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Paper tensile properties as determined by fibre origin in the coniferous wood matrix Sun, Bernard Ching-Huey 1970

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PAPER TENSILE PROPERTIES AS DETERMINED BY FIBRE ORIGIN IN THE CONIFEROUS WOOD MATRIX  by  BERNARD CHING-HUEY SUN B.Sc.A., N a t i o n a l Taiwan U n i v e r s i t y , 1960 M.Sc, U n i v e r s i t y of B r i t i s h Columbia, 1967  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE  REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  i n the Department of Forestry We accept t h i s required  THE  t h e s i s as conforming t o the  standard  UNIVERSITY OF BRITISH COLUMBIA September, 1970  In p r e s e n t i n g  this  thesis  an a d v a n c e d d e g r e e a t the L i b r a r y I  further  for  agree  scholarly  by h i s of  shall  this  written  the U n i v e r s i t y  make  it  freely  that permission  for  It  financial  of  of  Columbia,  British for  for extensive  gain  Depa r t m e n t Columbia  the  requirements  reference copying o f  I agree and this  shall  that  not  copying or  for  that  study. thesis  by t h e Head o f my D e p a r t m e n t  is understood  permission.  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  fulfilment  available  p u r p o s e s may be g r a n t e d  representatives. thesis  in p a r t i a l  or  publication  be a l l o w e d w i t h o u t my  ABSTRACT  T h i s study examines the h y p o t h e s i s o r i g i n i s maintained mechanical  t h a t c o n i f e r o u s wood f i b r e  even when p u r i f i e d p u l p s a r e s u b j e c t e d t o severe  ( b e a t i n g ) and chemical  (decrystallizing)  treatments.  Four t o f i v e i n t r a - i n c r e m e n t a l s u l p h a t e p u l p s o b t a i n e d from each of t h r e e s p e c i e s , e a s t e r n l a r c h fir  (Pseudotsuga menziessii  (Larix  lariaina  (Duroi) K. Koch), Douglas^  (Mirb.) Franco) and balsam f i r  (Abies balsamea  (L.) M i l l ) , were p u r i f i e d and machined t o one o r t h r e e l e v e l s EL (170 ± 45 ml C s f ) , DF (615 + 90 ml C s f ; 328 + 43 ml C s f ; 168 ± 62 ml C s f ) and BF (190  + 30 ml C s f ) .  T h e r e a f t e r , c e l l u l o s e supermolecular  s t r u c t u r e s were  a l t e r e d by monoethylamine s w e l l i n g , w i t h changes (48 ± 2% vs. 68 ± 2%) q u a n t i f i e d as f i b r e c r y s t a l l i n i t y index measured by X-ray d i f f r a c t o m e t r y . Paper sheet apparent  d e n s i t i e s and t e n s i l e parameters  (maximum s t r e n g t h ,  " s t r e t c h , " modulus o f e l a s t i c i t y and r u p t u r e energy) were  determined.  F i b r e s u r f a c e areas and sheet bonded s t a t e s were e s t i m a t e d by l i g h t s c a t t e r i n g c o e f f i c i e n t measurements. The  e f f e c t s o f wood o r i g i n on paper sheet  physical-mechanical  p r o p e r t i e s r e p o r t e d by o t h e r r e s e a r c h e r s were r e a f f i r m e d i n t h i s  study,  w i t h a l l f a c t o r s d e c r e a s i n g p r o g r e s s i v e l y a c r o s s growth, increments. The  d i f f e r e n c e s o f wood i n t r a - i n c r e m e n t a l , as w e l l as s p e c i e s  origins,  were not removed b y c o n v e n t i o n a l p u l p i n g and papermaking p r o c e s s e s , or a d d i t i o n a l treatments  such, as severe b e a t i n g o r major a l t e r a t i o n o f the  b a s i c c e l l u l o s e s t r u c t u r e s as p r a c t i c e d i n the study. i  ii  Paper sheet t e n s i l e p r o p e r t i e s were r e l a t e d d i r e c t l y t o sheet apparent  density.  C o r r e l a t i o n c o e f f i c i e n t s as h i g h as 0.979 and 0.989  were o b t a i n e d f o r 00% and 82% monoethylamine d e c r y s t a l l i z e d f i b r e s h e e t s , respectively.  Sheet d e n s i t y was i n v e r s e l y r e l a t e d t o wood s p e c i f i c  i t y and was found t o be independent and d e c r y s t a l l i z a t i o n  o f wood s p e c i e s , degree  grav-  of beating  treatments.  I t i s shown t h a t f i b r e bonding i n f l u e n c i n g paper sheet s t r e n g t h .  p o t e n t i a l i s not the o n l y f a c t o r  I n t r a f i b r e c h a r a c t e r i s t i c s , such as  c e l l u l o s e s u p e r m o l e c u l a r s t r u c t u r e s , have a h i g h l y s i g n i f i c a n t  effect  on paper sheet s t r e n g t h as w e l l . In a d d i t i o n , s p e c i f i c energy o f "bond f a i l u r e " energy  (irreversible  consumed p e r u n i t sheet s u r f a c e formed as r e s u l t o f t e n s i l e  i n g ) was h i g h e r f o r earlywood t i t y depends on b e a t i n g degree intra-incremental  than f o r latewood and d i f f e r s  sheets.  T h i s energy  quan-  a c c o r d i n g to s p e c i e s ^ as w e l l as  origin.  The paper sheet l i g h t s c a t t e r i n g c o e f f i c i e n t l a t i o n s h i p a l s o depended on wood f i b r e o r i g i n .  (L.S.C.)-density r e -  Earlywood  sheet L.S.C.  decreased w i t h i n c r e a s e d b e a t i n g and sheet d e n s i t y , b u t latewood L.S.C. remained  strain-  almost u n a f f e c t e d .  sheet  T h i s o b s e r v a t i o n e x p l a i n s why whole-  wood f i b r e sheet L . S . C . - d e n s i t y r e l a t i o n s h i p s v a r y w i t h pulp types as r e c o r d e d i n the l i t e r a t u r e .  TABLE OF CONTENTS  Page  ABSTRACT  . . . . . . . . . . . . . . . . . . .  TABLE OF CONTENTS  i  . i i i  LIST OF TABLES . . . '.  • • •  LIST OF FIGURES  v  vi  ACKNOWLEDGMENT  x  Chapter  I.  II.  INTRODUCTION  •  LITERATURE REVIEW F i b r e Morphology  1  .  3  and Paper T e n s i l e S t r e n g t h  3  Pulp Chemical Components and Paper T e n s i l e S t r e n g t h  . . .  F i b r e Strength  8 9  Factors A f f e c t i n g Fibre Strength E f f e c t of C e l l u l o s e C r y s t a l l i n i t y  12 on Wood, F i b r e  and Paper P r o p e r t i e s  16  I n t e r f i b r e Bonding  , •.  F i b r e Surface Area  19 21  Paper Sheet Bonded A r e a . F i b r e Bond S t r e n g t h .  '  25 28  iii  iv  Chapter  III.  Page  MATERIALS AND  METHODS . . . . . . . . . . . . . . . . . .  M a t e r i a l s and Pulp P r e p a r a t i o n  32  . . . . . . . . . . .  Treatments  32  .  Handsheet F o r m a t i o n  36 . . . .  40  Physical-Mechanical Tests  42  P h y s i c a l - O p t i c a l Tests  44  . . . . . . . . . . . . . . .  Sample N o t a t i o n  IV.  46  DISCUSSION  48  F i b r e Surface Area  48  I n t r a - i n c r e m e n t a l Handsheet Apparent D e n s i t y and Tensile Properties  V.  . . . . . . . .  The E f f e c t o f S p e c i e s on Handsheet T e n s i l e P r o p e r t i e s  59  A l t e r a t i o n o f Raw M a t e r i a l E f f e c t s by Pulp M a c h i n i n g  63  E f f e c t o f C e l l u l o s e S u p e r m o l e c u l a r S t r u c t u r e on Handsheet P r o p e r t i e s  66  S p e c i f i c Energy of "Bond F a i l u r e "  75  CONCLUSION  LITERATURE CITED  78  '  TABLES  FIGURES  52  .  82  97  . . . . . . . . . . . . . . . .  108  LIST OF TABLES  Table  •1.  2.  3.  Page  Summary of wood and p u l p c h a r a c t e r i s t i c s f o r m a t e r i a l s i n c l u d e d i n the study . .  97  Summary of p h y s i c a l - o p t i c a l and p h y s i c a l - m e c h a n i c a l p r o p e r t i e s f o r pulp types i n c l u d e d i n the study . .  98  Handsheet t e n s i l e p r o p e r t y - d e n s i t y l i n e a r r e l a t i o n s h i p s f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types . .  103  4.  Earlywood to latewood s p e c i f i c g r a v i t y (apparent d e n s i t y ) and t e n s i l e p r o p e r t y r a t i o s f o r D o u g l a s - f i r wood and (paper) . . . . . . 106  5.  R e s u l t s of t - t e s t showing the e f f e c t of c e l l u l o s e d e c r y s t a l l i z a t i o n treatments on handsheet t e n s i l e p r o p e r t i e s at comparable i n t e r f i b r e bonding s t a t e s ( r e l a t i v e bonded area) 107  v  LIST OF FIGURES  Figure  1.  2.  3.  4.  5.  6.  7.  8A.  Page  Sulphate raw p u l p y i e l d s , micro-kappa numbers and r e s i d u a l carbohydrate f o r e a s t e r n l a r c h , . D o u g l a s - f i r and balsam f i r r e l a t e d t o p o s i t i o n w i t h i n wood growth zone  108  Set-up f o r f r e e z e - d r y i n g treatments  (a) and d e c r y s t a l l i z a t i o n (b) . . . . . . .  109  D i f f r a c t i o n X-ray spectrum f o r d e c r y s t a l l i z e d Douglasf i r latewood pulp f i b r e s , DF-5-106-77  110  E f f e c t of unbonded f i b r e d e n s i t y efficient  Light  Light  on l i g h t s c a t t e r i n g c o I l l  s c a t t e r i n g c o e f f i c i e n t s f o r unbonded f i b r e s and s t a n d a r d pulp handsheets r e l a t e d t o p o s i t i o n w i t h i n wood growth zone  112  s c a t t e r i n g c o e f f i c i e n t s o f unbonded f i b r e s r e l a t e d to wood s p e c i f i c g r a v i t y . . . . . . . .  113  E f f e c t s o f s p e c i e s , pulp machining and f i b r e d e c r y s t a l l i z a t i o n treatments on d i s t r i b u t i o n o f pulp handsheet apparent d e n s i t i e s .  114  Handsheet apparent d e n s i t i e s f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d t o p o s i t i o n w i t h i n wood growth zone .  115  vi  vii  Figure  8B  >  &  8D. &  Page  8C.  8E.  9A. &.9B.  10.  11A. & 11B.  11C. & 11D.  12A.  Handsheet maximum t e n s i l e s t r e n g t h and s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) D o u g l a s - f i r pulps r e l a t e d to p o s i t i o n w i t h i n wood growth zone • • •  H6  Handsheet modulus of e l a s t i c i t y and t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) and amine t r e a t e d C82%) D o u g l a s - f i r . p u l p s r e l a t e d to p o s i t i o n w i t h i n wood growth zone • .  117  Handsheet bonded a r e a and r e l a t i v e bonded a r e a as determined by l i g h t s c a t t e r i n g c o e f f i c i e n t s f o r v a r i o u s p u l p types and r e l a t e d to p o s i t i o n w i t h i n wood growth zone  118  Scanning e l e c t r o n photomicrographs o f D o u g l a s - f i r s u l p h a t e handsheets showing: (a. & b.) DF-1/2^-525-00 c o l l a p s e d earlywood f i b r e s , and i n t r a f i b r e f a i l u r e s due to t e n s i l e s t r e s s i n g , and ( c : & d.) DF-5-106-00 unc o l l a p s e d latewood f i b r e s , and i n t e r f i b r e failures  119  L i g h t s c a t t e r i n g c o e f f i c i e n t s of unbonded f i b r e s (read a t 0.4 g/cm ) and s t a n d a r d p u l p handsheets r e l a t e d to handsheet apparent d e n s i t y f o r v a r i o u s p u l p types  120  Handsheet bonded a r e a and r e l a t i v e bonded a r e a as determined by l i g h t s c a t t e r i n g c o e f f i c i e n t s f o r v a r i o u s pulp types and r e l a t e d to handsheet apparent d e n s i t y .  121  Handsheet maximum t e n s i l e s t r e n g t h f o r u n t r e a t e d (00%) and amine t r e a t e d (.82%) p u l p types r e l a t e d to handsheet bonded a r e a as determined by l i g h t scattering coefficient  122  viii  Figure  12B.  12C.  12D.  13A.  13B.  13C.  13D.  14.  Page  Handsheet s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet bonded a r e a as determined by l i g h t s c a t t e r i n g c o e f f i cient  123  Handsheet modulus o f e l a s t i c i t y f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types r e l a t e d to handsheet bonded a r e a as determined by l i g h t s c a t tering coefficient  124  Handsheet t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet bonded a r e a as determined by l i g h t scattering coefficient  125  Handsheet maximum t e n s i l e s t r e n g t h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent d e n s i t y  126  Handsheet s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent density  127  Handsheet modulus of e l a s t i c i t y f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent d e n s i t y . . . . .  128  Handsheet t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) . and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent d e n s i t y  129  Handsheet apparent d e n s i t y o b t a i n e d at v a r i o u s pulp f r e e n e s s l e v e l s f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types as r e l a t e d to i n i t i a l wood s p e c i f i c g r a v i t y  130  ix  Figure  15.  16.  17.  18.  Page  Homogeneity of handsheet t e n s i l e p r o p e r t y - d e n s i t y l i n e a r r e l a t i o n s h i p s as shown by c o v a r i a n c e a n a l y s i s f o r p u l p types o f the study  131  Handsheet maximum t e n s i l e s t r e n g t h f o r amine t r e a t e d p u l p types as r e l a t e d to handsheet l i g h t s c a t t e r i n g c o efficient  132  Handsheet maximum t e n s i l e s t r e n g t h r e l a t e d t o c e l l u l o s e c r y s t a l l i n i t y index f o r D o u g l a s - f i r i n t r a - i n c r e mental pulps at various freeness l e v e l s  133  Handsheet s p e c i f i c energy of "bond f a i l u r e " f o r v a r i o u s pulp types as r e l a t e d to p o s i t i o n w i t h i n growth zone  134  ACKNOWLEDGMENT  The  author  acknowledges w i t h g r a t i t u d e v a r i o u s members of  F a c u l t y of F o r e s t r y , U n i v e r s i t y of B r i t i s h Columbia, who f u l suggestions W.  Wilson,  phases and  the  offered help-  d u r i n g t h i s work; w i t h s p e c i a l a p p r e c i a t i o n to Dr.  P r o f e s s o r , f o r h i s guidance i i i p l a n n i n g and  J.  experimental  d u r i n g p r e p a r a t i o n of the t h e s i s document.  G r a t e f u l acknowledgment i s a l s o made to Dr. R. W.  Wellwood,  P r o f e s s o r , Dr. A. Kozak, A s s o c i a t e P r o f e s s o r , and Dr. L. Paszner,  Re-  s e a r c h A s s o c i a t e , F a c u l t y of F o r e s t r y ; Dr. F. E. Murray, Head, D e p a r t ment of Chemical E n g i n e e r i n g , and Mr. couver F o r e s t P r o d u c t s  J . H e j j a s , Research O f f i c e r , Van-  L a b o r a t o r y , Department o f F i s h e r i e s and F o r e s t r y ,  f o r h e l p f u l suggestions  and  criticisms.  Acknowledgment i s a l s o g i v e n to Mr.  H. V. Green, S e n i o r  Microsco-  p i s t , Pulp and Paper Research I n s t i t u t e of Canada, f o r p r e p a r i n g the wood scanning  t r a c e s ; to Pulp and Paper Research I n s t i t u t e of Canada, f o r sup-  p l y i n g p a r t o f the wood m a t e r i a l s ; to Miss L. A. Cowdell,  and Mrs.  H e j j a s , T e c h n i c i a n s , f o r computer programming; to M e s s r s . R. C. P.  Chenjand H. J . Cho,  scanning  f e l l o w Graduate Students,  K.  Szymani,  for preparing  the  e l e c t r o n photomicrographs, measuring i n t r i n s i c v i s c o s i t i e s  and  measuring areas under t e n s i l e s t r e s s - s t r a i n c u r v e s , r e s p e c t i v e l y . The  author  i n P u l p i n g , Mr.  i s a l s o indebted  J . M.  Bagley,  to Dr.  J . L. Keays, A c t i v i t y  S u p e r v i s o r , and Mr.  i n g T e c h n o l o g i s t , Vancouver F o r e s t Products  R.  Advisor  C o r t e z , former P u l p -  Laboratory,  Department of  F i s h e r i e s and F o r e s t r y ; to Dr. B. M u l l i c k , A s s i s t a n t P r o f e s s o r ( P a r t - t i m e ) , x  xi  and Mr. G. Jensen, Research A s s i s t a n t , F a c u l t y of F o r e s t r y , to Dr. L. M. L a v k u l i c h , A s s i s t a n t P r o f e s s o r , and Miss P. A.. D a i r o n , Department o f S o i l S c i e n c e ,  Technician,  U n i v e r s i t y of B r i t i s h Columbia; to Mr. G.  H a r r i s , A c t i n g Head, F o r e s t Resource Technology, B r i t i s h Columbia  Insti-  t u t e o f Technology, f o r t h e i r  facili-  kindness i n a l l o w i n g use o f v a r i o u s  t i e s ; and to the U n i v e r s i t y of B r i t i s h Columbia f o r f i n a n c i a l during  the academic  programme.  L a s t , but n o t l e a s t , devotion  support  to Mrs. B.C-H. Sun, f o r h e r p a t i e n c e ,  and encouragement throughout these memorable y e a r s .  CHAPTER I  INTRODUCTION  Coniferous  wood pulps  to the paper i n d u s t r y .  provide  a valuable  source of f i b r e f u r n i s h  Pulp d i f f e r e n c e s a r i s i n g from gross wood v a r i a -  t i o n s between and w i t h i n s p e c i e s and even w i t h i n i n d i v i d u a l stems have been s t u d i e d .  L e s s f r e q u e n t l y , earlywood-latewood v a r i a t i o n s have been  used to e x p l a i n p u l p d i f f e r e n c e s , m o s t l y by comparing raw pulp  properties  through sampling o n l y two p o s i t i o n s w i t h i n i n d i v i d u a l growth i n c r e m e n t s . P u r i f i e d pulps prepared a c c o r d i n g  to numerous p o s i t i o n s w i t h i n c o n i f e r -  ous wood growth increments have r e c e i v e d l i t t l e a t t e n t i o n . The  p u r i f i e d wood f i b r e  ( t r a c h e i d ) s k e l e t o n i s comprised l a r g e l y  of aggregated c e l l u l o s e and some r e s i d u a l h e m i c e l l u l o s e s . most h e m i c e l l u l o s e s cessing.  of the o r i g i n a l wood m a t r i x  Although t h e r e a r e d i f f e r e n t o p i n i o n s  aggregation, l o s e chains  the commonly accepted  a r e removed d u r i n g  various c e l l wall layers.  pro-  r e g a r d i n g wood c e l l u l o s e  concept proposes t h a t i n d i v i d u a l c e l l u -  a r e a s s o c i a t e d as supermolecular r e g i o n s  which a r e f u r t h e r o r g a n i z e d  L i g n i n and  as m i c r o f i b r i l s , f i b r i l s ,  of d i f f e r e n t  order,  l a m e l l a e and f i n a l l y  D i f f e r e n c e s i n behaviour between earlywood and  latewood f i b r e s a r e a t t r i b u t e d to d i f f e r e n c e s i n w a l l t h i c k n e s s and a r r a n g e ment of the c e l l u l o s e a x i s . Hence, t h i c k e r - w a l l e d latewood f i b r e s a r e understood to p r o v i d e l e s s s u r f a c e a r e a per u n i t weight, h i g h e r i t y as r e s u l t o f papermaking processes  1  s t i f f n e s s and l e s s  than t h i n n e r - w a l l e d  conformabil-  earlywood  2  fibres. Pulp machining  (beating) i s known to reduce  p r o p e r t i e s between pulpsjustments,  M e c h a n i c a l a c t i o n causes  the d i f f e r e n c e s i n i n t r a f i b r e bond a d -  e x t e r n a l f i b r i l l a t i o n , p r o d u c t i o n of f i n e s and s h o r t e n i n g of  f i b r e s , as w e l l as i n c r e a s e d s p e c i f i c volume and s p e c i f i c s u r f a c e . f i b r e c h e m i c a l p r o p e r t y d i f f e r e n c e s a r e minimized then one might expect  with p u r i f i e d  t h a t extreme b e a t i n g s h o u l d obscure those  ces r e l a t e d to c e l l w a l l s t r u c t u r e .  Since  pulps, differen-  Thereby, f i b r e w a l l t h i c k n e s s , f i b r i -  l l a t i o n p a t t e r n and s t i f f n e s s should no l o n g e r a f f e c t paper p r o p e r t i e s and d i f f e r e n c e s a t t r i b u t e d to wood o r i g i n should d i s a p p e a r , i . e . , papers made from earlywood  and latewood  f i b r e s should have s i m i l a r  physical-mech-  anical properties. Treatments a r e known f o r f u r t h e r a l t e r i n g the c e l l w a l l s t r u c t u r e . The c e l l u l o s e supermolecular  order o r c r y s t a l l i n i t y may be reduced  f i c a n t l y by chemical t e c h n i q u e s w i t h o u t form.  Although  l o s i n g the o r i g i n a l f i b r e  signiskeletal  the c e l l u l o s e c r y s t a l l i t e dimension v a r i e s w i t h s p e c i e s ,  as w e l l as between earlywood  and latewood,  little  i s known c o n c e r n i n g the  e f f e c t of c e l l u l o s e c r y s t a l l i n i t y on paper p r o p e r t i e s .  Furthermore,  p a c k i n g o f c e l l w a l l s t r u c t u r e such as r e d u c t i o n of f i b r i l l a r  better  angle and i n -  c r e a s e of c r y s t a l l i t e w i d t h may accompany pulp and paper p r o c e s s i n g . T h i s study examines t h e h y p o t h e s i s t h a t c o n i f e r o u s wood f i b r e i d e n t i t y i s maintained, nical  even when p u r i f i e d  ( b e a t i n g ) and c h e m i c a l  pulps a r e s u b j e c t e d to severe mecha-  ( d e c r y s t a l l i z i n g ) treatments.  Paper handhsheet  p h y s i c a l - m e c h a n i c a l and p h y s i c a l - o p t i c a l measurements a r e used as t e s t teria.  cri-  CHAPTER I I  LITERATURE REVIEW  F i b r e Morphology and Paper T e n s i l e I t has been r e c o g n i z e d eid  ( f i b r e ) morphological  s t u d i e s and reviews  Strength  f o r some time t h a t c o n i f e r o u s wood traclv-  p r o p e r t i e s i n f l u e n c e paper s t r e n g t h .  (7, 11, 19, 21, 22, 26, 27, 129, 141, 142) have ex-  amined these r e l a t i o n s h i p s .  Factors  ( w i d t h ) , lumen diameter ( w i d t h ) ,  such as f i b r e l e n g t h , f i b r e  c e l l wall thickness, f i b r i l l a r  wood d e n s i t y , latewood p e r c e n t a g e , f e l t i n g c o e f f i c i e n t diameter r a t i o ) , Muhlsteph r a t i o area), f l e x i b i l i t y Runkel r a t i o  coefficient  (fibre  (lumen d i a m e t e r - f i b r e diameter  explaining various.observations.  ratio), cell  c a l c u l a t i o n s have been advanced  Each has e i t h e r p o s i t i v e o r n e g a t i v e  strength.  C e r t a i n c h a r a c t e r i s t i c s appear t o be i n t e r - r e l a t e d . f i b r e s are s l i g h t l y longer  angle,  (cell wall area-fibre cross-sectional  to diameter r a t i o and o t h e r  r e l a t i o n s h i p w i t h paper t e n s i l e  diameter  lengths  (double c e l l w a l l t h i c k n e s s - l u m e n diameter r a t i o ) ,  w a l l thickness for  Numerous  Latewood  than those of a s s o c i a t e d earlywood  (103, 149).  S i g n i f i c a n t r e l a t i o n s h i p s between f i b r e l e n g t h and wood d e n s i t y , growth r i n g w i d t h and h e i g h t w i t h i n stem have been e s t a b l i s h e d f o r Sctos  (Pinus sy-Zvestpi-s L.) (23).  Thin^walled,  a l l y a s s o c i a t e d w i t h low wood d e n s i t y t e n s i l e strength. and  pine  l a r g e diameter f i b r e s a r e usu-  CH), and t h i s f a v o r s h i g h paper  Wood w i t h t h i c k c e l l w a l l s , h i g h d e n s i t y , s m a l l  lumen d i a m e t e r s , as w e l l as l a r g e c e l l and a v e r a g e - t o - l a r g e  3  cell  lumen  4  diameters i s p r e s e n t The  i n the same t r e e  d e n s i t y of wood v a r i e s w i t h i n a growth increment and i n c r e a s e s  from earlywood to latewood studied Douglas-fir ported  (148).  (41, 43, 126, 149, 151).  (Pseudotsuga menziesii  I f j u and Kennedy (42)  (Mirb.) Franco) wood and r e -  t h a t t h e c e l l w a l l area and d e n s i t y of latewood were 1.8 and 2.5  times t h a t of earlywood, and t h a t the former v a r i a b l e i s a measure o f the l a t t e r .  Wood d e n s i t y i s c l o s e l y a s s o c i a t e d w i t h f i b r e diameter and  c e l l w a l l thickness  (103).  Coniferous  wood growth increments w i t h  high  latewood to earlywood r a t i o s a r e expected to have h i g h d e n s i t y ( 8 4 ) . A f t e r a d e t a i l e d r e v i e w on the i n f l u e n c e of f i b r e morphology on paper p r o p e r t i e s , Dinwoodie'(21) and Gardner density  ( c e l l wall thickness  f i b r e strength  or latewood p e r c e n t a g e ) , f i b r e l e n g t h and  i n descending order  a f f e c t i n g paper  (27) concluded t h a t wood  a r e by f a r the most important  factors  strength.  F u r t h e r work by Dinwoodie (22) on 14 softwood s p e c i e s , i n which he  s t u d i e d 12 a n a t o m i c a l c h a r a c t e r i s t i c s , confirmed the same order of  importance f o r these v a r i a b l e s .  He a l s o s t a t e d t h a t c h e m i c a l v a r i a t i o n  was l e s s important than a n a t o m i c a l f e a t u r e s , w i t h the e x c e p t i o n lose f l u i d i t y  ( r e c i p r o c a l of v i s c o s i t y ) .  chemical v a r i a b l e s was e x p l a i n e d softwoods.  of c e l l u -  The l e s s important e f f e c t o f  i n terms of low degree of v a r i a t i o n i n  The same view i s h e l d by Annergren et at. ( 4 ) .  F i b r e l e n g t h was p r o b a b l y t h e f i r s t l a t e d w i t h paper s t r e n g t h .  shorter  to be c o r r e -  I t has been found that f i b r e l e n g t h has a  d i r e c t e f f e c t on sheet t e n s i l e s t r e n g t h the c o n s i d e r a b l y  f i b r e property  f i b r e length  (.6, 18, 129, 141, 148), and t h a t  i n hardwoods i s the r e a s o n f o r lower  5  hardwood pulp s t r e n g t h as compared w i t h softwood p u l p s ( 3 9 ) . C o n t r a d i c t i n g the above f i n d i n g ,  (Pinus taeda L.) (146).  when s t u d y i n g l o b l o l l y p i n e and Marton (1) s e p a r a t e d  a reverse relationship  unbeaten Norway spruce  was found  F u r t h e r , Alexander  (Piaea abi.es (L.)  k r a f t pulp i n t o earlywood and latewood f i b r e s of d i f f e r e n t - l e n g t h tions.  They r e p o r t e d  t h a t sheets made from the l o n g e s t f i b r e s  hibited  a d e f i n i t e l y lower b r e a k i n g  s t r e s s e d that although  l e n g t h than t h e next f r a c t i o n  l o n g e r f i b r e s improve a l l sheet  frac-  (3 mm) ex-  Annergren et at. (4) reviewed t h e e f f e c t o f raw m a t e r i a l on sheet and  Karst.)  (2 mm). strength  strength  proper-  t i e s , w i t h i n the common l e n g t h v a r i a t i o n s o c c u r r i n g among softwoods, the average f i b r e l e n g t h has no l a r g e i n f l u e n c e on the p u l p . The and  longer  explained thereby  g e n e r a l o p i n i o n , however, i s t h a t f i b r e l e n g t h e x e r t s an e f f e c t f i b r e length i s considered  strength.  This i s  i n t h a t l o n g e r f i b r e s p r o v i d e more s i t e s f o r i n t e r f i b r e bonding,  b e t t e r use o f i n t r i n s i c s t r e n g t h t o d i s t r i b u t e  over l a r g e r a r e a s . fibres  t o improve sheet  This provides higher  from the paper web.  external stresses  f r a c t i o n a l r e s i s t a n c e to p u l l i n g  Moreover, i t was found t h a t the l o n g f i b r e i s  more f l e x i b l e (25), and t h i s f l e x i b i l i t y has d i r e c t  importance t o paper  structure. In the papermaking p r o c e s s , t e n s i o n , i n t e r f i b r e adhesion,  m e c h a n i c a l f o r c e s o f vacuum and p r e s s u r e ,  i n t e r f i b r e bonding and s h r i n k a g e , vidual fibres sile  (26).  f i b r e s a r e brought t o g e t h e r by s u r f a c e  as w e l l as c o i l i n g and t w i s t i n g of i n d i -  A strong r e l a t i o n s h i p  s t r e n g t h and paper d e n s i t y  i s r e p o r t e d between paper t e n -  (69, 70, 71, 72, 131).  governed c h i e f l y by p l a s t i c i t y o f the wet f i b r e s  (26).  Paper d e n s i t y i s Fibre plasticity,  6  f l e x i b i l i t y or c o n f o r m a b i l i t y are i n f l u e n c e d l a r g e l y by  f i b r e morphologi-  cal properties. F i b r e s w i t h h i g h d e n s i t y are c h a r a c t e r i z e d by l a r g e c e l l w a l l c r o s s - s e c t i o n a l areas and (26)  thick c e l l  s m a l l lumen d i a m e t e r s .  walls, Gallay  s t a t e d t h a t p u l p f i b r e s w i t h a h i g h degree of e l a s t i c i t y would have  h i g h " s p r i n g b a c k " a f t e r compression i n the papermaking p r e s s - a n d  thereby  by p r o v i d e  hand,  minimum p o t e n t i a l c o n t a c t s  f o r bonding.  On  the other  f i b r e s which are p l a s t i c r a t h e r than e l a s t i c have l e s s r e s i s t a n c e to compacting  forces provided  by  surface  s u l t of m e c h a n i c a l p r e s s i n g . f i b r e webs was  The  t e n s i o n and  compression-recovery response of wood  shown to be h i g h l y a f f e c t e d by  r a t i o s , as w e l l as f i b r e e l a s t i c i t y Earlywood and ture.  r e t a i n d e f o r m a t i o n as a r e -  fibre  length-to-diameter  (56).  latewood t r a c h e i d s d i f f e r i n some f e a t u r e s  Jayme and Hunger (49)  discussed  the response to d r y i n g and  the d i s c r e p a n t b e h a v i o r i n terms of d i f f e r i n g c o l l a p s i b i l i t y . and Mason (117)  s t a t e d that f i b r e c o l l a p s i b i l i t y served  f l a t t e n i n g of f i b r e s which allows flexibility.  l a r g e r contact  T h i s c o l l a p s i b i l i t y was  areas,  two  functions,  and  greater  tensile strength  (.129, 141  f  142).  the r a t i o of f i b r e lumen to  been found to r e l a t e d i r e c t l y This i s explained  as paper  to paper  tensile  r e l a t e d p o s i t i v e l y w i t h lumen w i d t h but n e g a t i v e l y  f i b r e diameter  (129.).  favorably l e n g t h and  i n f l u e n c e d by  fibre  (99).  strength being  I t was  as  a t t r i b u t e d to a f u n c t i o n of c e l l w a l l  a measure of f i b r e f l e x i b i l i t y ,  diameter ( . f l e x i b i l i t y r a t i o ) has  explained  Robertson  t h i c k n e s s , which d i s a p p e a r s r a p i d l y w i t h i n c r e a s i n g t h i c k n e s s As  of s t r u c -  a l s o shown (129)  felting coefficient  with  t h a t paper p r o p e r t i e s  (which i s r e l a t e d to  f i b r e diameter) but w i t h o n l y secondary importance to  are  fibre the  7  flexibility  coefficient.  Papers made from earlywood and latewood f i b r e types show d i f f e r ent p h y s i c a l - m e c h a n i c a l p r o p e r t i e s .  Comparisons  between the two c o n s t a n t -  l y show t h a t papers from earlywood f i b r e s a r e denser, have h i g h e r  tensile,  b u r s t and f o l d i n g endurance but lower t e a r s t r e n g t h than papers made from a s s o c i a t e d latewood f i b r e s  (4, 14, 21, 22, 9 6 ) .  B e s i d e s c l a s s i c works, two r e c e n t s t u d i e s have d i v i d e d and examined wood f i b r e i n t r a - i n c r e m e n t a l o r i g i n e f f e c t s a t s i x (14) o r more (96) l e v e l s . Nordman and Quickstrom (96) showed t h a t the b r e a k i n g l o a d , b r e a k i n g l e n g t h , modulus o f e l a s t i c i t y and e l o n g a t i o n of paper sheets prepared from i n c r e m e n t a l p o s i t i o n s , d e c r e a s e d , but the l i g h t  intra-  scattering coefficient i n -  c r e a s e d w i t h the i n t r a - i n c r e m e n t a l p o s i t i o n from earlywood. to latewood i n the growth increment.  T h i s v a r i a t i o n was o p p o s i t e to p r o p e r t i e s of the  c o r r e s p o n d i n g n o n d e l i g n i f i e d and d e l i g n i f i e d wood m i c r o - s e c t i o n s . et al. (14) s t u d i e d i n t r a - i n c r e m e n t a l handsheet  Brink  p r o p e r t i e s o f white f i r  {Abies aonoolor L i n d l . ) and r e p o r t e d that sheet d e n s i t y , b r e a k i n g l e n g t h and s t r e t c h a l l d e c r e a s e d from earlywood  to latewood.  Furthermore, the  d e c r e a s e of sheet d e n s i t y was r e l a t e d l i n e a r l y to p o s i t i o n w i t h i n ment.  Both s t u d i e s have e x p l a i n e d i n t r a - i n c r e m e n t a l handsheet  i n terms o f f i b r e m o r p h o l o g i c a l c h a r a c t e r i s t i c s , such as w a l l  incre-  variations thickness  and c o n f o r m a b i l i t y w h i c h p r o v i d e s l a r g e r bonded areas between earlywood f i b r e s than between latewood  fibres.  The works noted above, no matter whether wholewood or earlywood vs.  latewood p u l p specimens were examined, a l l i n d i c a t e t h a t the e f f e c t  of wood m o r p h o l o g i c a l p r o p e r t i e s on pulp and paper p r o p e r t i e s cannot be  8  ignored.  In a d d i t i o n , the few  w i t h i n increments incremental  s t u d i e s i n c l u d i n g more than two  a l s o c o n f i r m the important  positions  i n f l u e n c e of pulp f i b r e  intra-  origin.  Pulp Chemical  Components and Paper T e n s i l e  Strength  The c h e m i c a l p r o p e r t i e s of pulp f i b r e s have some e f f e c t s on paper tensile strength. (15).  A good review can be found i n the book e d i t e d by Casey  I t i s g e n e r a l l y agreed  t h a t the h e m i c e l l u l o s e has a b e n e f i c i a l  e f f e c t , but t h a t l i g n i n has an adverse The D. Don)  e f f e c t , on paper s t r e n g t h .  t e n s i l e s t r e n g t h p r o p e r t i e s of Monterey p i n e  (Pinus  pulp were improved by d e c r e a s i n g l i g n i n c o n t e n t , but were weakened  by removal of a l k a l i - s o l u b l e p o l y s a c c h a r i d e s below a c r i t i c a l The same e f f e c t was (145) .  vadiata  found w i t h E u c a l y p t u s  (Eucalyptus  level  (147).  vegnans F. M u e l l . )  In b o t h s t u d i e s the r e s e a r c h e r s s t a t e d t h a t some other changes i n  pulp p r o p e r t i e s , caused by c o n c e n t r a t e d sodium h y d r o x i d e e x t r a c t i o n ,  such  as the t r a n s f o r m a t i o n of c e l l u l o s e o r g a n i z a t i o n from c e l l u l o s e I to I I , reduced  i n t e r f i b r e bonding  c a p a c i t y j w e r e among the causes  of s t r e n g t h r e -  duction. Bleached  s l a s h pine  increased with y i e l d  (43.0  (Pinus e l l i o t t i i  Engelm.) k r a f t pulp s t r e n g t h  to 66.4%), as well^.as h e m i c e l l u l o s e content  (114).  R e t e n t i o n of h e m i c e l l u l o s e seems to enable b e t t e r s p e c i f i c s u r f a c e and' bonded area development i n :the b e a t i n g p r o c e s s w i t h o u t much r e d u c t i o n i n f i b r e strength. nin  Giertz  (28) argued  t h a t the presence of hydrophobic  r e n d e r s the " l i g n i n - h e m i c e l l u l o s e compound" r e s i s t a n t  to water  prevents the h e m i c e l l u l o s e from s w e l l i n g , which a f f e c t s .papermaking  lig-  and  9  p r o p e r t i e s m a i n l y i n f i b r e s t i f f n e s s and bonding a c t i v i t y . l o s e , on the other hand, has been c o n s i d e r e d  as an a d h e s i v e  Hemicelluwhich promotes  f i b r e l a t e r a l s w e l l i n g and  flexibility  t i o n and  through i t s g e l - l i k e s t r u c t u r e , i n c r e a s e s  fibrillation  and,  i n water, f a c i l i t a t e s f i b r e h y d r a the  d e n s i t y of paper. The  q u a n t i t y and  k i n d s of h e m i c e l l u l o s e a r e important  Jayme and L o c h m u l l e r - K e r l e r content  (51)  46).  s t a t e d t h a t some optimum h e m i c e l l u l o s e  e x i s t s f o r a c e r t a i n pulp  strength.  (28,  T h i s p o i n t of view was  i n order not  to o b t a i n a maximum o v e r - a l l  supported  by f i n d i n g s of Watson  (145) . Another v a r i a b l e i n pulp c h e m i c a l degree of p o l y m e r i z a t i o n  (D.P.).  s i l e s t r e n g t h of h i g h p o l y m e r i c off  cellulose  I t has been w e l l e s t a b l i s h e d t h a t m a t e r i a l s i n c r e a s e s w i t h D.P.  at a c e r t a i n minimum v a l u e .  the b r e a k i n g  components i s the  Jayme and  and  ten-  levels  Wellm (52) have shown t h a t  l e n g t h of pulp i n c r e a s e d q u i c k l y up  to 900  average D.P.  and  thereafter leveled o f f slowly. These f i n d i n g s demonstrate t h a t , although wood chemical  components on paper p r o p e r t i e s i s not  i n f l u e n t i a l than wood m o r p h o l o g i c a l chemical  Fibre  the e f f e c t of  c h a r a c t e r i s t i c s Is s t i l l  important  coniferous  (4) or  less  p r o p e r t i e s (22), the v a r i a t i o n i n pulp significant.  Strength A l t h o u g h the high, t e n s i l e s t r e n g t h of wood f i b r e has been known f o r  a l o n g time, i t s c o n t r i b u t i o n to paper s t r e n g t h was cently.  not e x p l o r e d  until re-  10  Clark  (.16)  recognized  as e a r l y as 1943.  The  the Importance of I n d i v i d u a l f i b r e  I n s t i t u t e of Paper Chemistry group r e l a t e d f i b r e  s t r e n g t h to paper i n t e r n a l t e a r i n g energy a b s o r p t i o n (29)  strength  found t h a t f i b r e s t r e n g t h was  i n 1944  (.45) .  Graham  f r e q u e n t l y the l i m i t i n g f a c t o r , i n s t e a d  of i n t e r f i b r e bonding, i n determining  the t e n s i l e s t r e n g t h of s t r o n g  papers.  Even so, the s i g n i f i c a n c e of f i b r e s t r e n g t h f a i l e d to a t t r a c t much a t t e n t i o n u n t i l Van  den Akker and h i s a s s o c i a t e s  of f i b r e f a i l u r e s  i n the t e n s i l e r u p t u r e  stantial fibre fraction failed greenof b e a t i n g was The  (140)  zone.  ( r a t h e r than p u l l e d out)  de-  tensile properties  has  A f t e r an e x c e l l e n t review of the a v a i l a b l e l i t e r -  e f f e c t s of wood and  Dinwoodie (21) l i s t e d  f i b r e p r o p e r t i e s on paper  i n d i v i d u a l f i b r e s t r e n g t h as one  important v a r i a b l e s a f f e c t i n g paper s t r e n g t h . i n h i s l a t e r work (22) and  (1) r e p o r t e d  even when the  moderate.  been examined r e c e n t l y .  again  They concluded that a sub-  i n f l u e n c e of f i b r e s t r e n g t h on sheet  ature concerning  counted the percentage  by Gardner  of the t h r e e most  T h i s view was  (27).  strength,  confirmed  Alexander and  Marton  a maximum t e n s i l e s t r e n g t h f o r spruce k r a f t pulp a t  0.7  3  to 0.9  g/cm  sheet  apparent d e n s i t y as a r e s u l t of combined e f f e c t s of  f i b r e s t r e n g t h and  i n t e r f i b r e bonding.  purposely  (weakened by m e c h a n i c a l treatment and  weakened  a c i d h y d r o l y s i s ) and pulps  together  t u r e and  and  normal s p r u c e  (Piaea  Bergman and  spp.)  Rennel (8) mixed subsequent  s u l p h i t e and  found a d e c r e a s e i n sheet b r e a k i n g  sulphate  l o a d , work to r u p -  s t r a i n a t f a i l u r e as the p r o p o r t i o n of weakened pulp was  in-  creased. In a d d i t i o n to the l i m i t e d i n f o r m a t i o n a v a i l a b l e c o n c e r n i n g  the  11  importance of c o n i f e r o u s f i b r e s t r e n g t h , t h e r e are s t u d i e s which r e l a t e hardwood sheet  s t r e n g t h to f i b r e s t r e n g t h .  E f f e c t s of hardwood  s t r e n g t h on sheet  s t r e n g t h i n c r e a s e w i t h degree of b e a t i n g  and  sheet  (131).  80%  of the b r e a k i n g  density  L a t t e r work (63, 131)  ficant  (129141)  r e p o r t e d t h a t more than  l e n g t h v a r i a t i o n of paper can be accounted f o r by  d i f f e r e n c e s i n paper d e n s i t y and f i b r e s t r e n g t h was  fibre  f i b r e s t r e n g t h , and  v i r t u a l l y n e g l i g i b l e at low  at h i g h sheet  sheet  t h a t the e f f e c t d e n s i t y , but  of  signi-  density.  F u r t h e r to f i b r e t e n s i l e s t r e n g t h , the shear modulus of paper sheets has  been found to be p o s i t i v e l y  w i t h i n the range of pulp y i e l d s The  (47% to 60%)  studied  stiffness  (9).  s t r e n g t h of i n d i v i d u a l pulp f i b r e s v a r i e s not o n l y between  and w i t h i n s p e c i e s but stem (53, 54,  65).  a l s o between earlywood and  latewood of a s i n g l e  H o l o c e l l u l o s e earlywood f i b r e s t r e n g t h s  c o n d i t i o n ) ranged from 47 X 10 spurce  correlated with f i b r e  QPioea sitchensi-s  3  p s i ( s l a s h p i n e ) to 117  (Bong.) C a r r . ) ] , w h i l e  those  X 10  (air-dry 3  psi  [Sitka  of latewood ranged  3 from 66 X 10  p s i [western hemlock  (Tsuga heterophylla  (Raf.) Sarg.)]  to  3  148 X 10  p s i [cypress (Taxodium distiehum  (L.) R i c h . ) ] (54).  f i b r e s t r e n g t h s have been r e p o r t e d by o t h e r s  (2, 53,  65,  66,  Comparable  78, 80,  148).  The modulus of e l a s t i c i t y of i n d i v i d u a l f i b r e s as d e r i v e d from tcvt t e n s i l e t e s t s , has been r e p o r t e d by 80). psi  These v a l u e s  range from 1.66  several researchers X 10^  p s i ( s l a s h p i n e ) to 4.26  ( S i t k a spruce) f o r earlywood f i b r e s and  pine (Pinus monticola wood f i b r e s  (54).  D o u g l . ) ] to 6.35  Leopold  (65)  (2, 53, 54,  X 10  2.37  X 10  psi  X  65, 10^  [western white  p s i (Douglas-fir) f o r l a t e -  t a b u l a t e d a lower earlywood modulus of  12  e l a s t i c i t y than t h a t r e p o r t e d southern p i n e t h a t not  (Pinus spp.)  CO.81  X 10  CO.95 X 10  psi) k r a f t pulps.  o n l y a r e latewood f i b r e s s t r o n g e r  maximum t e n s i l e s t r e n g t h and way  above,for Monterey p i n e  psi)  and  He a l s o showed  than those of earlywood i n  modulus of e l a s t i c i t y , but a l s o t h a t Nor-  spruce f i b r e s a r e g e n e r a l l y s t r o n g e r  than Monterey and  southern  pine  fibres. The weaker earlywood f i b r e s t r e n g t h has been a t t r i b u t e d to pit  frequency  C79).  higher  Other f i b r e t e n s i l e p r o p e r t i e s , such as s t r a i n a t  f a i l u r e , work to p r o p o r t i o n a l l i m i t and  rupture  have been s t u d i e d , and a l l  show d i f f e r e n c e s between s p e c i e s , as w e l l as d i f f e r e n c e s between earlywood and  latewood  (53,  54).  Jayne (53, 54)  observed t h a t the l i n e a r p o r t i o n s  of f i b r e t e s t  s t r e s s - s t r a i n curves were m a i n t a i n e d u n t i l the s t r e s s reached 50 of i t s maximum, and passing rather by H i l l  this yield  that deformation increased point.  He  studied  70%  a t an i n c r e a s i n g r a t e a f t e r  concluded t h a t wood f i b r e s are v i s c o e l a s t i c  than e l a s t i c m a t e r i a l s . (38), who  to  The  same c h a r a c t e r i s t i c was  demonstrated  i n d i v i d u a l f i b r e t e n s i l e creep b e h a v i o r .  These works r e v e a l t h a t c o n i f e r o u s wood f i b r e s a r e not o n l y v i s c o e l a s t i c i n n a t u r e , but as i n t r a - i n c r e m e n t a l  t h e i r s t r e n g t h p r o p e r t i e s v a r y w i t h s p e c i e s as w e l l  positions.  p o r t a n t l y to paper s t r e n g t h ,  Although f i b r e strength c o n t r i b u t e s  im-  i t s c o n t r i b u t i o n i s e f f e c t i v e o n l y when  f i b r e s are w e l l bonded.  Factors A f f e c t i n g Fibre  Strength  F i b r e morphology:  Except f o r f i b r e l e n g t h w h i c h was  the most important v a r i a b l e a f f e c t i n g s l a s h and  reported  l o b l o l l y pine f i b r e  as zero-  13  span t e n s i l e s t r e n g t h (24), l i t t l e work has been done r e l a t i n g  conifer-  ous  holocellu-  f i b r e s t r e n g t h to f i b r e morphology.  In c o n t r a s t , hardwood  l o s e f i b r e s t r e n g t h s have been shown to be h i g h l y a f f e c t e d by cal  p r o p e r t i e s (130).  C r o s s - s e c t i o n a l c e l l w a l l area a l o n e  for  89% of the t o t a l b r e a k i n g l o a d v a r i a t i o n .  n e g a t i v e l y a f f e c t e d f i b r e b r e a k i n g l o a d and  Fibrillar  the f i b r e s t r a i n v a r i a t i o n a t e q u i v a l e n t s t r e s s was  f i b r i l l a r angle Yield:  cell  As much as accounted  83%  f o r by  Working w i t h l o b l o l l y p i n e k r a f t f i b r e s , M c i n t o s h  times.  degraded r a p i d l y a t b o t h h i g h y i e l d l e v e l s and levels.  (78)  i n y i e l d , f i b r e b r e a k i n g l o a d and c r o s s - s e c t i o n a l  a r e a w i t h i n c r e a s e d cooking  t h e r e was  (64.2  The  latewood f i b r e b r e a k i n g  to 59.6%) and  low  (44% and  loads lower)  no a p p r e c i a b l e d i f f e r e n c e i n response  between  Earlywood f i b r e s responded d i f f e r e n t l y to y i e l d  showing a g r a d u a l decrease Chemical  angle not o n l y  alone.  reported a decrease  these two  accounted  f i b r e strength, per u n i t  w a l l a r e a , but I n f l u e n c e d the f i b r e s t r a i n p o s i t i v e l y . of  morphologi-  i n t e n s i l e breaking load with decreasing  changes, yield.  a n a l y s e s of latewood p u l p s showed a good c o r r e l a t i o n between  latewood f i b r e b r e a k i n g l o a d and mannan c o n t e n t , as w e l l as degree of polymerization. w i t h the d e c r e a s e a n g l e may  I t should be noted i n pulp y i e l d  (74a).  decreased  This reduction i n f i b r i l l a r  benefit f i b r e strength.  A l k a l i extraction:  Leopold  l o a d , c r o s s - s e c t i o n a l area and l o s e f i b r e s decreased Chemical  t h a t the f i b r i l l a r a n g l e  and M c i n t o s h  (66) found  that breaking  t e n s i l e s t r e n g t h of l o b l o l l y p i n e h o l o c e l l u -  with, e x t r a c t i o n by i n c r e a s e d a l k a l i c o n c e n t r a t i o n s .  a n a l y s e s showed t h a t t h e r e was  no c o r r e l a t i o n between f i b r e s t r e n g t h  14  and  glueomannan content  or change i n D.P.,  between f i b r e s t r e n g t h and  but a c o r r e l a t i o n was  the removal of xylan-based  T h i s d i f f e r e n c e i n e f f e c t s between x y l a n  and  to r e s u l t from t h e i r l o c a t i o n , o u t s i d e and nan)  f i b r i l s , which c o n t r i b u t e s d i f f e r e n t l y Spiegelberg  l e a f pine  (121)  (Pinus palustvis  s o l u t i o n and  hemicelluloses.  glucomannan was  considered  between (xylan) or w i t h i n to the t o t a l f i b r e  s e l e c t i v e l y extracted"latewood  (man-  strength.  f i b r e s of a l o n g -  M i l l . ) h o l o c e l l u l o s e pulp w i t h aqueous a l k a l i n e  r e l a t e d f i b r e m e c h a n i c a l p r o p e r t i e s to the r e s i d u a l h e m i c e l l u -  lose contents.  He  duced b r e a k i n g  s t a t e d t h a t the removal of h e m i c e l l u l o s e r e s u l t e d i n r e -  s t r e s s , modulus of e l a s t i c i t y , y i e l d p o i n t s t r e s s and  to r u p t u r e , but a p p a r e n t l y was  found  explained  as due  i n c r e a s e d c r y s t a l l i n i t y of the f i b r e s .  work  This  to b e t t e r a b i l i t y of the r e l a t i v e l y f l e x i b l e  cellu-  l o s e - h e m i c e l l u l o s e bond to r e d i s t r i b u t e the e x t e r n a l l o a d than the  rigid  c e l l u l o s e - c e l l u l o s e bond. Leopold  (65) found t h a t unbleached b i s u l p h i t e f i b r e s had  same t e n s i l e s t r e n g t h as k r a f t of e l a s t i c i t y .  B l e a c h i n g had  the  f i b r e s , but c o n s i d e r a b l y h i g h e r modulus l i t t l e e f f e c t on the t e n s i l e s t r e n g t h  and  modulus of e l a s t i c i t y of h i s k r a f t f i b r e , but reduced b o t h p r o p e r t i e s w i t h b i s u l p h i t e pulp f i b r e s . was  T h i s d i f f e r e n c e i n response to b l e a c h i n g  e x p l a i n e d by e f f e c t i v e removal of h e m i c e l l u l o s e from b i s u l p h i t e but  not from k r a f t p u l p s . k r a f t cooking  The  same study  l i q u o r a l k a l i n i t y and  on f i b r e t e n s i l e s t r e n g t h and  also revealed  s u l p h i d i t y had  e l a s t i c i t y , but  t h a t changes i n no  significant  that f i b r e c r o s s - s e c t i o n a l  area c o u l d be reduced c o n s i d e r a b l y by m a n i p u l a t i n g  these  i n c r e a s e i n k r a f t pulp y i e l d by adding sodium b o r o h y d r i d e proved f i b r e t e n s i l e b r e a k i n g  effect  factors.  The  slightly  im-  l o a d but reduced f i b r e c r o s s - s e c t i o n a l area  15  seriously.  T e n s i l e strength, and modulus of e l a s t i c i t y were t h e r e f o r e i n -  creased.  The  e f f e c t was  inhibited  f i b r e swelling.  Beating: affecting  regarded  Beating  as due  i s probably  f i b r e strength.  (129,  140,  demonstrated t h a t as b e a t i n g time was the p e r c e n t a g e of r u p t u r e d 71%,  and  t h a t sheet  one  of the most important  I t s e f f e c t on paper sheet  w i t h t h e degree of b e a t i n g  to  to glucomannan r e t e n t i o n w h i c h  141).  strength  procedures increases  Van. den Akker et al.  (140)  i n c r e a s e d from 0 to 55 minutes,  fibres i n tensile testing  t e n s i l e breaking  i n c r e a s e d from  l o a d i n c r e a s e d from 7.3  40  to  24.4  lb/in.  At 15 minutes b e a t i n g time, the percentage of broken f i b r e s i n -  creased  o n l y from 53 to 64% even when wet  to 1,000  p r e s s u r e was  i n c r e a s e d from  25  psi. Leopold  (65)  southern  s t u d i e d the e f f e c t of prolonged  spruce  and  pine  cluded  t h a t t h e r e was  (Pinus  spp.)  b e a t i n g on Norway  unbleached k r a f t p u l p s and  neither serious f i b r e structural  l o a d - b e a r i n g m a t e r i a l of the f i b r e been removed. no change i n f i b r e b r e a k i n g a consequence, the a i r - d r i e d  con-  damage, nor  had  Beating r e s u l t e d i n  l o a d , but reduced c r o s s - s e c t i o n a l a r e a s . f i b r e t e n s i l e s t r e n g t h and modulus of  As  elas-  t i c i t y were i n c r e a s e d . In c o n t r a s t to the above f i n d i n g , M c i n t o s h and different pine.  responses between earlywood and  Uhrig  latewood f i b r e s of  (80)  found  loblolly  B e a t i n g reduced the t e n s i l e l o a d , c e l l w a l l a r e a , t e n s i l e  strength  and modulus of e l a s t i c i t y w i t h latewood unbleached k r a f t p u l p , but  im-  proved the t e n s i l e b r e a k i n g  reduced  l o a d , t e n s i l e s t r e n g t h , e l a s t i c i t y and  c e l l w a l l a r e a of earlywood p u l p s .  The response of earlywood h o l o c e l l u l o s e  16  f i b r e s to b e a t i n g was the same as with, unbleached k r a f t earlywood The  e l a s t i c i t y o f latewood h o l o c e l l u l o s e decreased g r a d u a l l y , b u t the  t e n s i l e l o a d and s t r e n g t h were n o t a l t e r e d u n t i l a low f r e e n e s s 260  fibres.  ml  was  reached.  The above f i n d i n g was e x p l a i n e d  l e v e l of  i n terms o f t h e  m e c h a n i c a l treatment w h i c h caused a r e o r g a n i z a t i o n of the wet f i b r e w a l l fibrillar  structure  published  later  hemicellulose  C80).  This reasoning  (2) , t h a t b e a t i n g  agrees i n p a r t w i t h  that  causes d i s s o l u t i o n o f i n t e r f i b r i l l a r  and l i g n i n and t h e subsequent r e a s s o c i a t i o n of f i b r i l s r e -  duces c r y s t a l l i t e s i z e and w a l l f i b r i l l a r Mechanical c o n d i t i o n i n g : strength properties  angle.  Another treatment w h i c h a f f e c t s f i b r e  i s mechanical c o n d i t i o n i n g .  t h a t d r y i n g f i b r e under l o a d s  increases  I t has been found (55)  i t s c r y s t a l l i t e o r i e n t a t i o n , which  enables a more even d i s t r i b u t i o n of a p p l i e d s t r e s s among the f i b r i l s . t e n s i l e s t r e n g t h , e l a s t i c i t y and work to r u p t u r e were i n c r e a s e d maximum e l o n g a t i o n was reduced. havedvdifferently with respect underwent much g r e a t e r  The  although  Here a g a i n , earlywood and latewood b e to d r y i n g l o a d , i . e . , earlywood f i b r e s  changes than d i d latewood f i b r e s .  menon was observed when s u s t a i n e d  The same pheno-  t e n s i l e s t r e s s was a p p l i e d to d r i e d  f i b r e s (38).  E f f e c t o f C e l l u l o s e C r y s t a l l i n i t y on Wood, F i b r e and Paper  Properties  C e l l u l o s e i s one o f t h e main chemical components o f woody c e l l s . It  i s a l i n e a r polymer and many o f the polymer c h a i n s  a r e f u r t h e r aggre-  gated i n t o elementary f i b r i l s , • m i c r o f i b r i l s and f i b r i l l a r These f i l a m e n t s a r e i n t u r n wound h e l i c a l l y w i t h r e s p e c t  filaments. to the c e l l  axis  17  and form v a r i o u s l a y e r e d s t r u c t u r e s i n c e l l w a l l s . The way i n w h i c h t h e c e l l u l o s e c h a i n s a r e aggregated in  and o r i e n t e d  the c e l l w a l l s u p e r m o l e c u l a r s t r u c t u r e has been the s u b j e c t of many  studies.  An e x c e l l e n t review  (143) was p u b l i s h e d r e c e n t l y , which d i s ^  cussed n o t o n l y t h e f i b r e f i n e s t r u c t u r e b u t a l s o i t s r e l a t i o n to paper processing. I t i s g e n e r a l l y agreed and  secondary l a y e r s .  and  inner l a y e r s .  t h a t t t h e f i b r e w a l l c o n s i s t s o f primary  The l a t t e r i s a g a i n d i v i d e d i n t o o u t e r , middle  The m i d d l e l a y e r of t h e secondary w a l l c o n t r i b u t e s  the b u l k o f w a l l s t r u c t u r e , t h e r e f o r e d e t e r m i n i n g the p h y s i c a l ties of.fibres.  R e s u l t s from c h e m i c a l and X-ray a n a l y s e s have shown  t h a t the c e l l u l o s e c h a i n s a r e packed or  proper-  p a r t i a l l y into c r y s t a l l i n e regions  c r y s t a l l i t e s w i t h s o - c a l l e d amorphous r e g i o n s between them. C e l l u l o s e c r y s t a l l i t e dimensions  l i t e s a r e wider  i n earlywood  v a r y w i t h wood s p e c i e s .  than latewood  Crystal-  i n b o t h wood and p u l p s .  w i d t h i n c r e a s e s w i t h d e c r e a s i n g pulp y i e l d and prolonged r e f i n i n g  This action  (74a). Methods have been developed polymeric m a t e r i a l s .  t o determine  the c r y s t a l l i n i t y of  U s i n g X-ray d i f f r a c t i o n t e c h n i q u e , i t has been r e -  ported that c r y s t a l l i n i t y i s approximately c o t t o n and 55% to 65% f o r wood p u l p s  70% (50, 104, 106, 150) f o r  (50, 55, 6 4 ) .  Comparatively l i t t l e work has been'done i n r e l a t i n g wood p r o p e r t i e s to c r y s t a l l i n i t y .  P r e s t o n et al. (109) found  that c r y s t a l l i n i t y o f  C r o s s and Beven c e l l u l o s e i s o l a t e d from Monterey p i n e decreased p i t h to b a r k .  from  I n c o n t r a s t , Lee (64) s t u d i e d western hemlock pulp and  18  h o l o c e l l u l o s e and found t h a t c r y s t a l l i n i t y i n c r e a s e d  significantly  from  p i t h t o about 15 y e a r s of age, a f t e r which a more o r l e s s constant was m a i n t a i n e d .  Reported a l s o i n t h e same study was t h a t  value  crystallinity  of latewood h o l o c e l l u l o s e and p u l p was s i g n i f i c a n t l y h i g h e r  than t h a t of  earlywood. Murphey  (85) r e l a t e d wood c r y s t a l l i n i t y  to t e n s i l e s t r a i n and  found t h a t the degree of c r y s t a l l i n i t y v a r i e d as a f u n c t i o n of a p p l i e d load, i . e . , c r y s t a l l i n i t y increased with t e n s i l e load at a r a t e , b u t not w i t h l o a d d u r a t i o n .  The change was p a r t i a l l y  a f t e r removing the l o a d . Murphey e x p l a i n e d  t h i s phenomenon  decreasing retained as b e i n g  due to r e o r g a n i z a t i o n of the c e l l u l o s e c h a i n s , which i n c r e a s e d of c r y s t a l l i t e s  length  and t h e r e f o r e the degree of c r y s t a l l i n i t y .  J e n t z e n (55) measured the response of i n d i v i d u a l l o n g l e a f h o l o c e l l u l o s e f i b r e s to the s t r e s s a p p l i e d d u r i n g  pine  d r y i n g and found  that  there was no change i n c r y s t a l l i n i t y , b u t t h a t modulus o f e l a s t i c i t y , t e n s i l e s t r e n g t h , work to r u p t u r e creased.  and c r y s t a l l i t e o r i e n t a t i o n were i n -  Improvement i n f i b r e m e c h a n i c a l p r o p e r t i e s was a t t r i b u t e d to  increase i n c r y s t a l l i t e orientation. by H i l l studying  The same phenomenon was  observed  (38), who a l s o noted improved c r y s t a l l i t e o r i e n t a t i o n when the creep b e h a v i o r of dry latewood f i b r e s o f l o n g l e a f p i n e  holo-  c e l l u l o s e p u l p s Tinder t e n s i l e s t r e s s . Instead  of s t u d y i n g  the change i n c e l l w a l l c r y s t a l l i n i t y as a  f u n c t i o n of a p p l i e d m e c h a n i c a l s t r e s s , P a r k e r approach. ' He r e p o r t e d  (104) used a d i f f e r e n t  t h a t d e c r y s t a l l i z a t i o n of c o t t o n by ethylamine  caused an abrupt decrease i n paper sheet modulus of e l a s t i c i t y ,  tensile  19  strength and zero-span t e n s i l e strength.  Unfortunately, he was not able  to i s o l a t e the e f f e c t of c r y s t a l l i n i t y alone.  I n t e r f i b r e Bonding The strength and quantity of bonding s i t e s between f i b r e s are among the many f a c t o r s which a f f e c t paper sheet strength.  Nissan and  S t e r n s t e i n (90) discussed c e l l u l o s e - f i b r e bonding and reviewed experiments.  earlier  They concluded that the hydrogen bond appeared to' be the  main bonding between f i b r e s . mechanical strength (17).  This bond i s reported to provide sheet  Ranby (112) concluded  that cohesive forces  of i n t e r f i b r e bonds were mainly hydrogen bonds, i n v o l v i n g two or three hydroxyl groups of the r i n g and g l y c o s i d i c oxygen atoms on the basic u n i t s of c e l l u l o s e and hemicellulose chains.  The e q u i l i b r i u m distances  between atoms which are bonded by hydrogen /bridges depend;on.the nature of the atoms which the hydrogen i s b r i d g i n g and the presence of other groups or atoms. (89).  These distances vary from approximately o  In c e l l u l o s e the distance i s approximately  o 2.4 to 3.5 A  2.7 A (76).  gen bonds are t y p i c a l l y dipole i n nature and are quite weak.  The hydroThey can be  broken e a s i l y by the a d d i t i o n of a p o l a r medium or by mechanical s t r a i n ing  (112). In the papermaking process, water i s removed i n i t i a l l y by  t a t i o n a l or s u c t i o n forces.  gravi-  Accompanying the removal of water, f i b r e s  are brought c l o s e r together by surface tension 'which f a c i l i t a t e s i n t e r f i b r e bond formation.  Lyne and Gallay (68) described the e f f e c t of sur-  face tension s t a r t i n g at a f i b r e s o l i d s content of 11% to 12%.  With i n -  20  crease  i n f i b r e s o l i d s content  to 20%  to 25%,  gether w i t h i n c r e a s i n g f o r c e , m a i n l y by  surface tension forces.  t h i s stage,  i n t e r f i b r e bonding p l a y s  concept was  suggested by Ranee ( H 3 ) , who  web  the major r o l e .  and  age  to the  due  of  transmitted  tension  interfibre  intrafibre  shrink-  web.  There a r e numerous p o i n t s of e v i d e n c e i l l u s t r a t i n g b u t i o n of hydrogen bonding to paper s t r e n g t h . and  After  same g e n e r a l  to the s u r f a c e  that formation  bonding f i x e d i n t e r f i b r e c o n t r a c t i o n and  The  to-  s t a t e d t h a t the mechanism of  c o n t r a c t i o n d u r i n g d r y i n g o f paper was  between f i b r e s , f i b r e s h r i n k a g e ,  the f i b r e s a r e h e l d  Higgins  et al.  s u l t of h y d r o x y l  McKenzie and  the  contri-  Higgins  (82)  (37) reduced paper s t r e s s - s t r a i n p r o p e r t i e s as a r e -  group s u b s t i t u t i o n by a c e t y l a t i o n , p r o p i o n y l a t i o n  and  butyrylation. Paper p h y s i c a l p r o p e r t i e s are i n f l u e n c e d by (12, 13).  Strength  i n c r e a s e s w i t h m o i s t u r e content  c o n d i t i o n to a c e r t a i n l e v e l , and i n moisture.  The  i t s moisture  from the bone-dry  then d e c r e a s e s w i t h f u r t h e r  l a s t phenomenon has been c o n s i d e r e d  increase  as c h i e f l y due  weakening o f hydrogen bonds at h i g h m o i s t u r e l e v e l s which lowers By  i n h i b i t i n g formation  of i n t e r f i b r e b o n d i n g , one  form f i b r e webs w i t h l i t t l e bonding between the f i b r e s . demonstrated by commonly used t e c h n i q u e s , and  s o l v e n t exchange (83, 115,  124,  125)  T h i s has  used f o r p r e p a r i n g  to  strength.  can a c t u a l l y  such as f r e e z e - d r y i n g  handsheets f o r t o t a l f i b r e s u r f a c e a r e a measurements.  been (115)  unbonded  In f r e e z e - d r y i n g ,  the s u r f a c e t e n s i o n f o r c e i s removed, t h e r e f o r e bond f o r m a t i o n vented.  content  i s pre-  In the s o l v e n t exchange method, a l t h o u g h the s u r f a c e s a r e drawn  21  t o g e t h e r , the non-polar bonds.  Marchessault  s o l v e n t i s not conducive  et al.  to the f o r m a t i o n of  (.73) r e p o r t e d t h a t t e n s i l e s t r e n g t h s of  f r e e z e - d r i e d papers were o n e - t h i r d to o n e - h a l f of those prepared d r y i n g a t room temperature.  Rennel prepared  by  t o t a l l y unbonded paper  by f r e e z e - d r y i n g (.115), as has been done f o r the p r e s e n t  study.  The importance of i n t e r f i b r e bonding on paper s t r e n g t h s t r e s s e d by N i s s a n  (86, 87, 88, 89), who  r e l a t e d paper r h e o l o g y  s t r e n g t h p r o p e r t i e s to the number of hydrogen bonds.  Although  t h e o r y has been c r i t i c i z e d by Page (98) as u n a c c e p t a b l e , of hydrogen bonding i n governing  was  the  and Nissan's  importance  paper p r o p e r t i e s i s w e l l agreed  upon.  F i b r e S u r f a c e Area  There a r e two nal surfaces.  types of f i b r e s u r f a c e s , namely e x t e r n a l and  P a r t of the former i s the p o t e n t i a l s i t e f o r i n t e r f i b r e  bond f o r m a t i o n .  I n t e r n a l f i b r e s u r f a c e ; ( w i t h i n c e l l w a l l s ) r e l a t e s more  to c h e m i c a l a c t i v i t y of f i b r e . I n d i r e c t l y , a good r e l a t i o n e x i s t s tween i n t e r n a l s u r f a c e a r e a and  f i b r e s p e c i f i c volume, which has  shown to c o r r e l a t e w e l l w i t h bonded a r e a The  inter-  bebeen  (44).  s u r f a c e a r e a of p u l p f i b r e s v a r i e s c o n s i d e r a b l y , depending  on o r i g i n and  subsequent treatments.  Methods have been developed  measure the s u r f a c e a r e a of f i b r e s , but d i f f e r e n t r e s u l t s a r e  to  obtained.  These measured q u a n t i t i e s have been c a l l e d s p e c i f i c s u r f a c e a r e a as t i n g u i s h e d from t r u e s u r f a c e a r e a . a d s o r p t i o n methods and  concluded  Haselton  (.33) compared d i f f e r e n t  disgas  t h a t the n i t r o g e n a d s o r p t i o n measurement  22  and BET method o f c a l c u l a t i o n were the b e s t a v a i l a b l e . been used by many r e s e a r c h e r s  T h i s method has  (34, 115, 116, 124, 125, 128).  Stone and S c a l l a n (124, 125) summarized the r e s u l t s o f s e v e r a l i n v e s t i g a t i o n s and concluded  t h a t the n i t r o g e n a d s o r p t i o n method measured  2 s p e c i f i c s u r f a c e a r e a o f f i b r e s d r i e d fromvwater a t about 1 m /g of f i b r e . The  s p e c i f i c s u r f a c e area of water s w o l l e n f i b r e s d r i e d by s o l v e n t • exchange 2  was s e v e r a l times  l a r g e r than the above v a l u e , r a n g i n g up t o 200 m /g.  This  huge d i f f e r e n c e was a t t r i b u t e d t o measurement o f o n l y the e x t e r n a l s u r f a c e area  ( f i b r e and lumen s u r f a c e s ) o f the w a t e r - d r i e d f i b r e s i n c o n t r a s t to  these p l u s the i n t e r n a l s u r f a c e areas o f s o l v e n t exchange-dried The m u l t i - l a y e r s t r u c t u r e o f c e l l w a l l s has been w e l l These l a y e r s a r e aggregated i n water.  fibres. accepted.  t o g e t h e r when d r i e d and s e p a r a t e d when s w o l l e n  I n r e c e n t s t u d i e s , Stone and S c a l l a n (124, 125) proposed t h a t  t h e r e were up to s e v e r a l hundred l a m e l l a e i n the f u l l y w a t e r - s w o l l e n wall.  Each o f these i s d e s c r i b e d as approximately o  o 100 A t h i c k w i t h a  median s e p a r a t i o n o f about 35 A. These l a m e l l a e a r e drawn t o g e t h e r g r e s s i v e l y t o form a s i n g l e continuous g i b l e pore volume.  fibre  l a y e r , the c e l l w a l l , w i t h  pronegli-  S o l v e n t exchange d r y i n g methods r e t a i n the open s t r u c -  t u r e a f t e r the water has been removed, t h e r e f o r e making i t a c c e s s i b l e t o o the n i t r o g e n m o l e c u l e The spp.)  w h i c h r e c o r d s areas down t o 3.6 A s e p a r a t i o n  (115).  s p e c i f i c s u r f a c e areas o f spray d r i e d f i b r e s o f spruce  (JPi-oea  s u l p h a t e and p i n e  (Pinus spp.) s u l p h a t e p u l p s as measured by the 2 n i t r o g e n a d s o r p t i o n method were 0.977 and 1.02 m /g, r e s p e c t i v e l y . The 2 2 s p e c i f i c s u r f a c e areas o f the same p u l p s became 2.33 m /g and 2.59 m /g 2 2 when f i b r e s were f r e e z e - d r i e d , as w e l l as 7.44 m /g and 9.86 m /g r e s p e c t i v e l y , when they were s o l v e n t exchange d r i e d  (115).  23  It  i s e v i d e n t from t h e above i n f o r m a t i o n t h a t the d r y i n g method  causes tremendous d i f f e r e n c e s i n f i b r e surfaces-area measurements.  More-  over, w i t h i n the same method, the f i b r e s u r f a c e a r e a measurement v a r i e s w i t h s u r f a c e t e n s i o n of the f i n a l and to  exchange s o l v e n t , d r y i n g temperature  the amount of s o l v e n t r e t a i n e d i n the f i b r e s i s i n v e r s e l y the i n c r e a s e of f i b r e s u r f a c e a r e a  (83).  S i n c e o n l y the e x t e r n a l f i b r e s u r f a c e s , as loosened l a m e l l a e of the c e l l w a l l s , are i n v o l v e d i n i n t e r f i b r e bond i t would be erroneous of  fibril  T h i s view was  d i s c u s s e d and  or  formation,  to use the s w o l l e n s t a t e s u r f a c e a r e a as an  f i b r e bonding p o t e n t i a l . II  related  index  illustrated  II  g r a p h i c a l l y by K a m a s u r f a c e " of s w o l l e n  (60) , who  demonstrated mistakes  i n u s i n g the  "free  fibres.  S i n c e paper i s formed by removing water from wet  f i b r e webs, the  most r e p r e s e n t a t i v e f i b r e s u r f a c e a r e a s h o u l d be o b t a i n e d from waterdried fibre.  Due  to the i n h e r e n t f o r m a t i o n of bonds between f i b r e s  they a r e d r i e d from water, i t i s d i f f i c u l t bonded s h e e t s . t h i s property  T h e r e f o r e , techniques have been developed (34, 44,  61,  67,  wet  handsheets prepared  (L.S.C.)  from the same p u l p , but w i t h d i f f e r e n t degrees of  or modulus of e l a s t i c i t y .  t e c h n i q u e was  estimate  scattering coefficient  p r e s s i n g , were p l o t t e d a g a i n s t t h e i r c o r r e s p o n d i n g  s t r e n g t h was  to  un-  128).  As example, s u r f a c e a r e a or l i g h t of  to produce w a t e r - d r i e d ,  as  The  t e n s i l e strength  s u r f a c e a r e a read from t h i s p l o t a t zero  taken as an e s t i m a t e of the a r e a sought.  Although  c o n s i d e r e d as c l o s e to t h e t r u e w a t e r - d r i e d  a r e a , i t s r e l i a b i l i t y has been much questioned  this  f i b r e surface  (32, 59, 115,  128).  24  Besides  the n i t r o g e n a d s o r p t i o n method, t h e r e a r e many o t h e r s  used f o r measuring the f i b r e s u r f a c e a r e a . silvering  technique,  r a d i o c h e m i c a l and pose. 127,  These i n c l u d e  geometric,  f i l t r a t i o n r e s i s t a n c e and dye a d s o r p t i o n , w h i l e  o p t i c a l measurements have been developed  f o r the p u r -  S e v e r a l papers have been p u b l i s h e d d i s c u s s i n g these methods 135).  Among t e c h n i q u e s , o n l y the L.S.C. method w i l l be  (75,  reviewed  briefly. When a beam of l i g h t  travelling  to a second medium, the l i g h t  i n a homogeneous medium comes  i s r e f l e c t e d or r e f r a c t e d .  f a c e of the medium i s rough and  I f the  opaque, the i n c i d e n t l i g h t  i n a l l d i r e c t i o n s or s a i d to be d i f f u s e r e f l e c t e d .  sur-  i s scattered  When l i g h t  enters a  d i f f u s i n g medium, such as a sheet of paper, i t i s e i t h e r s c a t t e r e d back, absorbed o r t r a n s m i t t e d i f the paper i s of f i n i t e The  thickness  (122).  q u a n t i t y of l i g h t r e f l e c t e d back i s a f u n c t i o n of  a b s o r p t i o n and  scattering,  t h i c k n e s s of a p a r t i c u l a r paper, t o g e t h e r w i t h the  t i n g c h a r a c t e r i s t i c s of the background  (122).  reflec-  By u s i n g an e q u a t i o n  de-  r i v e d by S t e e l e (122), from the t h e o r y proposed by Kubelka and Munk, i t i s p o s s i b l e to c a l c u l a t e the L.S.C. of a paper  sheet.  By assuming t h a t o n l y the f r e e s u r f a c e s c a t t e r s l i g h t , Parsons (105) measured the L i S . C . of a paper sheet and ed s u r f a c e a r e a . specific all  A l i n e a r r e l a t i o n s h i p was  related  found  t h i s to i t s unbond-  between L.S.C. and  s u r f a c e a r e a of sheets measured by the s i l v e r i n g  f r a c t i o n s of a pulp except  have been r e p o r t e d subsequently  the f i n e s . by o t h e r s  technique  the for  Similar linear relationships (44,  114).  25  In a d d i t i o n , a l i n e a r r e l a t i o n s h i p was e s t a b l i s h e d between L.S.C. and  f i b r e s u r f a c e a r e a determined  b y n i t r o g e n a d s o r p t i o n measurements  (34, 116, 128) and by f i l t r a t i o n method  (44).  Although t h i s l i n e a r r e -  l a t i o n s h i p has been r e p o r t e d o f t e n f o r papers, a n o n - l i n e a r f u n c t i o n has been observed  f o r synthetic fibres (5).  U n f o r t u n a t e l y , t h e p r o p o r t i o n a l i t y c o n s t a n t r e l a t i n g L.S.C. and s u r f a c e a r e a v a r i e s w i t h t h e type o f p u l p has been accounted  (105, 114, 116, 128). T h i s  f o r as dependency of L.S.C. on the s i z e and shape of  f i b r e s i n a sheet.  Paper Sheet  Bonded Area  By i t s name, bonded a r e a  (B.A.) i s the a r e a w h i c h i s f i x e d i n  some manner between two elements,  such as f i b r e s i n a paper  The B.A. c a n be measured by e i t h e r o f two approaches. i s t o observe a microscope  structure.  The d i r e c t  approach  the s i z e and shape o f the bonded a r e a i n a sheet by u s i n g (101).  The i n d i r e c t approach i s to c a l c u l a t e the d i f f e r e n c e  between two measurable q u a n t i t i e s , the unbonded a r e a i n a sheet the e x t e r n a l s u r f a c e a r e a of the p u l p f i b r e s The  B.A. i s t h e r e f o r e A^_ - A . t u  (A ) and u (A. ) c o m p r i s i n g the s h e e t . fc  Due to i t s s i m p l i c i t y , the i n d i r e c t  approach has been used more f r e q u e n t l y . In a d d i t i o n to B.A. (sometimes c a l l e d ( 1 2 8 ) ) , t h e r e i s another  " a b s o l u t e bonded a r e a "  q u a n t i t y , r e l a t i v e bonded a r e a  (R.B.A.).  This  i s the f r a c t i o n o f t h e f i b r e e x t e r n a l s u r f a c e a r e a which i s bonded and i s expressed by t h e e q u a t i o n  I (A  -  A )/A ] .  T h i s R.B.A. has been em-  p l o y e d i n v a r i o u s s t u d i e s (44, 59, 62, 128) and has been examined c a l l y (59).  criti-  26  There are many methods a v a i l a b l e f o r d e t e r m i n i n g B.A. The  two most commonly used are gas  F o r the sake of s i m p l i c i t y  and  a d s o r p t i o n and L.S.C.  i t s nondestructive nature,  method has been used more o f t e n , and the a r e a determined  by  techniques. the l a t t e r  i s sometimes c a l i b r a t e d  the gas a d s o r p t i o n method (57, 59,  The use of L.S.C. i n d e t e r m i n i n g  the B.A.  area  l i g h t , and  (105).  against  116,  128).  or R.B.A. i s based  the assumptions t h a t o n l y those f i b r e s u r f a c e s not i n o p t i c a l reflect  or R.B.A.  contact  t h a t L.S.C. i s a l i n e a r f u n c t i o n of s p e c i f i c s u r f a c e  T h i s assumption has been accepted by many r e s e a r c h e r s  has been r e c e n t l y confirmed  a g a i n by Rennel (116).  a g i v e n p u l p , the L.S.C. was f a c e a r e a , and  on  d e f i n i t e l y determined  He by  and  states that f o r the unbonded s u r -  t h a t p r o p o r t i o n a l i t y of t h i s c o e f f i c i e n t to unbonded s u r -  f a c e area d i f f e r s from pulp to p u l p . S i n c e the e q u i l i b r i u m d i s t a n c e s between hydrogen bonded atoms v a r y from approximately  2.4  to 3.5 o  a r e s e p a r a t e d by as much as 600 A,  o A and  the o p t i c a l l y bonded s u r f a c e s  t h e r e has been much c o n t r o v e r s y  about  the degree of hydrogen bonded area i n the o p t i c a l l y bonded a r e a .  Nissan  and  observed  B.A.  S t e r n s t e i n (90) s t a t e d t h a t o n l y 0.001 was  i n a t r u e s t a t e of c e l l u l o s e - f i b r e bonding.  i t y between o p t i c a l and hydrogen B.A. et al.  to 3% of the o p t i c a l l y  (101)  argued t h a t , due  was  T h i s doubt of e q u a l -  q u e s t i o n e d by Jayme (47).  to the a c t i o n of hydrogen bonds, i t was  h i g h l y u n l i k e l y t h a t a p p r e c i a b l e unbonded area e x i s t s w i t h i n an contact area.  optical  Moreover, o p t i c a l l y bonded s u r f a c e s have been found  i n a c c e s s i b l e to the n i t r o g e n molecule Kallmes and  Eckert  Page  (57).  to be  Kallmes and B e r n i e r (57)  (59) examined the v a l i d i t y of u s i n g o p t i c a l methods  and  27  for  measuring R.B.A.  techniques  They found, t h a t t h e n i t r o g e n a d s o r p t i o n and L.S.C.  g i v e comparable R.B.A. r e s u l t s and concluded  that the o p t i c a l l y  bonded s u r f a c e s were t r u l y hydrogen bonded. Paper s t r e n g t h has been r e p o r t e d as a f u n c t i o n of B.A. or R.B.A. (100).  Parsons (105) noted t h a t the t e n s i l e s t r e n g t h of handsheets r e -  l a t e d l i n e a r l y to the o p t i c a l c o n t a c t area d u r i n g the e a r l y stages o f beating.  By u s i n g the same t e c h n i q u e ,  Ratliff  (114) confirmed  that  ten-  s i l e s t r e n g t h i n c r e a s e d w i t h B;A., w h i c h was approximately  a linear  tion with beating  a s i n g l e curve  time.  Ingmanson and Thode (44) o b t a i n e d  when t e n s i l e s t r e n g t h was p l o t t e d a g a i n s t sheet L.S.C. and t h i s s h i p was found to be independent o f b e a t i n g degree. (128) but  obtained  func-  relation-  Swanson and Steber  a s i m i l a r r e l a t i o n s h i p between L.S.C. and t e n s i l e  t h e i r r e l a t i o n s h i p was dependent on the degree of b e a t i n g .  strength, Instead o f  t e n s i l e s t r e n g t h , Luner et al. (67) found a l i n e a r r e l a t i o n s h i p between modulus o f e l a s t i c i t y and B.A. and t h i s was independent of the l i g n i n content,  extent  o f r e f i n i n g o r wet p r e s s i n g .  between modulus o f e l a s t i c i t y or b r e a k i n g II  The good r e l a t i o n s h i p s  l e n g t h and B.A. were  confirmed  II  by K a m a  ( 6 2 ) . Rennel  (116), however, found t h a t the r e l a t i o n s h i p be-  tween L.S.C. and b r e a k i n g  l e n g t h was a f f e c t e d by the l e v e l o f wet p r e s s i n g .  A l t h o u g h c o n f l i c t s e x i s t between v a r i o u s s t u d i e s , the e f f e c t o f B.A. on paper s t r e n g t h p r o p e r t i e s i s w e l l agreed. of f i b r e lumen s u r f a c e a r e a to A a b i l i t y of B.A. i t s e l f  Due to t h e c o n t r i b u t i o n  and A measurements, however, the r e l i t u i s In question.  28  F i b r e Bond  Strength  Sheet b r e a k i n g  l e n g t h has been expressed as a f u n c t i o n o f  bond s t r e n g t h , f i b r e s t r e n g t h and sheet  s t r u c t u r e (116).  An e q u a t i o n  has been d e r i v e d r e c e n t l y by Page (100) to p r e d i c t t h e t e n s i l e of paper.  B.A.,  F a c t o r s such as i n t e r f i b r e bonding shear s t r e n g t h ,  strength fibre  s t r e n g t h , l e n g t h and c r o s s - s e c t i o n a l a r e a , R.B.A. and f i b r e d e n s i t y were all  included.  This equation  s t a t e s t h a t , f a c t o r s a s s o c i a t e d w i t h bond-  i n g s t r e n g t h determine the s t r e n g t h of weakly bonded p a p e r s , w h i l e s t r e n g t h i s the predominate f a c t o r f o r s t r o n g papers. agreed to by o t h e r s  (91, 94) or a t b r e a k i n g  the e n t i r e s t r i p .  T h i s view has been  (79, 139).  When a s t r i p of paper i s s u b j e c t e d at pre-rupture  fibre  to l o a d i n g , bonds a r e broken  point  (101,  102) l o a d s  throughout  T h i s t r a n s f e r from bonded i n t o unbonded a r e a  to be an i r r e v e r s i b l e p r o c e s s  which can be d e t e c t e d  (91, 94, 95) or p o l a r i z e d l i g h t i n g can be d e t e c t e d  (101,  102).  by i n c r e a s e d  i s thought L.S.C.  The p o i n t where bond b r e a k -  o p t i c a l l y corresponds r o u g h l y  p o r t i o n a l l i m i t ) i n the s t r e s s - s t r a i n c u r v e (95).  to the y i e l d p o i n t  (pro-  T h i s e v i d e n c e has been  taken f o r r e l a t i n g bond breakage to paper p l a s t i c i t y ( 3 ) . When t e n s i l e f o r c e i s a p p l i e d to a w e l l bonded paper, t h e i n t e r f i b r e bonds a r e s u b j e c t e d  to simple  shear s t r e s s e s  (137).  Mayhood et al.  (77) measured the sheer l o a d s per o p t i c a l c o n t a c t a r e a o f softwood pulp and found t h a t m i l d b e a t i n g had l i t t l e u n i t f i b r e contact g/cm  2  area  (2.88  chemical  e f f e c t on t h e shear s t r e s s per  4 2 4 X 10 g/cm f o r m i l d l y beaten vs. 3.00 X 10  f o r unbeaten f i b r e s ) , b u t a s m a l l improvement was observed f o l l o w i n g  severe beating  (3.61  4 2 X 10 g/cm ) .  T h i s f i n d i n g l e d to t h e i r  conclusion  29  t h a t the dependency of paper t e n s i l e s t r e n g t h on pulp was  r e l a t e d t h r o u g h f i b r e s t r e n g t h and  characteristics  network geometry, r a t h e r  than  bond s t r e n g t h . The comparable magnitude of bonding shear s t r e n g t h was by M c i n t o s h (78) and M c i n t o s h and  Leopold  (79) when t e s t i n g bond  between l o b l o l l y p i n e earlywood f i b r e and tween latewood f i b r e s was fibres.  Stronger  approximately  reported  shive.  strength  The bond s t r e n g t h  be-  t h r e e times t h a t of earlywood  bonding between latewood f i b r e s than between earlywood  f i b r e s has been r e p o r t e d elsewhere  (.14,  119), and  latewood to earlywood  f i b r e bond s t r e n g t h f a l l s between the above d e s c r i b e d p u r e l y earlywood o r latewood c o m b i n a t i o n s .  The  e x p l a n a t i o n as advanced by  these  research-  ers included nonuniformity  i n c h e m i c a l make-up from f i b r e to f i b r e  (14,  78), p o s s i b l e l i m i t a t i o n by c e l l w a l l p i t s t r u c t u r e s on the t r u e bonded area  (79, 119)  and  t h a t latewood. f i b r e s u r f a c e s p r o v i d e a l a r g e r number  o f p o t e n t i a l bonding s i t e s per u n i t a r e a Bond s t r e n g t h has been r e p o r t e d and m e c h a n i c a l treatment.  B r i n k et al.  (119). to v a r y w i t h p u l p i n g c o n d i t i o n (14) found t h a t b e a t i n g  the bond s t r e n g t h between latewood f i b r e s but was earlywood f i b r e s .  not  reduced  significant  with  T h i s f i n d i n g seemed to be c o n t r a r y to t h a t of Mayhood  et al. (77). According the t e s t  to the d e s c r i p t i o n by Mayhood et al.  (77)  concerning  fibres: "The. experiment proceeded w i t h the s e l e c t i o n of a p a i r of c r o s s e d f i b r e s on the s u r f a c e of the f e r r o plate. Whenever p o s s i b l e the c h o i c e was made from among f l a t ribbon-shaped f i b r e s having c o l l a p s e d lumens."  30  The specimens s e l e c t e d by Mayhood et al. earlywood f i b r e s .  (77) can then be c o n s i d e r e d as  Moreover, the bond s t r e n g t h p r e s e n t e d  r e s e a r c h e r s was v e r y c l o s e to t h a t found by Mcintosh Taking  (78) f o r earlywood.  t h i s assumption i n t o c o n s i d e r a t i o n , r e s u l t s o f Mayhood et al.  and B r i n k et al.  f i b r e s was r e p o r t e d to decrease  Bond s t r e n g t h between latewood  w i t h d e c r e a s i n g pulp y i e l d  s t r e n g t h s between earlywood f i b r e s e i t h e r decreased r e l a t i v e l y unchanged as pulp y i e l d decreased No d i r e c t measurements  (14, 78).  Bond  (14) or remained  (78).  of bond r u p t u r e energy appear to have been  The i n d i r e c t method developed  used w i d e l y .  (77)  0 - 4 ) were a c t u a l l y p a r a l l e l to each o t h e r .  Pulp y i e l d a f f e c t s bond s t r e n g t h .  made.  by the above  by Nordman et al.  (91, 94) has been  In t h i s method, bond s t r e n g t h v a l u e s a r e o b t a i n e d  from the  s l o p e of s t r a i g h t l i n e r e l a t i o n s h i p between the energy i r r e v e r s i b l y  lost  i n t e n s i l e l o a d i n g - d e l o a d i n g c y c l e s and the i n c r e a s e i n L.S.C. T e s t e d on 19 d i f f e r e n t k i n d s o f p u l p s , the bond s t r e n g t h v a l u e s 5 were between 1.6 to 8.2 X 10 pentosan content  (94).  2 erg/cm  and r o u g h l y  L a t e r s t u d i e s (92, 93) have shown t h a t the energy  i n c r e a s e d w i t h h i g h h e m i c e l l u l o s e content h i g h wet  c o r r e l a t e d to the pulp  and b e a t i n g , b u t decreased  with  pressure. Stone 0-23) f o l l o w e d Nordman's approach and a l s o determined the  i n c r e a s e i n s u r f a c e a r e a by the n i t r o g e n a d s o r p t i o n method. 4 2 ranged from 0.8 to 2.2 X ues  t h i r t y t o f o r t y times  p l a y e d an important  10  Bond  energies  erg/cm , whereas the L.S.C. method gave v a l -  t h i s range.  Here a g a i n , h e m i c e l l u l o s e  r o l e i n energy v a r i a t i o n s .  content  31  Instead o f the l i n e a r r e l a t i o n s h i p Sanborn  found by Nordman et al. ,  (118) o b t a i n e d a c u r v i l i n e a r r e l a t i o n s h i p  i n L.S.C. and energy consumption.  T h i s was  between the i n c r e a s e  e x p l a i n e d as consumption  of  an a p p r e c i a b l e amount of energy i n deforming f i b r e elements, r a t h e r than f o r i n t e r f i b r e bond breakage a l o n e . segments was  T h i s d i s s i p a t i o n of energy i n f i b r e  c o n f i r m e d by Van den Akker i n h i s r e c e n t a n a l y s i s  ''Nordman's bonding  (138) o f  energy."  T h e r e f o r e , the assumption t h a t a l l i r r e v e r s i b l e energy l o s s d u r i n g the s t r a i n i n g p r o c e s s goes i n t o the f r a c t u r e used by Nordman et al.  o f i n t e r f i b r e bonds, as  to determine bond s t r e n g t h v a l u e s , i s i n doubt.  Furthermore, the a b i l i t y of l i g h t s c a t t e r i n g measurements to d i f f e r e n t i a t e new  surface o r i g i n a t i n g  from i n t e r f i b r e bond r u p t u r e or i n t r a -  f i b r e adjustments i s q u e s t i o n a b l e . At l e a s t , the more s e n s i t i v e  nitrogen  a d s o r p t i o n method i s not a b l e to d i s t i n g u i s h between these (123) . The c o h e s i v e f o r c e s between wood f i b r e s , or f i b r e bond appear to r e l a t e to f i b r e o r i g i n as m o d i f i e d by p u l p i n g and processes.  Moreover,  strength,  papermaking  s i n c e more earlywood f i b r e s a r e r u p t u r e d than l a t e -  wood f i b r e s i n the paper s h e e t , the f a i l u r e mechanism ( i n t e r f i b r e and/or i n t r a f i b r e ) may differences  provide differences  i n t o t a l energy consumption.  These  i n energy d i s s i p a t i o n p r o b a b l y cause the d i s c r e p a n c y between  Nordman et al.  (91, 94) and Sanborn  (118).  CHAPTER I I I  MATERIALS AND  METHODS  M a t e r i a l s and Pulp P r e p a r a t i o n  Materials: ted  For purposes of t h i s study t h r e e s p e c i e s were s e l e c -  f o r d i f f e r e n c e i n taxanomic o r i g i n , as w e l l as known d i f f e r e n c e s i n  wood q u a l i t i e s .  Abrupt t r a n s i t i o n between earlywood and latewood, h i g h  latewood percentage and wood s p e c i f i c g r a v i t y a r e c h a r a c t e r i s t i c s o f eastern larch  tsuga menziesii  (Larix  tavioina  '(Duroi) K. Koch) and D o u g l a s - f i r  (Mirb.) F r a n c o ) , w h i l e balsam f i r  (Pseudo-  (Abies balsamea (L.)  M i l l . ) has g r a d u a l t r a n s i t i o n , low latewood percentage and  specific  gravity. The two e a s t e r n s p e c i e s , EL  ( e a s t e r n l a r c h ) and BF  (balsam f i r ) ,  were s u p p l i e d by the Pulp and Paper Research I n s t i t u t e of Canada, and were c o l l e c t e d near S t . M i c h e l des S a i n t s , P.Q. DF  ( D o u g l a s - f i r ) was  o b t a i n e d from the U n i v e r s i t y of B r i t i s h  Endowment Lands, Vancouver, One d i s c was  i n January, 1966.  B.C.,  i n May,  The  Columbia  1965.  taken from each of the t h r e e t r e e s and kept i n green  c o n d i t i o n a t 35 ± 1° F. these d i s c s are l i s t e d  The age, diameter and growth c h a r a c t e r i s t i c s of i n T a b l e 1.  Three contiguous heartwood  crements were s e l e c t e d from each d i s c f o r c h i p p r e p a r a t i o n .  growth i n -  Ring w i d t h  and c u r v a t u r e , f r e q u e n c y of knots and d e f e c t s were c o n s i d e r e d i n the f i n a l s e l e c t i o n of increments examined. 32  The increment numbers,  growth  33  r a t e and latewood percentage f o r increments s t u d i e d  are. i n c l u d e d i n  T a b l e 1. S u b d i v i s i o n w i t h i n increment:  Each growth increment was d i s s e c t e d  i n t o s i x e q u a l p o r t i o n s by microtome s e c t i o n i n g .  Nominal 400 t o 500 m i -  crons t h i c k t a n g e n t i a l s e c t i o n s o f the same r e l a t i v e p o s i t i o n were blended t o g e t h e r  f o r each s p e c i e s , r e g a r d l e s s  ences i n c a r d i n a l d i r e c t i o n or age. wood c h i p s were obtained  intra-incremental of d i f f e r -  Thus, s i x groups o f i n t r a - i n c r e m e n t a l  from each o f . t h e  three  species.  They a r e d e s i g -  nated as numbers 1, 2, 3, 4, 5 and 6 (numbering from earlywood t o l a t e wood) and  a r e r e f e r r e d t o h e r e a f t e r w i t h the s p e c i e s p r e f i x EL, D F , o r B F .  Wood y i e l d s a r e r e c o r d e d  i n T a b l e 1.  Chip t h i c k n e s s was s e l e c t e d by c o n s i d e r i n g b o t h the w i d t h of increments t o be d i v i d e d and the r e l a t i o n s h i p between pulp f i b r e and  section thickness.  Preliminary  experiments showed t h a t s e c t i o n t h i c k -  nesses of 400 microns or more had l i t t l e Douglas-fir  Wood m i c r o - s p e c i f i c g r a v i t y : listed  e f f e c t on t h e average l e n g t h of  f i b r e s (3.3 mm) i n the experiment.  0.5 i n c h i n width and 1 t o 3 inches  to green volume.  Chips were a p p r o x i m a t e l y  i n length. The wood m i c r o - s p e c i f i c g r a v i t i e s as  i n T a b l e 1 a r e the average v a l u e s  increment p o s i t i o n (126).  f o r that p a r t i c u l a r w i t h i n  They a r e the r a t i o s of specimen oven-dry weight  The oven-dry weight was measured w i t h a Cahn E l e c t r o -  b a l a n c e which has a s e n s i t i v i t y ; o f 0.001 mg.  The specimens were r e s i d u a l s  from m i c r o - t e n s i l e t e s t specimens used i n another study within arbor  increment m i c r o - s e c t i o n s press.  length  (126), as c u t from  w i t h a c u t t i n g d i e mounted on a 1/2-ton  The dimensions were 2.5 mm by 100 mm by i 0 0 microns f o r  34  w i d t h , length, and dial ron.  indicator,  thickness.  The  t h i c k n e s s was  measured w i t h a p r e c i s i o n  ("Microcator") which, has s c a l e d i v i s i o n s down to one m i c -  S i n c e the c u t t i n g d i e produced  l e n g t h , these two  specimens having the same w i d t h  dimensions were o n l y o c c a s i o n a l l y  Sulphate p u l p i n g :  checked.  A i r - d r i e d c h i p s were p l a c e d i n 18  20-mesh s t a i n l e s s s t e e l w i r e baskets and pulped as one c a p a c i t y main d i g e s t e r and stalled  separate  cook i n the 3 0 - l i t r e  i t s s i x 1 - l i t r e capacity micro-digesters i n -  a t the F o r e s t P r o d u c t s L a b o r a t o r y , Department of F i s h e r i e s  F o r e s t r y , Vancouver, B.C.  The i n i t i a l  c o n d i t i o n s are noted i n T a b l e 1. randomly arranged  l i q u o r c o m p o s i t i o n and  heat exchanger,  Commercial DF  the v o i d i n the main d i g e s t e r and In the system,  blank  thereby a d j u s t  cooking l i q u o r comes from  then r e t u r n s t o the heat  At the completion of c o o k i n g , b l a c k l i q u o r was the cooked  Each k i n d of cooked  exchanger.  d r a i n e d o f f imme-  c h i p s were washed w i t h water p r i o r to d i s c h a r g e .  c h i p was  then d e f i b r e d w i t h an o r d i n a r y s t i r r e r  screened through a 8/1,000 i n c h cut f l a t  screen.  Pulp screened  pulp  micro-kappa number measured a c c o r d i n g to TAPPI Standard T 236 m-60 as m o d i f i e d f o r reduced  q u a n t i t y of p u l p  and r e s i d u a l l i g n i n i n p u l p  (134).  the r e s i d u a l c a r b o h y d r a t e  The  and  yield  and r e j e c t s percentage a r e i n c l u d e d i n T a b l e 1 t o g e t h e r w i t h raw  b e r , and  the  f l o w s from the bottom to the top o f the m i c r o - d i g e s t e r s ,  s p r a y s down i n the main d i g e s t e r and  d i a t e l y and  cooking  the s i x b a s k e t s of BF c h i p s  were p l a c e d s e p a r a t e l y i n the s i x m i c r o - d i g e s t e r s .  the l i q u o r to wood r a t i o .  and  The 12 baskets of EL and DF c h i p s were  i n the main d i g e s t e r , and  c h i p s were added to f i l l  and  (134)  (10), e q u i v a l e n t 40 ml K number screened y i e l d , micro-kappa num-  ( d i f f e r e n c e between the screened  35  y i e l d and  the r e s i d u a l l i g n i n ) a r e p l o t t e d i n F i g . 1.  Pulp p u r i f i c a t i o n : c h l o r i n a t i o n and according  Residual  l i g n i n i n pulp was  caustic extraction.  The  f u r t h e r removed  chemical-demand was  to the r e l a t i o n s h i p between the 40 ml  K number and  determined the c h l o r i n e  demand (.100%) , as w e l l as c a u s t i c soda requirement e s t a b l i s h e d by and Wayman (152).  C h l o r i n e demand at 120%  removal of l i g n i n and t i e s of c h l o r i n e and noted i n T a b l e  the s e p a r a t i o n  was  used to ensure e f f e c t i v e  of f i b r e s from s h i v e s .  The  Owing to the l e s s e r d e n s i t y of earlywood,  t i o n s of wood i n t r a - i n c r e m e n t a l  (126).  Therefore,  i n T a b l e 1.  Viscosity:  The  DF  and  The  3, 4,  5 and  6 for eastern  DF-  1/2,  3, 4,  5 and  6 for Douglas-fir,  BF-  1/2,  3/4,  5 and  rela-  to make up blending  as:  EL- 1/2,  The  varia-  f o r the most  quantities available after  14 blended p u l p s are designated  larch, and  6 f o r balsam f i r .  i n t r i n s i c v i s c o s i t y of some c e l l u l o s e f i b r e s be-  a f t e r the d e c r y s t a l l i z i n g  w i t h a Ubbelohde v i s c o m e t e r No.  Ia.  treatments was The  measured at 20 ± 0.01°  c e l l u l o s e solvent, modified  (EWNN, a l k a l i n e I r o n t a r t a r i c a c i d sodium complex), was  according  to the method developed by Jayme and  15  of a i r - d r i e d  ± 2 mg  The  some p u l p s were blended together  larger quantities after pulping.  solution  are  there  p h y s i c a l p r o p e r t i e s are known to be  t i v e l y s m a l l a t the b e g i n n i n g of increments of EL and  f o r e and  quanti-  1.  are always l i m i t e d q u a n t i t i e s of earlywood p u l p s a v a i l a b l e .  are g i v e n  Wilson  c a u s t i c added, as w e l l as treatment c o n d i t i o n s ,  Pulp b l e n d s :  p a r t of BF  by  El-Kodsi  (.48).  C  FeTNa  prepared Briefly,  f i b r e s were weighed out a c c u r a t e l y , d i s s o l v e d i n  36  50 ml of c e l l u l o s e lose  solution  solvent  (cyclic freezing  and thawing promotes c e l l u -  i n t h i s s o l v e n t ) and the e f f l u x  f o l l o w i n g e q u a t i o n s were used to c a l c u l a t e t - t n  t  sp  [n]  times were measured.  The  intrinsic viscosity:  o  [1J  o  [2]  =  c CI + 0.339  n  sp  )  where  = specific  n  [n] t  o  viscosity,  = intrinsic viscosity, = e f f l u x time f o r the s o l v e n t ,  t  = efflux  time f o r the s o l u t i o n ,  c  = s o l u t i o n c o n c e n t r a t i o n , grams of m o i s t u r e - f r e e f i b r e s per 100 ml o f s o l v e n t .  Treatments Pulp machining: effects ing  One way t o e v a l u t e the p e r s i s t e n c y of wood  on p u l p . p r o p e r t i e s i s to t e s t the pulp p r o p e r t i e s a f t e r  to low and h i g h l e v e l s .  B r i t i s h Columbia I n s t i t u t e  beat-  B e a t i n g treatments were a p p l i e d a t the of Technology, Burnaby, B.C., on a PFI m i l l .  37  With, the l i m i t e d q u a n t i t y of m a t e r i a l a v a i l a b l e , the DF p u l p s were b e a t en to t h r e e ( l i g h t which was  medium and heavy) l e v e l s w i t h the e x c e p t i o n of  5  t r e a t e d at o n l y two  levels  ( l i g h t and h e a v y ) .  were beaten t o c o n s t a n t 3,000 r e v o l u t i o n s were h e a v i l y beaten  to one  The EL p u l p s  (heavy l e v e l ) and  l e v e l of approximately  200  T a b l e 1. set  pulps  Thus, b e a t The  beater  and f i n a l f r e e n e s s (Csf.. m l ) , are l i s t e d i n  As can be observed, a l t h o u g h nominal  f r e e n e s s l e v e l s were "  these were not always a c h i e v e d w i t h the d i f f e r e n t Decrystallization:  the BF  Csf.  i n g i n c r e a s e d the o r i g i n a l 14 raw p u l p s to 23 pulp t y p e s . s e t t i n g , as w e l l as i n i t i a l  DF-3  pulps.  To examine the e f f e c t of f i b r e  supermolecu-  l a r s t r u c t u r e on handsheet s t r e n g t h , f i b r e s were d e c r y s t a l l i z e d by l i n g i n monoethylamine s o l u t i o n .  A f t e r b e a t i n g , the wet  swel-  f i b r e s used i n  these treatments were d r i e d i n o r d e r to c o n t r o l c o n c e n t r a t i o n o f the amine s o l u t i o n . t h i s purpose. from the wet  A f r e e z e - d r y i n g t e c h n i q u e to be d e s c r i b e d was  used f o r  B r i e f l y , a q u a n t i t y of water and some f i n e s were removed f i b r e s i n a sheet mold.  With the h e l p of water, the  were q u a n t i t a t i v e l y t r a n s f e r r e d i n t o a round bottom two-necked A f t e r more water was  fibres  flask.  removed through a 150-mesh s t a i n l e s s s t e e l w i r e  s c r e e n s e a l e d at one end of a g l a s s t u b i n g , the f l a s k and wet t e n t s were f r o z e n to below -100°C w i t h l i q u i d n i t r o g e n then  fibre  con-  connected  through, a 3-way s t o p - c o c k to the s i d e channel of a f r e e z e - d r y e r ( F i g . 2a). In o r d e r to ensure copper-constantan  thermocouples  the s u r f a c e of the wet Moseley s t r i p  t h a t the f i b r e s were t h o r o u g h l y d r i e d ,  were e i t h e r i n s e r t e d i n t o o r a t t a c h e d to  f i b r e pad.  c h a r t r e c o r d e r and  two  These were connected change i n f i b r e pad  to a d u a l - c h a n n e l  Itemperature vs.  dry-  38  ing-, time was  recorded.  The completion of d r y i n g was  i n d i c a t e d by both  pad c e n t r e and s u r f a c e temperatures r e a c h i n g the same l e v e l , i . e . , room temperature.  T h i s took about 16 to 18 hours under a 20 to 50 micron  Hg  vacuum. A f t e r d r y i n g , the thermocouples were r e p l a c e d by a s t o p - c o c k ( F ) . Sealed at the lower opening of the stop-cock was  a g l a s s tube  had a 150-mesh s t a i n l e s s s t e e l w i r e s c r e e n (4 mm  diameter) s e a l e d i n at  the lower end  (K) •  (B) which  A f t e r vacuum and c o o l i n g , monoethylamine s o l u t i o n of  v a r i o u s c o n c e n t r a t i o n s (65, 75 o r 77 and 82%) was c o n t a i n e d i n the r e a c t i o n f l a s k  added to the f i b r e s  (A) through a p r e s s u r e e q u a l i z i n g f u n n e l  (C) and a 3-way s t o p - c o c k (G). The whole s e t up  ( F i g . 2b) except the f u n n e l (C) was  immediately  shaken and p l a c e d i n a 3°C f r e e z e r f o r four hours w i t h f r e q u e n t s h a k i n g . At the end of the s w e l l i n g p e r i o d , vacuum s u c t i o n was the s t o p - c o c k (F) to remove the amine s o l u t i o n . f i b r e s q u i c k l y accumulated l o s s of f i n e s .  In the s u c t i o n s t a g e ,  D i s t i l l e d water was  added through the f u n n e l (C) to wash  removed through the w i r e s c r e e n ( H ) .  o c c a s i o n a l l y i n t r o d u c e d through e i t h e r G o r F  vacuum p r e s s u r e c r e a t e d by s u c t i o n .  A f t e r s i x washing  were allowed to c o n t a c t a i r f o r the f i r s t lamine s o l u t i o n .  through  o u t s i d e the w i r e s c r e e n , which reduced the  the f i b r e s and t h i s , t o o , was gen gas was  applied  Nitro-  to c o n t r o l the  c y c l e s , the f i b r e s  time a f t e r adding the monoethy-  The washed f i b r e s were s t o r e d i n d i s t i l l e d water f o r  f o u r days b e f o r e forming handsheets.  In s w e l l i n g , care was- taken to  s w e l l t h e f i b r e s i n an oxy-gen f r e e system i n o r d e r to minimize the d e g r a d a t i o n of  cellulose.  39  F i b r e c r y s t a l l i n i t y measurement: d i c e s of u n t r e a t e d and  The  relative crystallinity i n -  d e c r y s t a l l i z e d f i b r e s were measured on a P h i l l i p s  X-ray d i f f r a c t o m e t e r a t the Department of S o i l S c i e n c e , U n i v e r s i t y of B r i t i s h Columbia.  K  r a d i a t i o n , which has  a wave l e n g t h r a n g i n g  from  o  1.5405 to 1.5443 A", was o b t a i n e d from a copper t a r g e t and n i c k e l f i l t e r at  40 Kv and  20 mA.  angular aperture. ceiving s l i t counted  and  The X-ray beam was The  d e f i n e d by a d i v e r g e n t s l i t  d i f f r a c t e d beam was  d e f i n e d by a 0.1  a 1° angular a p e r t u r e s c a t t e r s l i t .  by a G e i g e r - c o u n t e r  tube and  as the X - r a y d i f f r a c t i o n spectrum  paper was  l o n g edges. of  l°/min. The  to 30°  talline  recorder  ( F i g . 3). X 25.4  mm  The  scanned between 29 = 10°  c h a r t speed was  0.5  air-dried  sheets  to 30°  two  at a speed  in/min.  r e l a t i v e c r y s t a l l i n i t y index was  method proposed by Jayme and K n o l l e (50). 10°  was  f i x e d to an aluminum p l a t e by Scotch tape along the T h i s b o o k l e t was  1°  wide r e -  signal  t r a c e d on an automatic  As specimen, a b o o k l e t of f o u r 15 mm of  The  mm  of  determined  a c c o r d i n g to the  A smooth curve was  drawn from  to p a r t i t i o n the a r e a under the s p e c t r o m e t r i c t r a c e i n t o c r y s -  (F, and F ) and  b e c r y s t a l l i n i t y index  amorphous f r a c t i o n s  (F ) ( F i g . 3).  The  relative  a ( C r I , %) i s t h e r e f o r e : F, + F b c CrI,  %  =  [3J F  The  F  , F  and F  were determined  each of the f r a c t i o n s .  2.  + F, + F a b c  The  by  weighing-,cut' out s e c t i o n s of  ~  c r y s t a l l i n i t y v a l u e s are i n c l u d e d i n Table  40  Handsheet  Formation  Standard handsheets: TAPPI Standard T 205 m-58  The handsheets  were formed a c c o r d i n g to  (133) i n a s t a n d a r d sheet mold, except  one e x t r a f i b r e d i l u t i o n and d r a i n - o f f were a p p l i e d i n o r d e r t o l a t e removal  of some f i n e s from p u l p s as o c c u r r e d w i t h  treatments.  A f t e r forming i n the sheet mold, wet  1.2  f i b r e sheets  (target  g m o i s t u r e - f r e e weight) were p r e s s e d t w i c e under 50 p s i p r e s s u r e be-  l y , w i t h b l o t t e r s being changed between these two wet combinations The  of wet  pressings.  s h e e t s , b l o t t e r s and p l a t e s were p r e s s e d  (23°C temperature;  Standard T 402 m-49  Seven  simultaneous-  50% r e l a t i v e h u m i d i t y ) as s p e c i f i e d  on unbonded f i b r e webs.  The measurement of f i b r e s u r f a c e area can be done Due  to the f o r m a t i o n of bonds between f i b r e s when  they a r e d r i e d from water at normal temperature, r e q u i r e d to p r e p a r e these m a t e r i a l s . i n the l i t e r a t u r e  i n TAPPI  (132).  Unbonded f i b r e :  Two  respective-  sheets were then d r i e d i n d r y i n g r i n g s and s t o r e d under s t a n d a r d  conditions  ty.  simu-  decrystallization  tween b l o t t e r s and m i r r o r p o l i s h e d p l a t e s f o r 5 and 2 minutes,  ly.  that  (34, 44,  The  a s p e c i a l technique i s  e x t r a p o l a t i o n method as  61, 67, 128) was  not used due  reviewed  to i t s u n c e r t a i n -  methods, i . e . , s o l v e n t exchange and f r e e z e - d r y i n g , were t r i e d f o r  these p r e p a r a t i o n s . S o l v e n t exchange d r y i n g u s i n g acetone t r i e d but q u i c k l y dropped.  T h i s was  f i b r e s which, caused d i f f i c u l t y t h e r e f o r e a f f e c t e d b a s i s weight  due  and b u t y l a l c o h o l was  first  to the r e t e n t i o n of s o l v e n t i n  i n d e t e r m i n i n g the t r u e sample weight, and L.S.C. c a l c u l a t i o n s .  and  41  D r y i n g by s u b l i m a t i o n  Cfreeze-drying) has been r e p o r t e d t o r e -  duce handsheet s t r e n g t h s e r i o u s l y . et al.  Van den Akker  C136)  and M a r c h e s s a u l t  (73) were a b l e to show t h a t f r e e z e - d r i e d handsheets were l e s s  than h a l f as s t r o n g as n o r m a l l y d r i e d s h e e t s .  This r e s u l t s from the  removal of s u r f a c e t e n s i o n f o r c e s d u r i n g paper d r y i n g . The f r e e z e - d r y i n g t e c h n i q u e was ment was  used i n t h i s study.  made f o r p r o d u c i n g unbonded handsheets.  As a f i r s t  An  improve-  trial,  wet  handsheets were f r o z e n a t -30° C then d r i e d i n a f r e e z e - d r i e r at vacuum p r e s s u r e s as low as 20 microns Hg. found t o have l i t t l e bond f o r m a t i o n may  A f t e r d r y i n g , the handsheets were  s t r e n g t h , but were s t i l l p a r t i a l l y bonded.  This  be e x p l a i n e d i n terms of water f r e e z i n g p o i n t depres-  sion i n c a p i l l a r y structures  (110) even w i t h temperature reduced to below  -30° C, hence removal of some l a s t water t r a c e s i n the l i q u i d i n s t e a d of s o l i d •state. To overcome t h i s problem, handsheets were q u i c k l y f r o z e n i n l i q u i d nitrogen  (-195.8° C) and then f r e e z e - d r i e d .  d i s c e r n i b l e s t r e n g t h were o b t a i n e d .  Sheets h a v i n g no  S i n c e t h e r e i s no known method f o r  t e s t i n g absence of bonding i n unbonded handsheets, the l a c k o f sheet s t r e n g t h was  taken as e v i d e n c e t h a t the f i b r e s were not bonded.  study showed t h a t e f f e c t i v e n e s s of t h i s treatment was  Further  not i n f l u e n c e d by  degree of b e a t i n g . In  the f i n a l p r o c e s s used f o r forming handsheets, wet  sheets were  formed i n a sheet mold a c c o r d i n g to TAPPI Standard T 205 m-58  (133), w i t h  the  e x c e p t i o n t h a t one e x t r a pulp d i l u t i o n and d r a i n - o f f were a p p l i e d to  remove p a r t o f the f i n e s .  The formed wet  sheet was  removed from the mold  42  t o g e t h e r with, the w i r e s c r e e n without p r e s s i n g . p l a c e d u p s i d e down r a p i d l y , but g e n t l y , on a f l a t was  supported by a smooth, s o l i d board.  water was  The wet  sheet, f o i l  temperature  had dropped  20 to 50 microns Hg,  two minutes,  i t was  possible  sheet without v i s u a l d i s t u r b a n c e of the  containing l i q u i d nitrogen.  to below -100° C, i t was  a f r e e z e - d r i e r and vacuum was around  30 to 50 ml of  and support combination were then g e n t l y  t r a n s f e r r e d i n t o a styrofoam box web  aluminum f o i l which  Approximately  A f t e r w a i t i n g f o r about  remove the w i r e from the wet  fibres.  was  a p p l i e d g e n t l y from a squeeze b o t t l e along the o u t s i d e of  the s c r e e n r i m . to  T h i s combination  applied.  When the  quickly placed i n  With a low vacuum c o n d i t i o n at  the f i b r e was  d r i e d w i t h i n 18 to 20 h o u r s .  Physical-Mechanical Tests  Tensile tests:  A l l paper s t r e n g t h and c y c l i c t e s t s were c a r r i e d  out i n a c o n d i t i o n i n g room a c c o r d i n g to TAPPI Standard T 402 m-49 A T a b l e Model I n s t r o n was  used f o r t e n s i l e t e s t s .  were clamped between two jaws (2.54 r a t e of e l o n g a t i o n of 0.127  (132) .  Specimens (15: mm  cm spacing) and s t r e s s e d a t a constant  cm/min (0.05 in./min) u n t i l the specimen  ruptured.  S t r e s s - s t r a i n curves were r e c o r d e d on an automatic s t r i p  recorder.  The  c h a r t speed used was  width)  25.4  was chart  cm/min (10 i n . / m i n ) .  B r e a k i n g l o a d and maximum e l o n g a t i o n ( s t r e t c h ) were read from the s t r e s s - s t r a i n curve. al  Load and e l o n g a t i o n at the y i e l d p o i n t  l i m i t ) were used f o r c a l c u l a t i o n of modulus of e l a s t i c i t y .  (proportionA r e a under  the curve was measured w i t h a p l a n i m e t e r f o r c a l c u l a t i n g the maximum t e n -  43  s i l e r u p t u r e energy.  Four specimens were t e s t e d f o r each, sample-type.  These data were used t o c a l c u l a t e sheet maximum t e n s i l e 2 (kg/cm ) , s t r e t c h (%), modulus of e l a s t i c i t y 3 energy Ckg-m/m  strength  2 (kg/cm ) , t e n s i l e r u p t u r e  2 and kg-m/m ) and b r e a k i n g l e n g t h  (m) .  Sheet d e n s i t y  3 (g/cm ) was c a l c u l a t e d from b a s i s weight and t h i c k n e s s measurements. Handsheet  t h i c k n e s s was measured  Cyclic tests:  w i t h a bench-type micrometer.  To determine the s p e c i f i c energy of "bond  failure,"  c y c l i c s t r a i n i n g - d e s t r a i n i n g t e s t s were c a r r i e d out on a T a b l e Model I n s t r o n a t the F o r e s t P r o d u c t s L a b o r a t o r y , Department F o r e s t r y , Vancouver, B.C.  o f F i s h e r i e s and  The same t e s t i n g c o n d i t i o n and r e p l i c a t i o n  number ( f o u r ) as f o r maximum-tensile  s t r e n g t h p r o p e r t i e s were-used.  The  same paper—types used i n the t e s t s d e s c r i b e d above were used a l s o i n t h i s study.  The average maximum s t r a i n f o r each k i n d of pulp o b t a i n e d above  was n o t e d .  Matched  paper s t r i p s were s t r a i n e d once o n l y a t 0.127 cm/min  to 90% of the observed maximum s t r a i n and then d e s t r a i n e d at the same r a t e as used f o r e l o n g a t i o n .  A s i n g l e s t r a i n - d e s t r a i n c y c l e was a p p l i e d .  The l o a d i n g - u n l o a d i n g h y s t e r e s i s loop was a u t o m a t i c a l l y r e c o r d e d on a n Instron recorder.  Areas e n c l o s e d by l o o p s were measured  with a planimeter  and c a l c u l a t e d as the maximum t e n s i l e energy a b s o r p t i o n t o o b t a i n the energy consumption.  The one i n c h l o n g p o r t i o n of the paper s t r i p  involved  i n the energy a b s o r p t i o n was c u t out and i t s oven-dry weight was measured i n o r d e r t o c a l c u l a t e the specimen b a s i s weight and energy consumption per gram o f f i b r e . The energy consumption  (ergs p e r gram of f i b r e ) a t 90% of the  maximum s t r a i n when d i v i d e d b y the c o r r e s p o n d i n g i n c r e a s e i n l i g h t  scatter-  44  ing c o e f f i c i e n t specimen was  ( L . S . C , as determined  by methods to be d e s c r i b e d ) of  d e s i g n a t e d as the s p e c i f i c energy of "bond f a i l u r e . "  the  This  i s the energy consumed per u n i t o p t i c a l s u r f a c e a r e a formed. The L.S.C. of s t r i p s were measured b e f o r e and a f t e r the straining.  T h e i r d i f f e r e n c e was  cyclic  taken as the i n c r e a s e i n L.S.C. (AS).  P h y s i c a l - O p t i c a l Tests Handsheet unbonded s u r f a c e a r e a measurements: Since the  optical  q u a n t i t y , L . S . C , i s r e l a t e d to the unbonded s u r f a c e area of a paper sheet  (116), i t can be used as an index of the amount of unbonded s u r f a c e  area i n a paper s t r u c t u r e .  The  f o l l o w i n g method was  used i n the p r e s e n t  study. L.S.C. measurements were taken at a wavelength of 457 my  with a  Z e i s s E l r e p h o r e f l e c t a n c e meter at the Vancouver F o r e s t Products  Labors  atory. and  A s p e c i a l sample a p e r t u r e , 13.5  mm  by 25.4  mm,  was  constructed  a t t a c h e d to the bottom of the o r i g i n a l c i r c u l a r a p e r t u r e .  With t h i s  r e c t a n g u l a r a p e r t u r e , 90% of the r e c t a n g u l a r paper specimen area by 25.4 ified  mm)  was  measured.  a p e r t u r e was  g r e s s i o n equations with, and without  the sheet. weight  15j.  mm  R e f l e c t a n c e of samples o b t a i n e d w i t h the mod-  reduced  to the "without m o d i f i c a t i o n r e a d i n g " by r e -  d e r i v e d from measurements on v a r i o u s k i n d s of paper  the m o d i f i e d  E q u a t i o n I4J  (15  was  aperture.  used to c a l c u l a t e the s c a t t e r i n g power, sW,  of  T h i s i n t u r n g i v e s the. L.S.C. when d i v i d e d by the sheet b a s i s  45  (R R ) - 1 In sW  where  =  n  co  [ — (R /R O  j R  "  ) - 1  ]  0 0  [4] R  co  sW  = the  sheet s c a t t e r i n g power,  R  = the r e f l e c t a n c e of a s i n g l e sheet backed a m a t e r i a l of zero r e f l e c t a n c e ,  R^  = the r e f l e c t i v i t y , or r e f l e c t a n c e opaque pad of s h e e t s .  of,  by  an  L.S.C. = — where  [5]  W = sheet b a s i s  weight.  Rather than measure the l a t e d from e q u a t i o n s p r e s e n t e d by  Steele  [6] and (122) .  r e f l e c t i v i t y , R^,  [ 7 ] , which are  t h i s may  transformed from the  T h i s mathematical m a n i p u l a t i o n has  where sheets of a g i v e n p u l p - t y p e are  a - -=  " —  Y  be  calcu-  equations  advantage  scarce.  l  r  ,  [6]  —  o R  where  R'  = Z-*  = reflectance  R^  t  =.  ]  [7  of a white background,  = r e f l e c t a n c e of a s i n g l e sheet backed by a w h i t e background, which has a r e f l e c t a n c e  T h e r e f o r e , only  t h r e e o p t i c a l -measurements, R  , R' O  sheet b a s i s weight are r e q u i r e d were done by  an IBM  f o r c a l c u l a t i n g L.S.C.  360-67 computer.  R'.  and  R  K  ,,  and  A l l calculations  46  F i b r e s u r f a c e area measurements:. As f o r handsheet unbonded s u r f a c e area measurements, the L.S.C, method was used to determine the f i b r e s u r f a c e a r e a f o r unbonded handsheets.  The unbonded handsheet i s b u l k y ,  which a f f e c t s the s u r f a c e area d e t e r m i n a t i o n by o p t i c a l methods. been shown t h a t L.S.C. i n c r e a s e s w i t h d e c r e a s i n g b u l k p r e s e n t study  confirm'such  (115).  an e f f e c t a t sheet apparent  I t has  Data of the  densities  lower  3 than 0.4 g/cm  .  The e f f e c t i s most o f t e n n e g l i g i b l e a f t e r t h i s p o i n t .  A 4.13 cm (1.625 i n . ) d i a m e t e r c i r c u l a r sample h o l d e r was s t r u c t e d f o r p r e s s i n g the unbonded specimen handsheet  con-  (1.625 i n . diameter)  3  to apparent  d e n s i t i e s v a r y i n g from 0.15  to 0.60 g/cm  each of s e v e r a l d e n s i t y l e v e l s were measured. by u s i n g equations sities  (Fig. 4).  .  Reflectances at  The L.S.C.s were  [4] to [7] and p l o t t e d a g a i n s t c o r r e s p o n d i n g For further.comparisons  calculated apparent  to be d e s c r i b e d , the L.S.C. a t  3  0.4 g/cm  was  taken as the f i b r e s u r f a c e a r e a  index.  The o p t i c a l g l a s s cover o f the sample h o l d e r had an e f f e c t on the reflectance reading. the c o r r e s p o n d i n g  T h e r e f o r e , r e f l e c t a n c e r e a d i n g s were c o r r e c t e d to  "without  c o v e r " r e a d i n g by u s i n g r e g r e s s i o n equations  e s t a b l i s h e d i n the same way as f o r the sample a p e r t u r e  calibration.  Sample N o t a t i o n S i n c e s e v e r a l wood o r i g i n s and pulp treatments the study, a n o t a t i o n i s used h e r e a f t e r f o r i d e n t i f y i n g  are involved i n these.  The s p e c i e s (EL, DF o r BF) i s f o l l o w e d by i n t r a - i n c r e m e n t a l o r i gin  (1/2, 3, 4, 5 o r 6 f o r EL and DF; 1/2, 3/4, 5 o r 6 f o r BF), Canadian  standard (615  f r e e n e s s o b t a i n e d by b e a t i n g  (105 to 705), o r i n some cases, L  ± 90 ml C s f ) , M (328 ± 43 ml C s f ) and H (168 ± 62 ml C s f ) a r e used  den-  47  w i t h DF  t o r e p l a c e exact f r e e n e s s l e v e l s , and f i n a l l y  tration  (%)  a p p l i e d (00, 65,  75 o r 77 and  82).  the amine concen-  CHAPTER IV  DISCUSSION  Fibre Surface  Area  P r i o r to examining e f f e c t s of the v a r i o u s m a t e r i a l s and on paper handsheet t e n s i l e p r o p e r t i e s , the r e l i a b i l i t y area measurements i s c r i t i c a l l y for  the d i s c u s s i o n .  reviewed  treatments  of f i b r e s u r f a c e  i n o r d e r to p r o v i d e background  Measurements o b t a i n e d by the L.S.C. method are taken  as i n d i c e s of the f i b r e s u r f a c e areas  ( e x t e r n a l and lumen s u r f a c e ) .  noted, unbonded handsheets were formed i n a standard s e q u e n t l y f r e e z e - d r i e d by a m o d i f i e d  As  sheet mold and sub-  technique.  Unbonded handsheet b u l k a d v e r s e l y a f f e c t s the L.S.C. (115, 122). T h i s i s f u r t h e r demonstrated i n t h i s study. handsheet L . S . C . - d e n s i t y  relationship  F i g . 4 shows the unbonded  f o r v a r i o u s f i b r e types  (BF-6 i s  not i n c l u d e d due to i t s unexpected i r r e g u l a r c o l o r ) achieved by p r e s s i n g i n the sample h o l d e r . These curves show t h a t :  (a) the L.S.C.-unbonded handsheet appar-  ent d e n s i t y r e l a t i o n s h i p d i f f e r s between earlywood and latewood.  The  L.S.C. of earlywood unbonded handsheets i n c r e a s e d r a p i d l y at lower densities  and then f l a t t e n e d o r decreased  gradually with further increase  i n d e n s i t y , w h i l e the L.S.C. of latewood and DF-3 f i b r e s i n c r e a s e d o n l y s l i g h t l y b e f o r e r e a c h i n g a constant  level;  (b) earlywood f i b r e s had h i g h e r  L.S.C. than latewood f i b r e s ; and (c) b e a t i n g i n c r e a s e d the L.S.C. of a l l earlywood and latewood unbonded handsheets. 48  49  When the unbonded handsheet i s p r e s s e d as d e s c r i b e d h e r e , i n i t i a l p r e s s u r e causes b e t t e r p a c k i n g i n the sheet Z - d i r e c t i o n ness) w i t h l i t t l e r e s i s t a n c e from the f i b r e s . ness improves  the L.S.C, r a p i d l y .  the  (thick-  T h i s decrease i n t h i c k -  Additional pressing further  reduces  sheet t h i c k n e s s , but a l s o c r e a t e s l a r g e r c o n t a c t areas between  fibres.  T h i s l e s s e n s the t o t a l area a v a i l a b l e f o r s c a t t e r i n g l i g h t . t i o n of these p o s i t i v e and n e g a t i v e e f f e c t s determines  The  combina-  the L . S . C . - d e n s i t y  relationship. The d i f f e r e n t response of earlywood L.S.C.-density r e l a t i o n s h i p to  pressure.  The  and latewood  i s p r o b a b l y due t o d i f f e r e n t  t h i n - w a l l e d earlywood  t a t i o n toward  of f i b r e f l a t t e n i n g .  c o n d i t i o n which b e t t e r r e f l e c t s l i g h t toward  The  resistance easily.  be brought  This i n turn adjusts f i b r e  2 (X and Y) from the 3 (X, Y and Z) i n i t i a l  tance meter due t o l e s s path  fibre  f i b r e s tend to f l a t t e n  P a r t of the r e d u c t i o n i n unbonded handsheet t h i c k n e s s may by a h i g h degree  f i b r e s i n the  orien-  dimensions,  interference.  t h i c k - w a l l e d latewood  f i b r e s have g r e a t e r r e s i s t a n c e to p r e s -  tances between f i b r e s , i n a d d i t i o n to improving can be observed  a  the p h o t o c e l l of the r e f l e c -  sure and sheet t h i c k n e s s r e d u c t i o n i s more l i k e l y caused by c l o s i n g  It  about  fibre  from F i g . 4 t h a t a c r i t i c a l  dis-  orientation. sheet apparent  den-  3  s i t y e x i s t s at a p p r o x i m a t e l y 0.4  g/cm  f o r most m a t e r i a l s s t u d i e d .  t h i s p o i n t the curves e i t h e r l e v e l o f f or s t a r t  to d e c r e a s e .  s t a n c e s e x t e n s i v e p r e s s i n g reduced L . S . C , perhaps  due  Above  In some i n -  to c a u s i n g more  p o i n t s o f areas of c o n t a c t . 3  The 0.4  g/.cm.r apparent  d e n s i t y i s not e x c l u s i v e l y r e l a t e d t o un-  50  bonded handsheets. apparent Besides  d e n s i t y r e l a t i o n s h i p s to zero s t r e n g t h , p r o v i d e s .the same v a l u e . t h i s study, a s i m i l a r c r i t i c a l v a l u e has been r e p o r t e d i n o t h e r  work (69, 70, energy  As w i l l be shown, e x t r a p o l a t i n g paper t e n s i l e s t r e n g t h -  71).  T h e i r paper e l a s t i c i t y , b r e a k i n g l e n g t h , t e n s i l e  a b s o r p t i o n ( s i m i l a r to. t h e . t e n s i l e r u p t u r e energy  i n this  study)  and d e n s i t y r e l a t i o n s h i p s , a l s o i n t e r c e p t e d the. d e n s i t y a x i s at a p p r o x i 3 mately  0.4  g/cm  .  T h e r e f o r e , t h i s p o i n t has been c o n s i d e r e d as  the  zero s t r e n g t h sheet d e n s i t y . 3 For these reasons, the L.S.C. of unbonded handsheets at 0.4 d e n s i t y was one  taken as the p o i n t f o r comparing f i b r e s u r f a c e a r e a s .  i n s t a n c e (BF-1/2) t h i s may  is s t i l l  r i s i n g at t h i s p o i n t .  f o u r earlywood  (1/2) pulps  not appear t o be.proper,  s i n c e the  g/cm In  curve  Comparison t o L.S.C. v a l u e s of the o t h e r  (one EL-1/2 and  t h r e e DF-1/2 p u l p s ) read a t  3 0.4  g/cm  d e n s i t y , as w e l l as subsequent p l o t s  ( F i g . 5) i n c l u d i n g  BF-1/2 v a l u e , p r o v i d e s e v i d e n c e . t h a t the BF-1/2 data  the  are.reasonable.  The L.S.C. d a t a are p r e s e n t e d i n T a b l e 2 and p l o t t e d a g a i n s t p o s i t i o n w i t h i n wood growth zone i n F i g . 5. graph,  As  can be seen from  the  the unbonded f i b r e L.S.C. v a r i e d w i t h i n t r a - i n c r e m e n t a l p o s i t i o n .  F o r both EL and DF d a t a , these v a r i a t i o n s r e l a t e i n v e r s e l y to the u s u a l i n t r a - i n c r e m e n t a l wood s p e c i f i c g r a v i t y and The  s t r e n g t h p r o p e r t i e s (126).  l e s s e l a b o r a t e BF d a t a f o l l o w the same p a t t e r n . Wood s p e c i f i c g r a v i t y i s mostly  substance  a measure of the amount o f wood  per u n i t volume, and can be used  m a t e r i a l p a c k i n g i n the wood. i n c r e a s e s from earlywood  to i n d i c a t e the degree of  The s p e c i f i c g r a v i t y of c o n i f e r o u s wood  to latewood.  As shown i n T a b l e 1, the  average  DF  latewood  study was  ( p o s i t i o n 4, 5 and  0.71  g/cm  3  6) green volume s p e c i f i c g r a v i t y i n t h i s  , w h i c h i s almost 2.4  times t h a t of the earlywood 3  ( p o s i t i o n 1/2)  s p e c i f i c g r a v i t y , 0.30  g/cm  .  In a converse way  the  L.S.C. (measured at a i r - d r i e d c o n d i t i o n ) , hence the s u r f a c e a r e a of unbonded latewood f i b r e s , seems to be to earlywood f i b r e s . L.S.C. v a l u e of 712  The l i g h t l y - b e a t e n DF earlywood f i b r e s had 2 cm /g, which i s almost 2.4 times t h a t of the 2  ponding latewood f i b r e s , 260 t i n g use  r e l a t e d by the same magnitude  cm  /g.  This r a t i o provides  ah corres-  evidence  suppor  of unbonded handsheet L.S.C. measurements f o r demonstrating  variation i n fibre properties.  Owing to the opening of i n t e r n a l  by b e a t i n g , the d a t a from medium- and h e a v i l y - b e a t e n useful for this  surface  f i b r e s are not  as  comparison.  F i g . 6 r e l a t e s unbonded f i b r e L.S.C. and wood s p e c i f i c g r a v i t y f o r v a r i o u s s p e c i e s and b e a t i n g treatments. meter earlywood f i b r e s had  higher  The  thin-walled, large dia-  s u r f a c e area per u n i t mass and  there-  f o r e gave h i g h e r L.S.C. than t h i c k - w a l l e d , s m a l l e r diameter latewood f i b res.  The  d i f f e r e n c e i n response between earlywood and  latewood  appeared to depend to a l e s s e r degree upon the s p e c i e s and  fibres  degree of  beating. The  v a l i d i t y of u s i n g L.S.C. ..as an index of f i b r e e x t e r n a l s u r -  f a c e a r e a should be d i s c u s s e d . collapsed  (111,  144),  and  S i n c e the f r e e z e - d r i e d f i b r e s are  the measured L.S.C. of unbonded handsheets i s  the. combined q u a n t i t y of both f i b r e e x t e r n a l and the v a l u e o b t a i n e d  little  lumen s u r f a c e  i s a p p a r e n t l y l a r g e r than the L.S.C. of the  areas, fibre  e x t e r n a l s u r f a c e area w h i c h i s r e s p o n s i b l e f o r the i n t e r f i b r e bonding.  52  Kallmes and E c k e r t  (59) s t a t e d t h a t t h e r e are twice as many r e f l e c t i n g  surfaces i n uncollapsed  f i b r e s than f o r c o l l a p s e d f i b r e s .  cannot be adopted t o a d j u s t the L.S.C. v a l u e s l a c k of c e r t a i n information concerning  This  "...  o f t h i s study, due to the  p r o p e r t i e s of t h e f i b r e s  studied.  By assuming t h a t the f i b r e lumen s u r f a c e has the same r e f l e c t i n g q u a l i t y as the f i b r e e x t e r n a l s u r f a c e , a c a l c u l a t i o n can be made. i n g t h e average t a n g e n t i a l arid r a d i a l f i b r e diameters and w a l l  By t a k -  thickness  of Washington grown D o u g l a s - f i r earlywood and latewood t r a c h e i d s  (data  c o l l e c t e d from s i x t r e e s ) from Smith's work (120), and by c o n s i d e r i n g the t r a c h e i d c r o s s - s e c t i o n as r e c t a n g u l a r i n shape, 58 and 81% of the t o t a l t r a c h e i d s u r f a c e s a r e e x t e r n a l f o r earlywood and latewood respectively.  Using  these percentages,  nal surface, excluding  fibres,  the a d j u s t e d L.S.C. ( f i b r e  exter-  2 lumen s u r f a c e ) o f DF-1/2-525 becomes 414 cm / g , 2  which i s almost double t h a t of DF-5-705, 210 cm /g. Although these adjustments a r e c a l c u l a t e d e s t i m a t i o n s  o n l y , they support  the e a r l i e r  ments i n t h a t the earlywood f i b r e s do have l a r g e r e x t e r n a l s u r f a c e d i n g lumen s u r f a c e area) a r e a than t h e corresponding I n t r a - i n c r e m e n t a l Handsheet Apparent D e n s i t y The  latewood  argu(exclu-  fibres.  and T e n s i l e P r o p e r t i e s  apparent d e n s i t y , t e n s i l e s t r e n g t h , s t r e t c h , modulus o f 3  elasticity,  t e n s i l e r u p t u r e energy (kg-m/m ) , t e n s i l e energy  absorption  2 (kg-m/m ) , as w e l l as b r e a k i n g pulps  l e n g t h f o r handsheets made from t r e a t e d  of d i f f e r e n t s p e c i e s and I n t r a - i n c r e m e n t a l  T a b l e 2.  The l e s s exact b r e a k i n g  are l i s t e d f o r r e f e r e n c e o n l y .  o r i g i n s are l i s t e d i n  l e n g t h and t e n s i l e energy a b s o r p t i o n Their counterparts,  t e n s i l e s t r e n g t h and  53  t e n s i l e r u p t u r e energy a r e used h e r e , s i n c e t h e s e c a l c u l a t i o n s i n c l u d e the t h i c k n e s s dimension, hence r e l a t e more c l o s e l y t o the degree o f i n t e r f i b r e bonding. The d e n s i t i e s o f paper handsheets p r e p a r e d f o r t h e study a r e p l o t t e d i n F i g . 7 as r e l a t e d t o s p e c i e s , degree of b e a t i n g and d e c r y s t a l lization  treatments.  The apparent d e n s i t i e s of 00% and 82% amine t r e a t e d  EL, DF-L (615 ± 9 0 ml C s f ) , DF-M  (328 ± 43 ml C s f ) , DF-H (168 ± 62 ml C s f )  and BF i n t r a - i n c r e m e n t a l handsheets a r e p l o t t e d i n F i g . 8A over the o r i g i n a l wood i n t r a - i n c r e m e n t a l p o s i t i o n s .  With the same i n t r a - i n c r e m e n t a l  p o s i t i o n s as x - a x i s , t h e sheet t e n s i l e s t r e n g t h , s t r e t c h , modulus of elasticity,  and t e n s i l e r u p t u r e energy of 00% and 82% amine t r e a t e d DF-L,  DF-M and DF-H f i b r e s a r e p l o t t e d  i n F i g . 8B to 8E.  As found by B r i n k et al. (14) and Nordman and Quickstrom ( 9 6 )  t  F i g u r e s 8A t o 8E c l e a r l y demonstrate t h a t a l l the p r o p e r t i e s examined v a r i e d w i t h r e s p e c t to o r i g i n a t i n g p o s i t i o n i n the growth r i n g .  Regard-  l e s s of the degree o f b e a t i n g , earlywood handsheets were always denser and s t r o n g e r than latewood handsheets o r than handsheets made from t r a n s i t i o n wood  fibres.  T h i s study f u r t h e r demonstrates t h a t f i b r e i n t r a - i n c r e m e n t a l gin  ori-  e f f e c t s e x i s t not o n l y w i t h u n t r e a t e d f i b r e s , but a l s o f o r f i b r e s w i t h  a l t e r e d supermolecular s t r u c t u r e s . 82% amine t r e a t e d p u l p f i b r e s  The average c r y s t a l l i n i t y  ( f i b r e s of d i f f e r e n t  index o f the  species, beating  levels  and p o s i t i o n i n growth r i n g ) i s 48.8%, which i s 19.1% lower than t h a t of u n t r e a t e d f i b r e s , 67.9%.  As w i l l be d i s c u s s e d , the amine treatment a l s o  decreased the degree of i n t e r f i b r e bonding.  Even w i t h reduced bonding  54  and  l e s s supermolecular  o r d e r , earlywood f i b r e s c o n s t a n t l y p r o v i d e d  handsheets w i t h h i g h e r d e n s i t y and  s t r o n g e r t e n s i l e p r o p e r t i e s than  those handsheets made from t r a n s i t i o n w o o d  or latewood  fibres.  F i g u r e s 8A to 8E a l s o show t h a t the e f f e c t of pulp o r i g i n on handsheet p r o p e r t i e s was even when the treatment s t r e n g t h , but  was  not e l i m i n a t e d by b e a t i n g  and  d i d not remove d i f f e r e n c e s between paper sheets made from I t i s noted  a l s o imposed e f f e c t s on sheet p r o p e r t i e s . the d e n s i t y of BF handsheets was  t h a t wood s p e c i e s  At comparable b e a t i n g  hgher than t h a t of EL and DF  the d i f f e r e n c e between the t h r e e s p e c i e s s t u d i e d was  s m a l l e r than t h a t w i t h i n growth increments The  treatments,  s e v e r e . B e a t i n g a l t e r e d o n l y the d e n s i t y  various intra-incremental f i b r e s .  But  fibre  levels  sheets.  obviously  of a s i n g l e s p e c i e s .  d i f f e r e n c e between earlywood and  latewood handsheet  strengths  has been r e p e a t e d l y e x p l a i n e d i n terms of t h i n n e r - w a l l e d , more f l e x i b l e earlywood f i b r e s which c o l l a p s e i n the s t o c k p r e p a r a t i o n or sheetmaking processes.  Thereby, earlywood f i b r e s have been thought to p r o v i d e l a r g e r  bonded a r e a  (B.A.) than the t h i c k e r - w a l l e d , s t i f f e r and  latewood  l e s s conformable  fibres. To examine t h i s i n the p r e s e n t  study, f i b r e s u r f a c e areas were  measured by the L.S.C. method on unbonded handsheets, w h i l e the bonded handsheet L.S.C. was area.  The  taken as the unbonded fraction-: of the f i b r e  d i f f e r e n c e between these  i n t h e sheet  structure.  n o n - d e c r y s t a l l i z e d and listed  i n T a b l e 2.  two  q u a n t i t i e s " i s considered•as"  Handsheet L.S.C. and  decrystallized  surface  B.A.  B.A.  v a l u e s f o r a l l the  f i b r e s of v a r i o u s o r i g i n s  are  These measurements on the n o n - d e c r y s t a l l i z e d f i b r e s  55  are p l o t t e d a c c o r d i n g It  to p o s i t i o n w i t h i n growth zones i n F i g . 5 and 9.  can be observed t h a t B.A. was h i g h e r  handsheets, r e g a r d l e s s of s p e c i e s . difference.  This information  I n the sheet  f o r earlywood than latewood  Severe b e a t i n g  s u b s t a n t i a t e s the above  forming p r o c e s s ,  Page (.99) r e p o r t e d  i n a 50% y i e l d b l a c k spruce s u l p h a t e  explanation.  The degree of f i b r e  depends on f i b r e w a l l t h i c k n e s s , p u l p i n g p r o c e s s , (31, 99).  this  f i b r e s tend t o c o l l a p s e due to  wet p r e s s i n g and s u r f a c e t e n s i o n f o r c e s .  drying conditions  d i d not d e s t r o y  collapse  y i e l d , beating  and  t h a t 55% of the f i b r e s  handsheet were c o l l a p s e d , w h i l e the  number of c o l l a p s e d f i b r e s when f r e e l y d r i e d decreased r a p i d l y from 65% to as l i t t l e  as 2%.  one to f o u r m i c r o n s .  The accompanying c e l l w a l l t h i c k n e s s Therefore,  from  i t can be assumed t h a t the earlywood  f i b r e s a r e mostly c o l l a p s e d and t h a t latewood f i b r e s a r e The scanning  increased  non-collapsed.  e l e c t r o n photomicrographs i n F i g . 10 show t h a t the l i g h t l y -  beaten earlywood f i b r e s shapes, w h i l e  (DF-1/2-525) a r e m o s t l y o f c o l l a p s e d  the h e a v i l y - b e a t e n  latewood f i b r e s  "pipe-shape" and can be c o n s i d e r e d Due to e s t a b l i s h m e n t  as  ribbon-  (DF-5-106) r e t a i n t h e i r  non-collapsed.  of o p t i c a l c o n t a c t between lumen s u r f a c e s i n  an e x t e n s i v e l y c o l l a p s e d f i b r e , the f i b r e lumen i s not l i k e l y to s c a t t e r light.  W i t h t h i s i n mind, and w i t h  evidence as presented  i n F i g . 10, one  can assume t h a t earlywood handsheet L.S.C. measures l a r g e l y the unbonded external f i b r e surface, while  t h e latewood handsheet L.S.C. i n c l u d e s both  the f i b r e e x t e r n a l and lumen s u r f a c e s .  S i n c e the unbonded handsheet L.S.C.  i s t h e sum from b o t h f i b r e e x t e r n a l and lumen s u r f a c e s , the B.A. i n a handsheet  obtained  by s u b t r a c t i n g the sheet  L.S.C. from the unbonded handsheet  56  L.S.C. would appear l a r g e r than t h e r e a l i n t e r f i b r e B.A. o f the earlywood handsheets and c l o s e t o or s l i g h t l y l a r g e r than those of t h e latewood handsheets. Although  the c a l c u l a t e d handsheet B.A. may be l a r g e r than the  r e a l i n t e r f i b r e B.A., any bond f o r m a t i o n between lumen s u r f a c e s may f u r t h e r p r o v i d e f i b r e r e s i s t a n c e toward e x t e r n a l f o r c e s . be o f s p e c i a l importance  f o r r e i n f o r c i n g earlywood  T h i s e f f e c t may  f i b r e s which  clearly  r u p t u r e d a c r o s s c e l l w a l l s i n the sheet f a i l u r e zone ( F i g . 1 0 ) . I t should be s t r e s s e d t h a t , because of t h e u n c e r t a i n t y of the degree of f i b r e c o l l a p s e , t h e B.A. data i n c l u d e d i n T a b l e 2 a r e o n l y culated estimations.  However, these c a l c u l a t i o n s do p r e s e n t  t h a t the i n t e r f i b r e B.A. o f earlywood latewood  evidence  handsheets i s h i g h e r than t h a t of  handsheets. R e l a t i v e bonded a r e a  f i b r e bonding bonding  cal-  (R.B.A.) r e l a t e s t h e numerous v a r i a b l e s i n  and i s p r o b a b l y a good q u a n t i t y f o r e x p r e s s i n g the r e a l i z e d  p o t e n t i a l of f i b r e s .  The R.B.A. v a l u e s f o r a l l handsheets a r e  l i s t e d i n T a b l e 2, and those f o r EL, DF-L, DF-M, DF-^H and BF non-decry-. s t a l l i z e d handsheets a r e p l o t t e d i n F i g . 9. earlywood  I t can be observed  handsheets had h i g h e r R.B.A. than t h e latewood  i s o t h e r evidence t h a t t h e earlywood  t h a t the  handsheets.  This  f i b r e s a r e b e t t e r bonded than the  latewood  f i b r e s i n these sheet s t r u c t u r e s , and t h a t d i f f e r e n c e s i n t h e  ability  t o form bonds between f i b r e s v a r i e s w i t h t h e i r i n t r a - i n c r e m e n t a l  origin.  T h i s d i f f e r e n c e was n o t removed even by i n t e n s i v e b e a t i n g . The R.B.A. v a l u e s a r e as h i g h as 83% f o r h e a v i l y - b e a t e n BF-1/2  and EL-1/2 f i b r e s .  Some s t i l l h i g h e r v a l u e s  (more than 90%) have been  57  r e p o r t e d i n the l i t e r a t u r e  (44, 57).  In f a c t , these h i g h v a l u e s are  not s u r p r i s i n g when i t i s c o n s i d e r e d t h a t f r e e f i b r e l e n g t h i n a sheet prepared  from w e l l - b e a t e n p u l p i s n e g l i g i b l e , and o n l y 1/5  the f i b r e l e n g t h i s f r e e i n sheets prepared  to 1/3  from unbeaten pulp  of  (58).  F i b r e e x t e r n a l s u r f a c e a r e a i s not the o n l y f a c t o r which i s r e s p o n s i b l e f o r R.B.A.  The p r e s e n t study examines t h i s concept. • As  example, w i t h i n wood s p e c i e s DF-3-680 and DF-4-170 had 2  comparable  un-  / g ) , but the l a t t e r  had  2  bonded f i b r e L.S.C. (472.4 cm  /g vs.  much h i g h e r R.B.A. (48.66 vs.  68.81%) as a r e s u l t of b e a t i n g .  between s p e c i e s comparison,  DF-1/2-380 and EL-3-215 had 2  c a l unbonded f i b r e L.S.C. v a l u e s l a t t e r had  approximately  475.6 cm  6.6%  (744.1 cm  /g vs.  h i g h e r R.B.A.  For a  almost 2  identi-  734.5 cm / g ) , but  These comparisons  the  suggest  t h a t some f i b r e p r o p e r t y other than e x t e r n a l s u r f a c e a r e a i n f l u e n c e s the p o t e n t i a l of f i b r e s to form bonded a r e a i n a sheet A positive relationship  structure.  should e x i s t between paper sheet den-  s i t y or r e l a t e d s t r e n g t h parameter and  the f i b r e bonding  B.A.  to 12D  Figures HA,  11C  i n g t h i s assumption.  and 11D  and  12A  I t i s observed  p o t e n t i a l or  p r o v i d e evidence  t h a t handsheet apparent  support-  density i s  d i r e c t l y r e l a t e d to f i b r e s u r f a c e a r e a (L.S.C. measurement), as w e l l as B.A.  and R.B.A.  L i k e w i s e , the sheet apparent  density i s d i r e c t l y re-  l a t e d to a l l t e n s i l e p r o p e r t i e s ( t e n s i l e s t r e n g t h , s t r e t c h , modulus of elasticity  and  t e n s i l e rupture energy).  r e p r e s e n t i n g the density-B.A.  Moreover, the s l o p e s of l i n e s  or strength-B.A.  i n c r e m e n t a l handsheets f o r e a c h p u l p - t y p e may  be h i g h e r than shown i n t h e s e f i g u r e s .  r e l a t i o n s h i p s of  (EL, DF-L,  DF-M,  T h i s i s due  DF-H  intraand  BF)  to d i f f e r e n c e s i n  58  c o l l a p s e between the earlywood  and latewood  f i b r e s , the e f f e c t of lumen  s u r f a c e on the L.S.C. measurements which, t h e r e f o r e , p r o v i d e s v a l u e s l a r g e r than the r e a l i n t e r f i b r e B.A. f o r earlywood wood  more than f o r l a t e -  handsheets. However, these p l o t s do support  the assumption  f i b r e s are b e t t e r bonded than those of latewood,  that  earlywood  and t h a t h i g h e r  early-  wood handsheet d e n s i t y and s t r e n g t h s do a r i s e from h i g h e r bonded a r e a s . In a d d i t i o n to the above d i r e c t e v i d e n c e r e l a t i n g handsheet p r o p e r t i e s t o B.A.,  t h e r e i s an i n d i r e c t way of examining  i n t e r f i b r e bonding  relationship.  Sheet  the sheet s t r e n g t h -  d e n s i t y r e f l e c t s the e f f e c t s of  s p e c i e s , f i b r e c o n f o r m a b i l i t y , cooking and b e a t i n g c o n d i t i o n s and may be taken a l s o as a convenient measure of the degree of i n t e r f i b r e (1, 63).  bonding  Good l i n e a r r e l a t i o n s h i p s have been r e p o r t e d between sheet  b r e a k i n g l e n g t h , modulus of e l a s t i c i t y , t e n s i l e energy sheet d e n s i t y (69, 70, 71, 72), as w e l l as between i n t h i s study.  a b s o r p t i o n and  B.A. and sheet d e n s i t y  Hence sheet d e n s i t y i s s e l e c t e d as another method f o r  e v a l u a t i n g the e f f e c t of i n t e r f i b r e bonding  on sheet t e n s i l e p r o p e r t i e s .  The 00% and 82% amine t r e a t e d sheet t e n s i l e s t r e n g t h , s t r e t c h , modulus of e l a s t i c i t y and t e n s i l e r u p t u r e energy  f o r each s p e c i e s and  b e a t i n g l e v e l as g i v e n i n T a b l e 2 a r e p l o t t e d a g a i n s t apparent d e n s i t i e s i n F i g . 13A to 13D.  A d i r e c t r e l a t i o n s h i p between these  p r o p e r t i e s and sheet density- can be observed. correlations  (Table 3) were o b t a i n e d , except  discussed l a t e r .  sheet  Highly s i g n i f i c a n t  linear  f o r some s t r e t c h data to be  These f i g u r e s and a n a l y s e s p r o v i d e evidence t h a t sheet  t e n s i l e p r o p e r t i e s are h i g h l y dependent on the degree of i n t e r f i b r e bonding.  59  Wood s p e c i f i c g r a v i t y appears t o be one of the most important f a c t o r s a f f e c t i n g paper sheet d e n s i t y and t h e r e f o r e sheet s t r e n g t h perties .  Examining the r e l a t i o n s h i p between paper sheet apparent  and wood s p e c i f i c g r a v i t y p r o v i d e s  information  wood o r i g i n on paper sheet p r o p e r t i e s . ship, solved according  concerning  These p l o t s show t h a t handsheet d e n s i t y decreased  density  the e f f e c t of  F i g . 14 i s a p l o t of t h i s  t o the DF sheet d e n s i t y - f r e e n e s s  pro-  relation-  relationships.  r a p i d l y as c o n i f e r o u s  3  wood s p e c i f i c g r a v i t y i n c r e a s e d  from 0.25 g/cm  t o a p p r o x i m a t e l y 0.45 g/  3  cm . ly.  Beyond t h i s s p e c i f i c g r a v i t y range, sheet d e n s i t y  changed more slow-  The e f f e c t appears to be independent of s p e c i e s , b e a t i n g  t a l l i z a t i o n , as p r a c t i c e d i n t h i s study.  and d e c r y s -  T h i s must r e l a t e to some f a c t o r  of c e l l w a l l s t r u c t u r e w h i c h responds t o the compacting f o r c e s i n h e r e n t i n the sheetmaking p r o c e s s e s pacting  (wet p r e s s i n g and s u r f a c e  tension).  f o r c e s do not seem to be i n t e n s e enough t o deform  f i b r e s obtained ner-walled  from h i g h e r  These com-  thicker-walled  s p e c i f i c g r a v i t y wood as e f f e c t i v e l y as t h i n -  fibres.  F i g u r e 14 shows a l s o t h a t even w i t h severe b e a t i n g  (pulp  freeness  to 180 ml C s f ) the dependency of paper sheet d e n s i t y on i n i t i a l wood spec i f i c g r a v i t y has n o t been removed.  T h i s f u r t h e r demonstrates t h a t the  p h y s i c a l and t e n s i l e p r o p e r t i e s of paper handsheets depend .cupon t h e raw material The  origin.  E f f e c t of Species  on Handsheet T e n s i l e  Properties  Evidence p r e s e n t e d i n t h i s study, n o t a b l y  as shown i n F i g . 12A to  12D and 13A t o 13D, demonstrates t h a t papers made from d i f f e r e n t s p e c i e s  60  are d i f f e r e n t i n t e n s i l e s t r e n g t h p r o p e r t i e s .  Because of s i m i l a r i t y i n  c o n i f e r o u s wood chemical c o m p o s i t i o n , Annergren et al. (4) a t t r i b u t e d s p e c i e s e f f e c t s to m o r p h o l o g i c a l d i f f e r e n c e s , e s p e c i a l l y those c i n g wood s p e c i f i c g r a v i t y .  influen-  Hence, low s p e c i f i c g r a v i t y wood g i v e s  h i g h d e n s i t y paper w i t h h i g h t e n s i l e s t r e n g t h but low t e a r r e s i s t a n c e , w h i l e h i g h s p e c i f i c g r a v i t y wood g i v e s o p p o s i t e paper p r o p e r t i e s . The BF wood of the p r e s e n t study was lower i n average g r a v i t y than the EL and DF woods (Table 1 ) .  Separated  specific  BF f i b r e s showed  s l i g h t l y h i g h e r unbonded s u r f a c e a r e a s , bonded areas and r e l a t i v e bonded areas than those from EL and DF woods (Table 2, F i g . 4, 5. , 6, 9A and 9B). As r e v e a l e d i n F i g . 8A, 13A and 13C, BF handsheets had h i g h e r  tensile  s t r e n g t h and modulus of e l a s t i c i t y at the same d e n s i t y than those o f EL and DF handsheets.  I n c o n t r a s t , F i g . 13B shows t h a t s t r e t c h o f EL paper  sheets was h i g h e r than w i t h DF and BF s h e e t s .  These o b s e r v a t i o n s a r e  examined as f o l l o w s . Giertz  (28) s t a t e d t h a t :  " t e n s i l e s t r e n g t h i s the same f o r a g i v e n d e n s i t y , i r r e s p e c t i v e o f whether, f o r i n s t a n c e , an unbeaten h e m i c e l l u l o s e - r i c h pulp o r a h i g h l y beaten, hot a l k a l i r e f i n e d pulp w i t h low h e m i c e l l u l o s e content i s used. The c l o s e r e l a t i o n s h i p h o l d s , of c o u r s e , o n l y as l o n g as f u r t h e r s t r e n g t h i s developed w i t h beating." Perng  and T a j i m a  (108) s t a t e d t h a t :  "the paper s t r e n g t h i s the same f o r a g i v e n d e n s i t y , r e g a r d l e s s of the d r y i n g p r o c e s s of wood, the a n a t o m i c a l f e a t u r e s and degree of b e a t i n g . "  These statements  g i v e an i m p r e s s i o n t h a t n e i t h e r wood  morphologi-  c a l o r i g i n , hence s p e c i e s , nor wood chemical composition has any e f f e c t  61  on paper sheet b r e a k i n g duced.  l e n g t h as l o n g as t h e same sheet d e n s i t y i s p r o -  This i s misleading. By a c a r e f u l examination  28,  and F i g . 1 i n r e f e r e n c e 108),  statements quoted. the b r e a k i n g  In both  o f p u b l i s h e d data  ( F i g . 1 i n reference  one may q u e s t i o n r e l i a b i l i t y of t h e  s t u d i e s the authors  ignored d i s t r i b u t i o n s of  l e n g t h - d e n s i t y r e l a t i o n s h i p f o r i n d i v i d u a l p u l p - t y p e s , but  j u s t drew a common curve p a s s i n g through a f r a c t i o n of the many p o i n t s available.  No s t a t i s t i c a l evidence was p r e s e n t e d  t o support  their state-  ments . The  t r e n d o f c e r t a i n s t r e n g t h - d e n s i t y r e l a t i o n s h i p s f o r each non-  d e c r y s t a l l i z e d pulp-type appears t o f a l l  (EL, DF-L, DF-M, DF-H and BF) o f t h i s  i n t o a common curve  ( F i g . 13A to 13D) .  the approach of G i e r t z (28) and Perng and Tajima  study  Not f o l l o w i n g  (108), c o v a r i a n c e  analy-  ses w i t h 4 r e p l i c a t i o n s f o r each sample was used t o t e s t homogeneity of the l i n e a r r e g r e s s i o n l i n e s  (handsheet t e n s i l e p r o p e r t i e s as f u n c t i o n s  of handsheet d e n s i t y ) f o r each s p e c i e s and each degree of b e a t i n g . I t was found  t h a t , w i t h t h e e x c e p t i o n of s t r e t c h , although t h e  r e g r e s s i o n l i n e s l o p e s may be c o n s i d e r e d t h e same, the i n t e r c e p t s a t zero sheet  apparent d e n s i t y were s i g n i f i c a n t l y d i f f e r e n t a t t h e 1% l e v e l .  This  i m p l i e s t h a t t h e r e l a t i o n s h i p between sheet  t e n s i l e strength properties  and  has s p e c i e s imposed as an im-  d e n s i t y as d e r i v e d f o r a l l p u l p s , s t i l l  p o r t a n t e f f e c t on the r e l a t i o n s h i p . The  c o v a r i a n c e a n a l y s i s of the n o n - d e c r y s t a l l i z e d p u l p s  demonstrates t h a t :  (Fig.'15)  (a) t h e EL, DF-L, DF-M and DF-H handsheets may be  d e s c r i b e d w i t h an i d e n t i c a l maximum t e n s i l e s t r e n g t h - d e n s i t y r e l a t i o n s h i p , but  the i n t e r c e p t o f the BF sheets was s i g n i f i c a n t l y d i f f e r e n t at;:the 5%  62  level;  (b) w i t h t h e e x c e p t i o n  of the common DF-M and DF-H r e l a t i o n s h i p ,  the s t r e t c h o f a l l handsheets behaved a c c o r d i n g  to a d i f f e r e n t f u n c t i o n ;  (c) a s i n g l e f u n c t i o n may be used t o d e s c r i b e the modulus o f e l a s t i c i t y d e n s i t y r e l a t i o n s h i p o f a l l handsheets; and (d) EL and BF handsheets were comparable i n a b s o r b i n g  t e n s i l e rupture  energy, but d i f f e r e d from DF-L,  DF-M and DF-H handsheets which were i d e n t i c a l t o each o t h e r i n energy absorption. Since  t e n s i l e p r o p e r t i e s of the v a r i o u s handsheets were compared  on the common b a s i s , apparent d e n s i t y  (degree of i n t e r f i b r e b o n d i n g ) , the  d i f f e r e n c e found between s p e c i e s , w h i c h d i d n o t appear w i t h v a r i o u s degrees o f b e a t i n g DF f i b r e s , property  strongly i n d i c a t e s that species  intrafibre  d i f f e r e n c e s a r e important. Another p o i n t of evidence  supporting  t h i s statement can be found  i n F i g . 12A t o 12D, where s p e c i e s e f f e c t s a r e compared a t the "same bonded area."  The d i f f e r e n c e s between l e v e l s of t h e l i n e s which connect the i n -  t r a - i n c r e m e n t a l p o i n t s w i t h i n c e r t a i n pulp ences between s p e c i e s . modulus of e l a s t i c i t y  BF sheets  clearly indicates d i f f e r -  Here, a g a i n , t h e t e n s i l e s t r e n g t h  ( F i g . 12A) and  ( F i g . 12C) o f BF handsheets p r o v i d e h i g h e r  than EL and DF s h e e t s . and  types  F u r t h e r , s t r e t c h o f EL i s h i g h e r  than that of DF  ( F i g . 12B).  Higher EL s t r e t c h i s p r o b a b l y  an i n h e r e n t wood f e a t u r e  w h i c h i s m o d i f i e d but n o t removed e n t i r e l y by t h e p u l p i n g , beating  values  and sheetmaking  (126),  purification,  processes.  The l a r g e r t e n s i l e r u p t u r e e n e r g y a b s o r p t i o n of EL and BF than DF handsheets i s e x p l a i n e d by t h e h i g h e r  t e n s i l e s t r e n g t h of BF and t h e  63  l a r g e r s t r e t c h of the EL handsheets. to  a r e a under the s t r e s s - s t r a i n curve, w h i l e i n other works (69,  71) energy and  Here the c a l c u l a t i o n i s r e l a t e d 70,  a b s o r p t i o n has been d e r i v e d as the product of b r e a k i n g l e n g t h  the c o r r e s p o n d i n g The  stretch.  comparable modulus of e l a s t i c i t y f o r a l l handsheets s t u d i e d  p r o b a b l y a r i s e s because t h i s q u a n t i t y i s determined  from the v e r y  p o r t i o n of the s t r e s s - s t r a i n curve and a l l t e s t i n g was low r a t e of s t r a i n .  early  done at constant  T h e r e f o r e , the q u a n t i t y does not r e f l e c t much d i f f -  erence between raw m a t e r i a l s . The  reason f o r h i g h e r BF sheet t e n s i l e s t r e n g t h than had  the o t h e r two known.  s p e c i e s at the same degree of i n t e r f i b r e bonding  The h i g h s p e c i f i c energy  c o u l d be one  of "bond f a i l u r e " between BF  of many p o s s i b l e reasons  (see  later  sections).  from  i s not fibres Owing t o  lower wood s p e c i f i c g r a v i t y , the s t r e n g t h of i n d i v i d u a l BF f i b r e s does not seem to be the cause, but e f f e c t s of other f i b r e d i f f e r e n c e s i n i n t e r nal  s t r u c t u r e c a n n o t l b e r u l e d out.  T h i s evidence  c l e a r l y demonstrates t h a t  the e f f e c t of s p e c i e s o r i g i n on paper t e n s i l e p r o p e r t i e s cannot be removed even by severe b e a t i n g  A l t e r a t i o n of Raw  treatment.  M a t e r i a l E f f e c t s by Pulp  Machining  P r o b a b l y no known p r o c e s s i s a b l e to a l t e r p u l p f i b r e p r o p e r t i e s as e f f e c t i v e l y as b e a t i n g . t h i s treatment  causes  As summarized by H i g g i n s and de Yong (35),  i n t r a f i b r e bond b r e a k i n g , e x t e r n a l f i b r i l l a t i o n ,  p r o d u c t i o n of f i n e s and  f i b r e shortening.  These i n . t u r n a f f e c t  s w o l l e n s p e c i f i c volume, s p e c i f i c s u r f a c e and f l e x i b i l i t y ,  the  as w e l l as  64  other  f i b r e p r o p e r t i e s and,  finally,  the bonded area, d e n s i t y and  p r o p e r t i e s of the f i n i s h e d paper sheet. treatment s h o u l d be  this  tensile properties.  i n c r e a s e i n e x t e r n a l s u r f a c e as a r e s u l t of b e a t i n g would be  r e f l e c t e d by i n c r e a s e d f i b r e L.S.C. L.S.C. of DF  f i b r e s d i d increase with  i n c r e a s e i n L.S.C. was As  effects,  a good method f o r examining the p e r s i s t e n c y of wood  raw m a t e r i a l d i f f e r e n c e s on sheet The  With such p o w e r f u l  strength  As shown i n F i g . 4,  5 and  6,  the degree o f b e a t i n g , but  h i g h e r f o r latewood than f o r earlywood  an example, b e a t i n g reduced the drainage  the this  fibres.  r a t e of DF-1/2 f i b r e s  from  2 525  ml  to 230  ml C s f , but  i n c r e a s e d L.S.C. from 713  cm  /g to o n l y  800  2 cm  /g.  The  DF-5  f i b r e s , on the o t h e r hand, had L.S.C. almost doubled  2 2 (260 cm /g to 476 cm /g) when beaten from 705 ml to 106 ml C s f . These trends f o l l o w the p a t t e r n of the i n c r e a s e i n s p e c i f i c s u r f a c e area of 2 2 DF earlywood (1.70 m /g a t 515 ml Csf and 2.34 m /g a t 215 ml C s f ) and latewood  (1.30  2 m /g at 715 ml  as r e p o r t e d i n the l i t e r a t u r e The bility  latewood f i b r e s  2 m /g at 145 ml  B e a t i n g renders  r e l a t i v e bonded a r e a .  Both the bonded a r e a and  bonded a r e a of DF handsheets i n c r e a s e d w i t h b e a t i n g . f a c t o r s was  higher  the wholewood sheet  duces the L.S.C.  the  the  F i g . 9A relative  Furthermore,  the  f o r latewood than f o r earlywood.  Almost a l l the p u b l i s h e d l i t e r a t u r e has creases  beating  promotes the development of b e t t e r i n t e r f i b r e  c o n f i r m t h i s concept.  i n c r e a s e i n these  Csf) by  and have lower degree of conforma-  earlywood f i b r e s .  bonding, hence h i g h e r bonded area and and 9B  2.45  (40).  are s t i f f  than the c o r r e s p o n d i n g  f i b r e s more f l e x i b l e and  Csf and  d e n s i t y and  shown t h a t b e a t i n g i n -  t e n s i l e s t r e n g t h , but a l s o r e -  T h i s i s o f t e n e x p l a i n e d as more of the unbonded  65  f r a c t i o n of the f i b r e s u r f a c e s having  been turned  into  s t a t e s by b e a t i n g , hence l e s s l i g h t i s s c a t t e r e d .  The  i n t r a - i n c r e m e n t a l pulps  of t h i s study  a p p l i e s o n l y to earlywood s h e e t s . shows t h a t b e a t i n g mental f i b r e s  handsheets  CFig.  obtained  in this  9B) by c o n v e r t i n g the i n t e r n a l thereby  8A to 8E).  Data i n Table 2 and F i g . 5 and  treatment as w i t h  earlywood  l a t i n g that although rendered  handsheets  was  DF-3)  be assumed  not  relationship  may  be  surfaces  The  unexpected  e x p l a i n e d by  b e a t i n g has much i n c r e a s e d the e x t e r n a l f i b r e  overcome and  still  prevented  use  postusurfibre  of the newly exposed  T h i s i n t u r n i n c r e a s e d the handsheet L.S.C. s l i g h t l y  i n a d d i t i o n to i n c r e a s i n g sheet  d e n s i t y , as w e l l as i n c r e a s i n g bonded a r e a  and  r e l a t i v e bonded a r e a even at the h i g h e r  one  can h y p o t h e s i z e  degree of b e a t i n g .  Therefore,  t h a t t h e change i n sheet L.S.C. by b e a t i n g depends i n  p a r t upon e f f e c t i v e n e s s of u t i l i z i n g The  illustrate,  the latewood f i b r e s more conformable, the i n i t i a l  s u r f a c e s i n bonding.  bonding.  j stronger  the bonded a r e a of a l l  i n t o bonded s u r f a c e s i n earlywood s h e e t s .  latewood handsheet L . S . C . - d e n s i t y  s t i f f n e s s was  (  11B  to b e a t i n g , most of the o r i g i n a l and newly exposed  were converted  n  (DF-1/2 and  i n t r a - i n c r e m e n t a l f i b r e s were i n c r e a s e d by b e a t i n g , i t may  f a c e and  a  into  appears to have been i n c r e a s e d s l i g h t l y .  S i n c e b o t h the e x t e r n a l s u r f a c e a r e a and  t h a t , due  surfaces  p r o v i d e s denser  and DF-6)  study  intra-incre-  6 ) , and  (DF-4, DF-5  DF  reasoning  ( F i g . 5 and  lowered by the b e a t i n g  handsheets, but  shows t h a t the above  Information  however, t h a t the L.S.C. of latewood not  response of  i n c r e a s e s the bonded area of a l l the DF  ( F i g . 9A and  external surface  o p t i c a l l y bonded  the exposed f i b r e s u r f a c e i n o p t i c a l  acceptance of t h i s h y p o t h e s i s  c o u l d p r o v i d e a fundamental  66  reason f o r the l o n g time anomaly observed w i t h pulp  sheet  L.S.C.-density  or L.S.C.-beating r e l a t i o n s h i p s , wherein major d i f f e r e n c e s occur pulp-types  with  (74, 105, 114, 116, 128).  T h i s s t u d y a l s o t e s t e d the p e r s i s t e n c y o f raw m a t e r i a l e f f e c t s at  one h e a v i l y - b e a t e n  as t h r e e b e a t i n g  l e v e l f o r three species  l e v e l s with a s i n g l e species  (EL, DF and B F ) , as w e l l (DF). As d i s c u s s e d  pre-  v i o u s l y , n e i t h e r e f f e c t s between s p e c i e s , n o r e f f e c t s w i t h i n wood growth zones (as expressed by t h e pulp can be removed by b e a t i n g . but  intra-incremental p o s i t i o n a l differences)  Severe b e a t i n g  only modified  the d i f f e r e n c e s ,  the i n f l u e n c e of raw m a t e r i a l o r i g i n p e r s i s t e d (Table 4 ) .  E f f e c t of C e l l u l o s e Supermolecular S t r u c t u r e on Handsheet P r o p e r t i e s F i b r e s from d i f f e r e n t possess d i f f e r e n t sheet  s p e c i e s and i n t r a - i n c r e m e n t a l o r i g i n s  f i b r e morphological  characteristics.  The e f f e c t on  p r o p e r t i e s was examined and confirmed i n t h i s study.  Properties  examined at comparable degree o f i n t e r f i b r e bonding and bonded  area  suggest that d i f f e r e n c e s i n raw m a t e r i a l e f f e c t s cannot be e x p l a i n e d i n terms of i n t e r f i b r e bonding a l o n e , effect  and t h a t some o t h e r  fibre  biological  such as the i n t e r n a l c e l l w a l l s t r u c t u r e could be of importance. S t r u c t u r a l d i f f e r e n c e s e x i s t between earlywood and latewood  f i b r e s as r e c o g n i z e d  i n terms of s t r e n g t h , f i b r i l l a r a n g l e ,  s i z e and response to p u l p i n g  and papermaking p r o c e s s e s .  crystallite  I n view of t h e s e ,  an examination of f i b r e s u p e r m o l e c u l a r s t r u c t u r e , s u c h as measured by degree of c r y s t a l l i n i t y , should raw  material  effects.  provide  some fundamental u n d e r s t a n d i n g o f  67  The  o r i g i n a l pulp  f i b r e c r y s t a l l i n i t y was a l t e r e d by s w e l l i n g the  f i b r e s i n various concentrations  o f monoethylamine s o l u t i o n .  The i n f l u -  ence o f these d e c r y s t a l l i z a t i o n treatments on f i b r e bonding p o t e n t i a l needs some d i s c u s s i o n . Data i n T a b l e  2 i l l u s t r a t e t h a t the monoethylamine d e c r y s t a l l i -  z a t i o n treatments a f f e c t e d the f i b r e bonding p o t e n t i a l .  The B.A. and  R.B.A. were decreased and sheet L.S.C. was i n c r e a s e d w i t h amine concent r a t i o n f o r a l l t h e pulps  except p a r t of the DF-4, DF-5 and DF-6 s e r i e s .  There a r e a l s o d i f f e r e n c e s i n R.B.A. and L.S.C. between the n o n - d e c r y s t a l lized  and t h e d e c r y s t a l l i z e d f i b r e s . All  the pulps which were s u b j e c t e d  dried p r i o r to swelling.  Preliminary  t o amine treatment were f r e e z e -  s t u d i e s showed t h a t sheets made from  f r e e z e - d r i e d f i b r e s had lower t e n s i l e s t r e n g t h and h i g h e r L.S.C. than those made from n e v e r - d r i e d formation properties  fibres.  T h i s weakening e f f e c t may be caused by i c e  which could produce a s m a l l n e g a t i v e (73).  bond f o r m a t i o n  e f f e c t on f i b r e bonding  I n a d d i t i o n , p o s s i b l e i r r e v e r s i b l e i n t r a f i b r e hydrogen  i n f r e e z e - d r y i n g l i m i t s bonding p o t e n t i a l ( 3 6 ) .  Preliminary  s t u d i e s a l s o showed t h a t the l o s s i n sheet  s t r e n g t h can be r e c o v e r e d  l a r g e l y by s w e l l i n g i n 65% amine s o l u t i o n ,  which does n o t reduce the f i b r e c r y s t a l l i n i t y . good e x p l a n a t i o n  tensile  f o r t h i s phenomenon.  McKenzie (.81) p r o v i d e d  He proposed t h a t a m i l d  a  swelling  agent causes no change i n f i b r e c r y s t a l s t r u c t u r e but reduces order i n the f i b r e amorphous regions-, i n c r e a s e s amorphous s u r f a c e a r e a and i n c r e a s e s the a v a i l a b l e i n t e r - m o l e c u l a r bounding s i t e s as a r e s u l t of bond breakage during  the swelling process.  Each o f these changes tends t o i n c r e a s e  68  f i b r e h y g r o s c o p i c i t y , e v e n t u a l l y bonded a r e a and bond d e n s i t y , hence increases  t e n a c i t y ( t e n s i l e strength)  McKenzie (81)  also provided  study. fibre,  He  sheet.  a d i s c u s s i o n which can be used to  e x p l a i n a l t e r a t i o n of bonded a r e a and the change i n L.S.C. w i t h  of the paper  r e l a t i v e bonded a r e a as w e l l  amine c o n c e n t r a t i o n  as found i n the  present  suggested t h a t d e c r y s t a l l i z a t i o n s w e l l i n g p l a s t i c i z e s  causes a g e n e r a l  t h e s u r f a c e , and cess occurs  as  the  rearrangement of the amorphous r e g i o n to smooth  thereby reduces s u r f a c e a r e a .  F i n a l l y , a shrinking  as the s w e l l i n g agent i s removed, which i n c r e a s e s  o r i e n t a t i o n to produce a w e l l - o r d e r e d  surface with  few  the  pro-  fibre  sites available  f o r i n t e r f i b r e bonding. Another p o s s i b l e reason f o r the l o s s of bonding p o t e n t i a l would be ly,  formation  of hydrogen bonds between the amine and  the hydrogen atom a c t s as a b r i d g e between two  ments, oxygen of the I t i s reasonable way  carbohydrate h y d r o x y l  fibre.  More p r o p e r -  electro-negative e l e -  group and  the amine n i t r o g e n .  to expect that the amount of hydrogen bonded i n t h i s  increases with  the amine c o n c e n t r a t i o n , which thereby reduces  a v a i l a b l e f o r i n t e r f i b r e bond In f a c t , Paszner  (107)  sites  formation. found t h a t d i f f e r e n c e s i n IR s p e c t r a of  amine t r e a t e d c e l l u l o s e s are l i m i t e d to l o s s i n i n t e n s i t y of the -OH  band  at 3400 ^ cm wave number, and  cm  w h i c h can be  the appearance of a new  band at 1600  ^  a t t r i b u t e d to the p r e s e n c e of a hydrogen bonded f u n c t i o n a l  group of amine i n the  cellulose.  The  l o c a t i o n , as s u r f a c e or i n s i d e the  f i b r e w a l l , where the amine i s bonded^ i s not known. f a c e bonded amine may r e s i d u a l amine i s not  Although f i b r e  be washed away more e a s i l y , the presence of impossible.  sur-  such  69  The r e c o v e r y of f r e e z e - d r i e d f i b r e bonding p o t e n t i a l by a p p l y ing  low amine c o n c e n t r a t i o n s i s assumed to r e s u l t from newly  exposed  s i t e s c r e a t e d by the s w e l l i n g a c t i o n , w h i l e a t the same time l i t t l e amine i s hydrogen bonded to c a r b o h y d r a t e h y d r o x y l groups. 2 Parker  (104) found a decrease i n f i b r e s p e c i f i c s u r f a c e  (4.00 m /g  2 to  3.24  m /g) as the s w e l l i n g agent, e t h y l a m i n e , c o n c e n t r a t i o n was  from 0 to 94%. to  increased  He proposed t h a t the i n c r e a s e i n amine c o n c e n t r a t i o n tends  r e l e a s e a t t a c h e d fragments from the p a r e n t f i b r e and t h a t t h i s  frac-  t i o n i s washed away through the w i r e s c r e e n at the bottom of the t r e a t ment v e s s e l . In the  the p r e s e n t s t u d y , p u l p s l u r r i e s were f i r s t  d r a i n e d once i n  handsheet mold to remove p a r t of the f i n e s b e f o r e f r e e z e - d r y i n g .  A f t e r s w e l l i n g t r e a t m e n t , the amine and washing water were removed through a pad of f i b r e s accumulated q u i c k l y on a 150-mesh s t a i n l e s s s t e e l w i r e s c r e e n of 4 mm  diameter.  A l t h o u g h t h e r e was  still  some l o s s o f f i n e s ,  t h i s s h o u l d not be so s e r i o u s as t o i n c r e a s e sheet L.S.C. 2.8 to  reduce the R.B.A. as much as 34%  47.0%  of EL-3-215-82).  ( i . e . , 81.2%  f o r EL-3-215-00 vs.  The most l i k e l y e x p l a n a t i o n f o r t h i s  t h e r e f o r e , i s l o s s of bonding s i t e s due to the s w e l l i n g The e x p l a n a t i o n proposed by McKenzie for  times and  difference,  treatment.  (81) can a l s o be  adopted  d e s c r i b i n g the i n c r e a s e i n R.B.A. and r e d u c t i o n of DF latewood  L.S.C. (DF-4, DF-5 from 77% to 82%  and DF-6)  (Table 2 ) .  as-.the amine c o n c e n t r a t i o n was  fibre  increased  The t h i c k e r - w a l l e d latewood f i b r e s a r e v e r y  s t i f f , w h i c h would have an adverse e f f e c t on the bonding  potential.  High s w e l l i n g agent c o n c e n t r a t i o n d e c r y s t a l l i z e s the f i b r e s and t h e r e b y  70  tends t o p l a s t i c i z e these f i b r e s .  This p l a s t i c i z i n g e f f e c t  improves  the f i b r e f l e x i b i l i t y , e n l a r g e s the c o n t a c t area between f i b r e s , and f u r n i s h e s more o p p o r t u n i t y f o r i n t e r f i b r e bond f o r m a t i o n . As e v i d e n t from t h e d a t a p r e s e n t e d i n T a b l e 2, t h e d e c r y s t a l l i z a t i o n treatment  decreased  the degree of i n t e r f i b r e bonding  t u r n i n f l u e n c e d t h e sheet t e n s i l e p r o p e r t i e s .  which i n  F i g . 16 i s a p l o t of the  r e l a t i o n s h i p between sheet t e n s i l e s t r e n g t h and L.S.C. f o r a l l the p u l p treatment  combinations  studied.  Each o f the w i t h i n increment  lines i n  F i g . 16 shows a maximum v a l u e w i t h 00% c o n c e n t r a t i o n and t h e r e a f t e r g r e s s i v e l y decreases w i t h 65%, 75% o r 77% and 82%  pro-  amine d e c r y s t a l l i z e d  f i b r e s , i n that order. I t i s apparent l i z a t i o n treatment  t h a t f o r the h e a v i l y beaten  caused  f i b r e s , the d e c r y s t a l -  a wide d i f f e r e n c e i n i n t e r f i b r e bonding  between  the 00% and 65% l e v e l s even though c r y s t a l l i n i t y of the l a t t e r one was not lowered  (Table 2 ) .  As a r e s u l t , t h e t e n s i l e s t r e n g t h was i m p a i r e d .  When comparing r e s u l t s from 65, 75 o r 77 and 82% amine treatment, the p l o t s f o r each h e a v i l y - b e a t e n and the DF-1/2 o f the l i g h t l y - and mediumbeaten  sheets a r e almost p e r f e c t i n v e r s e l i n e a r  relationships.  For the DF-3 t o DF-6 o f l i g h t l y - and medium-beaten f i b r e s , the t e n s i l e s t r e n g t h c o n t i n u e s t o decrease even w i t h the f i n a l decrease i n L.S.C.  The L.S.C. change may be due to f i b r e p l a s t i c i z a t i o n by 82%  amine c o n c e n t r a t i o n as d e s c r i b e d . l i z a t i o n treatment, strength.  A l s o as an outcome of the d e c r y s t a l -  f i b r e s may b e weakened and hence g i v e lower  This e f f e c t w i l l be discussed  Sheet  later.  t e n s i l e strengths are p l o t t e d against c e l l u l o s e  n i t y i n F i g . 17 f o r the DF f i b r e s .  sheet  crystalli-  S i m i l a r t o the f i n d i n g s of P a r k e r  71  (104), a c u r v i l i n e a r r e l a t i o n s h i p was o b t a i n e d f o r each f i b r e - t y p e .  The  same r e l a t i o n s h i p was o b t a i n e d between the modulus o f e l a s t i c i t y o r t e n sile  r u p t u r e energy  presented).  and the c e l l u l o s e c r y s t a l l i n i t y  A r a p i d then g r a d u a l decrease  ( t h e s e graphs a r e n o t  i n t e n s i l e s t r e n g t h , modulus  o f e l a s t i c i t y o r r u p t u r e energy was found as the c r y s t a l l i n i t y I t s h o u l d be noted appears  to r e l a t e  decreased.  t h a t l o s s i n sheet s t r e n g t h as shown i n F i g . 16 and 17 to both L.S.C. and c e l l u l o s e c r y s t a l l i n i t y  variations,  and p o s s i b l y o t h e r changes i n h e r e n t w i t h the d e c r y s t a l l i z a t i o n McKenzie (81) s w e l l e d f i b r e s w i t h e t h y l e n e d i a m i n e . w i t h the e x c e p t i o n o f e x t e n s i b i l i t y l y due t o treatment,  He found t h a t ,  ( s t r e t c h ) which decreased  the paper t e n a c i t y  treatment.  continuous-  ( t e n s i l e s t r e n g t h ) , energy  absorp-  t i o n and modulus of e l a s t i c i t y i n c r e a s e d s l i g h t l y when amine c o n c e n t r a t i o n was r a i s e d from 1% t o 20%, then decreased w i t h f u r t h e r i n c r e a s e i n amine concentration.  Parker  (104) was t r y i n g t o e s t a b l i s h a . r e l a t i o n s h i p be-  tween paper t e n s i l e s t r e n g t h o r modulus o f e l a s t i c i t y and f i b r e s t r e n g t h as reduced by changing  crystallinity.  Although he r e p o r t e d a d e g r a d a t i o n  i n these paper p r o p e r t i e s w i t h change.in no d e f i n i t i v e evidence was s u p p l i e d .  cellulose crystallinity  indices,  T h i s was due t o f i b r e s u r f a c e area  v a r i a t i o n accompanying the s w e l l i n g treatment. One p e r c e i v e s t h a t t e s t data on sheets which a r e made from e n t l y t r e a t e d f i b r e s can be used  differ-  t o e v a l u a t e f i b r e p r o p e r t i e s o n l y when the  sheets have the same s t r u c t u r e , and t h a t r e l a t i v e bonded a r e a i s the b e s t parameter to d e f i n e t h i s  (59).  I n the p r e s e n t study, f i b r e s o f the same  o r i g i n and b e a t i n g l e v e l b u t t r e a t e d by v a r i o u s amine s o l u t i o n tions, were  therefore involving different used  to  examine  the  effect  cellulose crystallinity of  cellulose  concentraadjustments,  c r y s t a l l i n i t y on sheet  72  p r o p e r t i e s at constant  r e l a t i v e bonded a r e a s .  W i t h i n each, of t h e DF-5-705, DF-5-106, DF-6-700 and DF46-340 f i b r e s , the amine t r e a t e d (.65, 77 and 82 f i b r e s ) comparable R.B.A.  These meet the requirements  sheets seemed to have  s e t down i n the l a s t  paragraph. A n a l y s i s o f v a r i a n c e showed t h a t t h e r e were s i g n i f i c a n t  differ-  ences (5% l e v e l ) between t h e R.B.A. of the t h r e e amine t r e a t e d f i b r e sheets w i t h i n each of the f o u r pulp o r i g i n s a n a l y s e s by t - t e s t  separated  or beating l e v e l s .  Further  the f o l l o w i n g f o u r p a i r s , DF-5-705-65 vs.  DF-5-705-77, DF-5-106-77 vs. DF-5-106-82, DF-6-700-65 vs. DF-6-700-77 and DF-6-340-65 vs. DF-6-340-82, as s t a t i s t i c a l l y n o n - s i g n i f i c a n t a t t h e 5% level  (Table 5 ) .  T h e r e f o r e , t h e i r c o r r e s p o n d i n g paper t e n s i l e p r o p e r t i e s  were a n a l y s e d . D i f f e r e n c e s i n sheet t e n s i l e s t r e n g t h , s t r e t c h , modulus o f e l a s t i c i t y and t e n s i l e r u p t u r e energy are examined by t - t e s t .  R e s u l t s showed  t h a t t h e r e were h i g h l y s i g n i f i c a n t d i f f e r e n c e s a t the 1% l e v e l cantly different treatments  (signifi-  at the 5% l e v e l f o r DF-5-106 s t r e t c h ) between the p a i r e d  f o r a l l s t r e n g t h p r o p e r t i e s examined.  The lower  amine concen-  t r a t i o n t r e a t e d f i b r e s always gave h i g h e r sheet t e n s i l e p r o p e r t i e s . I n t r i n s i c v i s c o s i t i e s of some of the amine s w e l l e d f i b r e s were measured and a r e p r e s e n t e d  i n T a b l e 2.  The d i f f e r e n c e i n v i s c o s i t y be-  tween t h e p a i r e d f i b r e s ranged from ± 0.53 to ± 4.46% o f t h e i r Furthermore, t h e s e v i s c o s i t i e s correspond merization  CD.P.).  to mechanical  to 700 to 800 degree o f p o l y -  T h i s i s h i g h e r than the DP, 400, c o n s i d e r e d  s t r e n g t h f o r most polymers  average.  critical  C97), but a t the boundary f o r  73  p u l p f i b r e s (52).  Therefore,  the change i n sheet t e n s i l e  properties  caused by u n i n t e n t i o n a l c e l l u l o s e m o l e c u l a r weight adjustments  during  the amine s w e l l i n g treatment i s c o n s i d e r e d n e g l i g i b l e . As  shown above, amine s w e l l i n g causes no  e i t h e r c h e m i c a l (107)  or p h y s i c a l (as shown by  p r o p e r t i e s except degree of c r y s t a l l i n i t y . at  the i n t r i n s i c v i s c o s i t y )  I t may  the same sheet r e l a t i v e bonded area and  as s e t by  apparent d i f f e r e n c e s i n  be  concluded  structure, fibre  the d e c r y s t a l l i z a t i o n treatments p r a c t i c e d has  f i c a n t negative  that  crystallinity  a highly  signi-  e f f e c t on the sheet t e n s i l e s t r e s s - s t r a i n p r o p e r t i e s .  Among the f o u r sheet s t r e s s - s t r a i n p r o p e r t i e s examined, s t r e t c h was  l e a s t a f f e c t e d by  a l t e r a t i o n i n the f i b r e s u p e r m o l e c u l a r s t r u c t u r e .  Reason f o r t h i s phenomenon i s unknown. have i n c r e a s e d  the  fibrillar  The  s w e l l i n g a c t i o n of amine  angle arrangement i n the c e l l w a l l .  been found t h a t f i b r e s t r a i n was t h a t f i b r e s t r e n g t h was  The  d i r e c t l y r e l a t e d to f i b r i l l a r  inversely affected  e f f e c t of f i b r e s t r e n g t h  on the degree of i n t e r f i b r e bonding.  It  has  angle,  and  (130).  on sheet t e n s i l e p r o p e r t i e s The  may  sheets d i s c u s s e d  depends  i n the above  3 s e c t i o n s had  d e n s i t i e s ranging  be p o o r l y bonded papers.  occurred  to 0.52  g/cm  .  They seemed to  But, when these d e n s i t i e s were compared to d a t a  from K e l l o g g and Wangaard (63) t h a t these v a l u e s  from 0.40  and  Tamolang et al.  (131), i t was  i n the range where s t r e n g t h  p l a y an i n c r e a s i n g r o l e i n d e t e r m i n i n g sheet  found  effects start  strengths.  B e s i d e s d i r e c t evidence on e f f e c t s of f i b r e c r y s t a l l i n i t y sheet t e n s i l e p r o p e r t i e s , the p l o t s i n F i g s . 12A support the  finding.  to  to 12D  and  These f i g u r e s show t h a t at comparable  13A  on  to 13D  interfibre  also  74  bonding s t a t e s , the handsheet t e n s i l e properties of h i g h l y d e c r y s t a l l i z e d sheets were i n f e r i o r to those of n o n - d e c r y s t a l l i z e d handsheets.  As has  been discussed i n the previous paragraphs, and according to the s t a t i s t i c a l analysis shown i n Table 5, the e f f e c t of f i b r e c r y s t a l l i n i t y on s t r e t c h i s l e s s apparent than on the other t e n s i l e properties.  This i s  probably because the s t r e t c h i s .more dependent on f i b r e i n t e r n a l propert i e s such as f i b r i l l a r angle than on the c r y s t a l l i n i t y .  Another possible  cause could be f a i l i n g of the paper s t r i p s at inconstant time.  Thereby,  the s t r e t c h accumulates experimental e r r o r . A f t e r describing the important c o n t r i b u t i o n of c e l l u l o s e c r y s t a l l i n i t y to paper sheet p r o p e r t i e s , i t i s worthwhile to examine the e f f e c t of raw m a t e r i a l o r i g i n on sheet t e n s i l e properties i n the h i g h l y decryst a l l i z e d condition. Fig.  8A shows that the sheet density has been reduced by the max-  imum d e c r y s t a l l i z a t i o n treatment.  The l o s s of i n t e r f i b r e bonding poten-  t i a l due to f i b r e s w e l l i n g i n amine can explain t h i s .  I t should be pointed  out, however, that v a r i a t i o n i n the intra-incremental handsheet d e n s i t i e s follows the same trend as with n o n - d e c r y s t a l l i z e d sheets. Fig.  8A to 8E demonstrate that even i n the h i g h l y d e c r y s t a l l i z e d  c o n d i t i o n , the e f f e c t s of f i b r e intra-incremental o r i g i n on sheet t e n s i l e properties cannot be removed.  Furthermore, the e f f e c t on sheet s t r e t c h  becomes more d i s c e r n i b l e ( F i g . 8C). This may be because, as has been shown by sheet L.S.C, density- and s t r e t c h data i n Table 2, F i g . 8C, 12B and 13B, dependency of sheet s t r e t c h on the degree of i n t e r f i b r e bonding decreases with the increase of i n t e r f i b r e bonding.  The dependency becomes  75  l e s s i n f l u e n t i a l a f t e r a c e r t a i n bonding  l e v e l has been a c h i e v e d .  f o r e poor i n t e r f i b r e bonding r e s u l t i n g from the d e c r y s t a l l i z a t i o n  Theretreat-  ment renders d i f f e r e n c e s i n i n t r a - i n c r e m e n t a l sheet s t r e t c h more o b v i o u s . When comparisons  are made among s p e c i e s and b e a t i n g treatments a t  the same i n t e r f i b r e bonding  c o n d i t i o n , F i g . 13A to,13D show  d i f f e r e n c e s a r e seemingly, q u i t e s m a l l . ( F i g . 15) i n d i c a t e still  that strength  R e s u l t s of c o v a r i a n c e a n a l y s e s  t h a t , i n . most c a s e s , the s t r e n g t h s o f t h e s e sheets a r e  s i g n i f i c a n t l y d i f f e r e n t from each o t h e r a t the 5% o r h i g h e r  Hence, i t can be s a i d t h a t even at the h i g h l y d e c r y s t a l l i z e d  levels.  condition,  n e i t h e r the e f f e c t of f i b r e . i n t r a - i n c r e m e n t a l p o s i t i o n , n o r the e f f e c t o f s p e c i e s on sheet t e n s i l e p r o p e r t i e s was removed.  Furthermore,  the  combination o f . s e v e r e b e a t i n g and . d e c r y s t a l l i z a t i o n treatments d i d not remove the raw m a t e r i a l S p e c i f i c Energy  effect.  o f "Bond F a i l u r e "  In response to t e n s i l e s t r e s s , sheet f a i l u r e may o c c u r e i t h e r w i t h i n the f i b r e mechanisms.  ( i n t r a f i b r e ) , between the f i b r e s  ( i n t e r f i b r e ) o r by both  The c o n t r i b u t i o n o f each depends upon the r e l a t i v e s t r e n g t h s  of i n t r a f i b r e and i n t e r f i b r e bonding. f i b r e s t r e n g t h and bonding  As has been reviewed, t h e latewood  shear s t r e s s are s e v e r a l times l a r g e r  those o f earlywood, b u t a l s o weaker i n i n t e r f i b r e bonding. ure i n v o l v e s more latewood  than  Hence, f a i l - r  f i b r e s b e i n g p u l l e d from the sheet s t r u c t u r e  r a t h e r than i n t r a f i b r e f a i l u r e s as o c c u r w i t h earlywood  fibres  ( F i g . 10).  Due to t h i s d i f f e r e n c e i n the n a t u r e o f f a i l u r e , an examination o f energy consumption  phenomena c o u l d be a u s e f u l approach  material-sheet property relationships.  f o r d e s c r i b i n g raw  76  The term, s p e c i f i c energy of "bond f a i l u r e , " as used by Stone (123), i s adopted here.  This i s defined as the energy which i s i r r e v e r -  s i b l y consumed to produce a u n i t increase i n the L.S.C. at 90% of the sheet maximum s t r e t c h .  I t should be stressed that t h i s term does not  n e c e s s a r i l y imply that a l l the energy i s consumed i n rupturing i n t e r f i b r e bonds.  This i s because part of the consumed energy i s d i s s i p a t e d i n the  f i b r e rather than i n the bond rupture (118, 138).  Instead of using  s t r e t c h , 90% to 95% of the maximum breaking load was used by Rennel (116) , who applied the same name. The s p e c i f i c energy of "bond f a i l u r e " f o r various f i b r e sheets can be found i n Table 2.  These r e s u l t s are further shown i n F i g . 18.  They show that the amount of energy consumed i n creating u n i t o p t i c a l surface area i s not constant, but v a r i e s with species, p o s i t i o n w i t h i n growth increment, and the beating treatment applied. Earlywood pulp sheets u s u a l l y possess higher s p e c i f i c energy than latewood sheets.  The low BF-1/2-160 sheet (Table 2) s p e c i f i c energy could  have been caused by i n t e n s i v e beating a c t i o n , which rendered the f i b r e s more e a s i l y broken with rather low energy consumption.  The higher BF sheet  s p e c i f i c energy than those of EL and DF sheets could explain why the BF sheets are stronger than the others when compared at the same degree of i n t e r f i b r e bonding.  The d i f f e r e n c e i n intra-incremental sheet s p e c i f i c  energies adds other evidence on why earlywood sheets are stronger than latewood sheets. Beating improves i n t e r f i b r e bonding p r o p e r t i e s , but also a l t e r s f i b r e s t r u c t u r e and strength.  Proper c o n t r o l of t h i s process may increase  77  sheet  specific  energy.  T h i s i s t r u e when comparing between t h e l i g h t l y -  beaten and medium-beaten sheets  o f DF.  gy o f a l l the DF h e a v i l y - b e a t e n  fibres  The d e g r a d a t i o n t o lower l e v e l s  l i g h t l y - and medium-beaten f i b r e s was unexpected. caused by b e a t i n g may be the reason sheets.  The p u l l i n g  menon c o u l d be i n v o l v e d . has  ener-  than b o t h the  Severe f i b r e damage  f o r i n f e r i o r s p e c i f i c energy of some  out o f unbroken f i b r e s  wood f i b r e web d u r i n g s t r a i n i n g  i n specific  from the h e a v i l y - b e a t e n  late-  ( F i g . 10) suggests t h a t some o t h e r pheno-  One p o s s i b l e reason  i s that i n t e n s i v e beating  l o c a t e d t h e s i t e o f f a i l u r e at t h e outer  l a m e l l a e o f the latewood  f i b r e w a l l by m e c h a n i c a l p e e l i n g a c t i o n i n a d d i t i o n t o f a i l u r e between and/or w i t h i n  fibres.  Information of Davies(20),  suggesting  such a mechanism can be found i n the work  who was a b l e t o show a d i s t u r b e d wavy appearance o f bonded  area between two h i g h l y f i b r i l l a t e d uity  pulp f i b r e s .  This d i s c o n t i n -  i n w a l l s t r u c t u r e as a p o t e n t i a l p o i n t of s t r e s s c o n c e n t r a t i o n under  a p p l i e d f o r c e cannot be r u l e d o u t . and  sulphate  Other evidence  can be seen i n F i g . 10C  10D, which show the c e l l w a l l f a i l u r e of the DF-5-106-00 f i b r e s .  Furthermore, the r e d u c t i o n of bond s t r e n g t h between latewood f i b r e s b e a t i n g , as r e p o r t e d by B r i n k et al. ( 1 4 ) , c o u l d be another The f i b r e sheets  difference i n specific  T h i s may be e x p l a i n e d  The v a r i a t i o n o f s p e c i f i c  origin  energy between t h e i n t r a - i n c r e m e n t a l  shear s t r e n g t h r e p o r t e d between latewood f i b r e s  fibre origin  reason.  i s not as wide as other s t r e n g t h p r o p e r t i e s which have been  discussed i n e a r l i e r sections. bond  with  and b e a t i n g  i n terms of h i g h e r (78, 119).  energy of "bond f a i l u r e " w i t h  species,  treatment f u r t h e r e x p l a i n s why the e f f e c t  on paper p r o p e r t i e s cannot be removed.  of f i b r e  CHAPTER V  CONCLUSION  The  e f f e c t s of c o n i f e r o u s wood o r i g i n on some f i b r e and paper  sheet p r o p e r t i e s were s t u d i e d .  Pulps d i f f e r i n g a c c o r d i n g to wood i n t r a -  i n c r e m e n t a l p o s i t i o n w i t h i n t h r e e s p e c i e s were examined i n b e a t i n g and c e l l u l o s e d e c r y s t a l l i z i n g treatments  f o l l o w i n g k r a f t cooking,  chlorina-  t i o n and c a u s t i c e x t r a c t i o n meant t o s i m u l a t e commercial p r a c t i c e .  Some  paper handsheet p h y s i c a l - m e c h a n i c a l and p h y s i c a l - o p t i c a l p r o p e r t i e s were t e s t e d a g a i n s t o r i g i n a l p o s i t i o n w i t h i n wood growth increments, as the paper sheet apparent are advanced from evidence 1.  density obtained.  The f o l l o w i n g c o n c l u s i o n s  o b t a i n e d i n the study:  Paper handsheet p h y s i c a l - m e c h a n i c a l p r o p e r t i e s were  much a f f e c t e d by f i b r e o r i g i n . criteria  as w e l l  Sheet apparent  d e n s i t y and t e n s i l e s t r e n g t h  (maximum s t r e n g t h , " s t r e t c h , " modulus of e l a s t i c i t y and t e n s i l e  r u p t u r e energy) decreased to r e g u l a r p a t t e r n s .  p r o g r e s s i v e l y a c r o s s growth increments  Values  f o r earlywood sheets prepared  according  from m i l d l y r e -  f i n e d pulps were 1 . 4 to 3.0 times h i g h e r than those o f latewood  sheets,  which compares i n v e r s e l y w i t h 1.3 to 5.0 times h i g h e r latewood v a l u e s obt a i n e d i n wood m i c r o t e s t i n g . e a r l i e r work w i t h wood ties.  Small between s p e c i e s d i f f e r e n c e s noted i n  t i s s u e s were expressed  a l s o i n paper sheet  Treatments as p r a c t i c e d i n the study r a i s e d  proper-  ( b e a t i n g ) or lowered  ( d e c r y s t a l l i z a t i o n ) the l e v e l of paper handsheet p h y s i c a l - m e c h a n i c a l  pro-  p e r t i e s , m o d i f i e d the earlywood-^latewood d i f f e r e n c e , but d i d not e n t i r e l y remove the e f f e c t of f i b r e  origin. 78  79  2.  Paper handsheet p h y s i c a l - m e c h a n i c a l p r o p e r t i e s were  related significantly  Cr = 0.817  to 0.989, except s t r e t c h at r =  0.218  to 0.974) to paper sheet apparent d e n s i t y , which proved to be a good parameter f o r w i t h i n and between s p e c i e s comparisons.  L i k e w i s e , paper  sheet apparent d e n s i t y r e l a t e d w e l l t o s p e c i f i c g r a v i t y of the o r i g i n a t i n g wood, wherein earlywood and latewood were d i s t i n g u i s h a b l e  even  f o l l o w i n g severe pulp.treatments. 3.  The study was  not a paper r h e o l o g i c a l examination, i n  t h a t times t o f a i l u r e of t e s t specimens were not c o n t r o l l e d . ultimate strain  Thereby,  ( " s t r e t c h " ) at f a i l u r e i n c l u d e s an e x t r a component of  e x p e r i m e n t a l e r r o r which i s shown by lower c o r r e l a t i o n l e v e l s than obt a i n e d w i t h o t h e r t e n s i l e s t r e n g t h parameters.  The p h y s i c a l - m e c h a n i c a l  r e s u l t s do d e s c r i b e , however, some s e c t i o n through a s t r e s s - s t r a i n - t i m e relationship. 4.  F i b r e and paper handsheet p h y s i c a l - o p t i c a l  properties  ( l i g h t s c a t t e r i n g c o e f f i c i e n t ) were used to c h a r a c t e r i z e f i b r e areas and paper sheet bonded s t a t e s .  surface  Unbonded f i b r e s u r f a c e a r e a r e -  l a t e d t o pad d e n s i t y a c c o r d i n g to o r i g i n , w i t h most f i b r e - t y p e s  showing  3 c o n s t a n t v a l u e s a t 0.4  g/cm  compaction.  T h i s was  found a l s o to be the  d e n s i t y a t which bonded paper handsheets b e g i n to show p h y s i c a l - m e c h a n i c a l strength. 5.  Between s p e c i e s d i f f e r e n c e s were observed when sheet t e n -  s i l e s t r e n g t h p r o p e r t i e s were compared a t the same degree of o p t i c a l bonding.  F o r example,  balsam f i r  sheets showed h i g h e r s p e c i f i c energy of  "bond f a i l u r e " than those made from e a s t e r n l a r c h and D o u g l a s - f i r .  Regu-  l a r p a t t e r n s w i t h i n growth increments were r e l a t e d t o the p h y s i c a l - m e c h a n i c a l  80  e f f e c t s observed.  In a d d i t i o n , the i n c r e a s e i n f i b r e s u r f a c e a r e a  (AS)  of paper s h e e t s d u r i n g c y c l i c l o a d i n g - u n l o a d i n g and s p e c i f i c energy sumed (E/AS) i n these i n t e r f i b r e adjustments was  con-  r e l a t e d t o wood o r i g i n .  Even f o l l o w i n g the most s e v e r e treatments the f i b r e i d e n t i t y was  main-  tained. 6.  The r e l a t i o n s h i p between l i g h t s c a t t e r i n g  coefficient  and sheet apparent d e n s i t y has been much used to compare papers made from whole-wood p u l p s t r e a t e d i n v a r i o u s ways, such as beaten t o d i f f e r ent l e v e l s .  T h i s study shows t h a t o n l y earlywood  i n t h i s way,  w h i l e latewood p u l p s remain u n a f f e c t e d .  o p t i c a l bonding o f newly exposed  p u l p s respond to b e a t i n g T h i s suggests  that  s u r f a c e depends a l s o on f i b r e o r i g i n  and  t h a t p r o p o r t i o n i n g between f i b r e types has importance not p r e v i o u s l y r e c ^ ognized. 7.  V a r i a t i o n s i n wood f i b r e f u r n i s h have been a t t r i b u t e d  l y t o d i f f e r e n c e s i n f i b r e bonding p o t e n t i a l as d e r i v e d from s u r f a c e and geometric f a c t o r s .  T h i s was  external  found to be o n l y p a r t l y  s i b l e f o r d i f f e r e n c e s observed i n the p r e s e n t study. f i b r e c e l l w a l l o r g a n i z a t i o n to sheet p r o p e r t i e s was even when f i b r e s were p o o r l y bonded as a sheet.  respon-  The importance also  former-  of  demonstrated,  Moreover, s i n c e  tensile  s t r e n g t h f e a t u r e s o f paper sheets compared a t the same bonded s t a t e v a r i e d markedly  a c c o r d i n g to c e l l u l o s e s u p e r m o l e c u l a r o r d e r , the former n o t i o n  seems i n c o m p l e t e . 8.  E v i d e n c e p r e s e n t e d i n t h i s study shows t h a t n e i t h e r  con-  v e n t i o n a l p u l p i n g and papermaking p r o c e s s e s , nor a d d i t i o n a l treatments as s e v e r e b e a t i n g o r major a l t e r a t i o n s of the b a s i c c e l l u l o s e  such  supermolecular  81  s t r u c t u r e remove the e f f e c t s of c o n i f e r o u s properties.  This persistence  tion studies  leads  wood o r i g i n on paper sheet  of f i b r e i d e n t i t y as shown here by i s o l a -  to q u e s t i o n s on c o n t r i b u t i o n of i n d i v i d u a l f i b r e  to whole-wood paper sheet  structures.  types  LITERATURE CITED  A l e x a n d e r , S. D. and R. Marton. 1968. E f f e c t of b e a t i n g and wet p r e s s i n g on f i b e r and sheet p r o p e r t i e s : I I . Sheet p r o p e r t i e s . Tappi 51: 283-288.  and S. D. McGovern. 1968. E f f e c t of b e a t i n g and wet p r e s s i n g on f i b e r and sheet p r o p e r ties: I. Individual f i b e r properties, Tappi 51: 277283.  3.  Algar,  W. H. 1966. E f f e c t of s t r u c t u r e on the m e c h a n i c a l propert i e s of paper. In C o n s o l i d a t i o n of the Paper Web. ed. F. Bolam, Tech, Sec. B.P. & B.M.A., London, p. 814-849.  Annergren, G. E., Rydholm, S. A. and S. V. Vardheim. 1963. 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The e f f e c t s o f ethylamine d e c r y s t a l l i z a t i o n of c e l l u l o s e f i b e r s on the v i s c o e l a s t i c p r o p e r t i e s o f paper. T a p p i 45: 936-943.  105.  Parsons, S. R. 1942. O p t i c a l c h a r a c t e r i s t i c s o f paper as a funct i o n o f f i b e r c l a s s i f i c a t i o n . Paper Trade J . 115(25): 34-42.  106.  Paszner, L. 1968. E f f e c t o f i n t e r - and i n t r a - c r y s t a l l i n e s w e l l i n g on c e l l u l o s e d e g r a d a t i o n by gamma-rays. Svensk Papperstid. 71; 822-828.  107.  108.  .  Private  communication.  Perng, W.. R, . and T. Tajima. 1969. I n f l u e n c e of,' d r y i n g on c h e m i c a l p r o p e r t i e s o f wood. I I . E f f e c t o f wood-drying on p u l p s p r e p a r e d from d i f f e r e n t a n a t o m i c a l f e a t u r e s o f wood ( e a r l y wood, l a t e wood, c o r e wood . outerwood). J . Japan Wood Res. S o c i e t y 15: 325-330. f  93  109.,  Preston, R. D., Hermans, P. H. and A. Weidinger. 1950. The c r y s t a l l i n e - n o n - c r y s t a l l i n e r a t i o i n c e l l u l o s e of b i o l o g i c a l i n t e r e s t . J . Exper. Botany. 1(3): 344-352.  110.  P u r i , B. R., Sharma, L. R. and M. L. Lakhanpal. 1954. Freezing point of water held i n porous bodies at d i f f e r e n t vapor pressures. J . Phys. Chem. 58(4): 289-292.  111.  Pye, I. T., Washburn, 0. V. and J . G. Buchanan. 1966. S t r u c t u r a l changes i n paper on pressing and drying. In. Consolidation of the Paper Web. ed. F. Bolam, Tech. Sec. B.P. & B.M.A., London, p. 353-367.  112.  Ranby, B. G. 1962. Summing up of the Symposium. In Formation and Structure of Paper. ed. F. Bolam, Tech. Sec. B.P. & B.M.A., London, p. 901-910.  113.  Ranee, H. F. 1954. E f f e c t of water removal on sheet p r o p e r t i e s . The water evaporation phase. Tappi 37: 640-654.  114.  Ratliff,  F. T. 1949. The p o s s i b l e c o r r e l a t i o n between hemicelluloses and the p h y s i c a l properties of bleached k r a f t pulps. Tappi 32: 357-367.  115.  Rennel, J .  1969. Opacity i n r e l a t i o n to strength properties of pulps. 1. Method f o r producing unbonded f i b e r s and determining t h e i r l i g h t s c a t t e r i n g c o e f f i c i e n t and surface area. Svensk Papperstid. 72: 1-8.  116.  . 1969. Opacity i n r e l a t i o n to strength of pulps. 4. The e f f e c t of beating and wet pressing. Pulp Paper Mag. Can. 70(10): T73-T80.  117.  Robertson, A. A. .and S. G. Mason. 1962. The r o l e of f i b r e c o l l a p s e i n papermaking. In Formation and Structure of Paper, ed. F. Bolam, Tech. Sec. B.P. & B.M.A., London, p. 639-650.  118.  Sanborn, I . B. 1962. A study o f i r r e v e r s i b l e , s t r e s s induced changes i n the m a c r o s t r u c t u r e o f paper. T a p p i 45: 465474.  94  119.  Schniewind, A. P., Nemeth, L. J . and D. L. Brink. 1964. Fiber and pulp p r o p e r t i e s . I . Shear strength of s i n g l e f i b e r crossings. Tappi 47: 244-248.  120.  Smith, D. M. 1965. Rapid measurement of tracheid c r o s s - s e c t i o n a l dimensions of c o n i f e r s : I t s a p p l i c a t i o n to s p e c i f i c g r a v i t y determinations. Forest Prod. J . 15: 325-334.  121.  Spiegelberg, H. L. 1966. The e f f e c t of.hemicelluloses on the mechanical properties of i n d i v i d u a l pulp f i b e r s . Tappi 49: 388-396.  122.  Steele, F. A. 1935. The o p t i c a l c h a r a c t e r i s t i c s of paper. I . The mathematical r e l a t i o n s h i p s between, basis weight, ref l e c t a n c e , contrast r a t i o , and other o p t i c a l properties. Paper Trade J . 100(12): 37-42.  123.  Stone, J . E. 1963. Bond strength i n paper. 64: T528-T532.  Pulp Paper Mag. Can.  124.  and A. M. S c a l l a n . 1965. A study of c e l l w a l l s t r u c t u r e by nitrogen adsorption. Pulp Paper Mag. Can. 66: T407T414.  125.  . 1966. Influence of drying on the pore structures of the c e l l w a l l . In "Consolidation of the Paper Web".- ed. F. Bolam, Tech. Sec. B.P. & B.M.A., London, p. 145-166.  126.  Sun, B. C. Author's f i l e .  127.  Swanson, J . W. 1956. Beater adhesives and f i b e r bonding — the need f o r further research. A review of the l i t e r a t u r e on beater or wet-end adhesives. Tappi 39: 257-270.  128.  129.  and A. J . Steber. 1959. Fiber surface area and bonded area. Tappi 42: 986-994. Tamalong, F. N. and F. F. Wangaard. 1961. Relationships between hardwood f i b e r c h a r a c t e r i s t i c s and pulp-sheet p r o p e r t i e s . Tappi 44: 201-216.  95  130.  Tamalong, F. N., Wangaard, F. F. and R. M. Kellogg. 1967. Strength and s t i f f n e s s of hardwood f i b e r s . Tappi 50: 68-72.  131.  . 1968. Hardwood f i b e r strength and pulp-sheet p r o p e r t i e s . Tappi 51: 1925.  132.  133.  134.  T.A.P.P.I.  1949. Conditioning paper and paperboard f o r t e s t i n g . T 402 m-49. TAPPI Standards. Tech. Assoc. Pulp Paper Industry, New York.  . 1958. Forming handsheets f o r p h y s i c a l tests of pulp. T 205 m-58. TAPPI Standards. Tech. Assoc. Pulp Paper Industry, New York. 1960. dards.  Kappa number o f p u l p . T. 236 m-60. TAPPI Stanr Tech.' Assoc. Pulp Paper I n d u s t r y , New York.  135.  Thode, E. F. and W. L. Ingmanson. 1959. Factors c o n t r i b u t i n g to the strength of a sheet of paper. I . E x t e r n a l s p e c i f i c surface and swollen s p e c i f i c volume. Tappi 42: 74-83.  136.  Van den Akker, J . A. 1952. A note on the theory of f i b e r - f i b e r bonding i n paper; the influence on paper strength by drying by sublimation. Tappi' 35: 13-15.  137. 42: 138.  . 1959. S t r u c t u r a l aspects of bonding. 940-947.  . 1969. An analysis of the Nordman "Bonding Strength". Tappi 52: 2386-2389.  139. of paper. 140.  Tappi  . 1970. Structure and t e n s i l e c h a r a c t e r i s t i c s Tappi 53: 388-400.  Lathrop, A. L., Voelker, M. H. and L. R. Dearth. 1958. Importance of f i b e r strength to sheet strength. Tappi 41: 416-425.  96  141.  Wangaard, F. F. 1962. Contributions p r o p e r t i e s of k r a f t p u l p s .  142.  of hardwood f i b e r s to Tappi 45: 548-556.  the  K e l l o g g , R. M. and A. W. B r i n k l e y , J r . 1966. Varia t i o n i n .wood and f i b e r c h a r a c t e r i s t i c s and pulp-sheet p r o p e r t i e s of s l a s h p i n e . Tappi 49: 263-277.  143.  Wardrop, A. B. 1969. 396-408.  144.  Washburn, 0. V. and J . G. Buchanan. 1964. Changes i n web s t r u c t u r e on p r e s s i n g and d r y i n g . Pulp Paper Mag. Can. 65: T400-T408.  145.  Watson, A.  146.  •  F i b e r morphology and  papermaking.  Tappi  52:  J. 1961. I n f l u e n c e of chemical c o n s t i t u e n t s on the papermaking p r o p e r t i e s of pulp from Eucalyptus vegnans. F. M u e l l . A p p i t a 14: 144-158.  and I. G. Hodder. 1954. R e l a t i o n s h i p between f i b r e s t r u c t u r e and handsheet p r o p e r t i e s i n Pinus taeda. Proc. APPITA 8: 290-307.  147.  and F. H. P h i l l i p s . 1963. The i n f l u e n c e of chemical c o n s t i t u e n t s on the. paper making p r o p e r t i e s of pulps from Pinus radiata. D. Don. A p p i t a 16: 165-175.  148.  Wardrop, A. B., D a d s w e l l , H. E. and W. E. Cohen. 1952. I n f l u e n c e of f i b r e s t r u c t u r e on pulp and paper p r o p e r t i e s . Proc. APPITA 6: 243-269.  149.  Wellwood, R. W. 1962. T e n s i l e t e s t i n g of s m a l l wood samples. Paper Mag. Can. 63: T61-T67.  150.  Wijnman,C. F. 1954. I n f l u e n c e of heavy b e a t i n g of c o t t o n f i b e r s m o l e c u l a r l e n g t h and c r y s t a l l i n i t y . T a p p i 37: 96-98.  151.  W i l s o n , J . W. WP7,  152.  1969. O r g a n i z a t i o n w i t h i n the c o n i f e r o u s Pulp Paper Res. I n s t . Canada. 17pp.  Pulp  on  growth r i n g .  and M. Wayman. 1957. A comparison of c h l o r i n e d i o x i d e b l e a c h i n g sequences on s u l p h a t e p u l p . Pulp Paper Mag. Can. 58: T137-T142.  TABLE 1. SPECIES  SUMMARY OF WOOD AND PULP CHARACTERISTICS FOR MATERIALS Larix  laricina  Pseudotsuga Franco  (DuRoi)K. Koch  WOOD CHARACTERISTICS  menziesii  INCLUDED IN THE STUDY (Mirb.)  Abies  balsamea  (L) M i l l .  65 35 56 49.2 27.7 4.1 3.6 48-50 19-21 37-39 3.0 3.4 3.6 19.7 36.8 45.1 L E, E, E. L, E„ E_ E, E E„ L, E„ L_ E, E„ E, L 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 0-16 16-33 33-50 50-67 67-83 83-100 0-16 16-33 33-50 50-67 67-83 83-100 0-16 16-33 33-50 50-67 67-83 83-100 26.1 25.6 26.2 44.0 58.2 48.0 39.6 40.6 55.3 98.6 115.8 98.5 19.9 21.2 21.9 22.6 30.1 33.0 (.2°6) • .398 .624 . 761 .402 .512 (.290) .324 .439 .657 .760 . 757 (. 299) (.245) 90.2 89.4 (49. 9) (46. 8) 56.7 69.5 89.4 94.6 55.5 79.0  Stem Age, y r Uiaineter (ave.), cm Growth Rate (ave.), mm/yr Wood 111 ends, Increment No. Growth Rate (ave.)^ n\ra/yr Latewood (ave.), %'  n  c  r  Within IncremenL, Po.sition/% Y i e l d , K (molsture-fgee) Spec!Tic Gravity (C) Scan Sol ids , Z  r  —  fl  —  SULPHATE PULPING Screened Y i e l d , "I Screen Rejects, % Micro-kappa No. 40 Ml. K. No ( c a l c . ) Lignin (cal.) X  40 0 57 28 8  0 0 7 6 7  41 1 57 28 8  4 43.6 2 0.7 3 49.6 5 26.6 6 7.4  7 0 0 4 4  44.9 0.0  44.2 1.4 38.4 23.2 5.8  44 0 57 28 8  15.7 7.0  13.0 6.0  12.0 6.0  18.6 7.0  44 0 49 26 7  — —  8 0 5 5 6  46 0 58 28 8  4 0 1 7 7  50 0 54 27 8  4 0 5 8 2  52 0 48 26 7  6 7 8 3 3  54 8 44 25 6  7 6 2 1 6  5K5 2.3 38.6 23.2 5.8  42 0 54 27 8  14.4 6.5  12.2 6.0  17.4 7.0  5 0 5 9 2  45 0 50 26 7  2 0 3 8 6  46 0 48 26 7  8 0 0 1 2  48.8 0.0 46.1 25.6 6.9  50.0 0.0 45.1 25.3 6.8  49 0 41 24 6  5 0 5 2 2  15.6 7.0  15 0 6 5  14.7 6.5  13.2 6.0  PULP PURIFICATION  •A Ch l o r l n e Added, Z e Caus t i c Added, % Pulp ISlends, P o s i t i o n / % Y i e l d , g (moi|ture Viscosity, PULP MACHINING, C S . E .  (ml)  18.6 7.0  18.6 15.8 7.0 7.0 l/2 0-33 15.5 7.3 E  free)  3 4 5 6 33-50 50-67 67-83 83-100 10.4 15.6 21.8 16.2 7.1 7.2 6.9 7.5 E  E  L  L  E  19.0 7.0  l/2 0-33 28.7 7.3  17.4 7.0  16.2 7.0  3 4 5 6 33-50 50-67 67-83 83-100 22.5 43.6 45.3 40.1 7.4 7.3 7.6 7.3 E  L  L  L  E  16.5 7.0  l/2 0-33 14.4 6.4  3/4 33-67 16.9 6.7 E  5 6 67-83 83-100 12.9 14.1 6.5 6.6 E  L  S  Initial Low Medium High  600  182  665  725  755  745  —  —  —  —  215  205  145  124  625 525 380230  705 680  —  210  '765 700 285 170  765 705 370 106  760 700 340 150  540  — —  160  695  700  —  —  —  220  205  725  — —  180  H, E and L r e f e r to Heartwood, Earlywood and Latewood. 3  From analyses  of Green Scanning Micropho.tometer t r a c e s , transmitted l i g h t  (30), or stem a n a l y s i s .  ''Moisture-free weight, green volume. c  N a 0 38.6 g/1, Na S 14.2 g/1 s u l p h i d i c y 31.1%; liquor-wood 2  2  ^120% e  5.1:1; 93 min 22 to 173°C, 30 min at 173°;  demand, 2% consistency, 25°C, 60 min; p o l y e s t e r bags, o  3% consistency, 70 C, 60 min; p o l y e s t e r bags.  ;  fFeTNa c e l l u l o s e solvent (48); 20± 0.01°C; 100% concentration. 8 9 . 6 charge, 10% consistency, 3.4 kg/cm pressure, 0.15 mm clearance, 5.26 m/sec r e l a t i v e speed; PFI m i l l . . g  TABLE 2 SUMMARY OF PHYSICAL-OPTICAL AND PHYSICAL-MECHANICAL  PROPERTIES FOR PULP TYPES INCLUDED IN THE STUDY  2 . ' LIGHT SCAT . COEFF. cm /g PULP  • v i s e .  TYPE  W  CRYST. INDEX  UNBONDED BONDED HANDSHEET HANDSHEET AREA  SPECIFIC R.B.A. °l,  7.  X10  APPAR.  DENSITY ENERGY 5 2 , 3 g/cm erg/cm  EL-1/2-182-00 65 75 82  7. 29  63.3 65.9 65.6 44.9  773. 9 •  128.1 19'). 9 234.0 371.2  645. 8 574. 0 539. 9 402. 7  83.45 74. 17 69. 76 ,52.04  5.43  .778 .763 .733 .647  EL-3-215-00 65 75 82  7.,06  66.5 68.9 64.3 46.4  743.5  140.0 210. 3 268.0 394.4  603.5 533..3 475. 6 349. 2  81. 17 71. 72 63. 96 46. 96  5.28  .748 .725 .669 .580  EL-4-205-00 • 65 75 82  7;.18  67.2 67.8 65.8 47.2  540. 7  148. 8 227.1 242.9 321.0  72. 49 392. 0 313.,7 . 58..01 55. 08 297. 9 219. 7 40.63  5.08  .642 .607 .563 .484  EL-5-145-00 65 75 82  6..90  67.5 69.0 68.7 47.0  528. 5  156.0 219.1 234.1 291.1  372. 5. 309. 5 294. 4 237. 5  70. 48 58.56 55. 70 44. 94  4.32  .608 .557 .513 .442  STRENGTH kg/cm^  STRETCH 7,  ELASTICITY X10  4  kfj/cm  2  TENSILE ENERGY  TENSILE RUPTURE ENERGY  MODULUS  TENSILE  AliSOR.  Xio'' kfvm/m  kg-ni/ni^  3  BREAKING LENGTH km  5. 3.7 5.45 5. 39 5. 36  5..77 5..03 4,.59 3,.13  38 .23 34 .-72 28 . 35 17..4 3  27,,53 25.,25 2 1.00 , 14.,13  13.54 12.19 10.23 6.71  892 805 673 36 7  5. 14 5. 16 5. 22 5..22  4.98 4..57 4,. 16 2.. 54  29 .08 28 .16 26 .42 16 .29  22.,55 21 ,29 . 2 I,66 . 15,,26  1.1.93 10.69 10.06 6.33  723 573 ' 494 256 .  5.04 4..98 4. 93 4. 00  4 .02 3,.45 3. 1 7 2..19  27 .67 1.9 .02 . 16 .58 7.. 36  24.,46 1.7..22 15., 53 8. 13  11.28 9.45 8.40 5.29  5.04 5.05 4..72 3.62  3,.64 2..93 2 .84 1.61  21 .93 15.. 80 13 . 14 4..67  19.,97 15..67 19..38 5.68  10.59 8.38 7.67 3.97  1053 930 750 434  644 467 413 176  Pulp types are i d e n t i f i e d according to wood species (EL, eastern l a r c h ; DF, D o u g l a s - f i r ; and BF, balsam f i r ) , (1/2, 3, 3/4, 4, 5 and 6), Canadian standard freeness (ml) and amine concentration (7.).  lntrn-incremc-ntal o r i g i n s -o  Table 2 (continued)  LIGHT SCAT. COEFF. cm /g  vise.  PULP TYPE  CRYST. INDEX  UNBONDED BONDED HANDSHEET HANDSHEET AREA  ID  EL-6-12A-00 65 75 . 82  R.B.A.  %  APPAR. DENSITY  XIO"* erg/cm  2  g/cm  68.2 70..0 ' 61..4 47. 7  532.9  164. 2 227.,7 287. 8 301. 4  368.,7 305.,2 245.,1 231.,6  69..18 57.,27 45.,99 43.,46  4.15  DF-1/2-525-00 65 77 82  67..4 67.,9 55.,8 44.,9  712.6  256..0 29 3. .5 375. 6 385.,2  456..7 419.,1 337..0 327..4  64,,08 58.,82 47,,30 45..94  4.29  .714 .690 .637 . .604  DF-1/2-380-00 65 77 82  67..6 66.. 7 55., 7 47.,2  744.1  189..3 246.,8 338.,0 355.,2  554..8 497..3 406.,1 389.,0  74,,56 66.,83 54.,58 52.,28  4.51  .775 .736 .691 .650  67..5 67..9  800.3  168. 4 214..2 242.,0 251. 5  631.,9 586.,1 558.3 548.,8  78.96 73.,24 69.,76 68.,57  4.15  472.4  242..5 280.,0 331..4 • 322. .3  229.,8 192..3 141.,0 150..1  48..66 40..71 29..84 31..77  3.88  DF-1/2-230-00 65 77 82  7.47  SPECIFIC ENERGY  31  47.8  DF-3-680-00 65  67..2 69..1  77 82  61..1 48. 3  TENSILE STRENGTH STRETCH  MODULUS ELASTICITY X10  kg/cm  4  kg/cm  2  TENSILE RUPTURE ENERGY  TENSILE ENERGY ABSOR.  BREAKING . LENGTH  X10 k^-m/m^  kg-m/m  km  4  596 456 266 176  4. 80 4. 85 4. 08 3. 49 .  3.54 3.02 2.19 1.66  18..92 14..94 7.. 7 5 4,, 5 5  17,.12 14..698 , .42 5 . .46  9.82 8.20 5. 39 3.96  926 736 473 390 ,  4. 37 3.99 4. 12 3.94  5.02 4.81 3.52 3.09  25,.92 1 8 , .81 14,.03 1 1. .14  20.,73 . 1 4 .90 , 1 I.74' . <),, 72  12.98 JO.67 7.43 6.45  1086 913 616 467  4. 41 4. 18 4. 61 4. 27  5.57 5.13 4.02 3.43  30..60 . 24..86 • 19 . , 75 14.,29  22..  1 7 18.. 15 1 >.64 1 I . 94  14.01 12.40 8.92 7.19  .797 .770 .747 .668  1165 1111 987 535  4. 72 5.00 5. 15 4. 89  5.66 5.69 5.21 3.47  35.,41 35.,59 33. 66 1 8 . 59  23. 79 24. 85 2 1 . 56 14. 75  14.46 14.43 13.22 8.01  .578 .554 .507 .465  564 412 234 187  3.61 3. 38 2. 78 2. 52  3.87 3.22 2.49 2.08  13.,16 9..11 4..67 .34  1.3.47 9 ,40 . 5., 53 4 .08 .  .607 .556 ' .494 .444  r  9. 76 7.43 4.80 4.03  Table 2 (continued)  LICHT SCAT. COEFF. cm /g  PULP TYPE  vise.  CRYST. INDEX  UNBONDED BONDED HANDSHEET HANDSHEET AREA  R.B.A.  W DF-•3-210-00 65 77 82  SPECIFIC ENERGY X10  5  erg/cm  APPAR. DENSITY 2  g/cm  3  MODULUS ELASTICITY  TENSILE STRENGTH kg/cm  TENSILE RUPTURE ENERGY  STRETCH X10  4  kg/cm  2  X10  4  kg-m/m  3  2  TENSILE ENERGY ABSOR.  BREAKING LENGTH  2 kg-m/m"  km  67.3 68.0 61.4 51.4  529.3  172.4 215.5 282.9 308.6  356.9 313.8 246.5 220.7  67.42 59.29 46.56 41.70  3.63  .671 .642 .591 .540  878 763 389 286  4.55 4.47 4.34 3.66  4.74 4.34 2.99 "2 .54  25.58 21 . RO .1.1 .93 7.60  22.31 18.65 11 . 8.  13.09 11.90 6.78 5.29  DF-4-700-00 65 77 82  69.3 70.2 62.4 48.2  290.5  153.0 20.1 .1 199.6 189.8  137.5 89.4 90.9 100.7  47.33 30.79 31.29 34.67  3.49  .528 .434 .393 .364  359 204 143 94  3.18 2.23 1.90 1.35  2.85 2.18 .1.80 1.43  7.40 3.1)5 1 .83 .88  .83 .74 52 .30  6.80 4.70 3.63 2.58  DF-4-285-00 65 77 82  66.3 69.9 60.6 48.6  403.6  153.0 190.1 212.2 218. 3  250.6 213.6 191.5 185.4  62.09 52.92 47.45 45.94  3.80  .580 .514 .471 .446  531 39 8 238 167  4.46 3.74 2.88 2.38  3.44 3.11 2.36 1.9 5  15.22 9. 83 4.84 2.88  .15.50 10. 39 5.4 5 V. 5 3  9.. 16 7 . 49 5.05 3! 76  69.9 69.4 63. 3 50.5  475.6  148.3 210.1 233.0 255.2  327.3 265.5 242.6 220.4  68.81 55.83 51.01 46.34  .618 .540 .519 .491  553 467 299 173  4.52 4.02 3.69 2.97  3.50 3.29 2.56 1.87  16.09 12.21 7.63 3.74  15.62 12.01 7.89 4.45  8.9 5 8.65 5.75 3.82  DF-4- 170-00 65 77 82  7.38  7.25  2.86  Table 2 (Continued)  2 . LIGHT SCAT. COEFF. cm /g  PULP TYPE  VISC.  CRYST. INDEX  UNBONDED HANDSHEET  BONDED HANDSHEET AREA R.B.A.  SPECIFIC ENERGY X10  DF-5-705-00 65 77 82  7.61 7.42  DF-5-370-00 65 77 82 DF-5-106-00 65 77 82  7.27 7.62 7.54  5  erg/cm  APPAR. DENSITY 2  g/cm  kg/cm  3  MODULUS ELASTICITY  TENSILE STRENGTH STRETCH 2  %  X10  kg/cm  TENSILE RUPTURE ENERGY 4 X10 kg-m/m  TENSILE ENERGY ABSOR.  BREAKING LENGTH  kg-m/m  km  69.0 . 71.2 65.9 50.3  260.5  137.7 160.7 163.0 155.2  122.8 99.8 97.5 105.3  47.15 38.31 37.43 40.43  3.56  .502 .447 .415 .397  297 239 149 102  2.,55 2. 11 1. 76 1. 52  2.96 2.73 1.99 1.50  5,.00 3 .36 1,.78 1..07  6,.06 4,.03 2,,29 1.,49  5.,92 5.,34 3.,59 2.,58  70.2 71.3 59.6 51.5  369.0  149.2 186. 3 ' 202.6 197.3  219.8 182.7 166.4 171.7  59.56 49.51 45.08 46.53  3.72  .538 .502 .466 .420  450 378 188 129  3. 96 3. 12 2. 37 • 2. 20  3.32 3.11 2.18 1.58  U ..7.3 7 .77 . 3 , .12 2 .02  11.,90 7.,91 3.,66 2.,75  8.,08 7.,39 3.,92 3.,18  72.4 71.2 62.7 52.8  476.1  163.7 206.0 234.7 232.4  312.4 270.1 241.3 243.7  65.62 56.72 50.69 51.19  2.98  .558 .513 .481 .429  470 . 458 261 179  3.,.54 3.,53 3. 19 3.,04  3.49 3.32 2.36 1.88  10 .79 10,.48 ' 5,.76 3 .75  10,,.60 1 1, .19 6.,48 5,.09  8., 31 9., 11 5..60 4.,45  142. 3 119.1' 116.5 125.0  46.80 39.16 38.30 41.12  3.70  .567 .481 .434 .406  380 266 144 105  2. 79 2. 27 1. 75 1. 57  3.46 2.80 1.89 1.52  7 ..02 4,.07 1 .73 , 1 ., 12  7.,66 4.,68 2., 2.2 1 ,. 5 5  6..69 5. 53 .3. 33 2. 59  215.6 179.7 160.3 182.2  56.89 47.42 42.30 48.08  3.79  .613 .519 . .487 .446  527 425 201 140  3. 79 3. 34 2.60 2. 49  3.67 3.39 2.11 1.68  12,.95 9., 33 3.,59 2.,56  13., 1 2 10. 0 5 4 .29 3. 35  9.08 8. 19 4. 15 3. 13  DF-6-700-00 65 77 82  69.6 74.3 62.8 55.3  304.1  7.31 6.90  161.8 185.0 187.6 .179.0  DF-6-340-00 65 77 82  68.7 71.4 59.1 49.9  379.0  6.96 7.61  163.4 199. 3 218.7 196.8  Table  LIGHT SCAT. COEFF.  vise.  PULP TYPE  2  cm /g  CRYST. UNBONDED BONDED INDEX HANDSHEET HANDSHEET AREA  SPECIFIC ENERGY  R.B.A. X10  DF-6-150-00  7.64  65 77 82  539.0  6.44  BF-3/4-220-00 65 75 82  6.69  BF-5-205-00  6.46  65 75 82  erg/cm  357.5 323.7 268.1 235.6  66,.32 60..06 49..73  137,,2 214,,5 250. 0 359.,5  685.9 608.6  5.,02  573.1 463.6  83..33 73..94 69..63 56.,33  160.,8 243..4 293,.0. 374,,5  527.4 444.8 395.2 313.8  76..65 64.,64 57..42 45.,59  5..86  176. 6  414.1 337.0 323.8  50. 3  70.,11 57,.06 54,.82 42,,14  5.,10  .253,.6 266 .8 341,.8  66.9 67.0 66.8 48.5  185.,6 252,,3 257., 7 334.. 2  65.2 69.0 66.0 45. 7  823.1  67. 3 68.0 66.3 46.4  688.2  67.7  590.6  66.7 67.0  6.58  5  181.,5 215.,3 270. 9 303.,4  72.4 60. 3 52.6  BF-1/2-160-00 65 75 82  BF-6-180-00 65 75 82  70.4  (continued)  .  248.9  3..45  2  APPAR. DENSITY  TENSILE STRENGTH  STRETCH  , 3 g/cm  kg/cm  %  .668 .589 .542 .509  43,.71-  3..45  .876  2  625 514 304 220  3.99 4.28 3.72  1365 1246  4.24 4.32 4.32 4.61  3.29  MODULUS ELASTICITY X10  4  kg/cm  4 .07 3,.38 2,.50 '  2 .06  •'7<i.4 3  7 .12 • 6..41 3,.60  .792 . .657  1059 534  .774  4.66  .718 .613 .  1265 1095 833 390  .673  1061  .633  905 802  4.10 4.10 4.55  5,.45 . 4. .88  .547  352  3.89  785 630 575 243  4.26  .638 .598 .478  •  4.53 4.33 4.23  .  3.99 4.14 3.16  2  TENSILE RUPTURE ENERGY X10  4  kg-m/m  TENSILE ENERGY ABSOR. 3  , / kg-m/m  BREAKING LENGTH  2  km  .16 .10 14,.22 7., 76 5.. 17  .14,,02 13,.0 1 8 . ,01  36.,91. 33,.61  24.,14 23.,03 20. 49 ,74 1 3.  15,.58 15,.50  29,.74 16.,87  5,.92  9 .34 8 .72 5..97 4 .34  13.. 39 8 , . 13  6,.63 5 .98 4,.97 3,.28  3 7 , .05 31 , . 59 23., 59 12., 18  26,,07 24. 81 1 7 ..79 1.(1. 9 5  16,.34 15..48 1 1 ,. 59 . 6, .36  6..14  27. 93 23,, 54 23..72  23. 2 3 19 . 12 1 9 ; 82  .15. 75 14,,09 12,.66  2,.78  9.,60  9. 35  4..74 3,.98 3..93 2,.27  21 ,29 . 1.5.,72 15. 99 5.,42  18. 49 14. 38 14. 4 8  1.0..65 9. 61  5..85  5.,08  6,. 43 12.,30  103  TABLE 3 HANDSHEET TENSILE PROPERTY-DENSITY LINEAR RELATIONSHIPS FOR UNTREATED (00%) AND AMINE TREATED (82%) PULP TYPES  REGRESSION MECHANICAL PROPERTY  AMINE CONC.  PULP TYPE  R  Maximum Tensile Strength ikg/cm /  00  2  82  EQUATION  Y = a + bX n = 16 o r 20 a  b  CORREL. COEFF.  b S E  E  r  EL  - 751.4  2266.5  .956  53.7  DFL  -1208.4  2966.0  .963  64.7  DFM  -1055.6  2721.2  .969  67.6  DFH  -1190.5  2912.5  .922  105.2  BF  - 520.3  2214.3  .899  109.1  EL, DFL, DFM -1072.8 DFH  2738.8  .956  75.8  EL  - 373.2  1260.5  .987  18.0  DFL  - 399.8  1287.0  .980  23.5  DFM  - 504.3  1488.2  .989  21.9  DFH  - 527.9  1529.6  .928  53.2  BF  - 456.6  1457.4  .951  34.6  EL, DFL  - 401.8  1304.4  .985  21.4  ' DFM, DFH BF - 527.6  1548.4  .959  41.0  Pulp t y p e s ' a r e i d e n t i f i e d as wood s p e c i e s and Canadian standard f r e e n e s s l e v e l s (EL f o r e a s t e r n l a r c h , 170 ± 45 m l ; DFL, DFM, DFH f o r D o u g l a s - f i r , 615 ± 90 ml, 328 ± 43 ml o r 168 ± 62 ml and BF f o r balsam f i r , 190 ± 30 m l ) . A l l the c o r r e l a t i o n c o e f f i c i e n t s , r , a r e h i g h l y s i g n i f i c a n t a t 1% l e v e l except as noted w i t h "n.s." ( n o n - s i g n i f i c a n t a t 5% l e v e l ) .  104 Table 3 (continued)  REGRESSION MECHANICAL PROPERTY  AMINE CONC.  PULP TYPE  %  Stretch  00  %  82  Modulus of Elasticity  00  kg/cm^  a  Y = a + bX n = 16 or 20 ~ b  CORREL. COEFF. r  SE,.  3.644  2.122  .635  .198  DFL  -1.222  7.834  .873  .344  DFM  ' 3.266  1.424  .372n. s.  .345  DFH  1.867  3.618  .568  .450  BF  3.692  0.846  .218n. s.  .384  DFM, DFH  2:574  2.541  .490  .407  EL  .0.594  9.503  .948  .274  DEL  -2.822  11.188  .971  .251  DFM  -1.533  8.909  .974  .205  DFH  -0.935  8.500  .907  .340  BF  -0.352  7.544  .942  .197  EL  -34692.3  116179.0  .979  1860.9  DFL  -22967.7  102609.0  .959  2376.7  DFM  -20623.5  96799.9  .943  3325.1  DFH  -20881.2  96364.3  .908  3829.2  BF  -8665.3  95928.4  .902  4646.5  114927.0  .911  5177.3  EL  EL, DFL, DFM, -30623.5 DFH, BF 82  EQUATION  EL  -13360.0  68532.5  .967  1560.8  DFL  -12914.9  71892.1  .965  1755.0  105  Table 3 (continued)  REGRESSION  EQUATION  Y = a + bX n = 16 or 20  CORREL. COEFF. r  MECHANICAL PROPERTY  AMINE PULP CONC. TYPE %  Modulus of Elasticity  DFM  -16901.8  78453.6  .967  2046.1  DFH  -12525.6  68598.8  .921  2508.7  BF  -13577.2  75596.3  .973  1306.7  DFL, DFM, DFH  -12999.2  70629.1  .952  2161.3  EL  -285232.0  823332.0  .858  37973  DFL  -453428.0  987431.0  .952  24831  DFM  -324245.0  799050.0  ,945  26996  DFH  -443163.0  983319.0  .893  42727  BF  -172734.0  649247.0  .817  46404  EL, BF  -208051.0  703492.0  .841  41560  DFL, DFM, DFH  -421830.0  946086.0  .933  33134  EL  -251151.0  677128.0  .973  13811  DFL  -163808.0  444846.0  .967  10621  DFM  -212658.0  544477.0  .985  9368  DFH  -258983.0  638590.0  .920  23574  BF  -229834.0  592587.0  .966  11622  kg/cm^  Tensile Rupture Energy  00  kg-m/m^  82  a  b  SE  T  TABLE 4 EARLYWOOD TO LATEWOOD SPECIFIC GRAVITY (APPARENT DENSITY) AND TENSILE PROPERTY FOR DOUGLAS-FIR WOOD AND (PAPER)  PULP FREENESS LEVEL, ml C.s.f.  Wood, g r e e n  Paper,  AMINE CONCENT'N,  %  c  air-dry  +  SPECIFIC GRAVITY (DENSITY)  MAXIMUM TENSILE STRENGTH  ULTIMATE STRAIN (STRETCH)  . RATIOS  MODULUS OF ELASTICITY  WORK MAX. (TENSILE RUPTURE ENERGY)  0.39  0.29  0.75  0.33  0.20  615 - 90  00  1.21  2.16  1.40  1.44  3.02  328 - 43  00  1.34  2.16  1.08  1.60  2.30  168 - 62  00  1.19  1.86  1.00  1.41  2.13  168 - 62  82  1.27  1.10  1.38  1.55  3.09  Data obtained from r e f e r e n c e (126). Average o f only 1/2 earlywood p o s i t i o n s ; as 4, 5 and 6 latewood p o s i t i o n s .  a l l o t h e r s a r e o f 1/2 and 3 earlywood as w e l l  107  TABLE 5 RESULTS OF t-TEST SHOWING THE EFFECT OF CELLULOSE DECRYSTALLIZATION TREATMENTS ON HANDSHEET TENSILE PROPERTIES AT COMPARABLE INTERFIBRE BONDING STATES (RELATIVE BONDED AREA) CALCULATED t-VALUE SHEET RELATIVE BONDED AREA  TENSILE STRENGTH  MODULUS OF ELASTICITY  TENSILE RUPTURE ENERGY  12.034  8.034  12.632  15.353  5.643  STRETCH  REPLICATION PULP TYPE DF - 5 - 705 65 vs. 77  2.390n. s.  DF - 5 - 106 77 vs. 82  1.170 n. s.  DF - 6 - 700 65 vs. 77  0.344 n. s.  12.590  11.084  5.907  DF - 6 - 340 65 vs. 82  0.776n. s,  30.267  12.673  21.198  7.556**  6.856  **  •kit  * 3.352  4.011  7.181  Pulp types are i d e n t i f i e d by wood species (DF f o r D o u g l a s - f i r ) , i n t r a incremental p o s i t i o n (5 or 6 ) , Canadian standard freeness (ml) and amine concentration (%). k  s i g n i f i c a n t at 1% l e v e l .  '<  s i g n i f i c a n t at 5% l e v e l . n•s• 'non-significant at 5% l e v e l .  Fig.  1.  Sulphate raw pulp y i e l d s , micro-kappa numbers and r e s i d u a l carbohydrate f o r e a t e r n l a r c h , D o u g l a s - f i r and balsam f i r r e l a t e d t o p o s i t i o n w i t h i n wood growth zone.  Yield Latewood  MicroKappa No.  Zones  Balsam F i r  •  Eastern Larch  •— Res. Carbohy. Douglas-Fir  20  40  60  INTRA-INCREMENTAL POSITION, %  80  100  109  F i g . 3.  D i f f r a c t i o n X-ray spectrum f o r d e c r y s t a l l i z e d D o u g l a s - f i r latewood p u l p f i b r e s , DF-5-106-77. 002  10  15  20 BRAGG ANGLE, 29°  .25  -30  Ill F i g . 4.  E f f e c t o f unbonded f i b r e d e n s i t y on l i g h t scattering coefficient. (Numbers b e s i d e ... the curves r e f e r to pulp i n t r a - i n c r e m e n t a l p o s i t i o n s and f r e e n e s s l e v e l s ) .  8  tvi  O  ~°  ^  *• 1/2-380  £-7  X  C\l  E o  < 6  to  < oa H Z LU O  u_ LU UJ  3- 210 4 - 170^, 5- 106 3- 6 8 0  •a c a  o  cr. ai < X  4- 285 6- 340-^ 5- 3 7 0  O  A  tr  LI 3  c o < _i o r> O  8 «-3-2l5  6-700-^ 4-700 °  1/2-182  <1 -7  x o a: <  5-705 2  4- 2 0 5 6-124 5- 145  UJ r-  to <  LU  01  0-2  0-3  UNBONDED  0-4 FIBRE  0-5  DENSITY,  0-6 g/cm3  J 0-7  112 F i g . 5.  L i g h t s c a t t e r i n g c o e f f i c i e n t s f o r unbonded 1 f i b r e s and s t a n d a r d pulp handsheets r e l a t e d to p o s i t i o n w i t h i n wood growth zone.  INTRA-INCREMENTAL POSITION, %  113 F i g . 6.  L i g h t s c a t t e r i n g c o e f f i c i e n t s of unbonded f i b r e s r e l a t e d to wood s p e c i f i c g r a v i t y .  Fig. 7.  E f f e c t s of s p e c i e s , p u l p machining and f i b r e d e c r y s t a l l i z a t i o n t r i b u t i o n o f pulp handsheet apparent d e n s i t i e s . (Numbers 1/2, r e f e r to p o s i t i o n s w i t h i n wood growth zones.)  treatments on d i s 3, 3/4, 4, 5 and b  0-9  ro  Eastern Larch  E o  Douglas Fir  Balsam Fir  0-8  jV)  Z 0-7  z  0-6  UJ  a: < OL a. <  0-5  rUJ UJ  V)  o  6*4  z < X 70 ±45  615190  328±43 STANDARD i i  CANADIAN J  00  65  75  82  00  1  65  L_  77  82  00  MONOETHYLAMINE  65  77  158+62 FREENESS,  90+ 30  ml  i 82  00  CONCENTRATION,  65  77 %  82  00  75  82  115 Fig.  8A.  Handsheet apparent d e n s i t i e s f o r u n t r e a t e d (00%) andamine t r e a t e d (82%) pulp types r e l a t e d to p o s i t i o n w i t h i n wood growth zone.  0.9 00% 82%  Csf  A  A EL (170 ± 45 ml)  °l  • i  DF (615 ± 90 ml)  . »2  DF (328 ± 43 ml)  0.8 °3  •  o DF 3  (168 ± 62 ml)  B BF (190 ± 30 ml)  B o 60  0.7  CO  W  p H  a  0.6  5! H W W «  CO  p  0.5  0.4 "  0.3 -  0  20  40  60  INTRA-INCREMENTAL POSITION, %  80  100  116 Fig.  8B. & 8C.  Handsheet maximum t e n s i l e s t r e n g t h and s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) D o u g l a s - f i r p u l p s r e l a t e d to p o s i t i o n w i t h i n wood growth zone.  INTRA-INCREMENTAL POSITION, %  Fig.  8D. & 8E.  Handsheet modulus of e l a s t i c i t y and t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) D o u g l a s - f i r p u l p s r e l a t e d to p o s i t i o n w i t h i n wood growth zone.  INTRA-INCREMENTAL POSITION, %  118 F i g . 9A. & 9B.  Handsheet bonded a r e a and r e l a t i v e bonded a r e a as determined by l i g h t s c a t t e r i n g coe f f i c i e n t s f o r v a r i o u s p u l p types and r e l a t e d t o p o s i t i o n w i t h i n wood growth zone.  INTRA-INCREMENTAL POSITION, %  119 10.  Scanning e l e c t r o n photomicrographs of D o u g l a s - f i r s u l p h a t e handsheets showing: ( a . & b.) DF-1/2-525-00 c o l l a p s e d earlywood f i b r e s , and i n t r a f i b r e f a i l u r e s due to t e n s i l e s t r e s s i n g , and ( c . & d.) DF-5-106-00 u n c o l l a p s e d latewood f i b r e s , and i n t e r f i b r e f a i l u r e s .  120 F i g . 11A. & 11B.  L i g h t s c a t t e r i n g c o e f f i c i e n t s o f unbonded f i b r e s (read a t 0.4 g/crn^) and s t a n d a r d p u l p handsheets r e l a t e d t o handsheet apparent d e n s i t y f o r v a r i o u s pulp types.  Csf  10  a-  pq  A  EL (170 ± 45 ml)  o,  DF (615 ± 90 ml)  cu  DF (328 + 43 ml)  O3  DF (168 ± 62 ml)  D  BF (190 ± 30 ml)  P  w 60  p 55 O  w  H 55 W  M CJ>  l-l Pn Pn W  o u o  53  M  Pi W H H  < to H W to H W W PC to P  0.3  0.4  0.5  0.6  0.7  0.8  HANDSHEET APPARENT DENSITY, g/cm"  0.9  121 F i g . " 11C. & 11D.  c  10  CM O  X CN  Handsheet bonded a r e a and r e l a t i v e bonded ' a r e a as determined by l i g h t s c a t t e r i n g c o e f f i c i e n t s f o r v a r i o u s pulp types and r e l a t e d to-handsheet apparent d e n s i t y . .  Csf A  EL  (170 ± 45 ml)  °.  DF  (615 ±.90 ml)  °2  DF  (328 ± 43 ml):  °3  DF (168 .±.62 ml)  •  BF (190 ± 30 ml)  6 a  <  < Q  W  /  14  -  Q  O  °2 Pi  " i 0  . i  i  2  1  1  1 .. .  < a w P> 53 o  w >  M  0.4  0.5  0.6  HANDSHEET APPARENT DENSITY, g/cm"  •  Fig.  00%  12A.  Handsheet maximum t e n s i l e s t r e n g t h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types r e l a t e d t o handsheet bonded a r e a as determined by l i g h t s c a t t e r i n g coefficient. .  82%  Csf  A  A  EL (170 ± 45 ml)  o,  o,  DF. (615 ± 90 ml)  0  2  ©  2  DF (328 ± 43 ml)  0  3  «  3  DF (168 ± 62 ml)  •  B  BF (190 ± 30 ml)  BONDED AREA, cm /g X 10  123 Fig.  x  rl-i  12B.  Handsheet s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet bonded a r e a as determined by l i g h t s c a t t e r i n g coefficient.  4  o  tr t-  00%  -82%  Csf  A  EL (170 ± 45 ml)  f,  DF  (615 ± 90 ml)  °2  »2  DF  (328 ± 43 ml)  °3  •s'  DF  (168 ± 62 ml)  A °l  D:  J  I  BF (190 ± 30 ml)  I  I  I  I  2  3  4  5  BONDED  AREA,  cm /g 2  L  6 X IO  2  12C.  00%  Handsheet modulus o f e l a s t i c i t y f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d t o handsheet bonded a r e a as determined by l i g h t s c a t t e r i n g coefficient.  82%  Csf  A  A  EL  (170 ± 45 ml)  o.  9.  DF  (615 ± 90 ml)  DF  (328 ± 43 ml)  DF  (168 ± 62 ml)  BF (190 ± 30 ml)  BONDED AREA, cm /g X 10  125 F i g . 12D.  00%  Handsheet t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet bonded area as determined by l i g h t s c a t t e r i n g coefficient.  Csf  82%  A  A  EL  (170  + 45 ml)  °l  •i  DF  (615  + 90 ml)  DF  (328 + 43 ml)  DF  (168 + 62 ml)  6  2  ?  °3  e  •  B  BF (190  + 30 ml)  2 2 BONDED AREA, cm /g X 10  -D  F i g . 13A.  00%  Handsheet maximum t e n s i l e s t r e n g t h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types r e l a t e d to handsheet apparent d e n s i t y .  82%  Csf  A  A  EL  (170 + 45 ml)  O,  •i  DF  (615  °2  °  DF  (328 + 43 ml)  DF  (168 + 62 ml)  m  BF  (190 + 30 ml)  2  °3  •  + 90 ml)  EL, D F j ,  A  DF , 2  DF  3  EL, DF DF , 2  0.3  0.4  0.5  0.6  0.7  HANDSHEET APPARENT DENSITY, g/cm"  D F , BF 3  0.8  0.9  13B.  Handsheet s t r e t c h f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent d e n s i t y .  82%  00% A  EL  (170 ± 45 ml)  DF  (615 ± 90 ml)  •2  DF  (328 ± 43 ml)  •3  DF  (168 ± 62 ml)  •  BF  (190 ± 3 0 ml)  •  °l  °  2  •  0.3  0.4  0.5  Csf  0.6  '  0.7  HANDSHEET APPARENT DENSITY, g / c m  3  0.8  0.9  128 F i g . 13C.  00%  Handsheet modulus of e l a s t i c i t y f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) pulp types r e l a t e d to handsheet apparent d e n s i t y .  82%  Csf  A  A  EL (170 ± 45 ml)  O,  9,  DF (615 ± 90 ml)  o  2  DF (328 ± 43 ml)  ©  3  DF (168 ± 62 ml)  D  BF (190 ± 30 ml)  B o  >> H  £l—  t-H U M H co  E L  '  DF , 2  D  F  r  DF , 3  <  W  o CO  W  v  0.3  0.4  0.5  0.6  HANDSHEET APPARENT DENSITY,  0.7 g/cm'  DF , DF 2  0.8  3  0.9  129  F i g . 13D.  Handsheet t e n s i l e r u p t u r e energy f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types r e l a t e d to handsheet apparent d e n s i t y .  00%  82%  EL  (170  '•, DF  (615  «, DF  (328  A  o a  3  n  o  Csf  DF  (168  BF  (190  X B I  oo  o w w g  !=> H  § M CO S3  W H  0.3  0.8  0.4  HANDSHEET APPARENT DENSITY,  g/cm"  0.9  F i g . 14.  00%  0.9  CO  e o  Handsheet apparent d e n s i t y o b t a i n e d a t v a r i o u s p u l p f r e e n e s s l e v e l s f o r u n t r e a t e d (00%) and amine t r e a t e d (82%) p u l p types as r e l a t e d to i n i t i a l wood s p e c i f i c g r a v i t y .  0.8  230 C \ 182^380  60 co 53 W O  §!  A  A  EL  o  ©  DF  •  B  BF  0.7  H 53  P-l  82%  • 160  HS0  180 ml C s f 00-PULP  0.6  300 ml C s f 00-PULP  H W W W CO  500 ml C s f 00-PULP 700 ml C s f 00-PULP  0.5  A205  O|70  HI80  0.4  t  180 ml C s f 82-PULP  124 A  A145  1066  • Latewoods (3 s p e c i e s )  Earlywoods —>j (3 s p e c i e s ) '  0.2  0.3  0.4  0.5  0.6  WOOD SPECIFIC GRAVITY,  0.7 g/cm  3  0.8  0.9  1.0 f— 1  o  F i g . 15.  Homogeneity of handsheet t e n s i l e property-density l i n e a r r e l a t i o n s h i p s as shown by covariance analyses f o r pulp types of the study.  Amine Cone.  Wood Species Canadian Standard Freeness,  %  ml.  EL  DF  BF  615 - 90  328 - 43  168 - 62  190 - 30  X  X  0  00  X  X  82  X  X  Stretch  00  0  82  X  0  00  X  X  82  0  00 82  Tensile Rupture Energy  DF  170 - 45  Maximum Tensile Strength  Modulus of Elasticity  DF  0  X  X @  c  X  X  X  X  X  X  0  X  X  X  0  X  0  @  c  Homogeneous e f f e c t s (5% l e v e l of p r o b a b i l i t y ) f o r p r o p e r t i e s are shown as the same mark w i t h i n row. S i m i l a r marks w i t h i n column have no meaning.  F i g . 16.  Handsheet maximum t e n s i l e s t r e n g t h f o r amine t r e a t e d p u l p types as r e l a t e d to handsheet l i g h t s c a t t e r i n g c o e f f i c i e n t . ( L i n e s connect 00% ( h i g h t e n s i l e s t r e n g t h ) , 65%, 75 or 77%, and 82% (low t e n s i l e s t r e n g t h ) f o r p o s i t i o n w i t h i n growth zone.)  F i g . 17.  Handsheet maximum t e n s i l e s t r e n g t h r e l a t e d to c e l l u l o s e c r y s t a l l i n i t y index f o r D o u g l a s - f i r i n t r a - i n c r e m e n t a l p u l p s a t v a r i o u s f r e e n e s s levels. (Numbers .beside curves r e f e r t o p u l p Canadian s t a n d a r d f r e e ness (ml).)  DF-5  DF-4  DF-3  DF-1/2  DF-6  O230 380  210  525  680  50  60  70  50  60  70  50  60  70  CELLULOSE CRYSTALLINITY INDEX  50  60  70  50  60  70  Fig. 18.  Handsheet specific energy of "bond failure" for various pulp types as related to position within growth zone.  DF (168 ± 62 ml) n BF (190 ± 30 ml)  t 20  40  60  INTRA-INCREMENTAL POSITION, %  80  100  

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