,  inferior  exceeding the  the  from u n r e f i n e d  properties  not  contribute  of  VE i s  formed  and Agarwal  quantities  arises  of  from  secondary  ( F e r g u s and G o r i n g  Handsheets  (Marton  VE d i f f e r s  lignin  guaiacyl  fibres.  of  While the  in  The  composition  always  by C o l l e y  1976),  it  of to  can  on  the  printing clean  the  of  hardwood  for  chemical  (Colley  was  found  1973, that  34  both  fibre  picking.  and  For  a  ratio,  an  vessel  element  picking  small  bleached  of  reached,  Several  chips  other  means  and Ward  had  kraft  sheet  proper  formation with  is  it  printing  papers.  Marton  as to  layer not  of  of  a  was as  al  noted  the  the Colley the  indicated  as  in  particularly i f the  is  VE f r o m  been r e p o r t e d f o r  for  also  1977,  (Nanko e t  increases  have  one  using VE  that  refining.  large  the  and e v e n more so  of  than  indicates  picking  1987)  (1979)  gave  tendency  (McGovern  fibres  of  found t h a t  common  cover  level  chemimechanically  vessel  effective  problem,  et  (1986)  This  most  size.  refining  picking  pulp.  (Ohsawa  pulps  whole VE i n TMP p u l p s ,  vessel  high  VE, regardless  cooking of  removal  a potential  mechanical  al  partial  p i c k i n g has  of  of  vessel  that  a freeness  further  sizing  techniques  hardwood  which  of  element  o f VE s i z e upon c h i p  the  was n o t  reduction  reported  before  vessel  vessel/fibre  the  vessel  surface  a very t h i n  Although vessel it  Also,  (1988)  suppresing  hydrocyclones  although  surface  of  of  reduction  and numbers  lower  Perhaps  1976) .  using  useful,  of  a  M u k o y o s h i et  bleached  reported.  application  pulps,  size  and  reduce  beyond  m i g h t be a r e d u c t i o n  been  al  p u l p p r e p a r e d by k r a f t  conventionally  pulp  in  time,  effective  refining.  prefiberized  there  et  affected  reduction  caused  could  only  changes  method  all  Nanko  was  a  beating  refining  this  morphology  species,  size,  mL CSF was  only  element  in  tendency.  However,  the  given  increase  consistency  400  vessel  stratified the al  paper 1987).  mechanical the  use  of  production  of  existence  of  i n CTMP p u l p s .  Since  35  these  mechanical  potential  of  possibly pulps,  kraft  more  vessel  however,  pulping  elements  However,  half  of  the  sulphite  CTMP  gram  fragments not  to  to  fraction  The q u e s t i o n pulp  survival  of  of  upon r e f i n i n g of  breakdown  but  considerable of  the  different pattern  of  literature  so  in  Giertz  material  of.a  B a u e r McNett  wood  were  Under  white The  of  alkaline whole VE  birch,  number  however,  difficult  (1977)  which  one-  VE as  not  been  well  as  V E . Of s p e c i f i c  breakdown u n d e r c o n d i t i o n s  of  of  to  ended  very  identify.  indicated  mostly  VE size  that  t h a t VE  up  in  the  Classifier.  way i n w h i c h VE breakdown o c c u r s has  but  minimum p a r t i c l e  expect,  increasingly  about  the  number  for  the  would p r o v i d e b a s i c of  the  Eucalyptus.  fine  whole  cause  present  doubled  would  findings,  refining  anticipated,  estimated that  conditions,  for  mechanical  breakdown in  are  is  d u r i n g TMP p u l p i n g .  One  the  in  effect  reported  counted,  w o u l d be  these  reduced  100/200  and  also  the  bonding  elements  It  will The  elements  almost  the  vessel  occur.  (1979)  al  fines  specified.  Contrary  been  et  decreased  particles  to  defibration  not  have  conformable  on  pulp  was  less  likely  not  the  processes  refining  of  surprisingly  were  and  vessel  into  and  size.  has  whole  do  element  Marton  disintegrated  small  rigid  vessel  far.  was  pulps,  picking is  of  mechanical  per  fibres  that mechanical  reduction  vessel  pulp  solved. particle  chip  of  the  Estimation size  information interest  in  is  wood s o f t e n i n g  of the and  distribution the  pattern  study  o f VE  refining.  36  III.  This  chapter  the  wood  the  pulps,  describes  species  analysis  and of  mechanical  used the  processes  methods  for  pulping,  and  pulping.  Specifically,  the  microscopic  fibres  procedures used i s  METHODOLOGY  presented  the  CTMP  and  defibration  characteristics  pulps  produced  were  species,  over  levels.  a broad  A total  of  selected.  • Pulp  presented  i n Table  3.1. Two  of  range  of of  the  the  during  experimental  3.1. mechanical  and b i r c h  on  the  woods.  Four  these  processes  refining  energy  codes  pulping  studied  and  for  each  consumption  24 p u l p s was a n a l y s e d f o r t h e  identification  in  breakdown  were  aspen  evaluate  involved  of  three  CMP)  each  two  species  properties  are  4.9.  h a r d w o o d s p e c i e s were importance  Michx.)  and w h i t e  each  Williams a  outline  and  Wood P r o c u r e m e n t  their  of  by  element  of  characterize  produce  in Figure  effects  (TMP,  to  to  techniques  vessel  A general  followed  species Lake,  diameter  cut hand.  into Any  splitting  of logs  to  Canada:  birch was  selected  aspen  (Betul'a  felled  at  cm a t  of  visible  breast  about decay  1.20 was  Alex 110  height  Fraser  years  length  them i n 4 q u a r t e r s a l o n g t h e  of  (DBH) .  removed  of  tremuloides  Marsh.).  the  m in  study because  (Populus  papyrifera  B . C . B o t h t r e e s were 22  for this  Forest age  and  at  and h a d  The t r e e s  from  grain  One t r e e  were  debarked the  by  logs  by  and c u t t i n g  out  37  WOOD PROCUREMENT  I DEBARKING X-RAY DENSITOMETRY CHIPPING & SCREENING CHIP MIXING  KRAFT PULPING  FIBRE LENGTH  VE SIZE % TW REFINER PULPING: TMP, CTMP, CMP LATENCY REMOVAL & SCREENING FRACTIONATION  HANDSHEETS  R48  VE SIZE PULP SLIDES LIGHT MICROSCOPY  X-SECTION  PAPER TESTING TEM  LIGHT MICROSCOPY gure  3 . 1 . General O u t l i n e of Experimental Procedures. V E : v e s s e l e l e m e n t s ; T W : t e n s i o n wood f i b r e s ; SEM:scanning e l e c t r o n microscope; TEM:transmission electron microscope.  38  the  affected  areas  considerable therefore DBH=30  this  portion  removed,  cm)  order to  w i t h a band-saw b e f o r e  was  of  a  taken  ensure  chipping.  Since  the  aspen  tree  was  affected,  second  aspen  tree  (80  years  from  an  a sufficient  area  near  and  of  Lytton,  age,  B.C.,  amount o f m a t e r i a l t o  a  carry  in out  investigation.  The  trees  were  characterized  direct  reading X-ray  means  of  Jozsa  and Myronuk  DBH,  and a t  length  values dried  heights  were  sections  (1986) .  cut  and  analysed  that  of  terms  40,  60  processed.  by  wood  to  The  (25  relative  according to  by  described  by  mm)  at  extracted provided  basic  volume)  1 in  as  density  and 80% up t h e  densitometry  per green  of  densitometry  Wood d i s k s  20,  corresponded  weight  in  thick tree  thin  wood  stem cross  density  density the  (oven  calibration  p r o c e d u r e d e v e l o p e d by J o z s a et al (1987) .  3.2.  P r o d u c t i o n and C h a r a c t e r i z a t i o n o f  Chips  Only  s o u n d wood p i e c e s were u s e d i n t h e  p r o d u c t i o n of  Some o f comply  the with  required  by  wood p i e c e s knife and In  a  be  split  maximum o f  the of  had t o  shape  each  9x9  and  species  f u r t h e r along the  in  (23x23  in  order to then  Machinery  a  freezer  remove screened  Equipment  at  of  were  chipped i n  about  oversized in  a  the  cm)  size  d i s k c h i p p e r . The c h i p s were  stored  were  logs  -7  Ltd pilot  scale  The  60 H . P . ,  six-  in plastic  bags  a  further  and f i n e s ,  continuous  Burnaby  chip  to  spout.  °C before  material  grain  cross-section  chipper  collected  chips.  screen  the  use. chips  Mill with  and two  39  decks:  an  upper deck w i t h  deck  with  holes  the  aspen  of  and  0.25  1.2 5 in  birch  in  (32  (6 mm).  chips  mm)  holes  The  and  solids  were  a  lower  contents  61.1%  and  of  59.4%,  respectively. Accept  aspen  mixed.  This  shovelling were t h e n This  chips was  from done,  by  two  trees  forming  cut  a  were  pile  of  thoroughly chips  them i n t o a d o u g h n u t - s h a p e a r r a n g e m e n t . The s h o v e l l e d back i n t o the  o p e r a t i o n was  repeated  The  p r o p o r t i o n of chips  mix  was  mixed  the  approximately together  representative characterized  to sample  by  a Wennberg C h i p  5  provide of  L a k e and  . Birch accept a  uniform chips  Lytton  chip  from  classification  Accept  chip thickness  each (Table  ASPEN  BIRCH  < 2  mm  0.8%  2 .8%  2-6  mm  94 .1  95.5%  > 6  mm  5.2%  1.7%  the also  furnish. species 3.1)  classification  SPECIES THICKNESS  in  c h i p s were  Classifier.  TABLE 3.1.  pile.  times.  accept  thickness  chips  c e n t r e t o f o r m a new  from W i l l i a m s  0.625:1  and  A was  using  40  T h e s e c h i p s were u s e d i n t h e m a n u f a c t u r e o f pulps For  (TMP) the  portion the  and  chemithermomechanical pulps  manufacture of  2-6  these  mm  two  of  chips  thick  pulping t r i a l s Fibre  was  screened  accepts  were  measured  from  species. Matchstick-like  and  by  used  the  separation  acid  (50/50)  occurred,  t h i c k n e s s and  the  from  randomly  of hydrogen  peroxide  CPPA  until  fibre  Standard  B.2P.  s t a i n e d w i t h t o l u i d i n e b l u e , and t r a c i n g t h e s e w i t h a  was  NEA  F i b r e Length  automatically  interval.  P r e p a r a t i o n of  This  study  for  each  produced covered levels  their 4.9  Each  into  corresponding  several pulp  points  pulp  processes  over  a r e g i v e n an  through  runs.  4.11.  um  of  l e n g t h measured class  apart.  a  wide  hardwood  Twelve p u l p s by  CTMP and  f r e e n e s s , as  corresponding  a  twenty-four  e n c o m p a s s e d TMP,  and  produced  on  s p e c i e s . The  four  slides  Pulps  i s based  from  projecting  Counter.  T h e s e i n t e r v a l s were 80  3.3.  selected  entered  by  for  fibres  an  measured  cut  boiled  in  Kraft  length  of  then  described  only  pulping.  c h i p s produced  gently  a  material.  p i e c e s were  and  (CMP),  Fibre  probe  was  as  pulps  for  c h i p s , macerated i n a mixture  acetic  (CTMP).  chemimechanical  were a l s o done u s i n g t h i s  l e n g t h was  selected  thermomechanical  which CMP  range  refiner were  were  c o n d i t i o n s and  each  refining  shown i n F i g u r e 3.2.  identification  prepared  pulps  of  these  pulps  code i n T a b l e  pulp p r o p e r t i e s are presented  energy  The  pulps  4.9, in  and  Tables  41  550  Refining Energy, MJ/kg  Figure  3.2.  Before  any  t o room The  R e l a t i o n s h i p between s p e c i f i c e n e r g y c o n s u m p t i o n and u n s c r e e n e d f r e e n e s s f o r t h e hardwood r e f i n e r pulps produced.  pulping  took place,  the  frozen  chips  were  thawed  calculated  from  charts  temperature.  refining  energy  consumption  was  recording  a watt meter output a t t a c h e d  The  pulps  p r o d u c e d were t e s t e d  hot  disintegration  were  stored  processed  as  i n sealed  immediately.  t o the  refiner.  f o r unscreened  freeness  described plastic  i n Section bags  at  about  5.4. -7  The °C  after pulps i f not  42  3.3.1.  Production of  In  primary  the  pressurized for  the  refiner  pulping,  laboratory  production  following  Thermomechanical P u l p s  of  a  refiner  Sunds  (300  TMP from  (TMP)  Defibrator  mm d i a m e t e r )  aspen  and  TMP 300 was  birch,  used  under  conditions:  -  Atmospheric Presteaming:  15 min  -  Preheating:  125  Temperature: Pressure:  16 p s i  (110  Time: -  Refiner  Housing:  -  Prex  -  Refiner  -  Impregnator  Refining  These  Temperature:  Marton  et  gap  al  1979,  run  pulp  at  to  the  was  Pattern:  (124  kPa) 1:3  Rotor  R3809  Stator  S3804 approx.  similar  production Law e t  the  a number o f  collected  18 p s i  °C  Compression R a t i o :  were  the  between  refining manner,  for  kPa)  128  consistency:  conditions  literature  one  Plate  °C  5 min  Pressure:  The  the  al  to  of  those  1985,  Koran  decreased  increase  the  refining  with d i f f e r e n t  of  selected  the from  refiner each  the 1982,  1988) .  was  outlet  in  hardwood TMP ( J a c k s o n  plates  pulps  reported  20%  stepwise energy. freeness  system.  during In  values  However,  species  for  a  this was only  secondary  refining. The  pulp  refined  obtained in  a  12  from in  the (300  primary mm)  system  diameter  was  further  Sprout-Waldron  43  laboratory  refiner  different was  levels  increased  decreased. 20  % and  Refiner In  an  was of  refining  The r e f i n i n g the  refining  effort  to  large  consistency  in  P r o d u c t i o n of primary used  refiner plate  The  chemical  in  a  liquor  all  the  pulp  this be  used  of  chips  the  solution  of  on t h e  amount  material  by of  because  trial  the  and the  accurate.  for  (CTMP)  TMP p r o d u c t i o n  refiner as  housing  carried  sodium  chips  pre-  before.  was  reagents  of  out  chips  were  hydroxide  was of  and  pre-heating adjusted  2% Na2S03  oven-dried chips.  as  to and  The l i q u o r  species.  pre-treatment  optimize  these  85°C.  material,  compressed of  to  used.  The same c o n d i t i o n s  the  was  15  at  However,  pre-heating,  consumption  for both  selected to  between  o f known c o n c e n t r a t i o n w i t h i n t h e  a  3% NaOH b a s e d  was  pre-steaming,  provide  used  plates  controlled  within  which  ratio,  The c o n c e n t r a t i o n  The  yield,  CTMP r u n s .  vessel.  13.6  kept  p a t t e r n were m a i n t a i n e d ,  expand  sodium s u l f i t e  pH was  was  considered to  pre-treatment  After to  refiner  refining process.  system  f o r the  and  allowed  passes  Chemithermomechanical P u l p s  compression  follows.  of  number  D2A507 p a t t e r n were  consistency  3.3.2.  steaming,  pulp  the  o b t a i n e d were not  was a l s o  the  amount o f p u l p p r o d u c e d i n any s i n g l e  difference  same  obtain  was  temperature  values  The  To  gap between t h e  measure  during  discharge.  energy,  with a designated  collected  the  of  atmospheric  a n d / o r the  plates  the  with  represented  hardwood CTMP q u a l i t y  typical (Higgins  conditions et  al  1978,  44  Sinkey 1985, For  and  Charters  freeness  it  was  possible  by d e c r e a s i n g  be made w i t h i n t h e the  case  of  a certain  of  pulp.  the  obtain  those  energy  also  out  of  TMP. As  severe  1987,  Law  et  al  in for  refining.  F o r the  This  levels  of  allowed  pulp  pulps  lower  could  not  be  increased  excessive  darkening  high freeness  were  levels  required  freeness. of  birch  case  to  100-300 mL CSF f r e e n e s s .  causing  refiner  the  low  (above  and a d d i t i o n a l p a s s e s t h r o u g h  of  The CTMP  in  order  conditions were  TMP, y i e l d  the to used  similar  to  determination  CTMP.  C h e m i m e c h a n i c a l P u l p s (CMP)  pre-treatment  assess  of  input  without  refining  attempted  to  chips  pulps  P r o d u c t i o n of  more  gap.  o n l y pulp's a t  secondary  for  3.3.3. A  range  discharge  birch  the  was  desired  mL CSF) were p r o d u c e d ,  atmospheric  for  1982,  obtain  plate  value,  Thus,  to  the  birch,  beyond  400  Jackson  V a l a d e and Law 1 9 8 8 ) . aspen,  In  1977,  of  differences  the in  production of  were p r e - t r e a t e d u n d e r t h e  -  Atmospheric Pre-steaming:  -  Chemical charge:  wood  chips  fibre  was  carried  development  pulp with t h i s following  upon  process,  the  conditions: 15 min  2% Na2SC>3 b a s e d on o v e n - d r i e d  chips  5% NaOH  chips  based  on o v e n - d r i e d  -  I n i t i a l pH o f  liquor:  13.0  -  L i q u o r t o Wood R a t i o :  5:1  -  Maximum T e m p e r a t u r e :  135 ° C  -  Time t o  50 min  Maximum T e m p e r a t u r e :  -  These  conditions  are  reported  in  time  temperature  and  1978, al  the  Sinkey  1979,  were  from  enough t o  were  of  and  Law  1988, to  if  produce f i b r e s  that  failed  was  placed  yield  al  if  the  evaluation.  cell  in  After  the  cook,  when no f u r t h e r  adjusting  3.3.4.  fibre  the  cook,  Waldron several  energy  pulps,  input  cross  illustrated  change  of  drastic could  weakened  inside these  water i n the  the chips  changes. color  of  in  measured from k r a f t  3.3.  fibre  discharge  were  from  were  refined  refiner.  each  selected  pulps  wood  were  (TW)  The p r e s e n c e  Figure  chips  for  Four  species  by  evaluation.  Pulps  kraft  tension  sections.  treated  produced  levels,  conventional  presence  the  atmospheric  Production of Kraft  Initially, the  after  from  et  observed.  Sprout  batches  Marton  was  a basket  complete  the  1977,  radially.  W a s h i n g was  in  the  al  More  wall  f o r 5 days w i t h f r e q u e n t  Immediately  of  pre-treatment  i n water  w a t e r was  et  1968,  soaked  the  terms  1968).  the  generally  compound m i d d l e l a m e l l a and  and  for  et  Leask  see  in  (Higgins  Allan  CMP f i b r e s ,  chips  those  particularly  removal.of the  of  than  pre-cooking  used here  known w e i g h t  digester  severe  and C h a r t e r s 1977,  cause complete layers  more  literature,  Valade  conditions  A  30 min  Time a t Maximum T e m p e r a t u r e :  of  produced to  fibres  by  tension  The p r o p o r t i o n o f cross  sections,  as  assess  analysis  wood f i b r e s TW f i b r e s shown i n  of is was  Figure  46  (OOAU* H%DBI  Figure  3.3.  C r o s s s e c t i o n o f a s p e n t e n s i o n wood. A H e r z b e r g reagent s t a i n e d purple the G - l a y e r s , while the l i g n i f i e d material turned yellow.  Figure  3.4.  Aspen k r a f t p u l p f i b r e s s t a i n e d w i t h T o l u i d i n e B l u e 0, s h o w i n g G - f i b r e s i n c r o s s s e c t i o n .  47  3.4. Kraft  pulps  separation species  were  also  used  cell  wall  layers  of  under  measuring  study.  the  determining mechanical  the  size  possible  vessel  Kappa Numbers  (approximate  yields  955  were  1110  through  further  3.4. P u l p  prior  Latency  is  largely  caused  56  higher 1987).  vessel  element  an  and  0 . 008  and b i r c h  of  required.  were  15.8  used  elements  breakdown  for  The p u l p s in  chip  in for  during  furnishes  and 1 5 . 5 ,  52%) ,  (0.2  respectively  which  were mm)  to  a  the  stress by  and  the  Latency  boiling  condition mechanical  consistency  of  values  H factors  then  washed  of and  slot  flat  screen  before  the  refiner  important  for  of the  pulping.  is  the  In  than  released  5  done  the  to  remove  mechanical  pulps.  fibre  and  wall  latency  mechanical  i n a p u l p showing  r e m o v a l was  1.2%  is  within  matrix of  cellulose  water  It  characterization  This results  strength  disintegration  evaluated.  lignin-hemicellulose  condition.  with  of  aspen  removed by h o t  produced  softens  were a l s o  two  processing.  latency  the  the  p u l p i n g f o r the  pulps  of  on  Processing  L a t e n c y was pulps  information  pulping.  were p u l p e d t o  before  these  original  samples o f  screened  gain  following  Further,  Representative  and  to  from lower  untreated  minutes  (1500  removal, pulp  its  fibre  stressed  freeness fibre  by d i s i n t e g r a t i n g  is  the  and  (Fahey pulps  revolutions)  i n a B r i t i s h Standard D i s i n t e g r a t o r .  at  a  The  48  pulp  was  then  according B)  in a  Fines  further  t o PPRIC flat  were  diluted  Standard  screen  with  recirculated  rest  of the pulp.  3.5.  Pulp  The  following  with  cold  Testing slots  water  and  Procedure  0.006  in  and e v e n t u a l l y  screened  PS-3  (Method  (0.15 mm)  collected  wide.  with  the  Testing tests  were  performed  on  t h e wet  mechanical  pulps: - Canadian  S t a n d a r d F r e e n e s s : CPPA S t a n d a r d C . l  - Shive Content: -  Bauer-McNett  Pulmac S h i v e A n a l y s e r  Classification  (28, 48, 100, 150 and 200  mesh s c r e e n s ) : TAPPI S t a n d a r d  Pulp  handsheets  were  prepared  according  C.4, w i t h  fines  recirculation.  The f i n e s  important  part  of  pulps  light  scattering  (Mohlin  ability  was  proportion  of  handsheets. according  prepared fine  The t o CPPA  in  material prepared Standard  to  CPPA  material  i n terms  and s u r f a c e  1982b). F i v e handsheets  specimen  were  mechanical  233 cm-82  quality  of  Standard i s a very bonding,  of the  sheet  were d i s c a r d e d b e f o r e a t e s t  order  to  retention handsheets A. 4 b e f o r e  reach  a  constant  f o r a l l subsequent were  conditioned  the following  tests  performed: - B a s i s Weight:  CPPA S t a n d a r d  D.12  - Bulk:  CPPA S t a n d a r d  D.5H  - Density:  CPPA S t a n d a r d  D.5H  49  -  Brightness:  CPPA S t a n d a r d E . 2  -  Light  CPPA S t a n d a r d E . 2  -  Opacity:  CPPA S t a n d a r d E . l  -  Tear  CPPA S t a n d a r d D . 9  -  Burst  -  Tensile  Strength:  CPPA S t a n d a r d D 3 4 . P  -  T e n s i l e Energy A b s o r p t i o n :  CPPA S t a n d a r d D.34P  -  Stretch:  CPPA S t a n d a r d D.34P  Scattering:  Strength:  CPPA S t a n d a r d D . 8  Strength:  CPPA U s e f u l Method 524  -Porosity: -  3.6.  Microscopy  A repeat the  set  pulps  of  so  Bauer-McNett f r a c t i o n a t i o n s  that  collection  of  suspension  passing  the  CPPA S t a n d a r d D . 2 9P  Smoothness:  third  pulp cloth, Light  the  but  not  was  fractions  P200 the  and s i x t h  material  fraction, 200  minute then  after  was  carried  out  test  about  collected had  microscope  transmission  electron  microscopy.  Pulp of  For 15  filtration  in  a  the  L of  between  started.  by  Nikon  The  through  a  EM-10C  Microphot-FX  microscopy  a JEOL JSM-840A s c a n n i n g m i c r o s c o p e . electron  A portion  the  was  of  scanning e l e c t r o n  resolution  3.6.1.  collected.  a sample  mesh s c r e e n  dewatered  Microscope, while  done u s i n g  c o u l d be  a l l o w e d to. d r y .  microscopy  Universal  the  was p e r f o r m e d on  was  A ZEISS used  was High  , for  Slides each  fraction  and e a c h  whole  p u l p was  sampled  50  to  prepare  was  uniformly  material dye  slides.  has  been  so  appropriate  stained  1978).  affixing  unstained  onto  extensively  Green  before  A suspension  and d r i e d  subsequently  1981,  medium left  spread  was  which  (Clark  an  microscopic  that  the  with  used  in  was  cover  slip.  index  for  The  Toluidine  applied A  0,  mounting  slides  were  a solution  observation  a  studies  as  few  pulp  Blue  biological  t h e y c o u l d be u s e d w i t h  refractive  material  a warm s l i d e .  Permount  the  of  under  of  phase  contrast. Because other  of  the  reagents  cellulosic included which wall  were  G-layer  Basic  stained green  Stain the  presence  in  also  from  Green the  the their were their  used  the  Study  chemically  of  for  Fibre  of  cross the  sections.  (fibres analysis  retained of  on  fibre  and  cross  the  aspen,  the  fibre  fibres,  lignified  by  highly  wall.  These  Method R C - 2 2 1 ) , lignified and  the  fibre  Herzberg  a purple  color  on  material.  is  a of  the  48  technique pulp  that  fibres  interest  mechanical  damage.  the  the  Control  Of p a r t i c u l a r  wall  in  Sections  included  and c e l l  fibres  produced  features  produced  examination  quality,  the  analysis  different  fibres  of  treated which  wood  distinguish  yellow  Cross  cross-sectional study  to  rest  G-layer  (CPPA S t a n d a r d B . 3 P )  3.6.2.  tension  (TAPPI R o u t i n e  G - l a y e r and g o l d  Fibre  of  in  pulping  assessment  of  based this  screen)  sections.  The  was R28  on  study  processes;  fibre  The B a u e r - M c N e t t R48  mesh  allows  surface fraction  prepared  for  fraction  was  51  c o n s i d e r e d t o o s m a l l t o p r o v i d e i n f o r m a t i o n over the e n t i r e pulp.  On  the  other  hand,  fractions  s c r e e n were c o n s i d e r e d t o be l a r g e l y the  long  fibre  fraction.  The R48  pulp,  two  samples,  attrition  fraction  f o r a l a r g e p o r t i o n of a screened 3.5. Twenty-four mechanical  passing  pulp,  the  48  mesh  products  of  always  accounted  as shown  i n Figure  pulps were s t u d i e d and, f o r each  consisting  of  150  fibres  each,  were  analyzed.  F i g u r e 3.5. R e l a t i o n s h i p between f r e e n e s s and t h e percent o f f i b r e s r e t a i n e d on a 48 mesh screen.  52  3.6.2.1. The  following  fibre  a)  P r e p a r a t i o n of  cross  steps  selected;  the  tests  were  R48 f r a c t i o n s  Solvent  the  butanol,  preparation  performed  on  were c o l l e c t e d  fibres  exchange  were  following  was  gradually  the  solvent  done  for  embedded  method by G o l d f a r b  about in  and  this,  in  turn,  about  -45  °C i n  a  Neslab  r o t a t i n g the  flask,  fibres  were  in  introduced Cryobath the  d r i e d under  an  Edwards  into  CB-60  material  vacuum a t  Freeze  hr  tert-  a l (1977) .  et  flask  °C  24  one  100%  i n b u t a n o l were p l a c e d i n a  -55  the  exchange  suspended  The  of  and n o t  The f i b r e s  slowly d)  the  were p l a c e d i n a c o n t i n u o u s  apparatus.  c)  in  dry.  The s a m p l e s  until  sections  completed  Bauer-McNett  allowed to b)  were  cross  sections:  Standard pulps  fibre  special  methanol  at  apparatus.  By  froze. a temperature  Dryer  Super  of  Modulyo  apparatus. e)  f)  The d r y ,  fluffy  fibre  a desiccator  in small  A p o r t i o n of  these  with  a  few  drops  of  Spurr  and c l e a r  color.  was  according  (Anon. into  1988b).  the  was  kept  labelled  vials  to  fibres  prepared.  used  material  Spurr  resin  was  placed  chosen  for  to  a  the  J.B.EM good  fibres  a glass  medium its  slide  previously  low  viscosity  preparation formula  Services  penetration were  in  avoid hydration.  over  embedding  The s t a n d a r d S p u r r  To e n s u r e  fibres,  was  u n d e r vacuum  Product of  subjected  the to  Note resin  several  53  cycles g)  of  The i m p r e g n a t e d fine  fibres  tweezers into  remove a i r i n t h e  were t h e n  f i b r e bundles  at  few  fibres  bundle  enough m a t e r i a l  was  produced.  Plastic the  up  gloves  and  were  rolled used  at  gently  to  aligned  least  a  picked  for  of  was  of  done  fibres.  carefully  Alignment  then  h)  g e n t l e vacuum t o  a  200  fibres.  time  until  Each bundle  between  prevent  with  skin  a  was  fingers.  contact  with  resin.  With the  fine tip  #301A  tweezers,  of  was  placed  embedding  capsules  were  evacuated  to  several  fibres  Hemi-hyperboloid t i p  a drop of  it  Spurr r e s i n  remove  When t h e  capsule,  of  capsule.  BEEM  tip.  roll  a silicone  contained  the  the  was  cycles  of  the  air  fibre  roll  filled  The  and h a d t o  bubble was  with  gentle  used.  usually  inside  resin  vacuum  be  the  and  until  no  into JBS  capsules  previously trapped tip  in  of  the  subjected  to  bubbles  were  observed. i)  Finally, in  capsules  a constant  11)  Six  16  analysis stripping fibre  at  70  labelled,  oven  °C.  The  closed  and  placed  (TAAB E m b e d d i n g Oven MKresin  was  cured  for  at  pulp  sample.  h.  capsules  However,  were  temperature  maintained  least j)  the  were  only of  two fibre  the  bundle  under a s t e r e o  of  prepared  for  them  selected  cross  silicone alignment  were  each  sections. capsules,  were  microscope.  The  for  the  actual  blocks,  after  containing  selected  after  the  best  observation  54  k)  The  cured  blocks the  middle  of  Dremel  M o t o - t o o l 395  microscope. provided glass 1)  were  A  fibre  t r i m m e d down  roll  length.  the  final  cut  block  just  This  with v a r i a b l e  A subsequent  to  speed  with  surface  was  a  done  the  with  under a  sharp  before  above  a  stereo  razor  blade  sectioning  with  knives.  LKB 2178  knives  Knifemaker  following  the  II  was  used  instructions  to  in  prepare  the  glass  corresponding  manual. m) U s i n g f r e s h l y in  a  prepared glass  microtome  Either  a  Sorval  Reichert-Jung very n)  slow  containing  known  to  contrast single 1981) .  1.5  blocks  um i n  Supercut  were  used  were  cut  thickness.  Ultramicrotome  the  p i c k e d up and p l a c e d  staining 1988a)  solution.  was  other  options.  B l u e 0 and B a s i c selectively  fibre  or  MT-2  for  However, in  It  cutting  stain  the  color  since  pH i s  other  G - l a y e r of it  has  kept  hand, tension  affinity  JBS  #197  a at  Basic  and  to  Green  a  after mix  give  of  Fushin  cellulose  wall  1978,  10 was  with  is  good in  a  Clark  differed  around  wood f i b r e s for  tissue  T o l u i d i n e Blue 0  contrast at  glass  staining  and s e c o n d a r y 1964,  al  a watch  contained  lignin  optimum s t a i n i n g  which  On t h e  et  in  for  Fuchsin.  stain  (O'Brien  A  selected  between m i d d l e l a m e l l a  softwoods 1988) .  were  several  Toluidine  of  Porter-Blum  2050  (Anon.  trying  sections  the  speeds.  The s e c t i o n s  stain  into  knives,  from  (Williams found  to  a pinkish  (Clark  1981).  55  The  commercial  before  it  staining  was  used  approximate time solution o)  The  placed  while  on  fine  q)  rest  of  were  dry,  Polybed  of  best  bleach  1988).  light  they  prevent  were  air  small  washing adhesion,  corner of  carefully  picked  slide  medium  on  (Anon. as  stain  out  placing  submerged  in  of  a mounting  the  the  top  1987)  cause r e t i c u l a t i o n w i t h the  an  Spurr  stained  cover  slip,  Polybed to  avoid  bubbles. in  section  of  a  for  dye w i t h t h e  Before  were t o t a l l y  sections,  analysis the  not  prepared  ensure  an  staining  with  water  to  embedding  does n o t  (Williams  sections  several  the  up  p r e p a r e d . P o l y b e d was u s e d h e r e  The s l i d e s to  picked  Teflon  of  and does  formation  then  of  medium b e c a u s e i t  the  for  the  t w e e z e r s and p l a c e d on a g l a s s  drop  fibres  were  block  sections  resin  times  10  sections  The pH o f  a  Once t h e  previously  minutes.  distilled  paper.  a  diluted  the  in  removing the  up w i t h  stain  briefly  absorbent  of  five  sections  immersed  and  to  was  neutral.  stained  loop,  p)  was  of  solution  fibre  but  D e f i n i t i o n of  With the  objectives  only  cross  combination of  way  flatness.  microscope.  3.6.2.2.  this  were Every  one  sections The  stain  was after  sections contrast  Categories  clamped  overnight  slide  contained  selected  inspection  chosen and  for  the under  provided  the  flatness.  Studied  i n m i n d and a f t e r  careful  observation  of  56  several fibre  sections,  cross  it  was  s e c t i o n s to  decided the  R e t e n t i o n o f Compound M i d d l e  b)  Retention of  c)  Exposure of  d)  Mode o f  e)  Radial  f)  D e l a m i n a t i o n of the  g)  Breakdown o f t e n s i o n  h)  P r o p o r t i o n of d i s t o r t e d  one  S  length, except  outer  S  layer,  fibres.  fibres  were  i.e.,  no  categories,  cut  were all  analysed.  the  and  fibres  at  considered  fibres  Also, the  that  the  the  lumen be  visible.  above-mentioned  since  exact  Figures  are  3.6  sectional  listed to  show  category  by c o u n t i n g the  feature  of as  fibre  it  was of  is  not their  diameter,  chart  identify  examples  recorded.  interest.  a  used  for  presented fibre  in  surface  i n Appendix F .  3.10  features  used to  every  centre  A sample  categories  for  within  no r e s t r i c t i o n was p l a c e d on minimum f i b r e  categories  a)  Lamella,  wood f i b r e s ,  A p p e n d i x B . The a b b r e v i a t i o n s  defined  categories:  layer,  2  separated  shive  to  recording  of  failure,  or  possible  analysis  layer,  2  separation of  these  bundle  the  S-t l a y e r ,  completely of  confine  following  a)  Only  to  Data  number o f  The  of  was fibres  categories  the  fibre  obtained that  were  cross  for  each:  presented  established  the and  follows:  Retention  o f Compound M i d d l e L a m e l l a  Fibres  cross  in  section  c o u l d be  (MLr):  classified  as  having  or  57  lacking the  a  middle  sharp  contrast  secondary  wall  and  cellulose Because middle  wall.  the  (ML)  from  primary here  as t h e the  evident  was  not  p e r i m e t e r of the Total  Retention entire  and  lignin  affinity  for  such  to  the  the  term  include  as  true middle  the  primary  compound m i d d l e  lamella,  wall.  Within  this  considered:  ( M L ( r = 0 ) } : when no  around  the  fibre  {ML(r<50)}: when t h e r e  ML b u t fibre  but fibre  it  was  cross  50% R e t e n t i o n total,  by  light cross  retention.  L e s s t h a n 50% R e t e n t i o n  than  wall,  were  was  More  great  primary  subdivisions  the  has  in  distinguishing  absorption  p e r i m e t e r of the  -  the  of  of middle l a m e l l a  of  lamella  polysaccharides  No r e t e n t i o n  retention  middle  defined  al 1964, G r e e n 1978) .  includes  zero  is  difference  0  stain  considered  several  section,i.e.,  -  Blue  difficulty  is  actually  category,  -  et  This  compound their  Thus ML was t r e a t e d  which  -  not  (O'Brien  lamella  lamella  to  Toluidine  does  of  around i t .  between  due  concentration. lignin  lamella  less  ( M L ( r > 5 0 ) } : when t h e  was  greater  cross  perimeter  the  i.e.,  100% r e t e n t i o n .  the  than  50%  retention of  the  section. when  the  50% o f  some  section.  (ML(r=100)}:  along  than  was  of  the  ML was  fibre  cross  present section,  58  Figure  3.6.  Hardwood r e f i n e r p u l p f i b r e s i n c r o s s s e c t i o n s h o w i n g : (a) ML r e t a i n e d , (b) d e l a m i n a t i o n o f t h e S2 l a y e r , (c) r a d i a l f a i l u r e , and (d) s e p a r a t i o n of the outer c e l l w a l l or " o u t / i n " effect.  59  '  Figure  Figure Figure  Figure  ' O r .  0  3 . 7 . Retention of l a y e r s shown as b r i g h t l i n e s around f i b r e s i n c r o s s s e c t i o n under p o l a r i z e d light. 3 . 8 . (a) P e e l i n g o f t h e M L . 3 . 9 . A s p e n p u l p f i b r e s showing (a) G - l a y e r s t r i p p e d from t h e l i g n i f i e d c e l l w a l l , (b) G - l a y e r i n s i d e the f i b r e . 3 . 1 0 . P u l p p r o d u c e d from c h e m i c a l l y - t r e a t e d chips showing (a) N o n - d i s t o r t e d f i b r e , and (b) distorted.  60 An  Index  f o r ML  provided  an  fibre  a  of  retention  indication  of  particular  .(MLrl) ML  pulp,  was  conceived.  retention according  f o r an to the  It  average following  formula:  MLrl  = M L ( r < 5 0 ) x 0 . 2 5 + ML ( r > 5 0 ) xO . 7 5 +• M L ( r = 1 0 0 )  Retention Under  of the  transmitted  filters, respect  the  S-L  layer  axis  light  -  No  the stage  around  the  case  of  ML  were c o n s i d e r e d  retention o f ML  of  layer  retention  of The  to the  m i c r o f i b r i l s are path  when  a  particular  of- c e l l u l o s e ,  and i t appears,  the fibre  i n the light  c o u l d be  means  respect  Due t o t h i s  (Cote  microscope,  f o r a particular portion  perimeter  evidence  line  with  of t h e former. with  layer  S-j_  the  to the light  section.  polarized  excellent  the cellulose  by t h e  as a b r i g h t  subdivisions  angle  of  and t o t h e c r y s t a l l i n e nature  polarization  i n  an  o r absence  Thus,  using  angle  provides  fibril  i n cross  i s polarized  section  fibril  perpendicular  i s viewed  rotating  As  large  almost  present, By  a  of the fibre.  arrangement  i n  layer  2  microscopy  the presence  has  arranged fibre  light  change  to the S  establishing  (S^r):  layer  when  1981) .  the  of the fibre  best cross  obtained. retention, i n this  following  category:  {S^(r=0)}: a n d no  the  light  when  there  i s no  polarization  due  >  .  .  .  61  to -  the  layer,  Less  than  retention the -  not  than  total  fibre  S-L  with  50% o f  section.  (S (r=100)}:  when  1  the entire  perimeter  (S^rl)  Index  the equation  the  retention i s of the  S-L layer  of the fibre  also  still  when  is  cross  S ^  layer  was  or  2  layer  through  3.10. However, o b s e r v a t i o n  when  t h e ML  not  essential  f o r assessing  Si  layer  top of  S  2  have  of the f i b r e  e x p o s u r e c a n be s e e n  is  on  the inner S ^ had  been  been  left  wall.  2  of S  layer  ±  (S e):  Example  2  S (r=100)  present,  may  attached to the rest  of the S  in  i n d i c a t i o n of S]_  (r>50)xO.75•+  However, may  calculated  fibre:  X  t h e ML  present.  was  to provide  f o r an a v e r a g e  that  the  Exposure  than  is  i . e . , 100% r e t e n t i o n .  i s clear  behind  there  50% o f t h e p e r i m e t e r  1  was  i s less  { ( r > 5 0 ) } : when  = S (r<50)x0.25 + S  1  removed,  cross  when  section.  retention  S rl  retention.  but t h i s  b u t i s more t h a n  retention  accordance  layer  layer  of the fibre  along  section,  It  {S]_ (x<50) } :  Retention  present  layer  Retention  50% R e t e n t i o n  cross  - T o t a l  S±  of the  perimeter  More  The  50%  i . e . , zero  through crossed  the possible  (Figure  i n Figures  presence  3.7). This  3.6  Nicols of the  category  is  62  actually the  defined  S-L l a y e r .  S-L,  there  For instance,  is  in  of  than  50%  The S  2  the  S  less  of  S  the  50%  retention  of  no r e t e n t i o n  of  layer  and  vice  S^ l a y e r means  less  2  This  the  category  previous  exposure  (S (e>50)}  and  2  exposure  2  is  layer.  2  than  exposure  i.e.,  the  a s i m i l a r manner t h a n  2  {S (e=100)}.  Index  two: 2  was  2  No  (S (e<50)},  total  (S el)  was  exposure calculated  follows:  S el  = S  2  Mode o f  2  attached  fibre  wall,  different  to  it,  separation  2  (e>50)xO.75 + S ( e = 1 0 0 ) 2  Outer Layer: lamella,  was  with  removed  was  or without  from  observed  to  when  surface, at  there  but  one e n d ,  as  was  part  ML s t i l l  of  shown  it  was  from  rest  occur  S±  of  in  with the  portion, portions  or  without  perimeter however, of  the  the  in Figure  of  remain outer  S^ the  layer  the three  layer  are  to  the  hanging  3.8. least  a portion  attached,  fibre.  attached  attached actually  . - ML s e p a r a t e d b u t n o t b r o k e n : when a t ML,  the  the  modes:  ML P e e l i n g :  loose  the  compound m i d d l e  layer  fibre  (e<50)xO.25 + S  Separation of  When t h e  -  of  one,  when t h e r e  exposure  (S (e=0)},  exposure  as  total  5 0 % exposure  subdivided  more  previous  More t h a n 5 0 % r e t e n t i o n  versa. than  by t h e  The to  the  ends  separates of  fibre,  separated  of  but  this i.e., not  63  removed.  This  "out/in  effect".  situations  e)  Radial This  when  the  Examples  of  D e l a m i n a t i o n of the there  was  the  exposed,  S  as  Because  of  in  wall,  an o p e n e d  -  -  as  the  some  typical  was  ruptured  section  this  category  are  presented  in  layer:  2  of  separation  whether  or  not  or  delamination  this  layer  was  3.6.  T e n s i o n Wood F i b r e s : the . r e l a t i v e l y it  of  was  cross even  i.e., fibre.  high  decided  proportion  of  to  these  include  sections. if  they  when t h e  are  G-layers no  longer  G - l a y e r has b e e n  Two d i s t i n c t  TW f i b r e s in  can inside  the be the  s t r i p p e d from  subdivisions  were  made  for  category:  G-layer the  S  layer,  2  differentiated  this  here  category.  cross  evidence  aspen,  analysis  fibre  illustrates  fibre  shown i n F i g u r e  Breakdown o f  found  3.6  designated  3.6.  within  g)  Figure  been  found under t h i s  occurred  Figure  When  has  Failure:  radially.  f)  category  inside  G-layer  G-layer from the  a  inside,  exposed:  fibre: as when  when  i n the the  surrounding f i b r e  TW f i b r e s  appeared  with  wood f i b r e s . G-layer  wall.  has  been  stripped  64  Both s u b d i v i s i o n s  are  i l l u s t r a t e d w i t h examples  in Figure  3.9.  h)  P r o p o r t i o n of D i s t o r t e d F i b r e s : While  examining  fibres,  it  swollen, the  was  fibres.  of  Such f i b r e s distorted  many  were  and e v e n c o l o u r e d d i f f e r e n t l y  from  called  these  and CMP  fibres  were  of  CTMP  when  compared  distorted  or  w i t h TMP  "d"  fibres.  in  comparison  with  non-distorted  fibres  of are  3.10.  Repeatability  pulp.  performed  samples A  for  procedures  3.7.  that  of  e x i s t e d w i t h i n CTMP o r CMP p u l p s . ' E x a m p l e s  different  each  sections  particularly  these  in Figure  3.6.2.3. Two  them,  Thus,  cross  observed  more r o u n d e d ,  rest  shown  fibre  of  Z-test each  150  for  fibres  each  difference  category  for  o u t l i n e d by W a l p o l e  were p r o c e s s e d  of  every  for  proportions  pulp,  was  according  to  microscope.  It  of  of  (1982).  S c a n n i n g E l e c t r o n M i c r o s c o p y (SEM)  The  SEM was  was  very  freeze  useful  for  dried fibres  composition Since  u s e d as  in  magnifications,  an  in  cross  of  qualitative or  SEM  light  analysis  of  surfaces  paper  surface  sections. can  attempt  section  the  examination  fractions,  and p a p e r c r o s s  samples  fibres  a complement  for  was  be made  viewed to  at  very  prepare  SEM o b s e r v a t i o n .  The  samples  high of  technique  65  involved  attaching  dissolving  away  conceived SEM  by  a  the  Spurr  Maxwell  samples.  A of  sheets  embedded  with  a sharp  cross  Before be  a  sample  coated  System  with  for  a  glass  normal  principle  and  of  cured  in  and f i n a l l y  solvents c o u l d be  (Williams observed  slide  following  before  sections  razor blade  with a mixture of  to resin,  (1978),  similar  preparation were  section  was  used  microscope,  where  the  cyanoacrylate  glue,  cut  the  glue  in  knife. for  40  1974) .  on  the  under the  dissolved  SEM, i t  a HUMMER  not  only  cross  IV  had  to  Sputtering  to  confirm  sections  in  the  of  cell  wall  the light  gain a d d i t i o n a l information i n  separation  terms  layers  upon  pulping. were c h o s e n  high freeness  CMP (ACMP-4 Spurr  A using  minutes The  and  embedded an  The s e c t i o n s  providing  study  fibre  also to  f o u r samples  900  this  made  T h e s e were t h e  of  was  1989).  g o l d - p a l l a d i u m under  in  but  details  of  of  5 min.  observations  Blocks  preparation  handsheets,  was  freeness  technique  the  TEM  Only  then  in  T r a n s m i s s i o n E l e c t r o n M i c r o s c o p y (TEM)  mechanical  a  applied  3.8.  of  and  were  before  high  under the TEM.  TMP (ATMP-1 and BTMP-1)  BCMP-4) fibres  pulps  were c u t  ultramicrotome stained  washing  permanganate  the  for observation  in  reacts  electron  a  both  species.  into  thin  sections  density  with  solution  distilled with  low  from  equipped in  and  the  a  of  water  diamond 1% KMnO^ (Parham  lignin,  contrast  means  thus for  66  differentiating  the  layers  differences  in  fibril  difference  in  shade  texture  is  evident  Panshin  and  taken  3.9.  for  Vessel  whole  pulp  with  a  size  with  between  (1980) .  pulps.  After  to  125  to  which  certainty. a  switch  the  larger  papers  terms  of  printing. these  Insufficient  but  staining.  a  a  different  as  shown  by  were  not  by  only  also  contrast  density  to  not  prepared from  a 4X o b j e c t i v e .  size  each of  could  be  of  and  tendency  were made system  each  for a successful  sufficient  large  picking  This  of  this  printing  dimensions  one  in  for  attempts  values  is  identified  relatively  concern  50  size  This  distribution  this,  only  done  minimum p a r t i c l e  linear  retained  was  the  achieved  slides  a minimum s i z e  Image A n a l y s i s .  area was  at  strength  the  p u l p i n g was  the  a potential  To i n v e s t i g a t e  some f r a g m e n t s  staining  the  surface  samples  provided  fragments  the  the  layers,  2  VE f r a g m e n t s  percentage  represent  in  of  photomicrographs  VE f r a g m e n t s  Also,  these  because  of  layers,  in  starting  increase  um and t o  in  size  measuring  fragments;  have  two  Several  particle  decided  included  process  and S  perception  these  Because  sample.  range  during  the  a 10X o b j e c t i v e ,  more  case  and  element  was  measured  wall.  o f VE breakdown d u r i n g m e c h a n i c a l  from  it  cell  E l e m e n t Breakdown  measuring  um ,  the  a n g l e between t h e  Zeeuw  each  The s t u d y by  de  of  cell  wall  even a f t e r  of  to  would vessel  particle. analysis layer  and  extensive  67 Comparisons  of  Contingency  Tables  (Steel,  and  processes  size  distribution  following  Torrie  and  refining  knowledge  fragments  energy  also  provided  was  by  complemented  the by  size  data  on t h e  s u r v i v a l of  handsheet and  circles  of  soaked  the  drawn to  with  provided  by  the  in  the  Whole  VE  number  the  size  of  of  VE  whole  and  uniform  weighed.  measured  of  each  allowed VE i n  yield  one  values,  circles  with t o l u i d i n e  in  outlined  was  the  gram  of  to  was  lost to  50  enough  whole VE  entire The be  pulp.  assuming  Tappi  2 mL were  counter.  results  in  taken  motion,  across  blue  were  The number o f  or  out  selected  two  The p u l p m a t e r i a l  these  species.  were  other  material  tally  study  punched  no p u l p p a r t i c l e s  a  one  under  were  procedures  microscope  aid  of  from  stained  75x25 mm p u l p s l i d e s .  number  pulps  The  suspension  pipette.  the  24  follows:  Six of these c i r c l e s  The d i s i n t e g r a t e d  with  as  diameter  according to  6 circles  the  on  prepared  overnight,  a plastic  slide  represent using  cm  counted under a l i g h t  each  of  pulps  one  this  p r e p a r e two  were of  from  species,  distribution  measured  but e n s u r i n g t h a t  process.  mL a n d ,  kraft  i n water  S t a n d a r d T401,  to  which s u p p l i e d • i n f o r m a t i o n  was  from, e a c h  oven-dried,  and d i s i n t e g r a t e d  in  VE  from each s h e e t .  random,  were  taken the  criterion  these' e l e m e n t s upon r e f i n e r p u l p i n g .  whole  from  randomly at  was  also  Eight  of  using  test  due  tested.  out  measured f o r c o m p a r i s o n .  e l e m e n t s p e r gram o f p u l p ,  number  Chi-Square  were  vessel  The  carried  Differences  1980).  f r o m k r a f t p u l p s was The  the  were  area  weight  taken  to  Then,  by  appropriate  68  yields  for  measured was  those  pulps  accurately,  from w h i c h y i e l d  the  number o f  values  c o u l d not  whole VE p e r gram o f  be  wood  calculated.  Separation  of  techniques  developed  based  on  applied  large  fibre  by  VE f r a g m e n t s by  (1973)  This  for  separation  pulps.  tried  the' J a c q u e l i n Apparatus f o r  from  chemically  fractions form  in  method  rich  treated in large  quantities of  hardwood c h e m i c a l of  aspect  ratio  were  the  enough  obtained.  pulps,  was  hardwood The  influence  have  handsheets  could  be  produced  Surface  strength  could  have  whole V E .  then  been  attempted. and  fibres,  could  allow  of  otherwise at  attempted  no  the  the  hardwood were  produced use  of  floes  did  not  due  tested,  on  the  small results  printing  provided  levels  to  to  relatively  VE  The  applied  satisfactory  and  further  separation.  VE p i c k i n g  before  is  sole  However,  similiar  and  pulps  also  whole  been  was  and s p e e d s  coherent  (1965),  pulps  properties  smoothness.  with  to  Agarwal  mechanical of  Even  the  technique  VE i n  refiner  VE f r a g m e n t s ,  and  of  concentrations  chips.  large  Marton  nature  stock  His  principle  chemical in  Several  attempted, f o l l o w i n g  (1966).  Jacquelin  flocculation.  Colley  was  of  that  surface  measurements  a f t e r ' removal  of  69 IV. 4.1.  A n a l y s i s of  The  results  techniques analysis  Fibre  and  Cross  Sections  discussion  employed  of  RESULTS  fibre  in  this  cross  on  the  study  repeatability  for  sections,  each  are  of  category  presented  the  of  the  i n Appendix  C.  4.1.1.  Retention  Table  4.1  degrees  the  shows  of  indices,  for  pulps  the  CTMP  pronounced  smaller  the  percentage  pulp  S ^ layer  rest  additional  1  every  of  presented  either  Compound M i d d l e L a m e l l a and S ^ L a y e r of  ML and S ^ r e t e n t i o n ,  ML and  from  of  more  or in  studied.  fibre fibres  the  reductions  the  in  similar  outer  was  CTMP  and  layers  was  freeness  than  of  that  removal  p u l p i n g . TMP  S ^ removed t h a n  Retention of  indicate  refiner  ML o r  different  MLr and S ^ r  patterns  in  with  fibres  removal of  The r e s u l t s  wall  CMP p u l p s .  with  including their  followed  the  fibres  generally CMP  in  did more  pulps,  but  accomplished  with  the  TMP  case  of  pulps. Table  4.2  displays  the  (Contingency  Tables)  distribution  patterns  that  distribution  the  performed of  significantly  for  species  refining  f  Table  as  4.3  the  compiles  show p e e l i n g  of  the  results  any  data  to  of  Chi-square  determine  ML and S-L r e m o v a l . patterns given  refiner  of  tests  differences The d a t a  removal pulping  in  reveal changed  process  or  proceeded. for  outer  the  layer  percentage and t h a t  of of  fibres  fibres  which showing  70  partial out/in  separation effect).  fibres  with  mainly  of  TMP f i b r e s  a characteristic  Exposure of  Table  4.4  presents  classified  under the  S  as  showed  of  identical Table changed  4.1.3.  to  The  percentages  as  of  those  frequently  aspen  index  exposure the  S  of  of  fibres  fibres  was  and  of  that  exposure  exposure.  than layer  2  CMP o r of  it  were of  TMP CTMP  the  more q u i c k l y ,  for  pattern,  the  S^  the  fibres fibres.  chemically-  particularly  in  inverted,  is  when  layer,  the  that  the  indicating  results S e 2  from  pattern  upon r e f i n i n g .  Damage of  fibres  Table  presenting  was  of  4.5.  failure  generally  chemically-treated birch.  radial  delamination Radial  i n TMP t h a n i n e i t h e r  than for  effect  fibres.  categories  exposed  showing  in  delamination from  their  one  significantly  summarized  proportion  apply,  Wall  pulp  of  fibres.  the  also  the  percentage  out/in  refiner  as  Layer •  2  different as  The  i n aspen p u l p  distribution  2  Cell  birch  the  became  S e  4.2  S  layer  2  aspen  the  of  (designated  a larger  peeling.  refining,  fibres  case  Since  S  upon  treated the  well  higher  However,  the  layer  presented  occasionally  4.1.2.  layer,  outer  outer-layer  appeared only  2  the  wood  more  the  failure S  2  as  well  layer,  are  occurred  CTMP o r CMP f i b r e s , pronounced  chips  and more  in  the  more  whereas fibres  pronounced  for  71  4.1.4. Table and  Distorted Fibres 4.6  lists  CMP p u l p s .  distorted  4.1.5.  distorted  contained  a  t h a n d i d CTMP p u l p s ,  fibres  larger  proportion  and a s p e n ,  fibres  f r o m CTMP  in  of  general,  than d i d  birch.  T e n s i o n Wood F i b r e s  proportion  the  chip  G-layers whether  of  supply,  presented in in  aspen as  in  R48  wood  percentage  "G ONLY")  G ONLY  a much l o w e r  Table of  fibres  kraft 4.8  pulp,  shows  aspen  (G-fibres)  the  refiner  or  inside  TMP p u l p s fibres  the  not  compared t o  pulp  o v e r a l l percentage  of  of  fibres,  rest as  showed  CTMP  31%  presence  fibre,  only  in  averaged  ( G - l a y e r s t r i p p e d from t h e  fibre.  of  4.7.  wood  from  fraction  isolation i.e.,  tension  measured  Table  the  wall,  original  also  of  p r o d u c e more d i s t o r t e d  The  fibre  percentage  CMP p u l p s  fibres  appeared to  as  the  of  the  in  the  a  high  and CMP, b u t  G-fibres  i n the  R48  fraction.  4.2. The  Pulp Properties pulp  characteristics  prepared are presented refining  energy,  i n Table  freeness,  fractionation.  In  accompanied  by  reductions  long-fibre  fraction  increases  in  evaluated  fines  general,  (also  content.  4.9.  shive  before  Included are  content  increasing in  freeness, shown  handsheets  in  TMP p u l p s  were  results  on  and B a u e r - M c N e t t  refining shive Figure consumed  energy  was  content,  and  3.5), more  and energy  72  to  a  did  given pulps  contents  freeness f r o m CTMP  of  Handsheet  bulk,  Table  4.10.  and  CTMP  strength  properties  stronger  than  and  sheet  those  surface  the  due test  a  the  refining  was  performed  roughness decreased  and  higher  as  on  nor the  the  of  pulp  brightness  concentration  light  in  scattering  concentration,  aspen  the  always  a  more  on t h e due  on and  h a d much  4.11  shows was  pretreatment is  than  not  rough  also  aspen.  show  large  pretreatment  surface  of  the  glazed  side  of  to  chemical  application.  Birch  pulps.  decreased  coefficient.  tear  denser  values  energy  chemical  for  species  did  considerably  p r o d u c e d rougher sheets t h a n . d i d aspen expected,  in  Porosity  chemical  measured  refining  increases  turn,  chemical  hand,  energy  in  were in  The e f f e c t  other  shown  TMP. T a b l e  of  4.11.  pretreatments  and b o t h ,  result  and  are  and o p t i c a l p r o p e r t i e s .  as  on  to  However, sheet,  alkali  than higher  followed  CMP s h e e t s  from  r e f i n i n g energy.  roughness,  pretreatment  As  it  chemical  evident.  than  where  of  from CTMP  4.10  except  with b i r c h giving higher porosity  variations  the  properties,  effect is  Tables  r e f i n i n g caused  CMP p u l p s  dramatically  Surface  sheet.  strength  strength  those  increased  when  properties  The  strength  evident  3.2)  and p r o d u c e d  and  and  trend.  reduced  Figure  in  F o r any g i v e n p u l p ,  in  porosity,  in  are presented  density  complex  higher  shown  fines.  density  strength  (also  and CMP p r o c e s s e s ,  properties  Sheet  sheet  level  with  increasing  pretreatment, At  comparable  gave b r i g h t e r p u l p s  than  as  did  alkali birch.  73  While  brightness  scattering little  showed  change  variation pulps  to  constant  increase  CTMP  or  the  birch  kraft  longer size  size  the  pulps.  Birch  aspen  frequency  For  concentration  of  contained  VE.  significant species. refiner  differences  processes  under  process,  on  estimates  their  are  among  the  TMP p r o d u c e d  structure  was  aspen  and  average show VE  birch  had  whereas  sizes,  as  pulps,  the  larger  both  CTMP  well  as  distribution  i n Table 4.15.  were l a r g e l y  due t o  It  show  whole  indicates  for the  and  pattern  a  given  different  When c o m p a r i n g s p e c i e s not  and  significantly  and 4.14  pulps  under  significant  VE  difference. whole  f o r VE p e r gram o f  4.16.  birch  um. The  refiner  study.  of  904  TMP p u l p s  TMP and CMP d i d  number  be  4.13  for  shown  VE from  aspen  larger  results  d i s t r i b u t i o n pattern  Results  Table  of  These d i f f e r e n c e s  same  size  test  i n VE s i z e  in  VE f r a g m e n t s ,  fragments  Chi-square  differences  the  small  TMP and CMP  although  to  of  um. T a b l e s  species,  of  found  an a v e r a g e  625  both  little  aspen.  size  VE were  distributions  respectively.  CMP  was  relatively  showed  species  sheets,  than  average  a s p e n VE w i t h  for  but  Opacity  both  refining,  Elements  presents  than  further  TMP p u l p s  opaque  values  Breakdown o f V e s s e l 4.12  For  most  higher opacity  for  on  CMP p u l p s .  refining.  provided  Table  VE  an  in  due  exhibited  4.3.  stayed  VE p e r  o r i g i n a l wood,  virtually  preserved  gram  to  no  a large  of  pulp,  are p r e s e n t e d  whole extent  VE,  and in  whereas  i n CTMP and  74  e v e n more so further  4.4.  refining  Fibre  Table for  i n CMP p u l p s .  d i s p l a y s the  This  is  aspen  fibres.  Wood s p e c i f i c are  involved.  of  of  fibre  length  higher  than  in  Figure  showed a wide  4.1  range  approximately 0.45.  for  of  in density  Appendix  density  Birch  bark trees  at  v a r i a t i o n from p i t h t o  D shows t h e different  pulped.  v a r i a t i o n of  heights  processes,  gave  up  1.33  mm f o r  0.90  mm f o r  breast  three values,  density  w i t h no  trees with values  definite  bark.  wood d e n s i t y  a tree  measurements  bark at  the  w h i c h were n a r r o w l y d i s t r i b u t e d a r o u n d 0.55 trend  of  the  g r a v i t y v a r i a t i o n s from p i t h t o  presented  two  Gravity  s h o w i n g an a v e r a g e  significantly  Aspen  average  last  number o f whole V E .  results  aspen and b i r c h p u l p s ,  birch.  an  reduced the  these  L e n g t h and Wood S p e c i f i c  4.17  height  Within  for  each  from p i t h of  the  to  three  Table  4.1. P e r c e n t a g e o f f i b r e s u n d e r t h e c a t e g o r i e s f o r M L a n d S-L r e t e n t i o n .  %ML RETENTION  defined  %S1 RETENTION  MLr MLr>50 MLr=100 INDEX  Slr=0  Slr<50  Slf>50  Slr=100  Sir INDE  PULP ID  MLr=0  MLr<50  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  33 40 37 47 5 29 39 40 17 40 51 46  32 24 33 26 15 17 10 23 20 19 14 21  21 22 16 19 22 19 21 17 14 17 9 19  14 14 14 8 58 35 31 20 49 23 26 14  38 37 34 29 78 54 49 39 65 41 36 33  28 36 30 41 4 24 37 37 14 32 46 42  17 22 25 13 8 16 6 17 14 21 11 14  27 19 19 28 22 17 18 17 15 14 11 17  28 24 26 18 66 43 38 29 56 33 31 27  52 43 47 42 84 60 54 46 71 49 43 43  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  40 44 51 63 16 33 32 37 22 36 30 43  11 12 7 9 5 5 8 6 6 9 7 7  11 12 8 10 5 12 8 12 9 9 10 1  38 32 34 18 74 50 52 45 63 46 53 48  49 44 41 28 79 60 60 55 71 55 62 51  35 43 49 60 16 30 28 35 22 31 26 31  10 9 7 7 3 4 5 4 2 6 5 6  14 13 7 9 3 7 6 6 6 4 7 5  40 35 38 24 78 59 61 55 70 59 62 58  53 47 44 33 81 65 66 61 75 63 69 63  76  T a b l e 4.2.  Dependency o f MLr, and S2_r o r S e , on energy i n p u t . Chi-square v a l u e s compared t o a c r i t i c a l v a l u e o f 16.92 (a=0.05, 9 d . f . ) . 2  MLr PULP TYPE  Sir or S2e  ASPEN  BIRCH  ASPEN  BIRCH  TMPs  •23.1  46.1  37.9  47.0  CTMPs  164.6  66.8  159.0  42.7  CMPs  144.2  52.9  109.9  20.2  CONCLUSION: Distribution pattern depends on energy input in all cases  77  Table 4 . 3 . Percentage of f i b r e s showing mode of s e p a r a t i o n of the outer l a y e r .  SEPARATION OF OUTER LAYER PULP ID  PEELING  OUT/IN  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  25 22 22 19 10 11 17 13 14 14 9 11  2 3 5 4 3 8 4 6 8 5 5 8  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  14 11 21 11 8 7 9 11 8 8 7 4  19 20 10 3 17 24 24 25 24 18 19 13  '  78  Table 4 . 4 . Percentage of f i b r e s under c a t e g o r i e s d e f i n e d f o r the exposure o f the S l a y e r . 2  %S2 EXPOSED P U L P ID  S2e=0  S2e<50  S2e>50  S2e=100  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  28 24 26 18 66 43 38 29 56 33 31 27  27 19 19 28 22 17 18 17 15 14 11 17  17 22 25 13 8 16 6 17 14 21 11 14  28 36 30 41 4 24 37 37 14 32 46 42  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  40 35 38 24 78 59 61 55 70 59 62 58  14 13 7 9 3 7 6 6 6 4 7 5  10 9 7 7 3 4 5 4 2 6 5 6  35 43 49 60 16 30 28 35 22 31 26 31  S2e INDEX v  ...  •  48 57 54 58 16 40 46 54 29 51 57 57 47 53 56 67 19 35 34 39 25 • 37 31 37  79  Table  4.5.  Percentage of f i b r e s  showing c e l l  CELL W A L L DAMAGE  PULP ID  RADIAL FAILURE  DELAMINATION  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  17 19 20 19 3 5 5 9 4 2 2 5  3 9 3 16 10 21 21 28 14 22 20 32  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  12 11 21 22 3 3 3 4 3 3 2 3  3 5 3 4 3 14 15 7 4 15 9 10  w a l l damage.  80  Table 4 . 6 . Percentage of distorted fibres i n r e f i n e r pulps from chemically-treated wood chips.  P U L P  ID  A S P E N  B I R C H  C T M P 1  69  64  C T M P 2  65  56  C T M P 3  54  62  C T M P 4  64  49  C M P 1  78  80  C M P 2  90  81  C M P 3  89  77  C M P 4  84  78  81  Table 4 . 7 . Percentage of t e n s i o n wood f i b r e s i n aspen by a n a l y s i s of c r o s s s e c t i o n s of k r a f t p u l p f i b r e s  BLOCK No.  TOTAL  T O T A L FIBRES N U M B E R OF PERCENT COUNTED TENSION WOOD TENSION FIBRES WOOD FIBRES  319  100  31  299  92  31  401  123  31  1019  315  31  82  Table 4.8. Percentage of t e n s i o n wood f i b r e s i n aspen , r e f i n e r R48 p u l p f r a c t i o n s . P U L P ID  G-LAYER INSIDE  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  13 13 11 11 33 29 27 26 32 32 30 25  * * * * NS NS NS NS NS NS NS  *  ONLY  TOTAL  6 6 5 4 1 1 2 4 1 1 1 3  19 19 16 15 34 30 29 30 33 33 31 28  * : significantly different from G-layer content in wood (level of significance d=0.05) NS: not significantly different  * * * * NS NS NS NS NS NS NS NS  Table  PULP ID  4 . 9 . A s p e n and b i r c h r e f i n e r p u l p c h a r a c t e r i s t i c s fibre size classification. REFINING UNSCREENED SCREENED PULMAC FREENESS SHIVES FREENESS ENERGY % mL mL MJ/ke  R28  28/48  48/100  100/150  150/200  P200  %  %  %  %  %  %  %  37.0 37.4 36.6 36.0 40.4 39.2 36.4 22.9 42.5 39.0 37.8 37.4  48.3 43.5 41.5 39.8 45.6 42.5 38.7 23.5 59.6 56.1 53.8 49.6  26.3 26.5 27.0 27.2 33.9 33.5 33.5 35.1 27.1 26.9 27.9 28.7  2.6 2.3 2.3 2.6 3.1 3.2 3.7 5.4 1.9 2.6 2.7 3.1  2.7 2.6 2.5 2.7 2.0 2.8 3.5 5.6 0.9 1.2 1.2 1.3  20.1 25.1 26.7 27.7 15.4 18.0 20.6 30.4 10.5 13.2 14.4 17.3  36.9 36.7 36.3 32.5  50.1 41.7 40.9 35.4 64.8 60.7 62.4 60.7 59.2 67.2 67.8 65.2  21.0 23.6 22.5 25.2 15.5 15.5 15.2 15.0 10.7 11.4 10.8 10.3  2.3 3.0 2.5 3.2 2.2 2.3 2.2 2.3 1.8 2.1 1.7 2.0  2.4 3.0 2.8 3.5 2.1 2.0 2.3 2.7 1.2 1.4 1.3 1.7  24.2 28.7 31.3 32.7 15.4 19.5 17.9 19.3 15.9 17.5 18.4 20.8  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  5.5 7.8 9.7 11.3 2.5 4.3 5.9 7.2 6.8 7.7 8.7 9.7  373 200 142 106 285 159 112 71 312 220 154 101  380 220 161 125 300 164 122 67 298 214 156 98  0.76 0.10 0.04 0.02 0.10 0.05 0.05 0.00 0:25 0.10 0.00  11.3 6.1 4.9 3.8 5.2 3.3 2.3 0.6 17.1 17.1 16.0 12.2  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  5.6 9.9 12.3 14.5 3.9 5.3 5.7 6.1 5.3 6.8 6.8 8.4  514 205 165 105 460 225 165 107 317 240 160 90  552 240 180 116 507 254 203 143 323 206 150 76  1.35 0.02 0.00 0.02 0.24 0.05 0.01 0.01 0.30 0.10 0.05 0.00  13.2 5.0 4.6 2.9 21.8 20.3 24.3 23.8 44.6 42.4 43.4 43.5  0.00  and  43.6  40.4 38.1 36.9 25.8 25.2 24.4 21.7  R48  84  Table  4.10. Physical  properties  BULK  DENSITY  cm /g  g/cm  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  3.15 2.90 2.64 2.52 1.91 1.91 1.98 1.68 1.87 1.80 1.71 1.66  0.317 0.345 0.379 0.397 0.524 0.524 0.505 0.595 0.536 0.556 0.583 0.603"  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  3.61 3.10 2.92 2.86 2.61 2.46 2.39 2.25 2.20 2.10 2.03 1.92  P U L P ID 3  3  0.277 0.323 0.342 0.350 0.383 0.406 0.419 . 0.445 0.454 0.475 0.494 0.522  of pulp  handsheets.  TEA * INDEX mJ/g  STRETC  TEAR INDEX mN.m /g  BURST INDEX kPa.m /g  TENSILE INDEX N.m/g  2.4 2.5 2.6 3.2 5.7 5.6 5.4 4.9 6.0 6.0 6.3 6.6  0.5 0.8 0.9 1.1 2.0 2.4 2.4 2.7 2.2 2.5 2.8 3.1  14 17 20 24 40 40 44 48 37 44 47 49  75 95 95 150, . 450 395 • 490 635 310 475505 555  1.08 1.12 1.00 1.23 1.78 1.59 1.79 2.04 1.32 1.64 1.65 1.71  0.3 0.6 0.8 0.9 1.7 2.2 2.5 2.8 2.8 3.1 3.5 3.7  8 15 19 20 35 43 46 52 45 49 55 59  25 100 70 ' 105 325- • 415 450 610 480 515 670 745  0.74 1.12 0.91 1.05 1.53 1.56 1.64 1.90 1.64 1.66 1.90 1.93  2  1.7 2.4 2.7 2.7 6.3 7.4 7.0 7.7 8.3 9.7 8.3 8.3  (*): Tensile Energy Absorption  2  ..  %  Table 4.11. Surface and o p t i c a l p r o p e r t i e s of p u l p handsheets. P U L P ID  POROSITY ROUGHNESS ROUGH Sheffield Sheffield  ROUGHNESS SCATTERING OPACITY BRIGHTNESS GLAZED COEFFICIENT Sheffield m /kg % % . 2  5 14 6 3 2  385 373 369 369 366 358 355 349 398 390 384 375  332 253 211 168 160 100 122 60 140 101 87 71  58 64 65 67 37 40 44 45 35 36 35 35  92.4 94.2 94.7 94.9 89.7 89.7 90.3 90.9 94.1 94.0 94.1 94.0  64 64 64 65 50 56 59 59 41 42 41 41  400 130 92 63 204 38 20 7 19 7 4 3  402 385 378 372 398 396 398 396 416 408 411 402  387 323 320 258 345 255 164 126 182 142 146 164  49 61 62 68 34 35 34 34 32 35 33 33  96.3 97.1 97.6 98.3 92.3 93.5 93.3 93.0 96.1 96.9 96.2 96.4  51 55 54 55 46 46 45 46 36 37 37 37  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  172 81 45 29 33 11  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  8  oo Cn  86  Table 4.12.  SPECIES  S i z e of v e s s e l elements from k r a f t  NUMBER VE MEASURED  ASPEN  50  BIRCH  50  '  A V E R A G E STANDARD STANDARD L E N G T H DEVIATION ERROR ym ym ym  pulps.  COEFFICIENT OF V A R I A T O N %  625  128  18  20.6  904  189  27  20.9  Table 4.13. Aspen v e s s e l element s i z e frequency a n a l y s i s (N=50) . LASS  BOUNDARIES  K R A F T TMP1  TMP2  TMP3  TMP4  CTMP1  CTMP2  CTMP3  CTMP4  CMP1  CMP2  CMP3  32 7 5 2 2 1 1 0 0 0 0 0 0 0 0 0 0 0  34 6 3 4 1 1 1 0 0 0 0 0 0 0 0 0 0 0  37 8 3 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0  11 7 6 4 4 6 3 3 3 0 0 1 1 1 0 0 0 0  8 11 8 9 2 3 0 1 2 2 3 0 0 1 0 0 0 0  11 11 6 10 2 1 0 1 2 2 0 4 0 0 0 0 0 0  18 12 8 6 1 1 1 0 2 0 1  6 7 4 4 0 2 5 1 2 7 5 2 3 1 0 0 1 0  13 7 6 2 1 1 2 2 2 4 2 3 5 0 0 0 0 0  10 7 6 4 3 1 0 4 1 1 3 2 5 2 1 0 0 0  CMF  pm 112.5 162.5 212.5 262.5 312.5 362.5 412.5 462.5 512.5 562.5 612.5 662.5 712.5 762.5 812.5 862.5 912.5 962.5  162.5 212.5 262.5 312.5 362.5 412.5 462.5 512.5 562.5 612.5 662.5 712.5 762.5 812.5 862.5 912.5 962.5  (+)  0 0 0 0 0 3 4 4 6 4 6 8 9 5 0 1 0 0  25 14 6 0 1 3 0 1 0 0 0 . 0 0 0 0 0 0 0  6 0 0 0 0 0 0  13 6 5 5 1 2 2 3 2 2 5 3 0 0 0 0 0 1  Table 4.14. B i r c h v e s s e l element s i z e frequency (N=50). :LASS 112.5 162.5 212.5 262.5 312.5 362.5 412.5 462.5 512.5 562.5 612.5 662.5 712.5 762.5 812.5 862.5 912.5 962.5 1012.5 1062.5 1112.5 1162.5 1212.5 1262.5  BOUNDARIES KRAFT TMP1 Um 162.5 0 22 212.5 12 0 262.5 0 8 312.5 0 5 362.5 0 0 412.5 0 0 462.5 0 1 512.5 0 1 1 562.5 0 612.5 1 0 662.5 1 5 712.5 3 0 762.5 3 0 4 812.5 0 862.5 3 0 912.5 • 6 0 962.5 5 0 1012.5 7 . 0 1062.5 3 0 1112.5 2 0 1162.5 2 0 1212.5 0 0 1262.5 4 0 1 0 (+)  TMP2 29 10 9 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  TMP3 34 4 5 4 1 1 . 0 0 0 0 0 0 0 1 0  6  0 0 0 0 0 0 0 0  analysis  TMP4 CTMP1 CTMP2 CTMP3 CTMP4 25 13 6 5 0 0 1 0 0  6  0 0 0 0 0 0 0  6 6 0 0 0 0 0  8 8 5 5 2 2 1 1 5 2 2 1 1 1 3 0 0 0 2 1 0 0 0 0  7 7 9 7 1 4 1 1 2 1 1 1 3  0  0 0 1 2 0 0 2 0  0 0  14 9 7 6 3 2 0 2 2 0 1 1 0 1 2 0 0 0 0 0 0  6  0 0  CMP1  CMP2  CMP3  19 6 9 2 2 2 1 1 2 0 3 1 1 1 0  13 10 5 5 0 2 1 1 2 2 1 1 1 0 0 1  14 7 8 6 3 1 1 3 1 1  16 11 3  23  4  0 0 0 0 0  6  3 3 1 0 1 0 0 2 2 0 1 0 2  1 0 0 1 0 0 2 1 0 0 1 0  0  0  •0  0  6  0 0  3 0  0  1  1 0  6  0 1 0 0 1 0 0 1 1 1 0 0 0  4  0 0 0 1 0 0  CMF  4 2 8  2  0  0 0 0 1  89  Table 4.15. Chi-square t e s t s on v e s s e l element d i s t r i b u t i o n (a=0.05). PULPS TESTED  size  NUMBER DEGREES OF CHI-SQUARE CHI-SQUARE RESULT PULPS IN FREEDOM CALCULATED CRITICAL TEST  A)  ASPEN REFINER PULPS BIRCH REFINER PULPS  12 12  55 44  221.5 131.7  73.3 60.5  * *  B)  ASPEN TMPs ASPEN CTMPs ASPEN CMPs  4 4 4  6 15 18  9.5 21.1 12.9  12.6 25.0 28.9  NS NS NS  C)  BIRCH TMPs BIRCH CTMPs BIRCH CMPs  4 4 4  9 18 12  13.0 20.4 13.4  16.9 28.9 21.0  NS NS NS  D)  ASPEN TMPs vs CTMPs ASPEN TMPs vs CMPs ASPEN CTMPs vs CMPs  8 8 8  28 28 42  110.4 136.8 65.1  41.3 41.3 58.1  * * *  E)  BIRCH TMPs vs CTMPs BIRCH TMPs vs CMPs BIRCH CTMPs vs CMPs  8 8 8  28 28 42  108.4 85.9 46.7  41.3 41.3 58.1  * *  ASPEN vs BIRCH TMPs ASPEN vs BIRCH CTMPs ASPEN vs BIRCH CMPs  8 8 8  21 35 35  28.7 53.4 41.1  32.7 49.8 49.8  F)  * : Significantly Different NS: Not Significantly Different  NS NS  * NS  90  Table 4.16.  S u r v i v a l of whole v e s s e l elements i n r e f i n e r pulps. WHOLE V E WHOLE V E PER PER P U L P ID GRAM GRAM OF P U L P OF WOOD (xlOOO) (xlOOO)  WHOLE V E SURVIVAL AS % V E IN W O O D  A-KRAFT A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMP1 A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  860 8 3 0 0 202 167 142 59 439 389 325 294  482 7 3 0 0 186 153 131 54 386 342 286 259  100 2 1 0 0 39 32 27 11 80 71 59 54  B-KRAFT B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  261 0 0 0 0 37 36 24 23 91 73 69 69  136 0 0 0 0 34 33 22 21 82 66 62 62  100 0 0 0 0 25 24 16 16 60 48 46 46  91  Table 4.17. Aspen and b i r c h f i b r e l e n g t h measurements.  SPECIES  N U M B E R OF FIBRES MEASURED  AVERAGE FIBRE LENGTH ym  STANDARD DEVIATION ym  COEFFICIENT OF VARIATION %  ASPEN  169  897  181  20.2  BIRCH  220  1326  266  20.1  92  0.3-  0  2  4 6 8 DISTANCE F R O M PITH, cm  ASPEN (W.LAKE)  Figure 4 . 1 .  BIRCH (W.LAKE) — —  Wood s p e c i f i c g r a v i t y v a r i a t i o n t r e e s used i n t h i s study.  10  12  ASPEN (LYTTON)  at DBH  f o r the  93  V.  5.1.  A n a l y s i s of F i b r e  This  section  is  separately. results given  topics of  that  the  analysis  of  will  be  discussed  repeatability fibre  cross  of  the  sections  is  R e t e n t i o n o f Compound M i d d l e L a m e l l a a n d S^ L a y e r  take  is  r u p t u r e d i n the  place  testing  separation boundary  e.g.,  is  directly  since  fibres  that  fibres  in  fibres  from t h e  of  only  lamella,  layer.  Transwall  failure,  2  for f a i l u r e across 1967, of  part  of  1968).  wood  a  wood  can  this  study.  surface  thus  the  of  differ  from  shive  The o b j e c t i v e exposed  different  refining  refining.  Yet,  it  processes is  of  to  recognized  i/S2  on  present  not  apply  analyzed,  i.e.,  fibre  bundle.  of  fibres  after  refining. from  analyzed  that  produced  certain  the  The  separated  separated  fibres  the  wall,  s t u d y wood f a i l u r e ,  the  and  the S  the  had a l r e a d y  the  in  cell  do  some d e g r e e  of  was n o t  surface  or  initially  that  In  were  consequently,  fibres  the  failure  fibres  wood m a t r i x and u n d e r g o n e  average  material  middle  types  analysis,  on  compound  isolated  not  depending  results  (Koran  these  modes  separation  failure  responsible  were  the  S  longitudinal plane,  Intrawall  the  and w i t h i n t h e  however,  rather  a variety  conditions.  broken  study,  in  within  other hand,  The  into  discussion  o b t a i n e d by t h e  When wood  and  Sections  i n Appendix C .  5.1.1.  can  Cross  divided  The  DISCUSSION  in but  under  degree  initial  the  mode  of of  94  separation quality It  can  play  an  important  should  be  emphasized  had  not  that  been  fact,  out  analysis  of mechanical pulp f i b r e s  based  softwood  fibres  polarizing filters layer  and,  techniques ML,  is  to  evaluating filters  the  had in  S]_  wood it  view the  same  has  wood  the  use  in  The  use  of  the  staining  or absence  of  the  this  fibres  the in  polarizing  presence to  of  advantage  Although  studies,  isolated  been  of  a definite  the  has  1983).  n e v e r been u s e d f o r q u a n t i t a t i v e  techniques  sections  were  practical,  to  the  microscopy.  Since  wall  it  S^  author's evaluation  from  However,  differentiation  in  hoped  the  sections  hardwood  techniques  cannot  that  changes  section wall  of t h i s  results  resin  of  c o u l d be layers  from  u n d e r t h e SEM  failed  obtained  cell  by means  discussing  cross  that  cross  the  in. dissolving  observation  to  staining was  layers  fibre  SEM  information  samples,  involved  observe  additional  Before  failure  retention  fibre  SEM.  presence  observe  the  or absence  make  quality.  to  section  on  pulps.  Although  fibre  to  and p r o v i d e s  used  and  presence  cross  hardwood  information  in cross  time,  surface  been  layer  refiner  SEM  surface  fibre for  (Kibblewhite  v i s u a l l y assess the  fibre  knowledge of  at  far  of  before  published  so  to  a new t e c h n i q u e  layer  fibre  analysis  carried  pulps.  on  In  an  refiner  Si  in  upon r e f i n i n g .  sections  of  role  to  provide  from be  light  applied  texture  to  between  observed allowed  under no  technique.  presented  in  Table  4.1  on ML  95  and  retention,  that,  after  the  occurs  at  Corson  (198 9) ,  pulps  for  of  the  in by  the  the  six  lower  R48  also  one  shape  largely  by  pretreatment  groups  of  pulp  (same  process  levels),  it  clear  fibres  the  mainly  t h a n by r e d u c i n g t h e i r freeness  aspen  CTMP  was  evident  shortening The  results  for  Chi-square tests  pulp  all  (A-CTMP4) ,  in  Table  4.1.  pulp  groups  of  the  fibre curves any  refining layers of  of but  acted rather  the  some  low  fibre  curves. and t h o s e  refining,  removal  the  species,  which  on d i s t r i b u t i o n p a t t e r n due t o  vary  exception in  the  confirms  within  surface  with the  from t h e s e  quantitative in  removing  length,  presented  ML and S^ r e t e n t i o n  by  in  these  and that  high  the  conditions,  is  the  This  of  the  100/150  increase  cannot  5.1,  in  of  influencing  general  as  Figure  fractions  pulps.  that  study.  occurred  an  to the  produced  fraction in  in  under  in  had  freeness  Although the  upon  expected,  the  which  place  were  shorter  (1982a)  without  freeness  was  change  in  took  shown  essentially  Gavelin  different  there  is  and t h e  resulted  fraction  set  This  establish  reached,  processes  fraction)  .little  to  mL CSF a c c o r d i n g  shortening  pulping  (48/100)  characteristics. were  a r o u n d 700  (P200  that  important  l i b e r a t i o n was  fibre  The r e d u c t i o n  fraction  fines  of  increased.  pulps,  observations  levels  fines  fraction  freeness  fibre  refiner  energy  150/200.  considered  no s e r i o u s  indicates  middle  P200  point  more  refining  and  is  freeness  Instead,  which  it  establish  fibre  of  Table  4.2  differences  of  the  surface  percentage  of  fact layers.  fibres  that As with  96  B I R C H TMPs  A S P E N TMPs  R28  2^48  4*100  100/150 150/200  P200  R28  28/48  48/100 100/150 150/200  P200  EH  A S P E N CTMPs  B I R C H CTMPs  a cu fu En  o w o EH  R28  S3  28/48  W O  w  {U  48/100 100/150 150/200  P200  R28  A S P E N CMPs  45-  28/48  48/100 100/150 150/200  P200  B I R C H CMPs  40+ 35  30-25"  f r £i  20-15  /  T  \A 1  /  r  -/•/•"  10+ 5 0  R28  28/48 48/100 100/150150/200 P200  BAUER McNETT  Figure  R28  28/48 487100 100/150150/200 P200  FRACTIONS  5 . 1 . B a u e r McNett f r a c t i o n a t i o n p a t t e r n s f o r a l l hardwood r e f i n e r p u l p s u n d e r s t u d y . S o l i d l i n e s : h i g h f r e e n e s s p u l p s ; d a s h e d l i n e s : low f r e e n e s s ; dotted l i n e s : intermediate freeness.  97  total  ML r e t e n t i o n ,  highest each  for  the  group,  energy  ML(r=100),  pulps  i.e.,  for  a p p l i e d was  pulps,  the  There  were,  compared  however,  for  lowest  on  fibre to  for  the  for  (MLrl),  values  which  the  low  freeness  differences  and  freeness  .  initial  There  retention  ML r e t e n t i o n . by  the  with  were of  groups  delineated  here  within  group of  was  generally  sufficiently refining zone.  fractions Thus,  is  high  the  to  in  results  the  allow  these  This  wall  that  showed in  tensile  -pulp  in  the  than  of  fibres  trends  complex  variation  fibres  from  i n TMP p r o c e s s i n g , the  ML was  preheating  separation  to  CTMP  some t r a n s w a l l studies  birch testing  at  percentage  compared  are  ML r e t e n t i o n  for  in  of  followed  and  general  lower  with  that  to  trends  presteaming,  pulps  agrees  the  The d e g r e e  the  these process  differences  more  fibre  by  indicate  (1957) who cell  the  concentrations by  respect  MLr i n d e x  the  Presumably,  supported  occurred.  Lagergren across  in  of  TMP p u l p s  chips.  softened  found  these  probably  for  pulps.  distribution pattern  ML. O n l y  four pulps.  conditions  This  the  terms  simplify  lower  present  in  of  to  chemically-treated lignin  important  ML and i n  retention  each  with  F i g u r e s 5.2 and 5.3 d e p i c t  different  total  also  also  was  between  and  different  these  development  The t r e n d o f ML r e m o v a l d e p e n d e d on t h e was  within  In  pulp, g r o u p s . species  was  refining  group.  surface  that  important  MLr i n d e x freeness  pulps  the  done  small  highest  those  also  work  relatively  with  and o f  the not or  the  ML  of  R48  o r CMP.  failure  had  by C a r l s s o n and  wood  failed  mainly  of  heated  water-  98  0-| 0  ,  1  1  .  1  100  200  300  400  500  1 600  C.S.F., mL Figure  5 . 3 . P l o t of percentage of f i b r e s with t o t a l -ML r e t e n t i o n a g a i n s t pulp f r e e n e s s .  99  swollen  specimens.  refining  of  ML  occur.  will  fibres. this As  refining  abrupt the  fibres of  levels  fibres  from  freeness  be  to  wood  removal  values  trends  of  of  chips  ML were  levels  of  reduction  the  set  the  shives  in  these  reached. produced  freeness,  the  than  over  accompanied pulps  (Table  from those values  those  f o r TMP  at  ML a n d ,  mL CSF were well  not  surface  pulp  300  ML was  does  from  about  the  separation  different  higher  were s t i l l  aspen o f TMP  fibre  pulps  values  of  in  quite  of  much  birch,  refining  100 mL CSF a r e  were  For  surface  ML f r o m t h e  for  rather  initial  since  the  a  whereas  exposed  by  the  levels  28%,  removal  until  recorded.  had o c c u r r e d l a r g e l y  along of  of  confirm  ML  occurred  separation  ML r e t e n t i o n  separation  was  ML r e m o v a l  of  freeness  of  1983)  mL C S F . T h e n ,  The  about  retention  when  29%.  of  high  Fibre  150  matrix,  At  fibres.  removal  continued,  change  to  largely  TMP p u l p s .  for  the  fractionation  conditions little  38%  chemically-pretreated of  atmospheric  (Kibblewhite  ML r e t e n t i o n  the  the  general  in  increase  r e d u c e d f r o m 49% t o  to  unless  an  enhances  close  of  from  allow  The  and  was  easily  that  radiata  TMP  were  reduction  appears  anticipated  when RMP and TMP p u l p s were c o m p a r e d .  slowly,  decreased  also  on Pinus  under  MLr i n d e x  is  chips,  This  observation  freeness  it  untreated  Studies  proceeded  It  reached,  50%. by 4.9)  the  This  the  the  smooth  expected  compared  to  TMP p u l p s . The c h e m i c a l p r e t r e a t m e n t s swelling  of  the  fibre  chosen  wall,  as  in this  well  as  study lignin  should  cause  sulphonation  100  (Giertz  1977) .  liberated of  pulp  birch  Wood t h e n  fibres  will  freeness.  coarse  sulphite  interesting  to  of  for  failure  was  fibre  pulping  soda  between  Dadswell  1958).  However,  degradation  It  wall is  shown  in  between  index,  for  levels  higher  fibres  since  it  clear  CSF,  was  With  of  300  et  achieved  study,  the  pretreatment  ML r e m o v a l as refining,  their  ML much q u i c k e r  5.3).  Aspen  birch  in  fibres,  of  in turn, ML, as  to  and  little  swell  the  which  pretreatment  °C, that  ML r e t e n t i o n  in  to  the  fibre  failed  also  very  at  which  approximately achieve  TMP p u l p  fibres.  and  TMP f i b r e s  the  high, It  liberation,  to  CTMP  by  percentage  MLr i n d e x .  point  of  The  is  which further 300  mL  the  same  CMP f i b r e s  lost  (Figures  showed a q u i c k e r  shown  (Wardrop  aim was  ML was  the  for  did  fibres  freeness  however, than  wood  at  values  those  m a i n mode  and CMP f i b r e s  of  had  is  t h e MLr  ML, t o  freeness  the  It  of  contributor point  yield  terms  major  rendered  removing  135  retention  o c c u r r e d at  not  mL C S F , r e s p e c t i v e l y .  the  high  for  ML l i g n i n .  expressed CTMP  case  conditions  in  °C to  levels  1980a).  layer  2  and t h e the  the  under  and  ML,  high  case,  those  degrade  80%,  S  at  al  that  the  be  was  and  total  from  further  In  under  and aspen  the  chemical  levels  pulps.  this  and  than  having  that,  refining  65  birch  presumably  (Iwamida  r a n g e d from 125  ranged  of  was  to  produced  the  rather than to  temperatures  shown  n o t e t h a t ML s e p a r a t i o n cold  within  ML r e t e n t i o n  also  conditions  mainly  fibre  fail  surfaces  separated  lignin  to  show h i g h  This  pulp  tends  slopes  5.2  response of  the  and than  curves  101  in  these  similar, On  to  other  hand,  within  decrease  similar  each at  for  trends  for  that,  aspen  for  effective  relative  species.  CTMP  at  relative  This  The i n d e x  to  index  than  of  of  was  aspen,  much  also  the  CTMP  4.1  it to  categories  refiner  than pulps  fibres  of  is  more  was  the  ML r e t e n t i o n birch the  for  MLr o f  an  fibres  is  seen t h a t  those in  TMP, where  with ML(r=100).  contained  a  large  of  with the  t h e MLr  aspen.  This  and  5.5.  of  birch.  This  fibres  with  as much t o  In g e n e r a l ,  proportion of  o f ML r e t e n t i o n .  to  than  for  ML compared t o  f o r aspen  i n F i g u r e s 5.4  implies  contained a high percentage  "patched" s u r f a c e p a t t e r n s are given  of  process.  species  reflecting  closer  same  retention  for  accounting  were  in general,  total  higher  values  CMP p r o c e s s  two  with  similar  This  r e t a i n e d ML c o n t r i b u t e d more t h a n t w i c e  MLr i n d e x  these  the  the  M L . From T a b l e  for  with p a r t i a l  partially  birch,  lower  were  -between  showed  drainage.  seemed  that  difference  gave  pulp  fibres  ML(r=100)  those  the  Although they  between  was p a r t i c u l a r l y n o t i c e a b l e  with  at  similar  MLr i n d e x  f i b r e ML t h a n t h e  thereby  retention  values  aspen  MLr  a  following values  indicated a value  fibre,  shows t h a t  rate  similar  difference  birch  the  of  followed  the  CMP f i b r e s  c o n t r i b u t i o n of  average  For b i r c h ,  more e v i d e n t .  MLr i n d e x .  fibres  levels  and CMP f i b r e s  i n removing the  overall  partial  CTMP  ML r e m o v a l ,  than  aspen.  lower  CTMP and CMP. F o r a s p e n ,  retention  the  reached  an e q u i v a l e n t  CMP and CTMP was  An  They  freeness.  the  trend  figures.  then, fibres  Examples of  102  F i g u r e 5.4.  SEM p h o t o g r a p h o f an a s p e n TMP f i b r e s h o w i n g u n e v e n e x p o s u r e o f c e l l w a l l l a y e r s ( P u l p ATMP4).  F i g u r e 5.5.  C r o s s s e c t i o n o f a s p e n TMP f i b r e s s h o w i n g p a r t i a l r e t e n t i o n o f ML ( p u l p A-TMP3).  103  It  i s important  of  MLr  e x h i b i t e d by  of  the  processes  CTMP f i b r e s , TMP.  to note  severe  study, TMP  that  pretreatment.  low  freeness  birch pulps.  I t can be  chemical  pretreatments  improve ML  o f ML or  it  layer  was  found  absence  was  presence  was  of the  observation  by  Aspen  of  than  concluded  either CMP  levels  values  and their  did  the  t h a t even  of the type  removal beyond  basically recorded fibre of the  but  not  provide  of  found  the  t o be  removed  the  used  that  in  the this  achieved  be  the  chips  but  examples boundary  case also of  species  of  the  study.  by  be  ultimate  The  the  fibre  separated not  only  for  TMP  for birch  and  in  retention f o r the  for fibres fibres. along  a s p e n TMP layer  the  the  same  2  the  layer  was  When  largely  ML  because  T h i s was  found  from c h e m i c a l l y - t r e a t e d  Figures or  -S^  to  o f ML.  layer.  by  replicas,  happens  the  i t was S  exposed  technique,.  surface  retention  surface, from  This  what of  whose  better assessed  TEM.  to  the  mentioned  layer  The  s u r f a c e under  cause  followed  I t s h o u l d be  i n f o r m a t i o n as  separation  differences  this  main  had  bulk  associated with  requires preparation of  from  layer  in  layer. the  layer.  the  fibre  only  bulk  closely  w a l l would p r o b a b l y  not  does  t o be  of the  however,  The  exceeded  levels  processing.  presence  to  were n o t  came c l o s e r t o t h e MLr  at  c o u l d not  Retention  was  fibres chemical  however,  corresponding more  TMP  with  counterparts  that f o r a given species, the  near  5.6  and  5.7  the  fibre  are S^/S2  fibres.  retention  between  general  pattern  processes as  for  or ML  104  Figure  5 . 7 . TEM p h o t o g r a p h o f a s p e n TMP f i b r e b u n d l e i n c r o s s s e c t i o n s h o w i n g s e p a r a t i o n o f t h e S± l a y e r near the S1/S2 boundary (pulp A-TMP1).  105  retention. For  There  instance,  there for  was  were i m p o r t a n t  when  aspen than t h e r e  was  that  surfaces  i n part  presented  f o r aspen  h a d more  supported  partial t o the S  ML  area  i n which the  Figure  the  for  removal  with but  ML  removal  that  d i d not  Thus,  will  have  aspen  S-j_ l a y e r .  exposed  many  t o have  e x p o s e d i n an a s p e n TMP  fibres  two  .tends  MLr  of  any  5.8,  5.10  to  MLr  aspen  a  This  fibres ranging  transitional  of the  fibre  show  o f ML  cause  a  and S-^r v a l u e s .  and  birch  layer  i s depicted  S-^r v a l u e s  refiner  and 5.11,  of S-jys  not only  pretreatments  indicating  separation.  2  that  the  reduced or  This  of  suggests  of the type  used  in to  increased the  play  separation  severity a  of  the  comparatively  that  application  relative  t o TMP the  a  fibres pulps,  f o r aspen,  in this  of the  smaller  of  difference  that  study  are  and S  layer.  chemical  as  F o r aspen,  t h e number o f  reduction  was  pulp,  f o r weakening t h e boundary between t h e  layers,' causing difference  between  figures  retention  responsible  appeared  (Figure 5.8). This  i s e x p o s e d . An example  pretreatment  also  chemical  with  the fact  i s a consequence  partial  between  by  i n Figures  last  chemical  o f MLr and S ^ r  as i t d i d i n b i r c h .  areas  disparity  the  illustrated  these  fibres,  applied,  5.9.'  Basically,  ML  TMP  layer  2  retained.and  small  was  ML r e t e n t i o n . The e x p o s e d s u r f a c e s  from  being  pretreatment  was f o r b i r c h f i b r e s  S-L r e m o v a l as c l o s e l y  follow fibre  chemical  a l a r g e r d i f f e r e n c e between v a l u e s  indicates  in  no  d i f f e r e n c e s due t o s p e c i e s .  2  The  pretreatment  role  than  the  106  A S P E N MLr  Q • ASPEN S i r BIRCH MLr BIRCH S i r  Figure  5.8  D i s t r i b u t i o n p a t t e r n o f ML and layer r e t e n t i o n i n a s p e n and b i r c h TMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-TMP3 and B-TMP3)  107  A S P E N MLr --E3--  ASPEN S i r BIRCH MLr —K —  BIRCH S1 r  >50 Figure  5.10.  =100  D i s t r i b u t i o n p a t t e r n o f ML and retention for a s p e n and b i r c h CTMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-CTMP2 and B - C T M P 4 ) .  A S P E N MLr --E3--  ASPEN S i r BIRCH MLr —K—  BIRCH S i r  <50 Figure  >50  =100  5.11. D i s t r i b u t i o n p a t t e r n o f ML and retention for a s p e n a n d b i r c h CMP p u l p s o f s i m i l a r f r e e n e s s ( p u l p s A-CMP3 a n d B - C M P 3 ) .  108  treatment for It  itself,  is  evident a  For  on  5.8,  was  7.82.  of  pattern  type  S  development point  for  "out/in"  1  effect  fibres  showed  this  aspen  fibres.  Birch  fibres  separations  unbeaten  kraft  Presumably, separation  S  feature  more  showed t h i s  delignification between t h e  S]_ and S  Figure  shown  is  clear quality  evidence  layers,  low  fibres in  was  a  the to  Clearly, than  did  of producing  layers  in  levels  of  4.3.  2  when  referred  frequently  S  an  separation  and  was  tendency  of  even  at  Table  layers  of  processed.  This  birch  MLr  value  detachment  depicted  2  of  visible  and  of  the  levels)  boundary.  is  for  it  even  freeness  in  as  2  present  the  species.  surface  was  This  presented  between  pulps,  2  the  Thus,  fibre  and  removed.  S /S  quality  critical  there  was  surface  and CMP c u r v e s  further preferential  birch  partial  the  wood b e i n g  (high  a l o n g or near the  the  of  the  layer  refining  TMP p u l p s  CTMP  fibres,  been 2  the  of  that  and on  respectively.  between  S-L f r o m t h e  than  pattern  pulp  had n o t  the  similar  freenesses.  calculated  for  for  were  and 5 . 1 1 , fibre  value  5.11,  on t h e  separation  fibre  layer  and  refiner  S]_ layer the  true  similar  conditions  larger  distribution  birch  in  (88.16)  also  heavily  starting  as  Chi-square  5.10  the  initial  of  a  was  Figures  depends  the  processing  of  5.10  response  significantly  This  that  for pulps  the  example,  distribution  MLr o r S^r p a t t e r n s  from F i g u r e s 5 . 8 ,  different  depending  For  the  CTMP a n d CMP f i b r e s  caused  in  since  even  Figure had  segments  in  5.12. caused of  the  109  Figure  5.12a.  Figure  12b.  Unbeaten b i r c h k r a f t pulp f i b r e s i n cross s e c t i o n showing gaps between t h e a n d S2 layers i n bright f i e l d illumination.  Same f i e l d  under p a r t i a l  polarized  light.  110  fibre. not  By  comparison, t h e  produce  chemical  these  separations  composition  interface  unbeaten aspen k r a f t 3.4).  did  Thus,  the  and bond s t r e n g t h at or near t h e S-jys  of the b i r c h  fibres  those  of t h e  aspen f i b r e s .  birch  fibres  i s thought t o be  chemical  (Figure  fibres  appear t o be  The  different  s e p a r a t i o n of caused by  a c t i o n s s i n c e they were not  than  and  S  mechanical  observed  2  in  2  and/or  in fibres  on  wood c r o s s s e c t i o n s . •At  freeness  birch  TMP  levels  higher  fibres  than  300  demonstrated  this  f r e e n e s s v a l u e s c l o s e r t o 100 mL in  only  partial  3%  the  l e a v i n g the  not observed  fibres high  produced levels  levels.  fibres.  CSF,  CSF,  about  out/in  20%  of  effect.  At  t h i s f e a t u r e appeared  Therefore,  most  of  the  S-^/^  s e p a r a t i o n s had r e s u l t e d i n t o t a l s e p a r a t i o n of  S-j_ l a y e r , was  of  mL  For  of  S  l a y e r exposed. T h i s marked  2  f o r b i r c h CTMP nor CMP from  these  effect  fibres,  even  trend  f i b r e s . Instead,  c h e m i c a l l y - t r e a t e d wood c h i p s  out/in  at  low  i t i s evident  pulp  that  the S /S  p o i n t where the S^ had  totally  but  remained  1  surrounding  example i n F i g u r e 5.13.  the  freeness  the  partial  birch  sheath  o f S^  layer,  but  fibres and were  ML  separated as  from the  S  2  i s shown  at  the  layer in  An extreme case o f an u n a t t a c h e d  are,  the S^  These f i g u r e s i n d i c a t e t h a t  least  i n part,  l a y e r s t h a t had not  from  gaps became l o n g e r , t o  2  fibres,  l a y e r i s shown i n F i g u r e 5.14. these  the  showed  s e p a r a t i o n s d i d not always r e s u l t i n removal o f the S^ the c e l l w a l l . Rather,  the  removed  covered  separated  during  the  by  from t h e  a S  2  mechanical  I l l  Figure  5.13. TEM p h o t o g r a p h showing d e t a i l o f t h e gap p r o d u c e d between t h e and S l a y e r s . The l a y e r had s e p a r a t e d b u t r e m a i n e d s u r r o u n d i n g t h e f i b r e ( p u l p B-CMP4). 2  Figure  5.14. B i r c h CMP p u l p f i b r e s i n c r o s s s e c t i o n . N o t e the f i b r e s i n which t h e l a y e r has c o m p l e t e l y s e p a r a t e d b u t s u r r o u n d s t h e f i b r e ( p u l p BCMP4).  112  defibration chemical  process.  pretreatment  increased  number  refining,  and  S  2  layers.  without  go  also  away  S  from  the  likely  the  and  layers  S  1  has  the  in  the  et  gap  case with  1989)  al  during  such  surface  i n TMP  as  process  relative  lack  of  Layers  hemicellulose-  in  failure,  increased  compared t o  as  longitudinal  instead  The  and  decompression  high  rigid  upon  the  momentarily.  the  the  Presumably,  elongate  fibres.  fibres  the  to  for  the  and  well  deform as  1962) ,  TMP  size.  as  1976), to  due  fibres  between  compression  fibres  fibre  birch  expanded  of  fibres  responsible  features  (Pearson  (Meier  1  be  extended  cycles  elasticity,  containing  to  of  retain i t s original  (Hoglund  causes  high  the  layer  in refining  rigidity with  out/in  The  forces  softening  seems  for  through  stresses shear  of  a memory t o  fibres  The  of  breaking  as  is  more  removal of  CTMP and  CMP  ML  fibres  supports t h i s i n t e r p r e t a t i o n . Giertz  (1977)  observable the  Si  on  layer  primary  the  that  the  wall  manner as  fibre  a  "rolling  surface  exposure  to  of  had  reported  wood  and  hardwood  was  softened  the  occurred as  if  layer with  the  S  chips in  were  by  the  layer  2  of  the  primary  wall  such  a  peeled pulp  Law  being  removal for  were  rolled  al  chips.  chemically  in  fibres.  et  of  hardwood of  way  off  s u g g e s t e d mechanism f o r r e m o v a l o f s p r u c e TMP consisted  mechanism  pretreatment  s p r u c e TMP  "skinnings"  sleeve"  explain  produced a f t e r chemical  indicated  pretreated,  also  the and  r e f i n e r pulps He  reported  that the  the same  This  was  (1985) .  The  surface back  layers  along  the  113  fibre  as a s l e e v e  layer  cracking  This  rolling  pulp  slides  cross birch  sleeve under  refiner  that  effect  was  highest  the light  the  CTMP  number  relatively  being CTMP  frequent.  8%  a n d CMP  Figure  not  t h e one s u g g e s t e d  sectioned  of the  i t . This  (Wardrop et be  noted,  view  at  based  pulps.  on  f o r aspen  analyzed  and  also  be  out/in  pulps,  in a  fibre  fibre  w i t h any  the  refiner  of  aspen  I t should  presenting  however,  off.  a n d n o t on  were n o t n o t e d  fibres  sleeve  by G i e r t z  t o the primary  was  fail  pulps,  at  the  sample.  skinnings  In  were  i n this  study  was  (1977). I t a p p e a r s as i f t h e and r o l l i n g  rolled  the point  of the  layer  5.16 shows a c a s e i n  back at  indicating  that the  which  skinning  the  b a c k seems t o be c a u s e d by t h e i n i t i a l l a y e r and n o t t h e p r i m a r y  i s supported  the  observed  wall. Figure  l a y e r had been  separation  to  of  small  of r o l l i n g  a p p e a r e d . The r o l l i n g  to  o r CMP  a r e due t o s e p a r a t i o n  which t h e fibre  skinnings  peeled  5.15 shows e x a m p l e s o f t h e s e .  mechanism  r a t h e r than  study  of the  on o b s e r v a t i o n s  microscope  of the fibres  The  skinnings  fibre  being  was b a s e d  In t h e present  pulps,  the helix  and l a m e l l a e  mechanism  i n aspen  stated  birch  and f i b r i l s  sections.  frequency  and, s i m u l t a n e o u s l y ,  S^/S2  by t h e t e n d e n c y  boundary  wall  o f hardwoods  for alkali  a l 1961, C a r l s s o n a n d L a g e r g r e n  external  soaked  wood  1957) . I t s h o u l d  however, t h a t t h e mechanism p r o p o s e d by G i e r t z was  based  on b i r c h  the  alkaline  investigation.  bisulfite  chemimechanical  pretreatment Thus,  pulp,  conditions  i t i s possible  that  and n o t  for  used  in  this  these  different  114  Figure  5.15.  B i r c h CMP f i b r e s showing r o l l i n g " (pulp B-CMP3).  "skinning" or  "sleeve  Figure  5.16.  B i r c h CMP f i b r e s s e c t i o n e d a t t h e p o i n t where skinnings occurred along the layer. Photograph taken under p a r t i a l p o l a r i z e d l i g h t (pulp B-CMP4).  115  conditions  might  be  s k i n n i n g mechanisms The  mechanism  attributed S  chemical the  S  It  was  presented  a  weak  and  hardwood  TMP due  removed from S /S 1  In  from  either  that  It  fibre  S  suggested is  fibre or  S  although the in  ML and  expose  chemical  matter  that  prevented 1  / S  2  S±  in  transition  skinnings  greater  CMP p u l p s ,  a  need  evidently  no  is  stronger  that,  surface  when  then  and  and  fibres  layer  2  was  might  skinning  birch  not  TMP  between t h e  even  is  the  spruce  hardwoods  study  TMP f i b r e s ,  CTMP  to of  the  outer or  S-L/S  2  did  layers  not were  proportions  probably because  also  obvious the  recorded  layer,  fibres  having  the  of  the  boundary.  not  that  only  of  the  somewhat for  were  outer  than  of  weak  as  a  also  layer  mode  of  classified peeled  away  ML a l s o o c c u r r e d l a r g e l y  The m a j o r  showed  ML p e e l i n g  length  appeared  observation  not  effect  were between TMP f i b r e s  TMP p u l p s  presenting  out/in  This peeling  category  fibres  the  having  the  fibres.  but  a  for  boundary,  2  of  The f a c t  in  4.3).  near  this  to  the  addition  (Table or  / S  different  bonds.  2  separation as  1  causing  transition  undergo  applied.  hardwood  fibres  Giertz  in this  exposure  1977). in  S  was  skinning  occur  to  However,  pretreatment  (Giertz  by  indicated  pretreatment  for  effective.  a p r o b a b l e weak  layer.  2  t o be  proposed  to  layers.  2  responsible  differences  and e i t h e r  a higher  longer.  TMP f i b r e s ,  portion This peeling  the  fibres layer-  attached  to  the  substantiates along  in  CTMP o r CMP  number o f  —mainly along  peeled  found  on  the S  the 1  / S  2  116  b o u n d a r y was more e f f e c t i v e An  i m p l i c a t i o n of the  that  chemical  fibrillation case  for  pulp  and  5.18  CTMP a  than  under  filaments  at  the  appearance  and  not  Marton layer TMP um  to et  was  of  al  They of  thickness  fact,  birch  the  of  of  pulps the  fibre  as TMP be  S  the  fibres  there  ML and S]_  30%),  2  5.17  TMP and  it  is  into  long  layer.  SEM  i n F i g u r e s 5.19  values,  more  Since  wall  the  the  Figures  fibre  (over  from  suggested  responsible  layer  initial  these  largely  f o r the  of  and  5.20  main d i f f e r e n c e is  that  it  due  to  this  was  with  layer  this  the  thickness  poor response  shown  restricted  TMP f i b r e s  of  the  Populus and B e t u l a ,  weak bond a t  strength  that  reported thicknesses  investigation,  retention  to  illumination. degree  TMP and CTMP  (1979)  species  present  the  freeness  be  in  stiffness  fibrillation.  pulping. for  in  to  f i b r i l l a t i o n i n aspen  o f R48 p u l p f i b r e s  lower  observed  appeared  is  increased  investigation,  birch  of  fibrillation  photomicrographs  not  this  contrast  between  originates  that,  and  extent  difference  that  in  was  (1977)  cause  from CMP o r CTMP p u l p s .  phase  retention  expected  show  those  would  This  used  aspen  compare t h e  large  layer  fibre.  from  pulps  was  the  conditions  fibres  fibrillated  mechanism p r o p o s e d by G i e r t z  pretreatment  of  the  t h a n f o r CTMP o r CMP f i b r e s .  than S^/S  2  S^  did  S-j_  hardwoods  to  0.12  it  to  um and  was  the  layers aspen  controls  S  2  0.21  In  not  t h e Sj_  presented  In less  of  seems t h a t  the  the  layer.  because  boundary. It  bond t h a t  the  respectively.  that  access  thick  of  of  of  the it  is  separation  of  117  Figure  5.18.  Whole a s p e n CTMP p u l p . N o t e l e s s e r f i b r i l l a t i o n compared t o t h e TMP p u l p ( p u l p A - C T M P 1 ) .  118  Figure  5.19.  SEM p h o t o g r a p h o f f r e e z e - d r i e d a s p e n TMP f i b r e s (R48 f r a c t i o n ) . The f i b r e s a r e s t r a i g h t , stiff and f i b r i l l a t e d ( p u l p A - T M P 4 ) .  Figure  5.20.  A s p e n CTMP R48 f r a c t i o n . F i b r e s a p p e a r e d t o more f l e x i b l e t h a n i n TMP ( p u l p A - C T M P 4 ) .  be  119  the  S-L  layer  and,  consequently,  the  exposure  of  the  S  on  the  2  layer.  5.1.2. The  E x p o s u r e and D e l a m i n a t i o n o f t h e  exposure  retention fact  of  of  layer  Sj_  The  results  shown,  layer.  allows for  of  index  2  As  ML  layer,  CTMP  or  Similarly,  more  S (e=100),  in  2  chemical not  a  lower  When  ML was  retention S  2  highest  the  of  exposure  total  S  S e 2  levels  retention  the  S e 2  2  pulps. the  S  showed near of  the  removed  in  aspen  resulted  than  birch  index  exposure. was  for  and t h e  much h i g h e r  in of  layer,  2  shows  S  particularly  as  showed  follows.  the  higher  with  TMP f i b r e s  pulps,  are  layer.  2  surfaces  of  that  study,  though aspen  percentage  birch  S  this  c o n t r i b u t i o n of for  species.  the  the  of  indices  2  TMP f i b r e s ,  TMP. B i r c h  The r e l a t i v e  S e  explained  in fibre  highest  of  are  freeness,  same  exposure,  c a n be  also  values  finding  used  2  are  pulp  the  exposure  S  versa.  and  retention  100 mL C S F , even  ML. T h i s  4.4  vice  had h i g h e r  This  most  and  2  against  from  ones  data  i n which p l o t s  low  made  S^ l a y e r s  index  the  had t o t a l  like  of  cause i n c r e a s e d exposure  TMP f i b r e s  freeness  from  TMP  treatments,  r e q u i r e d to  Birch at  the  as more r e t e n t i o n  and 5 . 2 2 ,  TMP p u l p f i b r e s  fibres  in  Table  2  pulps  are  the  and S ( e = 1 0 0 )  expected  CMP  of  depends  exposure  S^r,  in  i n F i g u r e s 5.21  respectively.  than  of  given  Layer  course,  layer  2  exposure  are  2  S  of  those  less  S e  S e  and t h e  layer,  2  r e l a t e d to  in part,  presented  S  the  inversely  the  the  S2  lower  had  fibres  the with  S (e=100)  to  relative  to  2  120  A-TMP  jk. A-CTMP x  A-CMP • B-TMP ® B-CTMP  M B-CMP  "0  100  200  300  400  500  600  C.S.F., mL F i g u r e 5.21.  0  P l o t of S2 freeness.  100  200  exposure index a g a i n s t  300  400  500  pulp  600  C.S.F., mL F i g u r e 5.22.  P l o t of percentage of f i b r e s with t o t a l l a y e r exposure a g a i n s t pulp f r e e n e s s .  S  2  121  aspen, S  which c a r r i e d h i g h p r o p o r t i o n of  exposure.  2  pulps S  featuring  layers  2  The  large  proportion  a partial  (out/in  correspondingly  separation  effect)  large  of  seems  number  fibres  with p a r t i a l  fibres  in  b i r c h TMP  between t h e  to  be  responsible  of  fibres  the  same  with  and  the  for  the  total  S  2  exposure. The  general  except  trends  that  they  retention  behavior  of  of  the  S  less  pretreatments than  of  as  the  S  Figures  and 5.24)  Concentric  delamination  of  the  (Ruel can  S  2  layer  in  be  at  treatment  softening  of  general,  the  S  pulp fibres more  wood  fact,  fibre  Thus,  show  that  chemical  were  the  slopes. 4.5  damage  and and  i n beaten  chemical  lamellar  demonstrated of  fibres  structure earlier  delamination subjected  because  cellulose  of  lamellae  present  delaminated  aspen  layer.  d i d show some d e g r e e o f  fibres  for  2  this  refining,  the  S  (Table  degree  the  within In  exposure  from  was  of  more  into  the  some  for to  layer.  2  In  the  pattern  steeper  occur  shown  followed  exposing  insights  S^r,  in  recorded  known t o  prior  accessibility  refiner  is  least  expected  in  originating  1979) .  expected,  chemical  the  5.22  for  been  inverted  displayed was  gain  (Wardrop 1 9 6 3 ) .  a l 1978,  et  layer to  fibrillation  fibres  curves  has  largely  the  and  effective  2  possible  layer  those  as  ML r e s u l t i n g  5.21  aspen  of  pulp  S^  of  as  Since,  followed  2  more  Delamination 5.23  S e  Figures  were  for birch,  the  retention  layer.  2  are  2  inverted.  MLr, the  i.e.,  S e  are  earlier,  MLr,  of  study,  CTMP  the and  hardwood  delamination.  in  to  In  and CMP  ASPEN REFINER PULPS  Figure  5.23.  Percentage of aspen r e f i n e r  fibres pulps.  showing  delamination  in  BIRCH REFINER PULPS  Figure  5.24.  Percentage of birch refiner  fibres pulps.  showing  delamination  in  123  than  in  TMP p u l p s .  treated even  chips  though  Chemical  As  presented  more  TMP f i b r e s  combined  concentric with  TMP p u l p s .  Therefore,  S  softening  of  chemical  Although of  this  separation  microscope, recorded the  it  for  exposure  pulps  once  the  with  the  S  is  and and  between  the  S  delamination layer  during  fibrillar in  Figure  S  took  to  nature  as  in  appears  the  to  as  seen  under  in  which  that,  showed  This  levels. external  was  The  of  related  the  degree  3.6).  true that  takes  place  this  differed  F o r CTMP  a r e p r o d u c e d . An example  had  is  layer.  In  the  somewhat  TMP  separation  from  pulps,  measured,  pulps.  gradual  treatment  other  particularly  from  recorded  as  with  delamination  quantitatively  cleanly,  light  implication  fines  refiner  the  f o r most  delamination  of  a  case  be  conjunction  indicates  be  more  mechanical  layer,  2  (Figure  mechanical  than  out  other  appeared  caused  point  not  place  layer  2  refining  layer.  2  wall.  delamination  the  S  the  to  production  although  delaminations,  of  softening,  layer.  2  chemically-  recorded  freeness  TMP and  with  cell  fibres  the  of  exposure  analyzed  exposed,  type  delamination within  of low  2  S  be  the  possible  However, degree  at  the  T a b l e 5.1  of  showing  delamination  2  the  could  features.  fibre  was  within  majority  total  limited  feature  from  delaminations  treatments  to  pulps  fibres  h a d more  pretreatment  extensive  expected,  fibres, occurred  and CMP f i b r e s ,  peeling  of  which  fines  is  shown  the  for  of  S  2  a  birch  5.25.  Delamination  of  the  layer  was  also  observed  in  124  Table 5.1. Percentage of f i b r e s with t o t a l S l a y e r exposure from among the f i b r e s showing d e l a m i n a t i o n . 2  P U L P ID  % OF S2(e=100) OF D E L A M I N A T E D FIBRES  A-TMP1 A-TMP2 A-TMP3 A-TMP4 A-CTMPl A-CTMP2 A-CTMP3 A-CTMP4 A-CMP1 A-CMP2 A-CMP3 A-CMP4  63 64: 56 69 7 45 79 66 14 54 64 64  B-TMP1 B-TMP2 B-TMP3 B-TMP4 B-CTMP1 B-CTMP2 B-CTMP3 B-CTMP4 B-CMP1 B-CMP2 B-CMP3 B-CMP4  30 50 33 67 63 77 96 75 58 89 70 66  125  Figure  5.25.  TEM p h o t o g r a p h o f a b i r c h CMP f i b r e s e c t i o n showing d e l a m i n a t i o n o f t h e (pulp B-CMP4).  in S 2  cross layer  126  chemically-treated  fibres  layers  wall  of  the  cell  and - t h a t  the  (Wardrop  1963).  remained  attached  should  layer  occur  in  the  of  TEM. I t  a wood f i b r e  has  Thus, to  under  it  a  higher  is  the  some  2  Sj_ l a y e r  in  chemical  and r e f i n i n g t r e a t m e n t s .  evidence  of  that,  delamination  upon  produce layer  removal,  fines were  measured,  with  fibrils  after  study,  as  5.1.3.  Distorted  When  does i t s  examining  treated  chips,  classified  it  into  resembled  fibres these  became  and  for  CTMP  types  of  evident  and 5.27  not  is  2  show  expected  if  will the  quantitatively can  occur  breakdown o f  removal  S  undergone  material  layer  deserves fines  to  and fibre  fibres that  the  of  TMP f i b r e s ,  i n shape  the  untreated  in  the  S^  further  fractions.  was  record  the  CMP p u l p s . be  shown  and fibres  the  in  Although the done  could  in  the  cross treated  former,  of  i.e., It  distorted  separation with  be  untreated  Figure .3.10.  proportion  better  chemically-  fibres  while  compared t o  as  would  from  treated  of  swollen,  decided  of  categories:  that  were d i s t o r t e d  thus  the  than  formation of  sections  two  section  was  and  i n the  appearance  rounded  Si  The p o s s i b l e  separation  cross  The  more  fibres.  the  when  It  ability  Although  the  delamination  F i g u r e s 5.26  bonding  than  have  layer.  all  Fibres  fibres.  fibres  that  that  lamellation  of  delaminated  of  role  degree  the  intact.  delamination  exhibit  that,  fibres  this  higher  removed  chemically-treated into  of  known  porosity  expected  S ,  is  an  of  image  127  128  analysis  system  intensities of  could  and shape  distorted  Obviously,  that  fibres  there  transitional  factors,  were many  results  that  refiner from  was  pulps  50-70%  seems  fibres  that  and  a  large  proportion  could  and from  birch,  5.28  These  fibres  to fibres  a n d 5.29)  of distorted  that  due  to  showed  fibres  in  approximately  f o r CMP  t o produce  possibly  considered  distorted.  75-90%  f o r aspen  microscopy.  be  chemically-treated chips,  f o r CTMP  than  light  treated.  or obviously and F i g u r e s  from  o f t h e number  similarity  4.6  t o be a t e n d e n c y  fibres  simple  according to t h e i r  (Table  there  an e s t i m a t i o n  untreated  were o b v i o u s l y u n t r e a t e d The  differences i n staining  was done u n d e r  between  were c l a s s i f i e d  detect  pulps.  more  There  distorted  better  liquor  penetration. Since  liquor  vessels  (Wardrop  consistent vessels hand, CMP  penetration  with  i n wood  1963), its  higher  chemicals,  but also  than  The r e s u l t s  CTMP.  showed in  this  chemical  comparatively  number  difference. treatment small  not only  longer  values o f VE  fibre  pretreatments  involved  initiated  the higher  and i t s t h i n n e r  the chemical  treatments  i s largely  times  were  through  the  f o r aspen  are  per unit  walls.  Nevertheless, conditions  different.  concentration  and h i g h e r  o f t h e number  of  On t h e o t h e r  markedly  higher  area  of  temperatures  of distorted  fibres  the large difference provided  d i f f e r e n c e i n t h e number  of  only  a  distorted  f i b r e s between CMP and CTMP. P r e s u m a b l y , t h i s was due t o t h e CTMP  screw  press  in  the  impregnation  system  ASPEN REFINER PULPS  100  90 oo  W £  80i  70 60  Q w  H  50  O  40  04  1 HTf  H oo  3  3  °i  20  10 0 Figure  1  2  3  4  1  2  3  4  5.28. P e r c e n t a g e o f f i b r e s showing d i s t o r t i o n i n a s p e n CTMP a n d CMP p u l p s .  ;  100  BIRCH REFINER PULPS  90-  1 Figure  2  3  4  1  2  3  4  5.29. P e r c e n t a g e o f f i b r e s s h o w i n g d i s t o r t i o n i n b i r c h CTMP and CMP p u l p s .  130  (compression through One the  which  treatment.  CMP  pulps,  fibres  It  liquor  investigation  mixtures  CMP  of  3:1)  which caused  cracks  i n the  chips  penetrated.  of  liquor  penetration  Results i n this produced  treated  were  under the  and  chemically  study  and  fibres  is  uniformity  of  showed t h a t b o t h  c o n d i t i o n s used  untreated  fibres,  treated particularly  CTMP  here,  although i n the  are most  case  of  pulps. should  between  be  mentioned  species  proportions. distorted precise image on  of  e v i d e n t a p p l i c a t i o n o f t h e number o f d i s t o r t e d  fibre and  ratio  or  The  effect  fibres  did  information,  effect  of  not  would  of r e f i n i n g  on  It  early  ribbons stone  is  shown highly  is  not  refining a  in  desirable  be  for  ribbons  smoothness fibre  crack (1963),  of  radial  transwall  enhance mechanical failure  may  pulps  in  refining,  development  on  intact  ribbon  formation  the  the  pulp  help  with  of More  of  an  conclusions  formation of  (Forgacs  a  1982b). part  also  According the  from  of  good  1963).  scattering  could  fibres.  starts  trend.  production  in  the  changes.  (Mohlin  i t  only number  draw  light  originate  failure  to  that  the  bonding,  the  with  shape  studies  distortion  known, on  needed  fibre  fibre  definite  groundwood o r r e f i n e r m e c h a n i c a l  These  of  possibly provided  (RF)  been  degree  follow  5.1.4. R a d i a l F a i l u r e has  the  processes  a n a l y s i s system,  the  that  and  Although initial  start  from  to  Forgacs  radial  failure  131  (cracks  or  splits)  unravelling number the  of  of the c e l l  fibres  frequency  been but  the  wall  i n which  of ribbons  observed also  of  not only  from  in  this  fraction  study.  fraction  radial  (Vecchi may  studied,  the  relative  amounts o f r i b b o n s  cell  wall  higher  f o r TMP  fibres, pulp pulp  (Table  although  might  c u t t i n g may and  5.1.).  softened wall  a  i t approached  reduced  R48  failed  10%  is  anticipated  proportions  t h a t was  radially  during  a s i n TMP,  that  would  the  R48  RMP  on  the  clearly  CTMP o r RF  this  implying  in  CMP this  particular that  refining  fibre  (Figures fibres  d i d not crack  but l i t t l e  3.5 were  the f i b r e  differences in  fibres.  will  of r a d i a l l y f a i l e d fibres  this  used  across  i n most  produce  even  higher  since refining  i s done  u n d e r a t m o s p h e r i c c o n d i t i o n s and t h e f i b r e s w i l l Presumably,  Vecchi  information  chemically-treated  that  and  proportions  i n A-CTMP4.  fraction  RF were f o u n d between CTMP and CMP It  has  softwoods  5. 30 and 5.31) was  t o t h e p o i n t where r e f i n i n g  t o t h e same e x t e n t  from  reliable  the fact  h a v e been p r e v a l e n t Otherwise,  to  formation  resembled  only minor  be a s s o c i a t e d w i t h  showed  relates  produced.  that  and was  pulps  48/100  4.5 and F i g u r e s  pulps  Ribbon  i n t h e R48  to provide  fibres  occurs  the  i n t e r m s o f f i b r e s h a p e s . The  i s expected  of  l a y e r . Thus,  1969, S c a r a m u z z i  the  fraction  proportion  subsequent  appear i n g r e a t e r  R48  The  the  2  failure  r a t h e r than  However,  i n the pulps  the S  i n mechanical  hardwoods  the middle  along  and  i n the pulp.  1968). T h i s c h a r a c t e r i s t i c in  fibre  c a u s e more t r a n s w a l l  be  failure  stiffer. as w e l l  ASPEN REFINER PULPS  1 2 3 4 1 2 3 4 1 2 3 F i g u r e 5.30. Percentage of f i b r e s showing r a d i a l aspen r e f i n e r p u l p s .  4 failure in  BIRCH REFINER PULPS  1  2  3  4  1  2  3  4  1  2  3  4  F i g u r e 5.31. Percentage of f i b r e s showing r a d i a l f a i l u r e i n b i r c h r e f i n e r pulps.  133  as  more c r a c k s  Whereas  little  fibres  due  pulps,  birch  low.  i n the  change  to  the  TMP p u l p s  showed  The  indicates  aspen  produce  may  in  refining  freeness  This  wall.  further  freeness.  to  fibre  be  number was  number  of  that  birch  may  propagate  related  to  the  radially-failed  detected  for  a s p e n TMP  higher' proportions  low  and  of  fibres need  cracks  w i t h ' RF more  cell  RF  at  at  high  refining  than  along  thicker  of  the  S  walls  wall.  2  of  birch  fibres. The in  results  for  RF i n  approximately  TMP f i b r e s  20%  of  the  reported  for  Pinus  radiata  indicated  that  81% o f  the  thus  leaving  The  S  2  ribbons  ribbons which  but  due to  into  mechanical  present  fact  that in  chemical  investigation similar  to  (Kibblewhite  cross  sections  that  TMP p u l p s to  (RF those  1983). were  conversion  as  1963).  pulp w i l l  a  good  is  He  intact,  To  case  a  certain  bonding  radially-failed  fibres  than  those  increased  pretreatment  CMP p u l p s ,  is  produced  fibre more  for  by  the  flexibility important  of  the  softwood  extent, S3  the  layer,  because  that  or  exposed  some  appeared and  CTMP  the  fibre  surface  1959) .  and  of  expose the  to  of  the  (Lange  CTMP  relative  fibrillation  gradual  content  much s t r o n g e r  indicates  of  fibrils,  provide  The  were  the  i n the  carbohydrate  only  are  TMP  only  (Forgacs  high  numbers  not  long  pulps  should  fibres)  fibre  fibrillation  possibly  layer,  this  19% as R F .  increased  CMP i s  in  of  its  in  small  these  pulps  TMP due  than  process, to  the  potential  134  benefits  which c o u l d a r i s e  5.1.5. Breakdown o f The  presence  aspen  refiner  normal then  of  wood  two  aspen  was  examined  all  contained  samples  extent  work  content across This  from  pulps low  of  provide all  of  obtained  because  was,  unbeaten inside  are  parts  staining  or  kraft  in  polars  the when  Due  task  G-layer observed  wood  from sample  wood.  They  The  birch  wood.  at  indication However,  of  the  and s t i l l allow  it  such  sections heights. would  comparisons  sections estimates  the  logs  were  in  the  would  of  G-fibre  different  such  to  which to  TW was  not with  refiner  have  removed  been before  decay.  decided  fibre.  of  i n many s l i d e  and  to  resemble  Alberta.  furnish.  counted  cross  of  in  estimates  tree  therefore,  the  chip  values  aspen  tension  the  sections  could give  accurate  fibre  cross  tension  the  Accuracy of  pulp  of  d i d not  region  of  an enormous  from  some  crystallinity, cross  in  the  accurate  wood  sections  cells  diameter  produced.  amounts  wood c r o s s  that  observing  The p r e s e n c e  River  show p r e s e n c e  not  of  while  Also a third  Peace  G-fibres  c h i p p i n g due t o It  the  noticeable  provided  values  identified.  chipped.  w o u l d have been  have  Structures  trees  unless the  were  noticed  examination  of  could  first  by  d i d not  Examination the  TW was  pulp slides.  confirmed  failure.  T e n s i o n Wood F i b r e s  fibres  the  from r a d i a l  the  assess  the  in  G-layer  fibril  gave  G-fibres  orientation  strong  pulp  would  from be  slides.  intact  and  polarization However,  the  high under  it  was  135  not  possible  reasons:  to  1)  the  encountered  on  possible the  average Thus, the  due t o  to  the  S  31% o f value  variation  5.34.  of  of  pulps  TMP p u l p s  furnish.  (Table  4.7  total  amount o f  was  taken  as  shown  in  indicates  of  light  was  then  fibres  being  G-fibres  and F i g u r e  in  3.4) . An  were  identical  in  the  Table  as  evidenced  was  4.8  G-fibres.  to  that  for  converted  there  by  the  is  their  G-fibre  a  of  the  into  total G-  that  of  walls  of  (when  formation  of  ribbons  r e d u c i n g the  same  time,  exposing  5.35  and 5 . 3 6 . abundant  This exposed  and  from  weight  the of  G-layers, is  as  consistent G-layers  in  This of  Presumably, the  walls  observed  with e a r l i e r RMP p u l p s  Gthe  G-layer),  promoted  R48 f r a c t i o n  c a n be  wood.  breakdown  (1965),  G-fibre  the  the  excluding  Boyce  the  the  thinner  Kaeiser  in  only  included,  conditions.  by  G-fibres  original  TMP p r o c e s s i n g  reported  Figure  the  preferential  G-fibres  in  aspen  of  under  the  the  retention  content  below  of  illustrated  lower  G - l a y e r s were  was  fraction  breakdown  significantly  that  R48  fibres  of  it  c h i p p e d and t h e n  significant  E v e n when f r e e  count  thereby  two  thickness  because  fibres,  the  R48 f r a c t i o n compared t o  as  G-layer  and 2)  kraft  used  G-fibres  T h e r e was  layer  for  pulp.  content  refiner  in  basis  layer.  2  o r i g i n a l wood w h i c h was  The  this  a c c u r a t e l y the p r o p o r t i o n of  raw m a t e r i a l  of  on  and 5 . 3 3 ) ,  sections  measure  this  refiner  in  substantial  cross  aspen  G-fibres  ( F i g u r e s 5.32  polarization Based  separate  the  ("skins"), and, in  at  the  Figures  observations from  Populus  136  Figure  5.32.  SEM p h o t o g r a p h o f G - f i b r e s i n a s p e n wood s e c t i o n showing t h i n G - l a y e r s .  cross  Figure  5.33.  SEM p h o t o g r a p h o f G - f i b r e s i n a s p e n wood s e c t i o n showing t h i c k G - l a y e r s .  cross  137  1  Figure  2  3  4  1  2  3  4  5.34. P e r c e n t a g e o f G - f i b r e s aspen r e f i n e r p u l p s .  1  2  3  4  i n t h e R48  fraction of  138  139  (Scaramuzzi  d e l t o i d e s  free  G-layers,  monitored seen  in  pulps.  are  is  the  R48 p u l p  to  the  action and  the  the  It  of  a certain G-layers  chips  weak  are  fibrillation  lateral  this  filaments  exposed would  a sheet There  was  G-layer  parent  or  any  to  is  at  other Day  expected refining. refining  delamination  5.38  presence  material  the  set  the  is  of  and  during  Figures  fibrillar  increasing  G-layers  (Cote  some d e g r e e o f  It  cross  On t h e  liberated,  the  to  distribution  bonding  show  the  and of  5.40 purple  expected  that  derived  from  interfibre  bonding  in  in  or  paper. no  pulps.  fraction  They  free  G - l a y e r w o u l d be  layer.  of  from f i b r e  pulp.  from G - l a y e r m a t e r i a l .  contribute of  this  free  appear  fractions  fibrillation  produce  hypothesis.  derived  of  the  as  a s p e n TMP  do n o t  the  into  initially  to  of  pulp  the  of  be  pulp,  integrity  evident  seems t h a t  the  extent  the  the  can  seen t h a t  of  presence  different  reported  s h o u l d be a b l e  support  CMP  in  fraction  The G - l a y e r s  shows  fraction.  o f . the  c a n be  show t h a t  N o r b e r g and M e i e r 1 9 6 6 ) ,  Once  it  every  particularly  breakdown to  produce  the  as  which  material  due  1965,  in  It  of  measured,  fractions  5.40.  maintained.  easily,  initial  hand,  through  present  The breakdown  quantitatively  different  5.37  analyses  G-layer the  the  largely  down  section in  within  not  These photomicrographs  G-layer break  although  Figures  G-layers  and V e c c h i 1 9 6 8 ) .  was  wood.  preferential  The not  total  breakdown  amount  significantly  On t h e  one  hand,  of  of  G-fibres  G-layers different  these  two  in from  the  CTMP R48  that  processes  of  pulp the  preserved  140  Figure  5.37. P r e s e n c e o f G - l a y e r s t h a t were d e t a c h e d t h e i r p a r e n t f i b r e s i n t h e R48 f r a c t i o n A-TMP3.  from of pulp  Figure  5.38. I s o l a t e d G - l a y e r s h o w i n g f i n e c e l l u l o s i c f i l a m e n t s d e t a c h i n g from t h e s u r f a c e . F r a c t i o n 48/100 f r a c t i o n o f p u l p A-TMP3.  141  Figure  5.40.  G-layer A-TMP3.  filaments  i n the  P200 f r a c t i o n  of  pulp  142  fibre  length  to  processing,  so  liberating small  chance  on  cracked  similar initially  and An  It  be  other  from  the low  the  rest  of  freeness evident  Examples o f  levels,  these  and  hand,  are  as  minimizing the  a  the  fibres  CTMP  and CMP  a  pattern  fibres,  at  48/100  fraction.  the the  only  radially,  followed  the  since  breaking  for  the  into  TMP  after  that,  G-fibres  R48  was  off  inferred  did  failed  thereby  stripped  is  the  increased.  presence value  shown  least  of  for  some  free  in Figure  G5.41  5.42. important  In  rolled  whereas  and  Overall,  The  behind  left  these  skins  are  likely  in  CTMP t h e s e  fibres,  area  or  as  of  based  shown.  skins  on t h e  when  be  appeared  free  these  to  F i g u r e 5.41  this  source  as  partly  lamellae.  s h o u l d be  apparent  G-  a  thin  skins  of  high  flexibility  shows e x a m p l e s  of  skins.  literature the  strength  effects only  liberation  are  normal f i b r e s ,  surface  the  that  bonding p o t e n t i a l  compared t o  these  regarding  "skins"  twisted  the  large  the  TMP p u l p s  ribbons,  and  consideration  concerns  occurs.  on  to  than  fibres  On t h e  sections,  for  breakdown  fibres  of  cross  that  at  of  CMP o r CTMP f i b r e s  of  Nevertheless,  layers  small.  breakdown  to  G-fibre  the  extent  chance  was  opened.  the  greater  the  G-layers  and  pulps,  of  fibre  for  much  that  G-layers  portion  measured  a  in  had of  chemical  liberated  in  indicated pure  beneficial  mechanical  pulps. large  some  In  pulps,  TMP p u l p s ,  numbers,  but  effects but  detrimental  G-layers they  o f TW  also  were may  not be  Figure  5.42  G - l a y e r exposed a t the c e n t r e o f a f i b r e w h i l e c o v e r e d by t h e f i b r e w a l l s a t t h e e x t r e m e s (pulp A-CTMP4).  144  responsible benefits clear.  for  from  part  the  On t h e  of  the  presence  other  of  hand,  in  this  the  may be n e e d e d .  present  would  seem  would  produce  that  sheets  with  normal  wood.  The  wood,  is  proportion  5.2.  VE  tendency  study  of  to  distribution pulp,  to  Because  a  positively  and  the  chemical  identify  VE  bulkier  for  is  of  use  in  i n terms  components It  from  proportion  a  of  of the  relatively  assessment  of  the  sample.  ones  with  Therefore, survival  VE was  o f VE f r a g m e n t s  size  G-layers  pulps  (measured  accurate  the  their  of  with  it  Elements  printing.  number  pulps,  thus  potential TW  obtained  liberated  assessing  specific  breakdown o f  results  compared  excellent  presumably  minimum  of  fibres,  if  provides  assess  the  from t h e  chemi-mechanical  G - f i b r e s i n a wood  are  the  to  TW  and p u l p p r o p e r t i e s .  that  during  important  designed  the  has  Breakdown o f V e s s e l  Whole  and an i n v e s t i g a t i o n  proportion of  related  of  on  collapsed  fibres  method  unknown  of  seem  The  is  for  TMP p u l p s  effect  proportion  developed  wood b e h a v i o r  simple  low  ribbons.  be  strength  i n which the  G-fibres)  each  lower  wood  studies  the  of  to  However,  for  fewer  technique  tension  study  in  TW  the  CTMP and CMP p u l p s t r e n g t h s study  formation  done  i n the  whole value  it  was  during  picking  considered  refining.  by m e a s u r i n g t h e  The size  p u l p and by c o u n t i n g ,  VE t h a t had  higher  to  fragments,  survived  be the  set  in  size  in  refining. order  to  frequency  145  distribution of  d i d not  particles  alone,  no  VE t h a t The  provide  smaller  conclusion  assess  size  whole  i n VE s i z e  whole  the  fewer  whole  minimum s e t  VE t h a t  d i d not  The r e s u l t s refining of  the  under  VE t o  a n d 5.44 pulps refiner  150  screen  This of  both  is  pulps  of  simplicity  that  the  size  than  the  of  breakdown o f  chip  the  size  Figures  5.43  different  the  different  It  should  be  at  in  zero  clarity.  frequency  particle  90% o f  (smaller  closed  and  is  pulp  reduced  under  was  there  show t h a t  here.  polygon  show  different  distribution for  It  values  is  would  size. VE f r a g m e n t s  um and about h a l f the  on  the  species.  studied  frequency  about  t h a n 250  um.  effectively  for  processes  with decreasing  TMP p u l p s ,  smaller  and 4.14  however,  findings  pulp i f  i n T a b l e s 4.13  because  to  do show  process.  produced  end,  but  used  two  refining  particles  the  the  o r i g i n a t e d from t h e  freeness  that  technique  if  whole  sizes.  particles  similar  anticipated  In  that  fine  size  lower  increase  more  TMP c o n d i t i o n s  pulping  number o f  (or o f  particle  mentioned the  wood  illustrate  of  information  different  F o r example,  production  this  V E , complemented  s u r v i v e the  fine  the  c a n t h e n be c o n c l u d e d t h a t  VE has  presented  of  distribution,  it  value)  With  counting  VE p e r gram o f  no y i e l d d i f f e r e n c e ) ,  on  drawn on t h e  the  distribution.  no d i f f e r e n c e numbers o f  of  um.  fragments  p r o v i d e d by  survival  particle  112.5  c o u l d be  were r e d u c e d t o  information  with  than  information  the  of  measured  were  them were s m a l l e r  than  openings  a Bauer-McNett C l a s s i f i e r .  A large  in  a  100  mesh  proportion  of  j . fi b  50  ASPEN  V.E. SIZE, m  f~w 1000  BH  1200  M  Figure  5 . 4 3 . F r e q u e n c y p o l y g o n s f o r VE s i z e pulps of s i m i l a r freeness.  600  800  1000  i n aspen  refiner  1600  V.E. SIZE, nm Figure  5 . 4 4 . F r e q u e n c y p o l y g o n s f o r VE s i z e pulps of s i m i l a r freeness.  in birch  refiner  147  s m a l l VE p a r t i c l e s the  majority  size to  the  categories.  be  reduced  mostly the  of  in  were  P200)  that  in  the  relative  (Giertz  (sieve  fine  energy VE  pulps.  It  can  fragments  of  of  the  experimental were  wide  regardless  4.15) .  Also,  almost  non-existent  minuscule  that  destroying  the  is  of  these  of  (only of  It  was  the  of  in  large  150/200  only  and Their  on t h e VE  also  amount  freeness  on  their  of  fines  whole  illustrated under  in  VE  B  VE) .  5.45  initial  breakdown  of  fractions the  due  to  of  of  Table  pulps  was  TMP showed  was  from is  effective  in  particles,  In f a c t any  wood c h i p s  a  It  fine  a high freeness. R48  the  and 5 . 4 6 .  TMP c o n d i t i o n s  the  in  information,  whole VE and c o n v e r t i n g them i n t o  no VE i n  C  these  aspen  This  Figures  refining  found and  in  freeness  and  difference was  (parts  whole  high  no  pulps  species  number  refining  virtually  concluded,  used.  but  the  TMP p u l p s ,  e v e n when t h o s e p u l p s were o f were  wood,  in  fragments  present  process  and  ranges  in  of  proportion  4.16,  refining,  VE be  depend n o t  original  found  wood e l e m e n t s .  distribution  refining,  will  and  said  However,  (100/150,.  refiner  however,  upon  VE a r e  fractions  the  survival  values  obvious  these  in  size  Table  um) ,  as  smaller  VE a r e  1977).  74  frequency  the  opening  pulp  the  refining,  of  for  small  in  s u r p r i s i n g that  fraction  p r o d u c e d by o t h e r Although  not  100/200  regardless  and  is  during  abundance by w e i g h t , size  it  accumulated  material  abundant  therefore, numbers  fragments  i n CTMP and CMP p u l p s  fine  fraction  also  also present  Thus, to  the  P200  was  there  TMP p u l p .  that  caused  148  ASPEN REFINER PULPS 100-  F i g u r e 5.45. Percentage of whole VE t h a t s u r v i v e d d u r i n g the r e f i n i n g o f aspen c h i p s .  F i g u r e 5.46. Percentage of whole VE t h a t s u r v i v e d d u r i n g the r e f i n i n g of b i r c h c h i p s .  149  the  VE  these the  fragmentation.  fragments  wood  almost  VE h a d  (Figures  In s p i t e the  of  the  conditions  for  break VE  fact  that  there  was  of  vessel  size of  their so  aspen  down  were  higher will  tendency  be d i s c u s s e d the  the  indicated  by  conditions,  later  of  lumen  diameter) .  This  water  saturation  of  Furthermore, guaiacyl i.e.,  the  units  more  Runkel R a t i o  lignin  (Fergus  (double  and  and  VE  size  birch  to  that  VE a p p e a r e d  aspen  VE as The  under  no  to  whole  generally  TMP  aspen  failure (1978)  conditions  through for  cell holds  wall for  temperatures  the  less  VE  cell  1970, heat  VE  high  producing transwall  and G o r i n g  cross-linked  the  birch,  similar  TMP p u l p s .  of  Yoneda  in  and  with  section.  condition  wood  4.12),  l a r g e r VE o f  birch  defibrated  defibration  pulp  b r e a k down compared t o  in this  and  cells  between  the  birch  pattern  Ohsawa  that  difference  aspen  even t h e  than  VE t o  wood  initial  i.e.,  low  birch  fact  The VE breakdown u n d e r TMP  Moreover,  the  after  finding.  (Table  distribution pattern  any. of of  The  this  for  found  that  readily  only  a significant  um  TMP p u l p s .  a size  in  904  reduced  TMP and k r a f t  elements  was  effective  e v e n more  Presumably,  and  TMP p u l p s .  found  followed  625  difference  reduced to the  s e e n between t h e  have but  down.  confirms  of  was  broken  and 5 . 4 4 ) ,  no  distribution  been  may  particles,  5.43  lengths  respectively,  refining  smaller  already  original  average  were  even  no o v e r l a p p i n g i s  curves  in  into  Further  shear  failure  thickness VE, up  even to  walls,  Hardell  et  sensitive  as  in  over after  170 rich  °C. in  a l 1980), than  the  150  syringyl the  lignin  stiffness  responsible  of  greater pulps  when  D and E)  either  in  the  a large  made  5.43  pulps  and  of  CTMP  of  the  preservation  and  same  VE seems  chips  were  wherein  found i n  Results  in  species.  of  some  whole  VE  of  TMP,  neither  Table  4.15 of  critical  when  distributions  o f TMP  the  shown g r a p h i c a l l y curves  overlap  This  A  these  between v a l u e s  also  CMP p u l p s  o f VE  refined.  c o u l d be  is  be  refining.  Chi-square  This  to  to  o b t a i n e d i n terms  between VE s i z e  5.44.,  contributes  of  difference  and  CTMP o r CMP p u l p s .  distribution  were  TMP p u l p s .  showed  were  Figures  kraft  the  calculated  comparisons and  results  l a r g e VE f r a g m e n t s  to  wall,  flexibility  chemically-treated  number o f  Chi-square  secondary  destruction during  different  compared  (parts  fibre  V E . The low  for t h e i r  Significantly breakdown  i n the  of  with  overlapping in  these  CTMP  nor  VE those  size of  indicates  two  refiner  pulps. As  in  the  case  distribution energy, and  was  given  change For  set  these  a  4.15). at  process  given  patterns CMP  showed  a  dependency  on  pulps  although  Again,  the  initial  and  species,  the  size  refining  when c o m p a r i s o n s were made w i t h i n a s p e c i e s  C i n Table  sizes a  patterns  CMP VE  (parts B  d i s t r i b u t i o n o f VE f r a g m e n t  breakdown o f and  wood i n t o  further  pulp  for  did  not  refining  patterns. species,  the  difference  (Chi-square values) were still  compared  was  (parts  significant  in  in  rather D the  and  VE  small E  case  in of  distribution when CTMP Table  and  4.15),  aspen.  The  151  relatively  small  differences  chemically-treated these  compared  softening  was  proportion  of  the  The  whole  of  of  VE s i z e  significant  effect  as  to  CTMP  and. l e s s It  both  to  difference  clear,  of  is  The  and  5.43  first  earlier,  the  whole  to  take  to  and  to  i n VE s i z e  A-CTMP4 more  a  larger  Yet  the  severity breakdown  distribution  on  the  one  fine  cutting  hand,  and  particles  in  both  CTMP  and CMP p u l p s ,  to  these of  some  pulps  large  CMP on  in  than  preserved  Reduction  wood  size  that  Thereby,  of  and CMP p r o c e s s e s ' .  i n p a r t due t o  large  5.44)  close for  place and  note  that there  appeared, at the  aspen,  VE s i z e  fragmented, fragments.  VE.  of  initial  CTMP  slightly  of  that  CMP p u l p s .  the  from  the  extent may  be  VE w o u l d  the more  require  refining.  peak  particularly  the  pulp  aspen,  VE p i c k i n g .  interesting  (Figures  of  difference  v a r y much when t h e  reported  the  large  indicate  and  since by  however,  whole  more e x t e n s i v e It  for  elements  birch  integrity prone  similar  pulps  preservation  CTMP  d i d not  production  is  in  the  CTMP and CMP may be  also  other.  for  refiner  the  pulps,  increased,  indicated  the  TMP  VE  VE were  between a s p e n  for  against  treatment  patterns  compared t o  responsible  of  distribution  wood,  between  set  after  were the  by t h e a  other  kraft  a  the  as  peaks.  mentioned  second  peak,  been  proceeded  number  of  Breakdown a p p e a r e d  VE h a d  fragmentation hand,  end,  two  distribution pattern  curve.  of  and CMP c u r v e s  essentially  But  the  number  CTMP  lower  polygon. followed  further  On t h e  i n both  of  initially from  these  VE r e m a i n e d  as  152  whole  entities  in  Figures  5.45  VE t h a t  d i d not  here  and  where  also  also  is  difference species)  provide  suggest  the  reveal  only  the  particle  size  that  fine  to  CTMP p r o c e s s . combined  freeness  on  mechanical  of  the  primarily (and  fact,  these  reduction  of  the  those  amount  as  in  the  case  severity  of  the  chemical  all  defibration  is  only  For  fibres  CMP v a l u e s .  instance, and  necessary  of  those  for  of  of  of  fibre  kraft VE  shows  for than lays that  breakdown,  treatment pulps VE.  and  that,  whole  This  kraft  of  i n CMP  temperatures  VE,  defibration.  o f VE  whole VE t h a n  p r o d u c e d whole VE i n amounts to  in  actually  application  TMP and  of  number  Regardless  more  cooking  but  a disparity  measured.  were c l o s e r  not  survived  which are  the  length  that  increased  chemical  higher  could  VE b r e a k d o w n .  with  preserved  F o r CTMP p u l p s ,  between  breakdown  depended  the  with  CMP p u l p s ,  TMP p u l p s .  value  The h i g h e r  cooking times,  somewhere the  minimum  an  of  VE  particles,  CMP p u l p i n g o b v i o u s l y  high  of  distribution,  of  distributions,  indicates very  number  species,  longer  and  CMP p u l p s  alone  extent  than  pulping,  is  on t h e  on t h e  smaller  the  number  In  distribution  the  S i m i l a r VE s i z e  the  the  It  and  refining  4.16  on  apparent.  of  size  about  VE c o n t e n t ,  CTMP  Table  process.  a r e b r o k e n down i n t o  did  in  information  becomes  information  nothing  refining. whole  that  complete  Such g r a p h s  results  between  effect  a given  clear  The  5.4 6 p r o v i d e  show t h e  whole VE f o r It  pulp.  b r e a k down d u r i n g r e f i n i n g .  the  between  figures  the  before preserve  Mechanical  linerboard-grade  pulps.  153  CMP p u l p s  have  CTMP w h i c h  larger  in turn,  same p a t t e r n  than  diameters  and  available  on  refining,  it  most damage  higher the is  (part  no  cutting  found,  number o f  and  5.4 6) .  than is  were  (1.3-1.6  um)  difference  follow  the  i.e., 1980).  unite  orifices  several  pits  was  (1.8-2.3  V E . The  fibril  wall minute  frequently  slit-like to  to  was  in. 5.45  wall  thickness  than  in  aspen  (1975),  be t h e of  the hand,  coalescent  (Panshin  apertures grooves  of  walls  of  On one  with  the  cause VE  apertures  confluent  form s p i r a l  The  fragments  um)  um),  inner  pulps.  to  (Harada 1 9 6 5 ) . (2-4  the  (Figures  angle  slit-like  to  however,  Goring  appears  the  significant  CTMP  reduced  and  between  CMP p u l p s  a  refining  as  the V E .  attributed  species,  readily  of  TMP o r  aspen  is  VE d u r i n g  were made  part  survived  Musha  are  These  in  larger  be'unlikely  fragmentation  pitting  of  of  A l t h o u g h VE c e l l  vessel  pits  be  between  to  birch  i n the  would  in birch  according  in  peeling  for  less  information  layers  found  The  VE a r e  walls,  no  surface  freeness  VE were more  direction  apertures,  cases  low  be h i g h e r  intervessel  Zeeuw  the  thinner  Although  than  TMP p u l p s .  however,  i n CTMP p u l p s  could  in intervessel  bordered p i t s  de  Only  fractions  of  distributions  were  from aspen.  reduction  birch  VE s i z e  whole VE t h a t  those  fibre  those  their  form o f  difference  Birch  r e p o r t e d to  size  i n the  which  in  important  the  of that  differences  effect  to  rigidity.  F i n Table 4.15).  difference  most  due  presumed  of  long  VE. Obviously,  peeling  w i l l be  of  l a r g e r than  to  fibres  When c o m p a r i s o n s species,  are  applies  preserved  amounts  and  in  many  that,  upon  154  refining,  facilitate  and  5.48).  pits  (8-12  not  On t h e um)  lead  to  the  unraveling  other  and t h e  hand,  aspen  separation  unraveling  of  of  the  has  the  pulps  has  more  VE i n  Also,  refining  higher  is  between  refining. refiner  V E . Instead,  It  than  birch  also  because  pulps  gram o f in  two  be  not  the  Due  intervessel  apertures aspen  did  V E were  resulted  in  The  large  species  only  because  aspen from  difference  is  accentuated  to  expect to  fibres On  and  the  the  1977) .  relative  Thus,  it  effects  is of  during  that  aspen picking  whole in  VE,  fibre  felting  but  length  in  birch  w o u l d h o l d VE f r o m other  number  h o l d VE d u r i n g p r i n t i n g i s  (Giertz  de  i n VE  vessel  more  fibres,  and t h e  collapsible,  of  and  VE s u r v i v a l upon  difference  longer  printing.  (Panshin  whole  a higher tendency  the  during  the  of  substantial to  birch  reasonable  extensive,  pulp to  birch  vessel  aspen.  these  more  anticipate  The  of  more  are  This  does  percentage  for  pulps,  picked  fibres  the  would  them.  is  being  wood t h a n  p u l p s w o u l d have  between  large  5.47  wood.  Zeeuw 1 9 8 0 ) .  content  (Figure  h a v i n g a h i g h e r p r o p o r t i o n o f VE s u r v i v a l  original  Aspen  VE  between p i t  b r o k e n down i n a more random f a s h i o n . refiner  the  hand, of  also  not  easy  these  two  aspen  fibres larger to  per than  clearly  species  in  picking.  effects  significant chemical Following  of in  chemical the  survival  pretreatment, this,  and  the  of  higher  mechanical VE. the  The  treatment more  survival  severe rate  are the  of V E .  a d d i t i o n a l r e f i n i n g causes f u r t h e r breakdown  155  Figure  5.47.  B i r c h VE f r a g m e n t s h o w i n g s p l i t t i n g a l o n g t h e l i n e of i n t e r v e s s e l p i t t i n g (pulp B-CTMP3).  Figure  5.48.  S i n g l e - w a l l e d VE f r a g m e n t s h o w i n g s e p a r a t i o n i n the d i r e c t i o n of i n t e r v e s s e l p i t t i n g (pulp BCTMP3).  156  of  V E . However,  set to  by the  the VE  the  relative picking  the  of  before,  the  Nevertheless, effects  of  tendency  fibres  and  the  is  starting  difficult  printing. in  conformable,  and  also  are  predict  conditions  Although of  was  applied  again to  survival  presumably  point  pretreatment  pretreatment  resulted  (and  the  chemical  it  during  conditions  parent  flexible  observed  conditions  chips.  treatment  as  on  more  the  severe  more whole V E ,  these  VE)  are  to  more  thus  able  hold  VE  refiner  pulps  produced  in  those  published  in  better.  5.3. The  Pulp  Properties  properties  obtained  this  study  the  literature  points There  need to were  properties the  are  typical  Thus, by  pulps aspen  the  be  the  pulps.  density  effect  was  showed upon  in  these  their  species.  Nevertheless,  differences  TMP p u l p s  for  values  mechanical  areas less an  pulps. chips  for per  in  several  with  unit  increase  The showed  chemimechanical  and  were  so in  In  refining. accompanied  CTMP  and CMP  that  light  scattering  to  pulps  essentially nature.  light  much so  possibly, other  showed  the  increased  gram.  pronounced,  optical  species  pulps,  TMP s h e e t s  due,  the  from b o t h  increased  refining  chemically-treated indicating  with  stressed.  unbonded  coefficient  the  agreement  these  coefficient  CTMP  reduction  for  behavior  higher  larger  in general  considerable  of  scattering  for  fibre  produced no  only  size from  change,  157  Brightness  values  original  high  brightness  chip  manufacturing  the of  than  for both pulps. was  sulphite  did  pulps  due  CMP p u l p s  high  due t o  at  the  initial  this  changed  treatment  also  or can to  CMP p u l p s . be the  the  level  treatment.  of  refining,  on t e n s i l e sheet  Further  into  the  the  a  high  pulp. in  shows t h e  strength.  density refining  was  fibres  increases  set  Further order  to  long-fibre  as  This  evidenced  Thereby, the  pulp  from  CTMP  TMP t o  interfibre  bonding  as  well  as  limitations.  This  is  influence  of  strong  As shown again  was  required.  chemical pretreatment  It  high  essentially  is  observed.  with c e r t a i n  i n TMP  in turn,  larger  chips  degree of  addition  and a l s o  Thus,  improved d r a m a t i c a l l y  i n Figure 5.49.  density  chips  values  Consequently,  degree of  was  of  in  values.  fractions  of  alkali  brightness  was  which,  i n more f l e x i b l e  a t t r i b u t a b l e both to  illustrated sheet  treatment  brightness  the  coefficient,  favor  pulp  the  hand,  marginally.  in  CMP  simultaneous reduce  other  of  this  resulted  properties  to  higher The  lower of  The  pulps.  and  in  and t h e  pulp  h i g h sheet d e n s i t y  strength  CTMP  provided birch  low b r i g h t n e s s  distribution  chemical  the  in  expected,  breakdown  fraction,  by  for  TMP p u l p s .  absorption coefficient  d i s t r i b u t i o n of  modify  found  scattering  size  only  wood  on t h e  The  refining  aspen  little  their  c a u s e d by h i g h l i g h t  for  The d a r k e n i n g e f f e c t  P r i n t i n g opacity, the  as  pronounced  applied  to  of  those  resulted,  treatment  higher  pretreatments  loss.  in  much  brightness  values  alkaline  values  were  set  in this by  sheet  the  figure, type  density.  of TMP  158  60  M  A-TMP o  50"  A-CTMP •  w  A-CMP  r  B-TMP  td  B-CTMP  20"  H  B-CMP 10-  0 0.25  0.3  0.35  0.4  0.45  0.5  0.55  0.65  0.6  SHEET DENSITY  Figure  pulps and  5 . 4 9 . R e l a t i o n s h i p between t e n s i l e s t r e n g t h and s h e e t d e n s i t y f o r a l l hardwood r e f i n e r p u l p s s t u d i e d .  had v e r y birch  fractionation fibre  length  sheet  density  slightly to  the  low  TMP  sheet pulps  patterns appear to  higher  and, for  densities  for  also  had  (Figure  5.1),  similar so  be u n i m p o r t a n t .  consequently, aspen  lower. Runkel R a t i o  of  TMP p u l p s . of  aspen  both  that  Rather, tensile This  fibres  is  species.  Aspen  Bauer-McNett effects the  due  to  levels  of  strength  were  presumably  which  may  due  render  159  them more  collapsible.  There  a drastic  was  produced  from  CMP p u l p s However, CTMP  in  sheet  chemically-treated  followed there  and  change  the  CMP i n  chips.  same l i n e  seemed t o terms  be of  density  when p u l p s  In  aspen,  i n i t i a t e d by t h e  little  difference  either  sheet  were  CTMP  and  TMP p u l p s .  between  density  or  aspen  tensile  strength. The  response  birch.  to  chemical  Although  sheet  comparable  to  values  substantial.  fibre but  was  is  could  also  difference 5.49  aspen,  fraction it  density  the  shift  suspected be  CMP p u l p s .  also  be  due  sheet  it  is  levels  CTMP p u l p s  r e q u i r e d lower  production  of  CMP  pulps.  interfibre chemical freeness followed The  Thus,  it  to  also  tensile  to  of  attain tensile  cause  for  that  those  of  strength  freeness,  be  the  seen  R48  i.e.,  level  (as  in  by r e f i n i n g t o  difference  in  followed CMP), o r  by  CTMP  using  freeness  pulp t e n s i l e  strength  Figure  hand, higher  level  of of  applying severe to  milder level of  at  strength  certain  in had  pulps  other  refining  a lower  in  The  CMP p u l p s  same t e n s i l e  by  change,  probably a  a  long-  fraction  On t h e  b o n d i n g c a n be o b t a i n e d by e i t h e r pretreatment  shown  the  that  strength  quality.  the  .  in  levels  this  fines  larger  seen  achieve  can  a  evident  a much l a r g e r  improved  than  equivalent  fines,  not  CTMP and CMP p u l p s  densities of  more  higher  the  to  attributed  However,  to  as  was  did  The i n f l u e n c e  between b i r c h  could  higher  pretreatment  (as  birch,  a  high  treatments in  CTMP).  relative  160  to  aspen  at  similar  sheet  chemically-treated  chips,  of  fraction  the  that  long-fibre  high  since  wood  birch,  with  compared t o higher  5.4.  density  0.45  strength  Significance  Despite  the  was  birch.  not  a  higher  pulp  layer (as  was  not  the  obtained chips  by  surfaces their  by  wood  them  tensile  index  various  pulps.  birch  the  high  is  is  measure  of  of  case,  levels  (0.55  the  evident  the  of  unless  Figure level that  the  5.50 of  S  2  shows  of  fibre  with  fibres  of  the  good  of  2  of  of  for  the  In S e  not  fact, index,  2  even w i t h ability  S  plot  bonding d i d  highest  bonding  the  contact  a  surface.  TMP p u l p s  to  their  exposure  interfibre  those  advantage  area  S^  levels  to  with  taking  quality  of  more  the  treatments  fibres  of  of  comparable  of  ribbons  be  flexibility  chemical  Thus,  to  removal  fibre  capable  capacity  weakest p u l p s .  production  this  found  The  values)  Thus,  not  against It  however,  CTMP o r CMP c o u n t e r p a r t s ,  produce  increased.  TMP p u l p s ,  produced the  to  was  lower.  density  are  bonding  between  in  density  layer  2  much  refining.  exposed  clear,  levels  r e n d e r e d CTMP a n d CMP p u l p s  S  application  to  higher  follow  sheet  the  prior  were  sufficient  indicated  is  from  Findings  that  strengths  It  pulps  superior  limitation  e x p o s e d i n TMP p u l p s t h a n i n t h e i r TMP  for  aspen.  of  fact  in  aspen),  than  levels,  may a l s o be due t o  much  for  density  their  and,  in  161  40 S2e INDEX R e l a n t i o n s h i p between t e n s i l e i n d e x a n d d e g r e e of exposure o f t h e S l a y e r f o r a l l hardwood r e f i n e r pulps studied.  F i g u r e 5.50  2  the  case  o f aspen,  cellulosic strength  with  material  with  the presence  from  G-layers,  CTMP o r CMP p u l p s .  of liberated  could  Figures  highly  n o t compete  5.51 t o 5.54  in show  t h e d i f f e r e n c e i n s u r f a c e a p p e a r a n c e o f h a n d s h e e t s made f r o m aspen  TMP  relative Despite if  their  limited  a n d CTMP fibre  pulps.  rigidity  t h e l a r g e amount bonding r o l e in  sharp  Even  a t low f r e e n e s s  c a n be  appreciable  o f TMP f i n e s  levels the  i n TMP  produced,  pulps.  i t seems a s  i n a c t i n g as b r i d g e s between f i b r e s i s contrast  to  the  behavior  in  CTMP  162  Figure  5.52.  SEM p h o t o g r a p h o f a h a n d s h e e t s u r f a c e A-CTMP1.  f o r pulp  163  Figure  5.54. SEM p h o t o g r a p h A-CTMP4.  of  a handsheet s u r f a c e  for  pulp  164  Figure  5.56. SEM p h o t o g r a p h o f h a n d s h e e t i n c r o s s s e c t i o n p u l p A-CTMP4. Note t h e d i f f e r e n c e i n f i b r e c o l l a p s i b i l i t y and b u l k compared t o TMP.  of  165  pulps.  This  handsheets lack  of  also  (Figures  illustrated  5.55  to  the  sheets.  more It  in  the  flexible  is  in  and 5 . 5 6 ) .  consolidation  opposed CTMP  is  cross  These photographs  sheet and  concluded  sections  from  well  that  TMP  show a  fibres  collapsed  fibre  takes precedence  over  p r o v i d e d by f i b r e  surfaces  of  potentials.  The  the  been  widely  that  the  main  that  found  contained  only  abundant  fibrillar  appeared  to  CMP, as  is  not  the  based  of  in  fines  on t h e  the  is the  information  about  the  of  the  obtained well and  in Figures  the  influence  fines  of  of fines  fraction  deserves removal  VE,  of  an  1977,  be  to the  CTMP  was  and CMP, but  also  TMP f i n e s CTMP  5.60.  Although  it  shape  and s i z e  of  strength,  attention. surface made  fraction)  results  it  from e i t h e r  pulp  was  1981)  produced.  study,  In f a c t ,  fibre  (P100  The  chemical  further  attempt  quality  material.  of  that  from  on  hardwood  and  those  5.57  said  produced  VE f r a g m e n t s ,  than  been  fines  in this  and l a m e l l a e .  has  of  could  as  benefit  of  (Giertz  strength  fibrils  quality  results  quality  cells  longer  breakdown  origin  ray  material  what  material  fines  as  pulps  has  strength  fibrils),  TMP, as  illustrated  clear  matter  on  have  in  experience from  low  It  poor q u a l i t y  acceptable  fines not  or  lacking  of  from the  that  the  any  of mechanical  literature.  the  improved the  paper  However,  the  for  due t o  completely  fraction  in  cause  pulp is  pretreatment so  fines  recognized  mechanical (almost  of  in  flexibility,  density,  importance  as  fibres  m e a s u r e d by s h e e t  high bonding  of  are  the Thus,  layers to  and  obtain  according presented  to in  166  Figure  5.58.  P200 f r a c t i o n o f a s p e n CMP p u l p o f s i m i l a r f r e e n e s s t h a n t h a t i n F i g . 5.57 ( p u l p A-CMP3)  167  168 Figures  procedures The  in  amount pulp  mentioned  of  large  material  seem  S  2  If  pulps.  If  fines  refiner  of  the  anything,  the  to  the  those  is  pulp,  it to  as  well of  due  to  than  the  particles  involved.  evident  as  the  fines  processes of  the  chemical  the  process the  for  amounts  Excluding  for  same  the  derived appears birch  from to  in producing  or  be  refiner  capacity  flexibility  composition  large  does  bonding  used  the  fraction  fines  cells,  2  150/200  considerable  particularly in  from  and  wall.  S  effect  expected,  fibre  proportion  fibre  cutting  100/150 as  of  may be due more t o  particles  the  is  the  between  a difference  fraction  and  from VE and r a y  TMP p u l p s ,  there  to  the  composition much  calculation  from the  contained,  layer  2  differ  layer, for  S  due  pulp  TMP f i n e s  from the  to  larger  the  this  and  i n Appendix E .  mostly  values  Otherwise  assumptions  originating  o f VE and r a y c e l l s ,  species. the  material  for  a s p e n CTMP p u l p s , not  listed  A-CTMP4 was  comparatively  amounts  are  of  earlier  fractions.  and t h e  5.62,  involved  large  layer  and  5.61  of  length  of the  these of  the  169  ASPEN REFINER PULPS  OH Figure  — — i — '— >— * — T — - r — - r — r 1  1  2  5.61.  3  4  1  2  3  L  L  4  L  1  T —'-H—' -1  2  3  4  E s t i m a t e d c o m p o s i t i o n o f t h e P100 f r a c t i o n f o r aspen r e f i n e r p u l p s a c c o r d i n g t o the o r i g i n o f the f i n e m a t e r i a l .  BIRCH REFINER PULPS TMPs  CTMPs  CMPs  Ml  H H pi  5"  1 Figure  5.62.  2  3  4  1  2  3  4  1  2  3  4  E s t i m a t e d c o m p o s i t i o n o f t h e P100 f r a c t i o n f o r b i r c h r e f i n e r pulps according to the o r i g i n of the f i n e m a t e r i a l .  170  Fundamental into  aspects  mechanical  important surface  of  quality  of  each  for  provide the  pulp.  produced  from the When  study  on  to  of  Mich'x.)  and 300  cross  cross the  this  fibres  was  of  layer  under  not  exposure  CTMP  It  or  was  or  extent  chemically-treated compound m i d d l e chemical  of  of  the The  trembling  birch  (Betula  u n d e r TMP, CTMP  of pulp freeness  of  fibres  from  levels  and by  presence of  the  were  were  R48  analyzed  stained  to  lamella  using  the  and  polarized layer,  the  evaluated. by  TMP p r o c e s s i n g when  that  the  surface  of  chemical quality  presented  high  to  those  particularly  fibrillation.  chips  showed  compared  CMP c o n d i t i o n s ,  fibre  most  fibres.  compound m i d d l e  exposure  shown  improve  and w h i t e  sections  manner,  assess the  2  pulp  Three-hundred f i b r e s  of  The  mL C S F ) .  sections  fibre  elements  assessment  These were r e f i n e d  produced  S  the  defiberization  a b r o a d range  In  to  was  refiner  the  fibres  pulps. did  layer  detail.  chips.  wall.  quality  proportions  used  in  differentiation  general,  birch  studied  hardwood  The  microscopy  surface  hardwood  prepared.  secondary  light  of  this  thin  were  each  breakdown  were  between 100 pulp,  fraction  the  tremuloides  CMP c o n d i t i o n s ,  For  SUMMARY  based  Marsh.)  (generally  In  was  (Populus  papyrifera and  pulps  aspect  investigation aspen  of  VI.  for  pretreatments in  In  more  terms fact,  of  S  2  fibres  retention  of  lamella.  pretreatment  was  applied  to  the  chips,  the  171  species  response  fibres 70%  had h i g h  at  pulp  values weak  that  had  layer.  chemical  pretreatment.  CMP a s p e n  fibres  increased  refining  decreased  faster  Consequently,  those  Other  at  TMP  fibres  processing. not  in  pulps  also  present  in  down i n t o were  from  nor  CMP  differences  showed aspen smaller  Not  fractions,  from  surface.  the This  chemically-treated  cell was  were  only  of  CTMP  fibres.  mL C S F ,  aspen  comparable  found  were  chips,  in  the  of  between  of  for  case  in  which  chip  TMP b u t  ribbon-like  the  the their  These  G-fibres  G-fibres  exposing  the  in  TMP p u l p s .  i n many c a s e s  wall, not  frequent  breakdown  only but  were  Formation  common  preferential chips.  pulp  100  2  ML r e t e n t i o n  from c h e m i c a l l y - t r e a t e d  pulps.  was  S  freeness,  exposure,  2  the  TMP f i b r e s .  resulting  therefore,  denuded  cellulosic  S  Radially-failed fibres  CTMP  particles,  of  removed.  ML i n  high  birch  levels  not  of  response.  for  o f S^/ML  application  of  about  fundamental  and t h o s e  pulps  the  o f ML,  exposing  the  of  aspen  was  these  Moreover  sheath  but  levels  showed for  for  did  a  over  and  retention  retention  a quick  it  freeness  obtained  important  high  than  by  to  the  Although was  high  back,  differently  and CMP  (MLr i n d i c e s  mL CSF) ,  layer,  2  CTMP  refining.  the  rolled  produced  CTMP and CMP p u l p s to  S  sometimes  responded  300  covered  from t h e  was  over  with  fibres  Birch  retention  further  with  along  birch  separated  Aspen  levels  slowly  boundary,  sheath  considerably. lamella  freeness  produced  This  and  middle  decreased S^/32  often  varied  broken  G-layers highly  the  G-fibres  the  G-layer  172  generally Other  remained i n s i d e  categories  sections  of  Delamination treated  when t h e  but  The  potential S  layer,  2  of  reduced  of  chemical  fibres  of  and  vessel  small  pretreatment  refining,  of  in  however,  relative destroyed  survival more  is  more  It  degree  of  elements  was  o c c u r r e d along the  more common  found  that  of  exposure  of  pulp the  flexibility  their  S  2  (as  the  superior  large  exposure  thereby producing  was  studied  wood  T M P processing  softening  for  the  due  survival  VE i n CTMP and CMP p u l p s . amount  aspen  since of the  The b r e a k d o w n o f VE and t h e  was  of  fine  whole  observed  in  the  intervessel  removal of the  VE i n  Birch  to of  Further these  between  and b i r c h .  failure  by  and t h e . p r o p o r t i o n  While  responsible  VE i n  line  birch.  was  (VE)  refining.  difference  easily,  in  is  despite  due t o  chemically-  severe.  fibre  Thus,  and  impregnation.  than  shape  remained s t i f f  reduced the  Considerable  layer  2  in  aspen  fragments,  whole  S  cross-  strength.  survived  into  fibre  chemical  frequency d i s t r i b u t i o n s  proportions  pulps.  TMP f i b r e s  the  VE t h a t VE  the  followed  density).  low d e n s i t y  whole  the  closely  sheet  breakdown  high  often  to  of  frequently  measured.  relate  c o m p a r i n g VE s i z e of  of  cross-sectional  were  rather  by  bonding  sheets  more  fibre  d i d not  measured  the  analysis  a p p e a r more  and  properties  layer,  the  d i s t o r t e d due t o  to  the  in  chip chemical pretreatment  strength  of  tends  of  fibres.  delamination  fibres  fibres,  Distortion  Pulp  discussed  included  proportion  the  the  VE were  VE  walls  pitting.  surface  layers  of  the in  fibres the  allowed  contained  CMP p u l p s , S  2  layer  longer quality  fraction  P100  TMP f i n e s  the  the was  also  composition  the .  of  of  amounts  fines  the  o r i g i n of  the  derived  Furthermore,  papermaking may  not  be  purposes, judged  CTMP o r  from the  TMP f i n e s  fines  Although  o f VE compared t o  material  larger. For  of  a Bauer McNett c l a s s i f i e r .  larger  amount  filaments. of  estimation  fibres' contained  however, only  on  the their  1 7 4  VII.  The  following  are  CONCLUSIONS  considered  the  major  conclusions  of  this  investigation:  1.  TMP p r o c e s s i n g fibres  chips.  with  refiner  F o r aspen  to  freeness  to  obtain  their  values  aspen  in  of of  of  Thus,  to  the  S  2  it  species  Improvements S-L l a y e r  effects  values  high  freeness  (as  measured  fibres strength  S  of  additional  1 0 0 mL CSF h a d t o  exposure Birch  equivalent  showed  of  ML and  produced  the  in pulp of  a  be  to  those  response upon  there  was on  an  the  were  due t o small  the  compared  S ^ layer  retention,  density)  exposure  of  followed  quality.  an i m p o r t a n t r o l e  S  2  with  for  surface  strength  example flexible  f r e e n e s s . TMP  layer.  sheet d e n s i t y  Fibre  i n the  the  low  of  Fibres  than  sheet  have  surface  the  by  surface  effect  to  were much more  fibre  the  removal  CTMP and CMP p u l p s ,  than  of  chemically-treated  conditions  density  fibres  ML and  development  applied  slower  from c h e m i c a l p r e t r e a t m e n t .  high  refining  S ^ layers  from  wood  fibres.  sheet  the  produced  l a y e r than normally  2  CMP p u l p s ,  removal  chips  from c h e m i c a l l y - t r e a t e d  and p r o c e s s i n g  of  with  the  wood  c a n be c o n c l u d e d t h a t  resulting  high  aspen  of  about  fibres  characteristics  the  or  TMP c o u n t e r p a r t s .  chips.  2.  and  pulps  CTMP  levels  refining  due  birch  w i t h h i g h e r exposure  obtained  than  of  levels  Tensile rather  quality did  development  of  not the  175  pulps.  3.  Thus,  it  not  hardwood  TMP low  of  flexibility.  fibre  the  fibre  surface  contrary,  chemical  at  pretreatments of  fibres  the  effect),  layers.  In  gaps  along  fibres  the  with  or  S  layers  2  separation  the  effect.  Thus,  the  larger  in  factor  to  in this  birch achieve  study  the  and  this  resulted  the  S /S 1  largely chips,  in  of  boundary,  giving  In  fibres gap  of  this  not  layer  made  between  f o r the  layer, was  these facile  initial  the  layers  2  in  responsible  aspen,  separation  improve  between  exposed.  this  be  2  S  l a y e r and f o r p r o v o k i n g t h e  than  more ML  d i d not  fibres,  thickness  the  Furthermore,  bond  near  On  fibres.  between  appeared to  of  levels.  lack  improve  exposure.  2  gives a  d i d not  weak  chemically-treated  and S  rather  a  layer  2  but  that  had g e n e r a l l y  freeness  implying  separation  S  fibres  used  TMP p u l p  exposure  2  study  of  resulting  showed  (out/in  Si  in this  terms  equivalent  fibrillation  from  used  in  S  properties,  chemically-treated  retention  Birch  lack of  strength  Chemical pretreatments the  4.  is  total  skinning  known t o the  be  limiting  from the  fibre  surface. 5.  TMP p r o c e s s i n g VE. VE,  of  wood c h i p s  Not o n l y d i d i t but  indeed.  most On  VE the  was  freeness  destroying whole  fragments  small  other  levels  in  p r o d u c e p u l p s w i t h v i r t u a l l y no produced  hand,  p r e s e r v e d whole VE i n CTMP p u l p s At  effective  close  to  were  chemical  very  pretreatments  and e v e n more so 300  mL  CSF,  i n CMP.  aspen  CMP  176  preserved wood,  while  general, their  80% o f  less  birch  than  as  6.  important  The  method wood  for  pulp  of  liberated shells. all  7.  the  31% o f the  failure  fibres,  while  that  the  results. of  of  effect in  the  CTMP  fibres was  fibres.  The  G-fibres  in  TMP p r o c e s s i n g in  contained  the  R4 8  abundant  from t h e i r  parent  G - l a y e r s was p r e s e n t and  CMP p u l p s  occurred in  generally  below:  G-fibres)  G-fibres  stripped  d e r i v e d from the  of  of  aspen  TMP p u l p s  were  fractions.  it  an  summarized  proportion of  amount  Also,  are  show p r e f e r e n t i a l - breakdown o f  Radial  In  intervessel  conditions  (presence  accurate the  pulp.  TMP f i b r e  the  because  T h e r e was  study  wood  assess  reduced  G-layers  generally  this  tension  to  Material  along  pulping  approximately  the  destroyed  walls.  of  of  provided  significantly fraction  as  in  VE s u r v i v e d f o r b i r c h .  readily  their  present  of V E .  of  developed  or  in  findings  presence  accounted  60% whole  well  breakdown p a t t e r n  Other  VE o r i g i n a l l y  breakdown  arrangement  species  the  VE were more  preferential  pitting of  about  below  the  did  in not  G-fibres.  20% o f  the  TMP p u l p  5% i n  CTMP  and CMP  pulps. 8.  Distortion result current enough  of  and d e l a m i n a t i o n chemical  techniques for  of  treatment of  describing  fibres of  recording and  were o b s e r v e d  the such  maximizing  chips. changes the  as  a  However, are  effects  not of  177  refining. to  be  developed  change 9.  The  A measure  of  techniques  large  the  of  of  c o u l d be  fibrillar effect  of  hand, but,  involved,  these  changes  recording  needs  of  shape  study  of  the  under  cross-sectional  detailed  the  analysis  standard  TEM p r o v i d e d more due  to  only  the  a  light details  intensity  limited  number  of of  observed.  fraction  material the  of  the  allowed  fibres  sections  fibres  fines  the  other  preparation  10. ' The  in  fibres  sample  extent  delamination.  used  On t h e  cross  the  facilitate  of  numbers  microscope. on  to  and e x t e n t  characteristics  of  TMP p u l p s  i n a d d i t i o n to  fines  r e s u l t i n g pulp is  of  not  fraction clear.  on  contained  abundant  many VE f r a g m e n t s . the  strength  of  The the  178  VIII.  Based  on  the  suggestions  a.  One  SUGGESTIONS FOR FURTHER RESEARCH  work  for  on  topic pulp  handsheets  degrees  of  S  other  produced strong b.  studied  could be  with with  of  within  the  S  these  of  a  given  on  CTMP the  flexibility provide  the  fibre  2  by  different fraction the  sheets sheet  S  effect  should  density  be  has  a  on f i b r e  pulp.  largely of  For  this,  fibres  could  flexibility  which  then  exposed  were  weak  CMP  pulps.  effect the  of  could  fibrillated,  achieved the  to  the  In  to  take  order  characteristics  an i n t e r s t a g e s h o u l d be  which  i n TMP  compared  beneficial  fibres  swelling  If  and  ribbon-like particles  potentially  pulps.  flexibility  quality.  or  s h o u l d be  strong  but  eliminate  the  of  achieved  long-fibre  since  individual  pulps  on s w e l l i n g of  sheets to  quality  layer  2  be  known  the  Also  influence  can  of  Only  production  TMP f i b r e s ,  degree  following  strength.  surface  corresponding  focusses  the  the  This  same d e n s i t y ,  on p u l p  the  advantage  study,  is  fibres  form the  measured  pulps,  of  of  analyzed for surface  Even and  be  study  fractions.  the  effect  The e f f e c t be  c.  at  of  exposure.  2  s h o u l d be u s e d t o the  this  strength.  testing  of  in  f u r t h e r r e s e a r c h c a n be made:  obvious  exposure  done  may  which, rigidity  treatment studied.  that  A high  translate  into  upon d r y i n g ,  could  of  fibres  is  the  179  main  reason  pulps,  with  exposure. proper  of  This  of  chemical  it  is  of  TW  can  now  fibrillation  done  standard  before  particular  of  that  the  high  layer  2  with  in  of  the  studied  the  cross  wood  sections  chip material. the  G-layers  filaments,  beneficial.  is  swell  can  their  of  also  use  be  of  and p o s s i b l y  after  be  effect  effect  should the  Since  the  The  refining  interest  will  S  s h o u l d be  G-fibres  the  hardwood  improved  analysis  G-layers  of  tension  is  known  an  enhance  denuding  from  ability  refiner  mixing furnish.  composition  a  the  these  quality The  as  G-fibres)  areas  of  may v a r y w i t h t h e  be  should  processes.  percentage  should  of  mentioned  level  the  bonding  particles  pulping  fixed It  geographical  pulps.  of  (measured  in  which  for pulping.  about  mechanical  wood  for  are u t i l i z e d  different by  be  i n TMP  treatment.  TMP p u l p s  to  determined  scattering for  be  layer  2  fibres.  be  hardwood  of by  in  prove  proportion  hardwoods  then  and p r o d u c e c e l l u l o s i c  process  Little  done  that  interstage  should  produce  p r o d u c e d from the  Of  The  may  S  density  wood p u l p q u a l i t y  be  treatments  parent  will  the  high  or p o s t - c h e m i c a l  assessed.  the  of  and  proportions  should  chemical  fibres  pulps  pulps  known  medium  tension  different  stripped off  e.  rigid  interstage  furnish.  h i g h exposure  other  These  The e f f e c t for  the  perhaps  species  d.  for  of  fines and  light  be  This fines that  refining.  from  studied could with  the  be a  fines  Thus,  it  180  is  recommended  different assess  that  levels  the  the  .fines  paper  The  sheet.  use  The  of  an  fibre  cross  swelling  between  The e f f e c t from  the  extent  On  be  of  section, degree be  the  their  the  to  of  the  S^  other  of the  fines  of  provide  fibres  due  analysis to  could  of  fibre  then  be  hand,  the  staining  maximize  the  contrast  and u n t r e a t e d  fibres.  analysis  of  studies  swelling  assessed  and  with  the  this  Other  distorted of  liquor  number method  of for  conditions.  presence  whole  a  on  could  restriction  of  whole  chips  is  VE i n not  and p i c k i n g t e n d e n c y  several  solution.  in  include  of  and  system  quantitative  could  of  the  affected  the  strength  printing,  fibres  of  Swelling  bonding  distortion  of  modified  pretreatment  presence  of  and  investigated.  analysis  chemically-treated  surface  a l s o be  retention  The  fibres  different g.  might  of  actual  penetration. swollen  enhance  The  cross  to  to  sections.  of  interesting  may p r o v e interaction  chemically  at  treatment  refining  could  in  interstage  and  applications fibres  would be  collected  TMP f i n e s .  the  to  be  of  measured.  techniques  It  treatment  due  effectively  material  quality  image  about  chemical  an  the  qualities  information to  of  in  fine  refining.  particles  different f.  of  effect  post-treatment  the  VE p r o v e s  options  are  to  known.  are be  refiner  Tests  recommended.  a problem  available  pulps  for  on If  during  attempting  181  On a more gap can  fundamental  found f o r b i r c h be  change  study,  fibres  investigated. in  fibril  substantial  in  reasons  include  between their  these  certain in  be p r e s e n t conditions.  other  advantage studied.  hardwood of  the  in  fibres  A weak  S-L/S  species.  exposed  S  2  a  2  layers,  2  abrupt  layers  and/or  composition.  birch  2  layers,  trees  grown u n d e r  learning  other  The  however,  b o u n d a r y may a l s o  After  layer,  initial  possible  wall  and S of  the  and S  chemical  a p p a r e n t weak b o n d between t h e may o n l y  for  between t h e  These  angle  changes  the  species  to  exist take  c o u l d be  182  LITERATURE  CITED  Allan,  R . , C . 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F u t u r e f u r n i s h r e q u i r e m e n t s for newsprint and m e c h a n i c a l printing papers. In P r o c . 1989 N e w s p r i n t C o n f e r e n c e , p . 105-109. J . B . 1989. A.S.P.E.N. (Aspen Scotomas and P a r a n o i a Ecological Naivity o r C h a n g i n g o u r V i e w s on A s p e n Acceptance. In Proc. 70th Annual Meeting CPPA Woodlands S e c t i o n . E105-E109.  *****  2  »=  '  S  ="  « *  warty l  a  S : 3  y  e  r  (1965, * * « * « • « = o r d i „ 9  o  °  u  f  t  e  r  g  t  o  J  a  i  the  secondar^Uu^  ^ r s  y  B  e  M  d  .  :  j  194  APPENDIX B: Chart used f o r recording categories of f i b r e s i n cross section.  Ui 7~ i O i  i  i  .  = i :  i •— -  i  -•"  j  -  •  i 1  i  • •  I  o •  z  • j  H\  ;x  -<5  ' u)  i  -J  —J u.-  >  u  ft  •:  :  :  !  :  i  •  i  ';  ;  '  •.  '  '  i  •  •  :  O "><.'  Ui <\»  K  o  ':  :  :  t. 1  «r  l  i  r  :  -  1  :  :  >'  '  !  ;  '  :  i  '  (-  if!  :  i  O in A  V) V  <  o  m  1  ;  :  .  .  .  :  :  :  •.  _..  ;  -  A  _J  O  .  in  .  .  .  .  .-.  ...  o • cJ  «n  *  V,  ^ ^  :  c o ^ -  i ^  •,.  c. ; ^  ! ^  ^  ^  ^  ' «o  ^  o  -  -  ^  £  V>  195  APPENDIX C: Results and discussion on r e p e a t a b i l i t y of the analysis of f i b r e cross sections.  Results Table  C.l.  analysis  shows  (150 f i b r e s  tested  by  level.  From  differences a  found to  give  of  tests  the  of  fibre  taken  328 t e s t s  any  at  every a  results,  definite  found t o  pattern  be  and  30  i.e.  o v e r 90% the  The c a s e s  significant, they  were  within  i n a summary i n T a b l e C.2. were  as  confidence  only  repeatability  two  pulp,  95%  performed,  significantly different showed  between t h e  from  proportions,  performed  cross-sectional  no agreement  each)  of  differences  distributed  was  of  total  as p r e s e n t e d  which the follow  categories  under which t h e r e  sub-samples  sample,  the  did  appear  in not  to  be  randomly i n Table C . l .  Discussion There  is  no  record  microscopical pulps.  presented 90%  of  analysis  Therefore,  techniques  the  literature  on c r o s s  the  involved  sections  statistical  was  precedent correctness  tests  for  significant  this were  work,  differences and  the  that  would  the  results  encouraging. occurred,  statistically  quantitative  o f hardwood r e f i n e r  From  It  that  there  indicate  the  obtained  in  indicated gap  allowable  between one  the  results  Although  is the  of  the  was e s t a b l i s h e d  repeatable.  comparison  of  repeatability  were  of  evaluation  pertinent.  i n T a b l e s C . l and C.2 i t  the  difference  in  over  is  no  relative terms  of  that  when  the  real  was  always  Table C . l . R e p e a t a b i l i t y o f t e s t s i n the a n a l y s i s o f f i b r e c r o s s s e c t i o n s , based on sub-samples o f 150 f i b r e s at a 95% confidence l e v e l .  F I B R E CROSS SECTIONAL FEATURE  ASPEN REFINER PULPS TMP CTMP 1 2 3 4  MLr=0% MLr<50% MLr>50% MLr=100% Slr=0%,S2e=100% Slr<50%,S2e>50% Slr>50%, S2e<50% Slr=100%,S2e=0% P E E L I N G OUTER L A Y E R OUT/IN E F F E C T RADIAL FAILURE DELAMINATION DISTORTED FIBRES G L A Y E R INSIDE G LAYER ONLY  1 2 3 4  CMP 1 2 3 4  TOTAL  * *  *  * *'  * *  *  * *  *  1 0 1 0 0 1 0 0 1 2 1 2 1 0 1 11  F I B R E CROSS SECTIONAL FEATURE  TMP  BIRCH REFINER PULPS CTMP  1 2 3 4  MLr=0% . MLr<50% MLr>50% MLr=100% Slr=0%, S2e=100% Slr<50%,S2e>50% * Slr>50%,S2e<50% Slr=100%, S2e=0% P E E L I N G OUTER L A Y E R OUT/IN E F F E C T RADIAL FAILURE DELAMINATION DISTORTED FIBRES  1 2 3 4  *  CMP 1 2 3 4  * *  * *  *  *  *  * *  * *  * *  * *  * *  TOTAL 2 3 0 2 2 4 3 1 1 1 0 0 0 19  *  : Significant  differences  between  subsamples  197  T a b l e C . 2 . Summary o f r e p e a t a b l e c a t e g o r i e s of f i b r e cross s e c t i o n s .  FIBRE CROSS SECTIONAL FEATURE  N U M B E R O F CATEGORIES (TESTS) ASPEN BIRCH  on t h e  TOTAL  MLr SlrorS2e P E E L I N G OUTER L A Y E R OUT/IN E F F E C T RADIAL FAILURE DELAMINATION DISTORTED FIBRES G L A Y E R INSIDE G LAYER ONLY  48 48 12 12 12 12 8 12 12  48 48 12 12 12 12 8  TOTAL  176  152  328  CATEGORIES: Not repeatable Repeatable  11 165  19 133  30 298  % Repeatable  94  88  91  _  96 96 24 24 24 24 16 12 12  analysis  198  less  than  7 fibres  subsamples  of  representing The f a c t  Table  fibre  the  of  human e r r o r  sectional  it  than  it  is  in  some  variation  i n the  error  wood  is  of  shown  wood  in  also  significant spread  to  improve  to  pulp,  in order.  in the  on  a  establish was  an  if  due  to  examination  These  include:  density  specific  Appendix D.  applied to  which c o n t r o l t h e i r  be  assumed  significant  then  Even  to  analysis),  mixed b e f o r e  if  was  large  it  from  is  because  within a  of  wood  minimize  representative  a  this fibres  measured  that  this  material  such  species,  of  the  (as  unlikely  the  a  within  a variation  refiner pulping  pulping to  that,  produced  gravity  such c h a r a c t e r i s t i c s  response  sectional  was  value  error  variation  subsample  the  categories  Human  was  as  concentrate  difficult  -  thoroughly  the  randomly  to  Sample p r e p a r a t i o n  would  for  possible  -  effect  average  the  be  may be  rather  Whilst  to  P r o d u c t i o n o f p u l p and s a m p l i n g  cross  the  characteristic.  -  as  for  taken  Variation  magnitude  It  that  causes of  of  was  appeared  actual  possible  cases,  3 fibres  ( l e s s t h a n 10%) i n w h i c h  repeatability or  than  -  tree,  by  In a l l  cross  cases  category.  less  category  repeatability  lack  The  the  suggests  particular  the  each  occurred,  C.l,  overall  the  in  that  differences  of  150 f i b r e s .  fibres  300  and g e n e r a l l y  was  variation. every  sample  pulp of  a  199  chip  mix.  Density variation,  a probable  cause  for lack  of  P u l p p r o d u c t i o n as a s o u r c e the  refining  specific  "pockets" within and  of  of e r r o r  fibres  a pulp  obtained was  with  refers  well  required  hot  mixed  not  over  pulp  weight  s c r e e n i n g and  quite  uniform.  production  taking  a  This  the  s h o u l d have been  error.  of  • Preparation  consisting and  staining  ones.  properly  the  rendered  satisfactory  large  of  cross  alignment'  presence  of  point  been  during  does n o t  at  which  a  done the  reached. should the  be  pulp  by  one  was  a p p e a r t o be fibres  tedious  of which were  important The  and  fibre  the  to  most  identify  technique  the a l t e r n a t i v e  used  technique  considered impractical The  identification  the  steps  layer. and  c o n t r i b u t e d as  long  sections  was  the  results,  one  satisfactory  preparation The  Fibre  fibres  was  number o f hardwood f i b r e s .  provided  is  until  sample  have  o f many d i f f e r e n t  critical  a  mixed  pulp handling.  sources  of a l i g n i n g  form  m i t i g a t e d or e l i m i n a t e d  f o r sample p r e p a r a t i o n may  alignment  in  Thus,  may  sampling  has  The  time  constant.  amounts  R48  variation  Methods u s e d  procedure  of  i s subsequently  disintegration  any  produced.  period  small  fractionation,  Thus,  process  subsequent  for  in  characteristics  disintegration. by  to variations  perfectly  different  pulp  be  i s being  a g i v e n p u l p . However, t h e p u l p  a  After  were  energy  sampled' f o r  from  by  pulps  seem t o  repeatability.  conditions while  experimental which  t h e r e f o r e , does n o t  s t a i n i n g methods  o f t h e ML.  a major source  were  Thus, of  s e c t i o n e d would  for also  sample  error. have  an  200  impact that  on  the  features not  their cross  section  along  the  entirely  that  the  of  near t h e i r  on  ends,  throughout to  play  There  the  sectional Although  through  features  be  ideal  out  on  staining  as  of  well  as  clearly  to  better  the  middle while  the  near  the  fibre  in  However, at  the  sectioned  difference  cut  assume  majority of  made  an  some  average  different  sectioning  under  the  electron fibre  a  places  does n o t  the in  cut  combined bias.  small the  in  the  appear  in  all  a  the  recording  light  of  sections with  a  with  number  of  difficulties  It  is  to  could  analyzed felt  w o u l d be  allows  very  The  were  diamond  system  fashion  error  fibres  microscope.  cross  microscope.  random  possibility  cross  TEM. T h i s  observer  in  was  analyzed  sections,  techniques  lies  the  human e r r o r  reduced i f  under  minimizes  however, field,  were  bias,  ultrathin  of  fibres  samples  analysis  observation  which  of  further  is  fibres  near t h e i r  that  represents  fibre,  those that  fibres  so  point  role.  a transmission  the  of  repeatability.  lengths,  assumption  reasonable  significant  contained  observer  probably  a  the  The  may r e p r e s e n t  subsample  possibility  the  minimize  were c u t  any  is  may be p o s s i b l e  a significant  is  than  testing  their  it  fibre  second  probably  at of  middle  subsample  when  length  the  producing  categories  features.  fibre  However,  at  It  the  thus  section  cut  ends.  a  entire  an e n t i r e  i n one  section  of  correct.  fibres  features  fibres  cross-sectional  that  carried  knife, the  use  for of  high  resolution,  principal  limitation,  fibres  viewed  encountered  in  and  one time  201  required  for cutting  addition,  there  system.  TEM  large  are  was  amounts  high  used  costs in  observations  made u n d e r t h e  retention  ML and  of  and t o  observe  additional  fibres  in cross  section.  I n summary, of on  lack  the  samples.  of  however, fibre  for  there  cross-sectional  to  exposure  using  i n terms of  the  S  between  characteristics  the  layer,  2  of  the  subsamples.  c o u l d be s i g n i f i c a n t  the  of  c o u l d be drawn on t h e 10% o f  in  a TEM  confirm  regarding features  approximately  proportions that  study  in  microscope  the  conclusion  repeatability  differences  possible, of  of  no c l e a r  light  details  ultrathin sections;  involved  this  layer,  of  the  source tests It  is  variation  within  pulp  202  APPENDIX D: V a r i a t i o n of wood s p e c i f i c gravity from p i t h t o bark at d i f f e r e n t heights (as %) of the tree stem.  SG DISTRIBUTION, ASPEN TREE FROM LYTTON, B.C. 1  0.6T  °' 0 3  2  4  6  8  10  12  12  —  0.& 0.50.4  0 3  0  2  4  6  8  10  2  4  6  8  10  0.6-  ' 0 3  DISTANCE FROM PITH, cm  12  2 03 APPENDIX D  (continued)  SG DISTRIBUTION, ASPEN TREE FROM WILLIAMS LAKE, B.C. 1  0.6T  '• 0 3  2  4  6  8  10  2  4  6  8  10  0:6-  ' 0 3  DISTANCE FROM PITH, cm  204 APPENDIX D  (continued)  SG DISTRIBUTION, BIRCH TREE FROM WILLIAMS LAKE, B.C. 0.6l  :  DISTANCE FROM PITH, cm  205  APPENDIX E: Calculations involved i n the estimation of the o r i g i n of the material i n the P100 f r a c t i o n . Assumptions: 1.  The v a l u e s p r e s e n t e d i n T a b l e s E . l and E . 2 f o r a s p e n and b i r c h a r e a p p l i c a b l e t o t h e wood s a m p l e s u s e d i n t h i s study.  2.  A l l t h e components o f e l e m e n t s i n T a b l e E . l have t h e same d e n s i t y , so t h a t t h e v a l u e s c a n a l s o be t a k e n as w e i g h t percentages.  3.  Any l o s s  4.  Any m a t e r i a l removed from t h e t h e P100 f r a c t i o n o f t h e p u l p .  5.  The w e i g h t o f VE f r a g m e n t s from t h e p r o p o r t i o n a l to t h e i r s i z e .  6.  Material  of m a t e r i a l  affects  from t h e G - l a y e r s  is  evenly  a l l the  fibre  elements.  surface  ends  up  frequency tables  not taken i n t o  in are  account.  Procedure: 1.  Ray c e l l s S i n c e t h e r a y c e l l s were s m a l l e r t h a n 150 um, i t i s t a k e n that all this material passed the 100 mesh screen o p e n i n g s . V a l u e s o f 4 and 10% o f t h e wood w e i g h t were t a k e n f o r a s p e n and b i r c h , r e s p e c t i v e l y .  2.  V e s s e l elements I t was c o n s i d e r e d t h a t a l l V E f r a g m e n t s l a r g e r t h a n t h e l o w e r c o n f i d e n c e l i m i t o f t h e mean f r o m t h e k r a f t p u l p VE size distribution, c o u l d be r e g a r d e d as whole V E . The r e s t were c o n s i d e r e d VE f r a g m e n t s . From t h e s e f r a g m e n t s , the p o r t i o n i n c l u d e d i n the f i r s t c l a s s interval, was t a k e n as t h e w e i g h t o f VE p a s s i n g t h e 100 mesh s c r e e n . This portion, m u l t i p l i e d by t h e p e r c e n t a g e o f VE t h a t . were f r a g m e n t e d , t i m e s t h e v a l u e s f o r VE from T a b l e E . l , gave t h e w e i g h t o f VE i n t h e P100 f r a c t i o n .  3.  ML m a t e r i a l V a l u e s f o r ML p l u s M L c c , as d e f i n e d i n T a b l e E . l , were t a k e n f r o m t h i s t a b l e and m u l t i p l i e d by t h e p o r t i o n o f ML t h a t was removed from t h e f i b r e s .  4.  S-j_ l a y e r m a t e r i a l The proportion of S-]_ l a y e r m a t e r i a l to that, of the s e c o n d a r y w a l l was c a l c u l a t e d from v a l u e s p r e s e n t e d i n T a b l e E . 2 , and m u l t i p l i e d by v a l u e s f o r f i b r e s e c o n d a r y w a l l i n T a b l e E . l . The r e s u l t s were t h e n m u l t i p l i e d by  206 the p o r t i o n fibres. 5.  of S i material  that  was  removed  from t h e  S2 layer material T h i s was c a l c u l a t e d by s u b s t r a c t i n g t h e v a l u e s o b t a i n e d i n p o i n t s 1, 2, 3 and 4 (above) from t h e weight o f t h e P100 p u l p f r a c t i o n .  Table E . l PERCENTAGE VOLUME OF COMPONENTS OF ELEMENTS (Source: Musha & Goring 1975) FIBRE  ASPEN BIRCH  '  VESSEL  RAY  S  ML  MLcc  S  74.0  6.0  3.0  11.0  2.0  3.0  1.0  73.4  5.2  2.4  8.2  0.8  10.0  0.0  *: Assuming the middle lamella width found for fibres S: secondary wall; ML: middle lamella; cc: cell corner  Table E.2 FIBRE DIMENSIONS IN CROSS SECTION (microns) DIAMETER TOTAL SI (1) SECONDARY LAYER WALL(l) (2) ASPEN  18.8  2.55  0.12  BIRCH  19.5  3.60  0.21  (1) : Musha & Goring (1975) (2) : Marton et al (1979)  ML*  S  ML*  207  APPENDIX F : ABBREVIATIONS  ML  Compound M i d d l e  MLr  Retention  MLrl  Compound M i d d l e L a m e l l a R e t e n t i o n  ML(r=0)  No R e t e n t i o n  ML(r<50)  MLr on l e s s fibre cross  ML(r>50)  MLr on more t h a n 50%, b u t l e s s f i b r e cross section  ML(r=100)  Total  S^r  Retention  S-^rl  S-L l a y e r  S (r=0)  No R e t e n t i o n  S (r<50)  S-jr on l e s s fibre cross  S (r>50)  S^r on more t h a n 50%, b u t l e s s f i b r e cross section  S (r=100)  Total  S e  Exposure of the S  S el  S  S (e=0)  Zero exposure  S (e<50)  S e on l e s s fibre cross  S (e>50)  S e on more t h a n 50%, b u t l e s s fibre cross section  S (e=100)  Total  RF  Radial  TW  T e n s i o n Wood  VE  Vessel  1  1  1  1  2  2  2  2  2  2  2  o f Compound M i d d l e  Lamella  o f Compound M i d d l e  Index  Lamella  t h a n 50%, b u t more t h a n section  Retention  Lamella  layer  t h a n 50%, b u t more t h a n section  of the S  Exposure  2  x  than  zero  of the  100% o f t h e  layer  layer Index  of the S  2  layer  t h a n 50%, b u t more t h a n section  2  Exposure of the S  Element  100% o f t h e  Index  of the  Failure  of the  layer  Retention  2  than  zero  o f t h e Compound M i d d l e  of the  Retention  layer  Lamella  2  layer  than  zero  of the  100% o f t h e  

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