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Some gluing characteristics of ocotea usambarensis (engl.) Mungúre, Waweru 1988

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SOME GLUING CHARACTERISTICS OF OCOTEA USAMBARENSIS (ENGL.)  by WAWERU MUNG'URE B.Sc. For., University of Nairobi, Kenya,  1984  A THESIS S U B M I T T E D IN P A R T I A L F U L F I L L M E N T OF THE REQUIREMENTSFOR THE DEGREE OF MASTER OF SCIENCE  in T H E F A C U L T Y OF G R A D U A T E STUDIES DEPARTMENT  OF  FORESTRY  W e accept this thesis as c o n f o r m i n g to the r e q u i r e d standard  THE UNIVERSITY OF BRITISH C O L U M B I A October  1988  © W a w e r u M u n g ' u r e , 1988  In  presenting this  degree at the  thesis  in  University of  partial  fulfilment  of  of  department  this or  thesis for by  his  or  requirements  British Columbia, I agree that the  freely available for reference and study. 1 further copying  the  representatives.  an advanced  Library shall make  it  agree that permission for extensive  scholarly purposes may be her  for  It  is  granted  by the  understood  that  head of copying  my or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of  t-p ±£c,  7 ft.V  The University of British Columbia Vancouver, Canada  Date  DE-6 (2788)  ? / //  ABSTRACT  The wood  gluability  (Ocotea  o f a Kenyan t r o p i c a l  usambarensis)  temperature  curing resin  formaldehyde  (PRF),  Machine-planed water,  Using ft )  adhesives, p h e n o l - r e s o r c i n o l (UF),  polyvinyl-acetate  o f sodium h y d r o x i d e ,  3% n i t r i c  acid,  either  alcohol-benzene,  or l e f t  untreated  gluing.  a double  glue  spread  and t h e m a n u f a c t u r e r s  2  room-  used.  10% s o l u t i o n  before  Four  camphor  wood s a m p l e s were e x t r a c t e d w i t h  surface t r e a t e d with (control)  investigated.  urea-formaldehyde  (PVA) a n d c a s e i n were  hot  was  hardwood,  o f 410.6 g/m  recommended  2  (85 l b p e r 1000  assembly times  of each  o f t h e 4 g l u e s , wood b l o c k s a p p r o x i m a t e l y  25.4 x 101.6 x 304  mm  G l u i n g and p r e s s i n g  (1 x 4 x 12 i n ) were b o n d e d t o g e t h e r .  were c a r r i e d pressure  o u t a t room t e m p e r a t u r e  o f 1,379  kPa  (200 p s i ) was  (21-24°C) .  A pressing  a p p l i e d over  a period of  24 h . After of both  conditioning, the joint  failure  t h e u n t r e a t e d a n d t r e a t e d b l o c k s were d e t e r m i n e d  t h e ASTM s t a n d a r d g l u e b l o c k s h e a r w i t h PVA  s t r e n g t h a n d wood  test.  a n d c a s e i n were t e s t e d d r y .  f o r PRF were t e s t e d d r y , a f t e r  cold  The b l o c k s b o n d e d  Block  soaking,  shear  specimens  and b o i l i n g i n  water.  B l o c k s b o n d e d w i t h UF were t e s t e d d r y a n d a f t e r  soaking  i n water.  Statistical  analysis  j o i n t s b o n d e d w i t h PVA  showed t h a t s t r e n g t h o f  adhesive  was  by  significantly  cold  adhesion i m p r o v e d by  iii s u r f a c e t r e a t i n g w i t h weak n i t r i c  acid,  prior  However, none o f t h e f o u r wood p r e - t r e a t m e n t s improved g l u a b i l i t y failure  i s concerned.  solution,  o f camphor wood w i t h s o d i u m  hydroxide  and e x t r a c t i o n w i t h a l c o h o l - b e n z e n e , p r i o r t o  enhanced  Removal  i t s gluability  with casein  adhesive.  o f t h e a l c o h o l - b e n z e n e - s o l u b l e and s o d i u m  hydroxide-soluble extractives bond  significantly  o f camphor wood w i t h PVA as f a r as wood  Surface treatment  gluing,  to gluing.  significantly  increased dry  s t r e n g t h o f t h e b l o c k s b o n d e d w i t h PRF a d h e s i v e .  However, o n l y t h e a l c o h o l - b e n z e n e  extraction  i n c r e a s e d wood  failure. The  cold  soak t r e a t m e n t  s t r e n g t h o f b l o c k s bonded percentage  generally  reduced t h e bond  w i t h PRF a d h e s i v e .  was i n c r e a s e d b y t h e c o l d  Wood  failure  soak t r e a t m e n t  except i n  b l o c k s made w i t h s o d i u m h y d r o x i d e - t r e a t e d wood. The b o i l in  treatment  a l lthe treatments  was o b s e r v e d t o r e d u c e b o n d s t r e n g t h  except  i n the control.  t h e sodium h y d r o x i d e t r e a t m e n t , t h e increased  as a r e s u l t  of the b o i l  U n t r e a t e d camphor wood b o n d e d Bond  s t r e n g t h was s i g n i f i c a n t l y  treatment.  Other  amount o f wood  than i n  failure  treatment. w e l l w i t h UF a d h e s i v e .  r e d u c e d by c o l d  soak  iv  TABLE  OF  CONTENTS  ABSTRACT TABLE OF  i i CONTENTS  L I S T OF  TABLES  L I S T OF  FIGURES  iv v i i ix X  L I S T OF APPENDICES ACKNOWLEDGEMENT 1.0  2.0  3.0  xi  INTRODUCTION  1  1.1  Wood P r o d u c t s  1.2  Scope and  I n d u s t r y i n Kenya  1  O b j e c t i v e o f Study  3  LITERATURE REVIEW  6  2.1  Effect  of Extractives  2.2  E f f e c t s of Chemical Prior to Gluing  MATERIALS AND  on G l u i n g  Treatment  6  o f Wood S u r f a c e s 14  METHODS  21  3.1  Wood Samples  21  3.2  Wood A d h e s i v e s  21  3.2.1  Casein  21  3.2.2  P h e n o l - r e s o r c i n o l - f ormaldehyde  22  3.2.3  Urea-formaldehyde  22  3.2.4  Polyvinyl-acetate  22  3.3  Experimental Design  23  3.4  Experimental Procedure  24  3.5  3.4.1  Specific  3.4.2  Wood pH  3.4.3  Total  gravity  determination  determination  extractives  P r e l i m i n a r y Experiments  content  24 25  determination..25 25  V  3.6  3.7  T r e a t i n g o f Wood Samples P r i o r 3.6.1  Extraction  3.6.2  E x t r a c t i o n w i t h h o t water  3.6.3  Surface treatment  with n i t r i c  acid  3.6.4  Surface treatment solution  with  hydroxide  4.0  alcohol-benzene  26 26 27  sodium  28 29  Main Experiment 3.7.1  3.8  with  t o Gluing  29  Adhesive a p p l i c a t i o n , p r e s s i n g and conditioning of test joints  30  3.7.2  P r e p a r a t i o n o f b l o c k shear  31  3.7.3  T e s t i n g procedure  32  3.7.3.1  Dry t e s t  32  3.7.3.2  C o l d soak t e s t  32  3.7.3.3  Boil test  33  specimens  S t a t i s t i c a l Analysis  33  RESULTS AND DISCUSSION  34  4.1  Wood C h a r a c t e r i z a t i o n  34  4.2  G l u i n g w i t h P o l y v i n y l - a c e t a t e (PVA) A d h e s i v e . . . . 35 4.2.1  Dry t e s t :  Bond s h e a r  s t r e n g t h a n d wood  f a i l u r e percent 4.3  35  Gluing with Casein Adhesive  38  4.3.1  4.4  Dry t e s t : Bond s h e a r s t r e n g t h a n d wood f a i l u r e percent G l u i n g w i t h P h e n o l - R e s o r c i n o l Formaldehyde Adhesive 4.4.1 4.4.2 4.4.3  Dry t e s t : Bond s h e a r f a i l u r e percent  42  s t r e n g t h a n d wood 42  C o l d soak t e s t : Bond s h e a r wood f a i l u r e p e r c e n t Boil test: Bond s h e a r f a i l u r e percent  38  s t r e n g t h and 44  s t r e n g t h a n d wood 45  vi  4.6  C o m p a r i s o n o f Bond S t r e n g t h T e s t s f o r Wood B l o c k s Bonded w i t h P h e n o l - r e s o r c i n o l Formaldehyde Adhesive 4.6.1  4.7  G e n e r a l d i s c u s s i o n on g l u i n g camphor wood w i t h p h e n o l - r e s o r c i n o l formaldehyde adhesive  G l u i n g w i t h Urea Formaldehyde 4.7.1 4.7.2  Dry t e s t : S h e a r s t r e n g t h and wood f a i l u r e percent C o l d soak t e s t : wood f a i l u r e  5.0  SUMMARY AND  REFERENCES  CONCLUSION  47.  49 51 52  Shear s t r e n g t h and  percent  52 54 57  vii  LIST  OF TABLES  Table  Page  1  Type o f t e s t s  2  Formulation  3  T o t a l e x t r a c t i v e s content  4a  Average bond s t r e n g t h o f b l o c k s bonded PVA ( d r y t e s t )  4b  5a 5b 6  7a 7b 8a 8b 9  10a 10b 11a lib  of glues  A v e r a g e wood f a i l u r e PVA ( d r y t e s t )  61 and g l u i n g c o n d i t i o n s i n camphor  wood  o f b l o c k s bonded  62 63  with 64 with 65  A n a l y s i s o f v a r i a n c e f o r bond s t r e n g t h o f b l o c k s b o n d e d w i t h PVA ( d r y t e s t )  66  A n a l y s i s o f v a r i a n c e f o r wood f a i l u r e o f b l o c k s b o n d e d w i t h PVA ( d r y t e s t )  66  S t a t i s t i c a l r a n k i n g by Duncan's m u l t i p l e r a n g e t e s t f o r b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s b o n d e d w i t h PVA  67  Average bond s t r e n g t h o f b l o c k s bonded c a s e i n (dry t e s t )  with 68  Average bond s t r e n g t h o f b l o c k s bonded c a s e i n (dry t e s t )  with 69  A n a l y s i s o f v a r i a n c e f o r bond s t r e n g t h o f b l o c k s bonded w i t h c a s e i n (dry t e s t )  70  A n a l y s i s o f v a r i a n c e f o r wood f a i l u r e o f b l o c k s bonded w i t h c a s e i n (dry t e s t )  70  S t a t i s t i c a l r a n k i n g by Duncan's M u l t i p l e Range t e s t f o r b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s bonded w i t h c a s e i n  71  Average bond s t r e n g t h o f b l o c k s bonded PRF ( d r y t e s t )  72  A v e r a g e wood f a i l u r e PRF ( d r y t e s t )  o f b l o c k s bonded  with with 73  /Analysis o f v a r i a n c e f o r bond s t r e n g t h o f b l o c k s b o n d e d w i t h PRF ( d r y t e s t )  74  A n a l y s i s o f v a r i a n c e f o r wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( d r y t e s t )  74  viii  12a 12b 13a 13b  14a 14b 15a  15b 16  17 18a 18b 19a 19b 20  Average bond s t r e n g t h o f b l o c k s bonded PRF ( c o l d soak t e s t ) A v e r a g e wood f a i l u r e o f b l o c k s PRF ( c o l d soak t e s t )  bonded  with 75 with 76  A n a l y s i s o f v a r i a n c e f o r bond s t r e n g t h o f b l o c k s b o n d e d w i t h PRF ( c o l d soak t e s t )  77  / A n a l y s i s o f v a r i a n c e f o r wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( c o l d soak t e s t )  77  Average bond s t r e n g t h o f b l o c k s bonded PRF ( b o i l t e s t )  78  A v e r a g e wood f a i l u r e PRF ( b o i l t e s t )  of blocks  bonded  with with 79  A n a l y s i s o f v a r i a n c e f o r bond s t r e n g t h o f b l o c k s b o n d e d w i t h PRF ( b o i l t e s t )  80  A n a l y s i s o f v a r i a n c e f o r wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( b o i l t e s t )  80  S t a t i s t i c a l r a n k i n g b y Duncan's M u l t i p l e Range t e s t f o r b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF  81  Comparison o f bond s t r e n g t h t e s t b l o c k s b o n d e d w i t h PRF  82  results of  Average bond s t r e n g t h o f b l o c k s bonded UF ( d r y t e s t ) A v e r a g e wood f a i l u r e UF ( d r y t e s t )  o f b l o c k s bonded  with 83 with 83  Average bond s t r e n g t h o f b l o c k s bonded w i t h ( c o l d soak t e s t ) A v e r a g e wood f a i l u r e ( c o l d soak t e s t ) Summary results  o f b l o c k s bonded w i t h  o f b o n d s t r e n g t h a n d wood  UF 84 UF 84  failure 85  ix  LIST  OF FIGURES  Figure 1  2 3  4  5 6  7  8  9  10  11 12  Page A v e r a g e b o n d s t r e n g t h a n d wood f a i l u r e o f wood f a i l u r e o f b l o c k s b o n d e d w i t h PVA (dry t e s t )  86  A v e r a g e b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s bonded w i t h c a s e i n (dry t e s t )  87  A v e r a g e b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( d r y t e s t )  88  A v e r a g e b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( c o l d soak t e s t )  89  A v e r a g e b o n d s t r e n g t h a n d wood f a i l u r e o f b l o c k s b o n d e d w i t h PRF ( b o i l t e s t )  90  Bond s t r e n g t h a n d wood f a i l u r e o f u n e x t r a c t e d b l o c k s b o n d e d w i t h PVA/ c a s e i n , PRF a n d UF adhesives (dry t e s t )  91  Bond s t r e n g t h a n d wood f a i l u r e o f h o t w a t e r e x t r a c t e d b l o c k s b o n d e d w i t h PVA, c a s e i n , and PRF a d h e s i v e s ( d r y t e s t )  92  Bond s t r e n g t h a n d wood f a i l u r e o f n i t r i c a c i d t r e a t e d b l o c k s b o n d e d w i t h PVA, c a s e i n and PRF a d h e s i v e s ( d r y t e s t )  93  Bond s t r e n g t h a n d wood f a i l u r e o f NaOH t r e a t e d b l o c k s b o n d e d w i t h PVA, c a s e i n a n d PRF a d h e s i v e s ( d r y t e s t )  94  Bond s t r e n g t h a n d wood f a i l u r e o f a l c o h o l b e n z e n e e x t r a c t e d b l o c k s b o n d e d w i t h PVA, c a s e i n a n d PRF a d h e s i v e s ( d r y t e s t )  95  Form a n d d i m e n s i o n s o f b l o c k specimen  96  Shearing  tool  shear  test 97  X  LIST  OF A P P E N D I C E S  APPENDIX I .  Species d e s c r i p t i o n  98  APPENDIX I I .  ASTM standard, D 905-81  99  APPENDIX I I I .  ASTM standard,  104  xi ACKNOWLEDGEMENTS  I wish to who  was  my  e x p r e s s my  thesis  supervisor.  standing guidance during preparation  out  the  the  thanks are  assistance  valuable  preparation  the  this  L.  and  g r a d u a t e t r a i n i n g and  due  t o Dr.  Paszner  under-  thesis  Barrett  for  his  suggestions  through-  study.  the are  Dr.  also  discussions  due  we  S.  Avramidis  i s thankfully A.  Dr.  P.  Marshall  analysis.  t o my  fellow  students  Dawson-Andoh and had  during  noted.  Kozak and  statistical  A g u s t o Q u i d e , Ben  lively  J.D.  numerous h e l p f u l  e x p r e s s e d t o Dr.  Appreciations  for  t o Dr.  professional  a d v i c e o f f e r e d by  t h e i r a d v i c e on  especially,  His  of t h i s t h e s i s  Thanks a r e for  and  c o u r s e o f my  The  my  gratitude  i s g r a t e f u l l y acknowledged.  Special constant  sincere  i n the  Simon  course of  Ellis  preparing  thesis. The  f i n a n c i a l backing of Canadian  D e v e l o p m e n t A g e n c y and  International  Kenyan Government, a l s o made t h e  study  possible. Special patiently  e n d u r e d my  Finally, wise,  thanks are  to  t o my  wife,  S e r a h Wangui, who  a b s e n c e f r o m K e n y a f o r two  t h o s e who  d e s e r v e t o be  gratitude.  due  I d i d not  remembered,  mention but  I also  s e n d my  has  years. who, sincere  other-  1  1.0  1.1  Wood P r o d u c t s The  rapidly t o FAO  and w i l l  i n Kenya,  million  o f wood The  i n the future.  rising  According  o f t h e consumption o f i n d u s t r i a l i s expected  m^ by t h e y e a r  rapid  i n Kenya h a s b e e n  continue to r i s e  (10) estimates  continuing tion  I n d u s t r y i n Kenya  demand f o r wood p r o d u c t s  roundwood, 1.067  INTRODUCTION  to rise  2,000.  from  7 4 0 , 0 0 0 m^ t o  These f i g u r e s  indicate a  i n c r e a s e i n t h e volume o f d o m e s t i c  consump-  products.  g r o w t h o f wood p r o d u c t s  consumption  i n Kenya i s  a t t r i b u t a b l e t o a r a p i d p o p u l a t i o n growth, e s t i m a t e d annual  r a t e o f 4%, and t h e i n c r e a s i n g p e r c a p i t a  o f wood and wood p r o d u c t s , ment i n t h e s t a n d a r d f o r wood p r o d u c t s ,  as a r e s u l t  of l i v i n g .  consumption  of a general  To meet t h i s  within the constraint  a t an  improve-  rising  of a fixed  demand forest  l a n d b a s e , two o p t i o n s open t o t h e Kenyan government more i n t e n s i v e available  forest  utilization decades,  forest  management t o m a x i m i z e y i e l d  l a n d and more r a t i o n a l  of the available  wood.  timber  i n Kenya i s b e i n g  i n the  o f wood p r o c e s s i n g  addressed.  Due t o t h e h i g h demand f o r wood p r o d u c t s , growth f o r e s t  manipulations  of the e f f i c i e n c y of  c o n v e r s i o n and t h e u t i l i z a t i o n  r e s i d u e s has n o t been a d e q u a t e l y  from t h e  O v e r t h e p a s t two  c o n s i d e r a b l e measures o f s i l v i c u l t u r a l  However, t h e improvement  a  and e f f i c i e n t  o f t h e growing t r e e s s t o c k has been implemented country.  are:  rapidly  the largeo l d -  depleted.  T h i s has  2 resulted  i n a decrease  structural  timber,  i n the a v a i l a b i l i t y  especially  f o r hardwoods.  o f t h e wood i n d u s t r y , i n Kenya, a l m o s t the  g r e a t e r u s e o f r e c o n s t i t u t e d wood As  of s o l i d Thus t h e f u t u r e  certainly  lies  with  products.  t h e i n d u s t r y s h i f t s more t o w a r d s r e c o n s t i t u t e d  products  there w i l l  adhesives  be an i n c r e a s i n g l y  to convert  g r e a t e r use o f  second-growth timber  into serviceable  products. Gluing industries  i s one means by w h i c h t h e w o o d - p r o d u c t s fill  t h e gap between m a r k e t needs and wood  I f t h e t r e e s a r e n o t l o n g enough, jointed  into  supply.  s h o r t e r p i e c e s a r e end-  l o n g e r p i e c e s ; i f t h e wood i s n o t wide enough,  n a r r o w p i e c e s a r e e d g e - g l u e d i n t o w i d e r m a t e r i a l ; i f t h e wood is cut  o f low q u a l i t y ,  out and t h e r e m a i n i n g The  timber, joints  quality  i n such  wood w i t h gluing  and o t h e r n a t u r a l d e f e c t s a r e  pieces are glued together (34).  o f wood p r o d u c t s  such  as p l y w o o d ,  laminated  and p a r t i c l e b o a r d , a n d t h e p e r f o r m a n c e o f g l u e d manufactured items  upon t h e s u c c e s s  The  the knots  glue  as wood f u r n i t u r e  o f g l u e bond f o r m a t i o n  i s a complex p r o c e s s ,  (15) .  depend  Bonding of  because the q u a l i t y  of a  o p e r a t i o n i s d e p e n d e n t on a l a r g e number o f f a c t o r s .  failure  to properly control  any one o f t h e s e  result  i n a d e f e c t i v e o r weakened g l u e  faulty  j o i n t s may be c a t e g o r i z e d as r e l a t e d t o :  (i)  joint.  f a c t o r s can  The c a u s e o f  t h e k i n d o f wood a n d i t s p r e p a r a t i o n p r i o r t o gluing;  (ii)  the type,  q u a n t i t y and q u a l i t y  of the adhesive;  3  (iii)  the compatibility  of the gluing process with the  wood a n d a d h e s i v e  used;  (iv)  joint  d e s i g n , assembly time  and c l a m p i n g  pressure;  and (v)  post-treatment finished  glue  A number o f t h e s e  or exposure  conditions of the  joint.  factors  are i n t e r r e l a t e d  such t h a t  change i n one may r e q u i r e a change i n a n o t h e r . these  factors  on a g l u e d j o i n t  varies  from  a  The e f f e c t o f  adhesive t o  adhesive (10). In b o n d i n g  wood w i t h a d h e s i v e s  wood i s n o t a u n i f o r m varies be  significantly  substance,  b u t a complex m a t e r i a l t h a t  i n many o f i t s p r o p e r t i e s a n d i t w o u l d  a mere c h a n c e i f t h e same b o n d i n g  w o u l d be s u i t a b l e factors  f o r the entire  extractives,  moisture  durable glue  joints.  role  o f wood s p e c i e s .  include;  to gluing  content,  f a c t o r s p l a y s an i m p o r t a n t  m a t e r i a l and p r o c e d u r e  range  r e l e v a n t t o good a d h e s i o n  surface texture, aging p r i o r  and  one must be aware t h a t  wettability,  and s p e c i e s  and p H ) .  Wood  (density,  Each o f these  i n the formation of strong  Usually, i t i s therefore, d i f f i c u l t  t o p i n p o i n t which p l a y s a g r e a t e r r o l e than t h e o t h e r . Furthermore,  some o f t h e s e  factors  are closely  r e l a t e d (41,  19)  1.2  Scope a n d O b j e c t i v e o f S t u d y Ocotea  abundant  usambarensis,  commonly known as camphor wood, i s  i n t h e montane r a i n  forests  of Tanzania  and K e n y a .  4 Camphor wood i s y e l l o w - b r o w n , and  darkening  has a medium t e x t u r e w i t h marked  on r a d i a l l y power  sawn f a c e s .  and h a n d t o o l s .  characteristic  The t i m b e r However,  on e x p o s u r e  stripe  or ribbon  works e a s i l y  wood were u s e d  f u r n i t u r e making.  difficulties  f o r composite  There  content  strong durable glue Adhesion,  both  gluability  have b e e n  products  observed  species,  dried  delamina-  lumber.  i s not the s o l e determining  Thus,  factor  and h e n c e s t r e n g t h o f t h e g l u e b o n d s , i s  o f wood t h e s u r f a c e c h a r a c t e r i s t i c s  bond f o r m a t i o n a r e q u i t e complex. appears  to affect  extraneous  adhesion  components  on  the  1  in  adhesion  of the f a c t o r s  glue  that  i n t h e wood  (15).  No  formal  i n Kenyan hardwoods  and  nature  their  adhesion.  The main o b j e c t i v e of the e x t r a c t i v e s  affect  out t o i n v e s t i g a t e t h e s p e c i f i c  of the e x t r a c t i v e s present effects  One  t h a t may  In the  i s t h e amount and t y p e o f  present  s t u d y has b e e n c a r r i e d  probable  of a  bond.  a f f e c t e d by t h e s u r f a c e p r o p e r t i e s o f t h e s u b s t r a t e . case  like  and i n  are reports of g l u e - j o i n t  e v e n f o r j o i n t s made u s i n g k i l n  wood m o i s t u r e  with  i t has a moderate  i n Kenya's wood i n d u s t r y when c e r t a i n hardwood  tions  figure  (6).  Over t h e y e a r s , g l u i n g  camphor  to a i r  of t h i s  study  i s t o determine  i f any  removed by v a r i o u s s o l v e n t s c o n t r i b u t e s t o  p r o b l e m s i n camphor  wood.^  The q u a l i t a t i v e a n a l y s i s o f t h e v a r i o u s e x t r a c t i v e s camphor wood i s b e y o n d t h e s c o p e o f t h i s s t u d y .  present  5 The  study proposes a hypothesis that  of  camphor wood s u r f a c e s  3%  nitric  acid,  or e x t r a c t i o n  water, p r i o r t o The  gluing,  following  (i)  the  with  shall  gluing  amount o f  water, in  (iii)  and  solution,  with alcohol-benzene,  be  samples u s i n g viz;  four  (PVA),  and  soda the  gluing characteristics;  the  e f f e c t of  e f f e c t of  surface  hot  (UF),  water,  cold  extractives  (oxidation)  acid solution,  on  of on  and  c o l d w a t e r soak and the  temperature  casein;  treatment  characteristics;  b e f o r e t e s t i n g , on bond.  room  e f f e c t of t h e i r removal  the  the  camphor wood  (NaOH) s o l u b l e  camphor wood w i t h weak n i t r i c  (iv)  hot  phenol-resorcinol  alcohol-benzene,  camphor wood and  gluing  solid  (PRF), u r e a - f o r m a l d e h y d e  caustic  the  and  investigated:  polyvinyl-acetate the  1 0 % sodium h y d r o x i d e  i m p r o v e s g l u e b o n d and d u r a b i l i t y .  adhesives,  formaldehyde  (ii)  treatment  c h a r a c t e r i s t i c s of  (unextracted) curing  chemical  strength  boil  of the  treatments, wood-glue  6  LITERATURE  2.0  This  section  literature  covers a selected  (i)  e f f e c t s of e x t r a c t i v e s  (ii)  e f f e c t s of  Woods o f  on  (24).  tropical  extractive  of  Extractive  (i)  the  al.  (25)  tree  cell  (13,  by  subdivided  39).  Many  high  acetone,  lignin  and  total  sometimes s m a l l  mineral  alcohols,  solvents  benzene,  c h l o r o f o r m or methylene  amounts  matter;  r e m o v a b l e by  o r more o f n e u t r a l  ether,  the  c o n s i s t i n g of c e l l u l o s e ,  s u b s t a n c e s and  a n d / o r one  extraneous  groups:  e x t r a c t i v e s which are  ether,  vary  substantially  i n t h e i r study of the  into four  walls,  of p e c t i c the  and  (39).  hemicelluloses,  (ii)  nature  quantities  characterized  components o f A m e r i c a n p u l p w o o d s , substance of the  surfaces  i n the  e x t r a c t i v e s t h a n sapwood  hardwoods a r e  et  and  o f wood  vary widely  H e a r t w o o d n o r m a l l y has  content  Isenberg  gluing,  Gluing  d i f f e r e n t species  higher quantities of the  existing  gluing.  amount o f t h e i r e x t r a c t i v e s . tree  on  chemical treatment  E f f e c t of E x t r a c t i v e s  within  review of  on:  p r i o r to  2.1  REVIEW  cold  water  such  as  petroleum  chloride;  7 (iii)  substances which though not but  are  not  (iv)  substances  t h e s i s , the  extraneous m a t e r i a l  products. that in  the  the  r o l e of  gluing  properties  types  of  increase results  could  be  (15,  refers  of the  living  tree.  i n wood i n d u s t r i e s  extractive  empirical  17,  (45)  studies  some t i m e s be  28,  content, wood  point  very  investigated  strength  important  the  gluing  Resorcinol  and  gravity.  obtained.  study.  addition  and  trend  decreasing  was  phenol-  These  satisfactory for  general  that  of  wood f a i l u r e  with  T h e s e s u g g e s t e d some  They p o s t u l a t e d  r e s u l t of d e f e c t i v e  with the that  such  surfacing  adhesive  in  interference o r due  to  two  gluing  However, some anomalous  o f wood c o n s t i t u e n t s  species. the  equally The  out  39).  d o m e s t i c w h i t e oak.  in specific were a l s o  or  to  used f o r r e c o n s t i t u t e d  e x t r a c t i v e s may  Burma t e a k .  joint  as  ( i v ) above, t h a t i s ,  a d h e s i v e s were e m p l o y e d i n t h e  interference certain  resins.  o f t w e n t y - n i n e t r o p i c a l A m e r i c a n woods i n  and  increasing  s u c h as  tree  have b e e n n o t i c e d  a d h e s i v e s were n o t  w h i t e oak  living  o f wood, w i t h h i g h  Wangaard  t o Burma t e a k and resorcinol  oxalate  from s e v e r a l  o f wood  T r o o p and  calcium  ( i i ) and  hardwoods, a r e  Results  wall,  such  c r y s t a l s of  secretions  difficulties  tropical  solvents,  term e x t r a c t i v e ( s )  under  or  when c e r t a i n s p e c i e s e.g.  of the  identified  Gluing  and  cell  and  secretions  In t h i s  of the  r e a d i l y r e m o v a b l e by  starch grains silica;  part  the  8 character and  of  chemical  components,  waxes w h i c h o c c u r  in varying  s u c h as  gums, r e s i n s ,  amounts as  oils,  extractives  in  many woods. Narayanamurti extractives tree.  He  varies  points  hygroscopicity,  that  swelling  o f wood i s o f  surface  extractives and  horizontally in affect  Their  occidentalis)  type phenolic  r e s i n adhesive,  e x t e n t by  amount o f  not  deposit  meet t h e  The  various (teak)  the  extractives on  g l u e and gated.  on  the  et  t h i s exudate.  industry  al.  exhibits,  and  from s p e c i e s  an  on  quality exterior  a markable  bonds  for exterior the  glue. to  on  glueline  amount o f  the  adhesives. catechu  t i m e and  surface  The and  rigidity  influence effect  Tectona  The  extractives  modulus o f  e f f e c t may  species.  The  a f f e c t the  vary  of  animal investiviscosity  from g l u e t o  e f f e c t s of teak  were more p r o n o u n c e d t h a n t h o s e o f t h e  of  grandis  u r e a - f o r m a l d e h y d e r e s i n , were  They c o n c l u d e d t h a t of  to  The  develop glue  as  report  f r o m Acacia  A e r o l i t e , an  rigidity  the  P l y w o o d p a n e l s made  standard  (36)  s e t t i n g of  gelation  and  high  (5).  Narayanamurti extractives  using  i s influenced  bond q u a l i t y i n c r e a s e d  decreased  at  e f f e c t on  usually  from v e n e e r s e x h i b i t i n g heavy d e p o s i t s  quality.  the  o f m a c h i n e d wood, a s u g a r y e x u d a t e .  the  a  importance.  o f g l u e bonds o b t a i n e d w i t h t h i s s p e c i e s ,  w h i c h do  d i s t r i b u t i o n of  s h r i n k a g e o f wood, and,  special  (Larix  the  and  have o t h e r e f f e c t s .  Western l a r c h the  concluded that  both v e r t i c a l l y  out  t e m p e r a t u r e s may gluing  (35)  Acacia  glue  extractives  species.  9 Hancock on  (21) s t u d i e d  the formation  veneers.  of glue  He n o t e d t h a t  f o r m i n g a weak g l u e  the influence  of native  bonds w i t h h e a t t r e a t e d heat  bond.  fatty  Douglas-fir  i n a c t i v a t e d t h e veneer,  He p o s t u l a t e d  that,  acids  thus  t h e removal o f  w a t e r f r o m wood, a n d t h e a p p l i c a t i o n o f h e a t , p e r m i t s t h e migration acids and  of fatty  acids  r e d u c e t h e w e t t a b i l i t y o f v e n e e r and a l s o  depth o f p e n e t r a t i o n Chugg and G r a y  wood, r e p o r t adhesives,  that  is  surface  extractives  Goto e t al.  joint  soluble  soluble  extract  glue  catalysed  Extractives  also  lower  bond. of t r o p i c a l  t h e r e l a t i o n s h i p between t h e g l u e  However, g l u e  i f the e f f e c t of s p e c i f i c  They a l s o n o t e d t h e v a l u e  joint  (30) r e p o r t s  (Dryobalonops  unsaturated polyester  gravity i s  o f pH and p e r c e n t a g e  e f f e c t s on t h e g l u e  t h a n w e t t a b i l i t y and s p e c i f i c  extractives  phenol-  with the decrease of percentage of ether  had l e s s important  k a p u r wood  elata  and p e r c e n t a g e o f e i t h e r c o l d o r h o t w a t e r -  extractives,  Kawamura  Afrormosia  (20) i n v e s t i g a t e d t h e g l u i n g  increased  excluded.  rate  t h e s e t t i n g o f most  e x t r a c t i v e s was n o t s i g n i f i c a n t .  strength  affect  o f t h e wood and r e d u c e w e t t a b i l i t y , w h i c h  They c o n c l u d e d t h a t strength  inhibit  animal glue,  e s s e n t i a l f o r a strong  woods.  using  and p o l y v i n y l a c e t a t e .  tension  The f a t t y  of glue.  (17) i n a s t u d y ,  particularly  formaldehyde, the  o n t o t h e wood s u r f a c e .  joint  strength  gravity.  on t h e i n f l u e n c e  lanceolata) resin varnish.  of extracts  from  i n the curing of Certain portions  were shown t o impede t h e p o l y m e r i z a t i o n  of the  of the  10 polyester of the  resin varnish.  On  the  other  k a p u r wood e x t r a c t i v e s had  Sakuno and species cantly  report  Goto that  (40)  in their  specific  glue  c o r r e l a t e d with percent  formaldehyde, T h e r e was  no  f o r woods o f significant  significance) percent  no  hand, o t h e r  portions  inhibitory effect.  study of t h i r t y joint  ether  specific  strength  extract, gravity  was  for  0.8  six  urea-  and  c o r r e l a t i o n (at 5 p e r c e n t  between g l u e  f o r wood s p e c i e s  joint  with  strength  specific  and  signifi-  less. level  ether  of  extracts  gravity higher  than  0.8. Imamura e t tives  on  spp.).  gluing  al.  (26)  and  coating  Further, polyester Kawamura  i n h i b i t e d the  the  extractives  the  certain portions Onishi  on  and  the  and  cold)  Goto and  ability  as  well.  As  ether-soluble  of p h e n o l i c  curing already  e f f e c t was  of  with the  extractives.  unsaturated  noted  For  by  only  (37)  i n v e s t i g a t e d the  alcohol-benzene  influence  The  amount o f h o t  the  water  compressive  g e l a t i o n time of  and  cold  ureaincreased  water-soluble  c o l d water e x t r a c t i v e s the  d e c r e a s e s w i t h d e c r e a s e i n pH.  of  s o l u b l e wood e x t r a c t i v e s  t o w h i c h wood e x t r a c t i v e s were added,  increased  resin.  extractives.  setting material.  formaldehyde,  of  shown by  g e l a t i o n t i m e o f u r e a - f o r m a l d e h y d e and  strength  extrac-  {Dryobalanops  n-hexane and  gluing  inhibiting  of the  e f f e c t o f wood  i n h i b i t e d the  resin varnish, (30),  the  o f k a p u r wood  They a l s o n o t e d t h a t ,  extractives  (hot  studied  gelation  Alcohol-benzene  time  soluble  11 extractives  also  formaldehyde,  affected the gelation  though t o a l e s s e r extent  W e l l o n s and Krahmer  time of ureathan water  extract.  (47) a n a l y z e d a random a s s o r t m e n t o f  d e l a m i n a t e d e x t e r i o r hardwood p l y w o o d s w i t h t h e a i m o f mining the causes f o r d e l a m i n a t i o n . are  several  the  adhesive  less  factors  that  failed  could  be l e a c h e d  Weak g l u e l i n e s wood s u r f a c e  there If  t o wet a n d p e n e t r a t e t h e wood, a weak a n d  d u r a b l e g l u e b o n d w o u l d be f o r m e d .  could  that  cause such d e l a m i n a t i o n .  may have b o n d e d t o a t h i n l a y e r  its  They s t a t e  deter-  also  dissolve  the adhesive  of extractives  from t h e g l u e l i n e ,  might  Also,  that  later  hence t h e d e l a m i n a t i o n .  occur i f the e x t r a c t i v e s  at the  i n t o t h e a d h e s i v e and e i t h e r  c u r e o r make i t t o o v i s c o u s  accelerate  t o p e n e t r a t e t h e wood  structure. Anaike  e t al.  k a p u r wood e x t r a c t s adhesives. the  (3) r e p o r t  on t h e g e l a t i o n  Water e x t r a c t s  gelation  on t h e i n h i b i t o r y e f f e c t o f  were more e f f i c i e n t  o f u r e a and urea-melamine r e s i n s  methanol e x t r a c t s .  They d e l a y e d t h e g e l a t i o n  r e s i n more e f f e c t i v e l y t h a n t h a t Ether  of the urea  a n d n-hexane e x t r a c t s  resin i n retarding  followed  of the urea  o f t h e urea-melamine  had l i t t l e  by  resin.  o r no i n h i b i t o r y  effect. Jain important  e t al. role  (28) o b s e r v e d t h a t  i n gluing  o f Shorea  extractives robusta  formaldehyde and p h e n o l - f o r m a l d e h y d e The  i n h i b i t o r y e f f e c t o f Taxus  extractives  on t h e c u r i n g  play  a very  (sal) with  urea-  resins. mairei  heartwood  of the unsaturated polyester  resin  12 has  been r e p o r t e d  itself  by L e e e t al.  and t h e e t h e r - s o l u b l e ,  water-insoluble  (27).  The m e t h a n o l  the water-soluble  fractions derived  polyester Lee  r e s i n s , b u t t h e n-hexane s o l u b l e e t al.  Diospyros  (33) s t u d i e d  inhibitory resins.  resin.  of unsaturated f r a c t i o n d i d not.  on t h e c u r i n g  The m e t h a n o l e x t r a c t  of unsaturated  was  polyester  fractionated into  a c i d and e t h e r - s o l u b l e  phenolic  ether-soluble  neutral,  gluability  (1) i n v e s t i g a t e d  o f k a p u r wood by s t u d y i n g  o f wood e x t r a c t i v e s  resin.  The s t r o n g  soluble  part  water-insoluble  the i n s u f f i c i e n t the e f f e c t of the curing  on t h e r e s o l t y p e  and t h e e t h e r - i n s o l u b l e showed s t r o n g  of the r e s o l r e s i n .  part  Kanazawa  phenolic  of the  curing  e t al.  ether  ethanol-  i n h i b i t o r y e f f e c t s on  However, t h e  ether-soluble  f r a c t i o n showed no o r l e s s e r e f f e c t .  temperature during  Raising the  tended t o reduce the i n h i b i t i o n .  (29) r e p o r t e d  on t h e p o o r g l u a b i l i t y o f  t e a k wood w i t h u r e a r e s i n a d h e s i v e s . effects  neutral,  a c i d and weak a c i d f r a c t i o n s o f t h e  benzene e x t r a c t i v e s  neutral  and  acid,  d i d not.  Abe a n d A k i m o t o  curing  water-soluble  several  fractions  showed an i n h i b i t o r y e f f e c t b u t n - h e x a n e - s o l u b l e  reaction  showed an  Among t h e s e f r a c t i o n s , n-hexane s o l u b l e  ether-soluble  fractions  of the  The m e t h a n o l e x t r a c t  e f f e c t on t h e c u r i n g  fractions.  extract  the i n h i b i t o r y e f f e c t of  sp h e a r t w o o d e x t r a c t i v e s  unsaturated polyester  and t h e  from t h e methanol  showed an i n h i b i t o r y e f f e c t on t h e c u r i n g  extract  of hot-water e x t r a c t i v e s  They i n v e s t i g a t e d t h e  on t h e c u r i n g  reaction of  13 the  adhesive.  The  insoluble part, resin  was  water e x t r a c t ,  found to  e s p e c i a l l y i t s methanol  r e t a r d the  g e l a t i o n of the  urea  adhesive. Chow and  failure  (16)  examined a d h e s i o n s t r e n g t h  Phenol-resorcinol  casein  joint  Chunsi  r e l a t i o n s h i p s i n wood-glue bonds o f  hardwoods. and  hot  shear strength  extractive  content  essentially Abe  the  and  of  (2)  no  that  reported  woods.  o f Goto et on  the  wood e x t r a c t i v e s on  f r o m k a p u r and  study.  r e s u l t s demonstrated that  extractives Yatagai extractives,  and  Takahashi  f r o m 70  extractives. varnish  The  Slay  et  extractives  al.  (20).  curing  of  the  wood s p e c i e s ,  of  the  resol resins. wood  c u r i n g time  E t h y l ether,  solvents  the  e f f e c t of on  of  resol.  acidity  rate of  c u r i n g time of the  of  n-hexane,  f o r removal of no  the  influence varnish  on  the the  was  n-hexane e x t r a c t i v e s . al.  (45)  i n v e s t i g a t e d the  from p r e s s u r e - r e f i n e d  w h i t e oak,  used i n the  finding is  a c e t o n e e x t r a c t i v e s had  urea-formaldehyde r e s i n . hickory,  This  examined the  resin varnish.  The  glue-  r e l a t i o n s h i p with  wood were u s e d i n  curing  m e t h a n o l were u s e d as  curing time.  p r o l o n g e d by  (48)  tropical  unsaturated polyester a c e t o n e and  apitong  i n t e r f e r e s with the  formaldehyde  e f f e c t of a c i d i t y  the  Extractives The  urea  They c o n c l u d e d t h a t  significant  substrate  same as  Ono  some t r o p i c a l  had  wood  s i x Burmeses  formaldehyde,  a d h e s i v e s were u s e d .  and  study.  red  Six oak,  Their  catalytic  f i b e r s on  species  g e l time  o f wood, b l a c k  sweet-gum and  findings  the  e f f e c t s of  loblolly  indicate that  the  of  Tupelo, pine  were  gel  time  14  of the UF r e s i n was a f f e c t e d by a d d i t i o n extractives. increased 2.2  The g e l time of the r e s i n - e x t r a c t i v e  exponentially  as i t s pH  Rapp (45)^ i n v e s t i g a t e d  (Guaiacum  o f Wood S u r f a c e s P r i o r t o  the p o s s i b i l i t y of u s i n g v a r i o u s  treatments t o improve the g l u a b i l i t y o f lignum v i t a t e officinale)  resinous e x t r a c t i v e s  by removal of at l e a s t p a r t  alcohol.  o f the  c o n t a i n e d i n lignum v i t a e wood.  the treatments a p p l i e d t o normal machine-planed solvents  mixture  increased.  E f f e c t s of Chemical Treatment Gluing  surface  o f small amounts o f  Among  lumber were  such as carbon t e t r a c h l o r i d e , benzene, acetone and The most s u c c e s s f u l  treatment was an a p p l i c a t i o n o f  10% c a u s t i c soda s o l u t i o n , wiped on the s u r f a c e , remain f o r 10 minutes,  allowed t o  and removed by washing with water.  r e s o r c i n o l r e s i n was employed.  A  The average r e s u l t s a r e shown  below: Shear  strength (psi)  Wood f a i l u r e (%)  1185  ( 8,170 kPa)  22  Washed with NaOH  1770  (12,204 kPa)  30  Sanded; washed with NaOH  2000 (13,790 kPa)  37  Control  (untreated)  O r i g i n a l not seen.  C i t e d from Troop and Wangaard (45).  15 I n one s e r i e s tion  of tests  the results  o f s a n d i n g and c a u s t i c  (19,030 kPa) w i t h 56% wood In a s t u d y c a r r i e d was shown t h a t  with and  soda t r e a t m e n t  a resorcinol  o u t by Gamble B r o s . ,  extractive) adhesive,  i n c r e a s e d wood f a i l u r e .  a n d wood f a i l u r e  untreated control Troop  from  (Tectona  of this  shear s t r e n g t h technique  63 t o 83% i n c o m p a r i s o n  (45) c o n c l u d e d t h a t  with r e s o r c i n o l  adhesive.  with  Burma t e a k  treatment  gluing  The j o i n t s h a d an a v e r a g e  shear-  In a s t u d y done a t t h e F o r e s t P r o d u c t s (4)) i t was f o u n d t h a t improved The e n t i r e  does  before  s t r e n g t h o f 2040 p s i (14,065 kPa) a n d 92% wood  hardwoods.  joint  specimens.  a n d Wangaard  soda  to gluing  1025 t o 1262 p s i (7,067-8,701  require preliminary  caustic  surface  prior  the joint  By means  not n e c e s s a r i l y  (Madison  2760 p s i  I n c . (45)3 i t  grandis)  with acetone  improved  s t r e n g t h was i n c r e a s e d f r o m kPa)  averaged  failure.  washing o f teak  ( c o n t a i n s an o i l y  o b t a i n e d from t h e combina-  Laboratory  surface treatment  the g l u a b i l i t y group  failure.  of certain  of treated  joints  when g l u e d w i t h a n i m a l g l u e showed 51% g r e a t e r s t r e n g t h a n d 97% more wood f a i l u r e  w i t h 10%  American (13 s p e c i e s ) average  than the untreated  joints  o f t h e same s p e c i e s g l u e d u n d e r s t a r v e d - j o i n t  conditions.  similar  However, one  species contains  t r e n d was o b s e r v e d w i t h c a s e i n (osage-orange) a large  Original  gave s t r i k i n g  results.  amount o f e x t r a c t i v e s  not seen.  Cited  from  glue.  Troop  A  Osage-orange  and i s v e r y  difficult  a n d Wangaard ( 4 5 ) .  to  join  with casein  practically  glue.  U n t r e a t e d osage-orange  no a d h e s i o n ; t h e j o i n t s  showed an a v e r a g e  s t r e n g t h o f o n l y 294 p s i (2027 kPa) and no wood After  treatment  with caustic  soda,  wood showed  t h e average  failure. joint  was o v e r 3000 p s i (20,684 kPa) a n d t h e wood f a i l u r e Knight, at  r e p o r t e d by Hancock  shear  (22), i n d i c a t e s  strength was 35%.  that  i t was  one t i m e common p r a c t i c e t o wipe t h e s u r f a c e s o f many  hardwoods w i t h a s o l u t i o n  o f 10% sodium  a n i m a l g l u e , i n o r d e r t o improve Narayanamurti on wood g l u i n g that  (35) n o t e d t h a t  i s of special  improvement  bond  h y d r o x i d e , when u s i n g  strength.  the effect  importance.  of g l u a b i l i t y  of extractives  He f u r t h e r  o f heartwood  after  noted  extraction  was e v i d e n t . Thomas  (44) h a s shown t h a t  removal  t h e e t h e r and b e n z e n e - s o l u b l e p o r t i o n the t r o p i c a l  wood o f d e t e r m a  considerable  increase  phenolic  resin.  The r e m o v a l  joint  obtained with a caused i n  a chemical  as t h e  incompatibility  and t h e w a x - l i k e  substance  w i t h t h e wax removed, a s a t i s f a c t o r y .  c a n be o b t a i n e d w i t h Hancock  quality  w i t h melamine-formaldehyde  He c o n c l u d e d t h a t  d e t e r m a and t h a t  Mez), c a u s e d a  of the extractives  e x i s t s between p h e n o l - f o r m a l d e h y d e in  o f t h e wax p r e s e n t i n rubra  i n the gluebond  change i n t h e b o n d q u a l i t y adhesive.  (Ocotea  of a large part of  phenol-formaldehyde.  (22) showed t h a t  d r i e d D o u g l a s - f i r veneer  t h e r e d u c e d a d h e s i o n o f oven-  i s primarily  t i v e migration to the surface.  the result  of extrac-  He a l s o d e t e r m i n e d  that the  17 acetone or  a combination  extractable  f r a c t i o n s were r e s p o n s i b l e  Wangaard and extractives  on  Granados  from  They f o u n d out  s h i p between t o t a l sites  complexes modified  (14)  (pH  that  there  - 4.05).  the  improving  i t .  of the  Few  bonding agents,  and  adhesive  as  t o b e t t e r pH Chen  accessibility  material. chromium  typical  phenolic  have had  j u d g e d by  used the  the  were  bond q u a l i t y o f  controls.  the  complex than  He  treated postulated  a d h e s i v e mix  chromium c o m p l e x e s  may  bonding  p l y w o o d p a n e l s made w i t h with the  relation-  veneer surfaces  improving the  used  i n e f f e c t i v e as  a deleterious increase  e f f e c t on  in viscosity.  r e s u l t s were more e n c o u r a g i n g  studied  the  w e t t a b i l i t y of  e f f e c t of e x t r a c t i v e removal some t r o p i c a l  M a c h i n e d wood s u r f a c e s  of e i g h t  w i t h a 10%  sodium h y d r o x i d e ,  s o l u t i o n of  alcohol-benzene. glued  of  were  the When due  compatibility.  (15)  a d h e s i o n and  significant  glue-bond q u a l i t y rather  of the  have r e n d e r e d t h e  a u r e a r e s i n was  no  o f v e n e e r s w i t h chromium  v e n e e r s compared f a v o r a b l y  itself  was  of  tropical  i n e x t r a c t i v e content  Douglas-fir  purpose of  effect  Nine  e f f e c t of various  impaired  pH  wood.  the  solutions  may  i n v e s t i g a t e d the  studied  treatment  high  inhibition.  e x t r a c t i v e content  The  the  and  f o r the  low  plywood.  that  17%  methanol/benzene  or  1.95  f o r the  3 to  sorption  for e i t h e r high Bryant  (46)  w a t e r - v a p o r s o r p t i o n by  hardwoods r a n g i n g used.  o f a c e t o n e and  tropical  After reconditioning,  w i t h u r e a - f o r m a l d e h y d e and  on  hardwoods. species  were  acetone, wood b l o c k s  treated  and were  resorcinol-formaldehyde  18 resin  adhesives.  controls.  Untreated  wood b l o c k s  were u s e d as  The r e s u l t s i n d i c a t e d t h a t t h e a d h e s i v e  strength  was i m p r o v e d b y a l l t h e t r e a t m e n t s  species,  except  wettability  one.  joint  i n a l l the  E x t r a c t i v e removal treatment  improved  a n d i n c r e a s e d pH o f wood i n a l l t h e s p e c i e s  tested. e t al.  Jain  o f Pinus  gluing  subjected benzene,  roxburghii  veneers.  phenol-formaldehyde  cold-set  UF g l u e ,  case o f ether, i s only  UF, d e f i n i t e  test  strength  ( c o l d - s e t and h o t - s e t ) and a l c o h o l - s o l u b l e ) i n case o f occurred i n  s a m p l e s t h a t an  was n o t i c e d .  With  s a m p l e s were o b s e r v e d i n d r y a n d b o i l - t e s t  of gluing with  h o t water e x t r a c t e d  PF ( w a t e r - s o l u b l e )  hot-set  values samples.  indicated that  samples and e t h e r  extracted  samples  I n t h e c a s e o f PF ( a l c o h o l -  t h e r e m o v a l o f e x t r a c t i v e s seemed t o a b a t e  gluability.  However,  improvements i n case o f h o t water and e t h e r  b e t t e r than the c o n t r o l s .  soluble)  unextracted  1% NaOH a n d e x t r a c t i v e f r e e s a m p l e s .  alcohol-benzene extracted glued  and  The r e s u l t s showed t h a t ,  t h e r e s u l t s were b e t t e r w i t h  Results  successively.  an improvement i n d r y - s t r e n g t h  i nboil  were  alcohol-  and a l s o  i n t h e case o f e t h e r - e x t r a c t e d  improvement  extracted  (water-soluble  Veneers  ether,  the extracted  Urea-formaldehyde  a d h e s i v e s were u s e d .  but  h o t water,  were made u s i n g  o f e x t r a c t i v e s on  from I n d i a .  1% NaOH s o l u t i o n i n d i v i d u a l l y  (control)  it  (Chir)  t o e x t r a c t i o n with  Plywood p a n e l s  and  (27) s t u d i e d t h e e f f e c t  19 Roffael extractives  a n d Rauch  (38) i n v e s t i g a t e d  on t h e g l u i n g  o f oak p a r t i c l e s w i t h  phenol-formaldehyde r e s i n . tives  f r o m o l d oak t r e e s  buffering general,  capacity  favourably tion  with  brought using  affected  a r e more a c i d i c a n d e x h i b i t  the g l u a b i l i t y  a higher  In  of the p a r t i c l e s .  about a f u r t h e r  improvement  a l k a l i n e PF r e s i n .  Addition  considerably  instead  Extrac-  o f water  i n the g l u a b i l i t y  o f oak  o f s o d i u m h y d r o x i d e (3% improved t h e g l u a b i l i t y o f  particles. (18) e x a m i n e d t h e g l u e l i n e  bond d u r a b i l i t y o f s o u t h e a s t A s i a n  extraction  and p l a n i n g  of veneers.  species  were e i t h e r p l a n e d ,  caustic  solution,  of p h e n o l i c was t h a t , followed  or l e f t  one p e r c e n t  In  species  untreated before gluing.  caustic  One o f t h e i r  extraction  and d i d n o t c o n s i s t e n t l y  1983, K e l l y  surface  bonded s o l i d  solvent wood  Two  f o r 60  seconds,  darkened the  increase  the  failure. e t al.  wood p a n e l s :  Five  types  conclusions  (31)  investigated  the effects of  a c t i v a t i n g r e a g e n t s on t h e s h e a r s t r e n g t h  hydrogen peroxide, periodate.  after  w i t h a one p e r c e n t  by a 6 0 - s e c o n d r i n s e b e f o r e g l u i n g ,  p e r c e n t a g e o f wood  characteristics  Veneers o f f i v e  extracted  a d h e s i v e s were u s e d .  veneer surfaces  five  from younger t r e e s .  1-n s o d i u m c a r b o n a t e s o l u t i o n  D o u g a l e t al. and  extrac-  o f oak p a r t i c l e s w i t h b o i l i n g w a t e r  r e l a t e d t o d r y wood) oak  of  alkaline  The r e s u l t s showed t h a t  than those  extraction  the influence  nitric  acid,  potassium p e r s u l f a t e  d i f f e r e n t wood s p e c i e s  sulfuric  of  acid,  and p o t a s s i u m were u s e d i n t h i s  20 study:  t h r e e hardwoods a n d two s o f t w o o d s .  was u s e d ,  the reagents  a c t e d as c a t a l y s t s  b r i d g i n g m a t e r i a l s such results such  demonstrated  activation  as l i g n i n  that  acid  reagent  activation In summary,  acidic  effect  wood p a n e l s  was h i g h l y  c a n be b o n d e d by  dependent  wood e x t r a c t i v e s ,  nitric  and p a r t i c u l a r l y t h e  were shown i n t h e p a s t t o s e r i o u s l y  and l e a s t  Neutralization  of adhesives.  The  on  inhibitory (resorcinol)  -  urea-formaldehyde.  with a l k a l i  solutions  (1-3%) o r  removal  s o l v e n t s was n e c e s s a r y t o o b t a i n a c c e p t a b l y  s t r o n g g l u e bonds.  The e x t e n t o f t h e i n h i b i t o r y  shown t o be p r o p o r t i o n a l extractives  on t h e s u r f a c e  Prolonged  was most p r o n o u n c e d on c a s e i n , p h e n o l  with s u i t a b l e  The  However, t h e s h e a r  and wood s p e c i e s u s e d .  with the s e t t i n g  formaldehyde  also  for activating  was shown t o d e g r a d e t h e wood s u b s t r a t e .  extractives,  interfere  adhesive  and h e m i c e l l u l o s e s .  o f t h e wood s u r f a c e .  strength of the products activating  solid  No wood  was  to the concentration of acidic  w i t h even r e l a t i v e l y  effective.  effect  low c o n c e n t r a t i o n s b e i n g  21 3.0  3.1  Wood Samples s a m p l e s o f camphor wood, Ocotea  Air-dry in  M A T E R I A L S AND METHODS  form  o f sawn lumber w i t h d i m e n s i o n s  x 609.6 mm  usambarensis,  o f 25.4 mm  (1 i n x 4 i n x 24 i n ) were o b t a i n e d f r o m  separate timber  yards  i n N a i r o b i , Kenya.  and j o i n e r y  sawn.  The s a m p l e s ,  stacked with relative an  12.7 mm  humidity  a i r speed  three  i n the  i n d u s t r y i n Kenya.  Some o f t h e b o a r d s were q u a r t e r sawn w h i l e flat  mm  Thus, t h e s a m p l e s  s h o u l d r e p r e s e n t t h e camphor wood p o p u l a t i o n u s e d furniture  x 101.6  on a r r i v a l  i n Vancouver,  (0.5 i n ) s p a c e r s between,  room  [dry bulb  approximately  others  were  were  i n a 50 ± 2%  23 ± 1°C (73.4 ± 2°F) h a v i n g  70 m/min  (200 f t / m i n ) ] t o p e r m i t  controlled conditioning. 3.2  Wood  Adhesives  Four  r o o m - t e m p e r a t u r e c u r i n g g l u e s were u s e d  study. urea-  in this  The c a s e i n , p h e n o l - r e s o r c i n o l - f o r m a l d e h y d e formaldehyde  Chemical  Company  (PVA) was  (PRF) a n d  (UF) r e s i n s were s u p p l i e d by B o r d e n  (Canada) L i m i t e d .  The p o l y v i n y l - a c e t a t e  s u p p l i e d by Crown P a i n t s a n d B u i l d i n g  Products  (Kenya) L i m i t e d .  3.2.1  Casein Casco-casein  readily  42-28G  mixed w i t h water.  i s a premium g r a d e g l u e t h a t i s I t i s room c u r i n g and i s  22 recommended f o r i n t e r i o r u s e . g l u e bond r e q u i r e m e n t s  I t complies with the type I I I  o f Canadian  Standard A s s o c i a t i o n  (CSA)  0132.2 M 1977 ( 8 ) . 3.2.2  Phenol-resorcinol-formaldehyde  C a s c o p h e n LT-75 i s a l i q u i d a d r y powdered h a r d e n e r ,  resin  catalyst  FM-282C, p r o d u c e s  r e s o r c i n o l - f ormaldehyde a d h e s i v e t h a t setting.  T e s t s i n Borden l a b o r a t o r i e s  representative 0112.7-1960 produces  (Type  of this  Casco  and weatherproof  glue that  indicate  that  It  b o n d w i t h wood ( 8 ) .  1 urea r e s i n  adhesives  i s a cold-setting  cures t o a h i g h l y  I t meets t h e r e q u i r e m e n t s  urea-  water-resistant  o f CSA 0112.5-M1977 f o r t y p e  (7) .  Polyvinyl-acetate  Polyvinyl  resin  t o be u s e d  the manufacturer, hardeners. partially  temperature  Urea-formaldehyde  formaldehyde  fluids  a phenol-  f o r wet u s e s e r v i c e .  UF 109 w i t h 221 h a r d e n e r  3.2.4  i s room  with  a d h e s i v e meet CSA s t a n d a r d  1) s p e c i f i c a t i o n  a waterproof  3.2.3  bond.  lots  w h i c h when m i x e d  emulsions  a t room t e m p e r a t u r e normally without  The a d h e s i v e diffuses  coagulates.  There  a r e m a r k e t e d as m i l k y - w h i t e i n t h e form  addition  s u p p l i e d by  of separate  s e t s when t h e w a t e r o f t h e e m u l s i o n  i n t o t h e wood a n d t h e e m u l s i f i e d i s no a p p a r e n t  chemical curing  associated with the hardening of t h i s  resin  reaction  adhesive (41).  23  The  resin  emulsions  subjected  to  sustained  periods,  resistance  3.3  loads  at  to  possess  variables,  glue  indicated  below:  only  was  carried  The  design  types  and  wood.  Levels  Glues  Four  Wood  Five  Replicates  (assemblies)  Duplicates  (shear  glue.  tests  wood  the  are  (120°F)  water  and  for  moisture  were  level  experiment design  included  used  was  two  as  PVA Casein UF PRF  -  u n e x t r a c t e d wood (control) extracted with hot water surface treated with dilute n i t r i c acid  -  surface treated with 10% sodium hydroxide solution extracted with a l c o h o l benzene . -  (for (for (for (for  blocks)  carried  completely  -  Three Three Six Nine  (shear  a  -  blocks/assembly)  combinations  one  49°C  using  The  -  Only  f a i r  out of  Variables  q  above  joints  Design  experiment design.  The  when  (19).  randomized  Total  creep  temperatures  and  Experimental  The  tend  out  as  (unextracted  PVA) casein) UF) PRF). Five 405^  indicated  in  wood)  used  was  Table  with  1.  UF  3.4  Experimental Procedure 3.4.1  S p e c i f i c gravity determination  S p e c i f i c g r a v i t y was determined by o b t a i n i n g green and oven-dry volume o f four specimens, each 25 mm x 25 mm x 77 mm (1  i n x 1 i n x 3 in) i n s i z e . The specimens were soaked i n a s t e e l c y l i n d e r  filled  with water f o r 4 days, at 827 kPa (120 p s i ) t o make sure they were water s a t u r a t e d .  The l e n g t h , width and t h i c k n e s s  dimensions, o f the water s a t u r a t e d specimens, were taken at 3 d i f f e r e n t p o i n t s , t h e ends and the c e n t e r o f the specimen. Green weight and volume o f each specimen was determined. The specimens were then o v e n - d r i e d at 103 ± 2°C t o constant weight. of  The b a s i c  (green) s p e c i f i c g r a v i t y o f each  the specimen was c a l c u l a t e d as f o l l o w s :  Green s p e c i f i c g r a v i t y = (cJe'eV^volume* Where:  O.D weight  1  = weight o f oven-dry  D  e  n  s  i  t  y  o  f  water  specimen.  Green volume = volume o f water s a t u r a t e d  specimen.  The average v a l u e of t h e f o u r specimens was adopted as t h e s p e c i f i c g r a v i t y o f camphor wood. 3.4.2  Wood pH d e t e r m i n a t i o n  The sawdust  generated d u r i n g the i n i t i a l  c u t t i n g of t h e  boards, b e f o r e g l u i n g , was used f o r pH d e t e r m i n a t i o n .  25 F i v e grams o f sawdust was mixed with 50 cm-* o f d i s t i l l e d water.  The mixture was allowed t o stand f o r 2 h w i t h  occasional s t i r r i n g .  Then t h e mixture was f i l t e r e d and t h e  f i l t r a t e used f o r pH d e t e r m i n a t i o n u s i n g a standard pH meter. Average pH value o f f i v e samples  (wood sawdust and  d i s t i l l e d water) was taken as t h e pH o f camphor wood at room temperature. 3.4.3  T o t a l e x t r a c t i v e s content  determination  Again,  sawdust generated d u r i n g t h e c u t t i n g o f t h e  boards b e f o r e g l u i n g p r o v i d e d t h e wood powder t h a t was used i n t h i s p a r t o f t h e study.  Three s o l v e n t s :  water, and 1% sodium hydroxide were used.  alcohol-benzene,  The procedure  adopted by ASTM (see Appendix I I I ) was f o l l o w e d when conducting t h i s 3.5  test.  Preliminary  Experiments  To determine  t h e b e s t c o n d i t i o n s f o r g l u i n g camphor  wood, some p r e l i m i n a r y experiments wood b l o c k s approximately  were conducted.  Camphor  25.4 mm x 101.6 mm x 304.8 mm  x 4 i n x 12 i n ) were used i n t h i s p a r t o f t h e study. b l o c k s were p l a n e d down t o a t h i c k n e s s o f 19 mm prior to gluing.  (1 i n  The  (3/4 i n ) j u s t  U s i n g a double glue spread o f 410.6  g/m  2  (85 l b p e r 1000 f t ) and t h e recommended assembly times o f 2  each o f t h e 4 g l u e s , t h e f o l l o w i n g g l u i n g c o n d i t i o n s were tested:  26 (i)  G l u i n g and for  (ii)  24  24  Sections  of  11)  The  8 and  1,379  kPa  21-23°C,  (200 p s i ) .  p r e s s i n g a t room t e m p e r a t u r e ,  three  (see F i g u r e  glued blocks.  with  a pressure  h u s i n g u n d e r 1,724  each glue,  modified the  h using  G l u i n g and for  For  p r e s s i n g a t room t e m p e r a t u r e ,  glued test  kPa  stocks  21-23°C,  (250 p s i ) .  were made.  s p e c i m e n s were c u t  Five from each  of  s p e c i m e n s were t e s t e d i n a c c o r d a n c e  9 o f t h e ASTM s t a n d a r d ,  D905-81  (Appendix  ID • The and 3.6  was  first  a d o p t e d f o r t h e main  one  this  different  study.  of the  to  Gluing  g r o u p s o f camphor wood s a m p l e s were u s e d  E a c h g r o u p o f s a m p l e s was  following  results  experiment.  T r e a t i n g o f Wood Samples P r i o r Five  in  s e t o f c o n d i t i o n s gave s a t i s f a c t o r y  randomly  assigned  treatments:  (i)  e x t r a c t i o n with  alcohol-benzene;  (ii)  e x t r a c t i o n with  (iii)  s u r f a c e treatment  with  3%  (iv)  surface treatment  with  10%  hot  water; nitric  acid;  sodium  hydroxide  solution; (v) 3.6.1  no  (control).  E x t r a c t i o n with  For t h i s b e n z e n e and  treatment  treatment  two  alcohol-benzene  a s o l v e n t c o n s i s t i n g o f one  volumes of  95%  ethanol  was  samples c o n s i s t e d o f m a c h i n e - p l a n e d p i e c e s  used. o f 25.4  volume  The mm  of  wood x  101.6  27 mm  x 304.8 mm  were p l a c e d  (1 i n x 4 i n x 12 i n ) i n s i z e .  samples  i n a g l a s s t a n k a f t e r w h i c h t h e t a n k was  with alcohol-benzene solution. g l a s s pane and s i l i c o n ensure that  The  g r e a s e was  t h e s e t up was  allowed to stand  The t a n k was  covered with a  a p p l i e d a l l around t o  airtight.  The s a m p l e s  were  f o r 6 d a y s , a t room t e m p e r a t u r e  (21-24°C) ,  w i t h two r e n e w a l s o f t h e a l c o h o l - b e n z e n e s o l v e n t . days t h e a l c o h o l - b e n z e n e s o l u t i o n  was  After six  replaced with  and t h e s a m p l e s were a l l o w e d t o s t a n d f o r 24 h . was u s e d t o e x t r a c t  filled  the alcohol-benzene solvent  methanol  The m e t h a n o l f r o m t h e wood  samples. Then t h e s a m p l e s were c o n d i t i o n e d u n t i l  most o r a l l o f  t h e two s o l v e n t s m e n t i o n e d above,  had e v a p o r a t e d .  o f e a c h sample  [1.6 mm  was  lightly  planed  down t o a t h i c k n e s s of t e s t  After  o f 19 mm  3.6.2  Extraction  this,  was  The g l u i n g ,  carried  w i t h hot water  i n a water b a t h c o n t a i n i n g Extraction  4 8 h, w i t h two c h a n g e s  cutting  out i n accordance  25.4 mm  (1 i n x 4 i n x 24 i n ) were u s e d .  soak f o r 24 h .  planed  earlier.  M a c h i n e - p l a n e d camphor wood s a m p l e s , x 609.6 mm  during  t h e s a m p l e s were  (3/4 i n ) .  specimens and t e s t i n g  w i t h t h e method o u t l i n e d  placed  might have  f r o m t h e c o r e t o t h e s u r f a c e o f t h e sample  the c o n d i t i o n i n g p e r i o d .  face  (l/16th in)  removed] t o remove any e x t r a n e o u s m a t e r i a l s t h a t migrated  One  was  The s a m p l e s  mm were  c o l d water and a l l o w e d t o  carried  of water.  x 101.6  o u t a t 97 ± 2°C f o r  At t h e end o f t h i s  28 treatment  t h e s a m p l e s were c o n d i t i o n e d  conditioning  chamber s e t a t 80% r e l a t i v e  49 ± 1°C (120 ± 2°F) ] . eliminating/reducing core  of green  The 1°C  This  s t e p was  any m i g r a t i o n  t o t h e wood s u r f a c e ,  drying  f o r one week i n a humidity  aimed a t  o f e x t r a c t i v e s from t h e  which u s u a l l y occurs  wood s a m p l e s were c o n d i t i o n e d  (73.4 ± 2°F) ] r e l a t i v e  humidity  content  was  a t 50%  until  [dry bulb  attained.  a n d c r o s s - c u t t i n g i n t o 304.8 mm c u t t i n g of t e s t  Conditioning o f 19 mm  (12 i n ) p i e c e s .  specimens and t e s t i n g  was  Surface  Camphor suitable in  treatment  with  nitric  size,  approximately  brushed onto t h e s u r f a c e s  19 mm percent  The  section(s).  acid  x 101.6 mm nitric  x 304.8 mm  These  u n d e r an i n f r a - r e d  source f o r  30 m i n . A f t e r t h e t r e a t m e n t  the board  surfaces  n e u t r a l i z e d by w e t t i n g  distilled  water f o l l o w e d  with  t h e wet s u r f a c e t o ammonia  e q u i l i b r i u m moisture content humidity  (C.T.H.) room.  were  vapour f o r f i v e  s a m p l e s were t h e n c o n d i t i o n e d  (3/4  a c i d s o l u t i o n was  t h a t were t o be j o i n e d .  s u r f a c e s were t h e n h e a t - t r e a t e d  The  (3/4  wood s a m p l e s were m a c h i n e - p l a n e d and c u t i n t o  x 4 i n x 12 i n ) . A t h r e e  exposing  was  done  following the procedure o u t l i n e d i n the preceding  3.6.3  23 ±  the d e s i r a b l e  f o l l o w e d by p l a n i n g t h e s a m p l e s t o a t h i c k n e s s  gluing,  due t o f a s t  lumber.  e q u i l i b r i u m moisture  in)  [dry bulb  again  by minutes.  to the desirable  i n a c o n t r o l l e d t e m p e r a t u r e and  Gluing,  cutting of test  specimens,  2 9  and  testing  was  carried  outlined earlier 3.6.4  The  out i n accordance with  t h e method  on.  Surface  treatment  with  sodium h y d r o x i d e  solution  wood s a m p l e s were m a c h i n e - p l a n e d a n d c u t t o s i z e ,  approximately  19 mm  x 101.6 mm  x 304.8 mm  (3/4 i n x 4 i n x 12  in).  The wood s u r f a c e s , t o be j o i n e d , were w i p e d w i t h  piece  of c l o t h  consisting  saturated with  o f 10 p a r t s by w e i g h t  soda) a n d 90 p a r t s were r i n s e d w i t h  of water.  distilled  clean white c l o t h u n t i l Following the  this  step,  3.7  Main  o f sodium h y d r o x i d e  (caustic  water and t h e n wiped d r y w i t h  they  showed no d i s c o l o r a t i o n .  Gluing,  carried  cutting of test  out i n accordance with the  above.  Experiment  From t h e r e s u l t s  obtained  i n the preliminary  experiment  f o l l o w i n g c o n d i t i o n s were u s e d f o r a l l t h e f o u r (i)  A glue  spread  (ii)  Gluing  a n d p r e s s i n g a t room t e m p e r a t u r e  (iii)  Press  (iv)  P r e s s i n g t i m e o f 24 h .  pressure  o f 410.6 g/m  2  o f 1,379 kPa  decay  from d e f e c t s  s u c h as k n o t s ,  glues:  (85 l b s p e r 1000 f t  2  b i r d s eyes,  g r a i n and  short  ) .  (21-24°C) .  (200 p s i ) .  Camphor wood s a m p l e s w h i c h were o f s t r a i g h t free  a  t h e t r e a t e d s a m p l e s were c o n d i t i o n e d t o  a n d t e s t i n g was  method d e s c r i b e d  solution  A f t e r 10 m i n u t e s t h e s u r f a c e s  d e s i r e d moisture content.  specimens,  the  sodium h y d r o x i d e  a  grain,  and u n u s u a l d i s c o l o r a t i o n s w i t h i n t h e s h e a r i n g  area  30 were u s e d . dimension The  was p a r a l l e l  b l o c k s were p l a n e d j u s t i n pairs  same s p e c i f i c  surfaces  direction  to the longest  of the block.  assembled the  The g r a i n  prior  to gluing  and  i n s u c h a way t h a t b l o c k s o f a p p r o x i m a t e l y gravity  ( a i r d r y ) were g l u e d t o g e t h e r .  o f the b l o c k s remained  u n s a n d e d and f r e e  from  The  dirt.  The m o i s t u r e c o n t e n t o f t h e wood a t t h e t i m e o f g l u i n g was  9-12% b a s e d  representative  3.7.1  on o v e n - d r y  weight  as d e t e r m i n e d by u s e o f  samples.  Adhesive a p p l i c a t i o n , of t e s t j o i n t s  pressing  and  conditioning  E a c h g l u e was m i x e d a c c o r d i n g t o t h e m a n u f a c t u r e r ' s instructions  a n d u s e d w i t h i n t h e recommended  A g l u e s p r e a d o f 410.6 g/m joint  formulation  spread manually  (pot l i f e ) . sq. f t . )of  The w e i g h e d amount o f  with a rubber r o l l e r .  o f t h e g l u e s and g l u i n g  The  c o n d i t i o n s u s e d a r e shown  T a b l e 2. The  at  (85 pounds p e r 1,000  a r e a d o u b l e s p r e a d was u s e d .  a d h e s i v e was  in  2  time  g l u e - c o a t e d b l o c k s were t h e n a s s e m b l e d  room t e m p e r a t u r e  (200 p s i ) f o r 24 h . were c o n d i t i o n e d  (21-23°C) w i t h a p r e s s u r e o f 1,379 The b l o c k s ,  at a r e l a t i v e  upon r e m o v a l  kPa  from t h e p r e s s ,  h u m i d i t y 50 ± 2% a n d a t a  temperature  o f 23 ± 1°C (73.4 ± 2°F) f o r a p e r i o d  after  t h e y were c u t i n t o t e s t  which  and p r e s s e d  specimens.  o f 7 days,  31 3.7.2 Due  P r e p a r a t i o n of block shear  to the l i m i t e d  m a t e r i a l which modification  was  amount and w i d t h o f camphor wood  a v a i l a b l e t o conduct  of the t e s t  camphor lumber h a d  specimens  specimen  a nominal  this  s i z e was  study, a  required.  w i d t h o f 101.6  mm  mm  (1 3/4  x 44.4  adopted  mm  x 12 mm  for this  w i d t h was  (1 3/4  study.  c h e c k e d t o be  validity  of the t e s t  Stickler geometry, effect  i n x 2 i n x 3/4  l e n g t h had  6.4  mm  of l i t t l e  i n x 3/4  (1/4  44.4  was  s i g n i f i c a n c e t o the  specimen  shear strength.  a significant  i s due  in)  mm  in) r e d u c t i o n i n  ( 4 3 ) , i n a s t u d y on b l o c k s h e a r  specimen  w i d t h has no  On  effect  length of shear plane p a r a l l e l observed,  x 50.8  results.  concluded that  on u n i t  mm  i n ) a m o d i f i e d specimen,  i n x 1 3/4  The  The  (4in).  I n s t e a d o f t h e ASTM s t a n d a r d b l o c k o f 44.4 x 12 mm  slight  significant  t h e o t h e r hand,  on u n i t to grain  t o optimum d i m e n s i o n  specimen  shear s t r e n g t h . of 1 inch,  of the block  A  he shear  specimen. The  b l o c k shear specimens  the g r a i n  direction  during test.  was  were c u t i n s u c h a way  parallel  to the d i r e c t i o n  S u r f a c e s were smooth, p a r a l l e l  of  t o each  loading other  and p e r p e n d i c u l a r t o t h e h e i g h t .  The  each  specimen  a t t h e g l u e l i n e was  measured t o t h e n e a r e s t  0.25  mm  i n ) and t h e s h e a r a r e a  (0.01  The described  specimens  were l e f t  i n Section  3.7.1  w i d t h and  that  of  calculated.  i n the c o n d i t i o n i n g  until  length  tested,  atmosphere  except d u r i n g the  32 cutting  operations.  The  were t r e a t e d b e f o r e  they  3.7.3 The  Testing block  shear  v a r y i n g between  in.)  i n s t e a d of the  Tinus  shearing uniform  1677.4 and  in this  1 8 0 6 . 4 mm  test  specimens  (3 s q .  2  study (2.6  2  had  and  shear  2.8  sq.  i n . ) o f t h e ASTM  machine/  containing a self-aligning  distribution  a p p l i e d at  the  movable head at  of  l o a d , was  a uniform  rate,  a rate of  used  seat  fitted to  (D905-  with a continuous 6.35  x  mm/s  d r y b l o c k s were t e s t e d f o l l o w i n g  the  with  a  ensure  ( F i g . 12).  10"^  The  load  motion (0.015  of in/min)  failure. 3.7.3.1 The  outlined was  specimens used  hydraulic testing  was  to  boil  shear'specimen.  Olsen  tool  and  were t e s t e d .  1 9 3 5 . 5 mm  standard block A  soak  procedure  area  81)  cold  Dry  above.  recorded  and  test  Shear the  shear  strength  at  glueline  area between the  nearest  failure  stress  0.25  percentage  mm  (0.01  Cold  portion  (see  failure  i n  soak  f o r each t e s t  strength calculated.  in kilopascals  o f wood f a i l u r e  3.7.3.2  A  2  at  procedure  two 2  was  was  the  l a m i n a t i o n s measured t o  the  rounded.  recorded  based  shear  on  ) , and  (kPa)  The  block  Estimated  f o r each  block.  test  Table  2)  of the  phenol-resorcinol-formaldehyde  and  test  specimens glued  urea-formaldehyde  were  with  33 soaked i n c o l d water,  a t 21°C  While  were t e s t e d t o f a i l u r e  still  wet, t h e y  method t o t h a t u s e d and  percent  f o r t h e dry specimens.  wood f a i l u r e  Boil  test  The  test  was u s e d  i n water f o r 4 h and t h e n  + 3°C (140 + 5°F) f o r 20 h . boiled ±  again  in a  dried  recorded.  specimens  The t e s t  specimens  estimated  3.8  wet.  strength  o f 60  4 h, c o o l e d i n w a t e r a t 21  Eventually, the percentage  and t h e s h e a r  were  s p e c i m e n s were  3°C (70 ± 5°F) and t e s t e d by l o a d i n g t o f a i l u r e  were s t i l l  glued  at a temperature  Then t h e t e s t  i n water f o r another  similar  Shear s t r e n g t h  only f o r the test  with phenol-resorcinol-formaldehyde. boiled  (75°F) f o r 48 h .  o f e a c h s p e c i m e n was  3.7.3.3 boil  (70°F) t o 24°C  while  they  wood f a i l u r e  was  calculated.  Statistical Analysis The  failure  average  values of both  were c a l c u l a t e d .  the shear  s t r e n g t h a n d wood  S h e a r s t r e n g t h a n d wood  failure  were a n a l y s e d s e p a r a t e l y . One way shear  analysis  s t r e n g t h and wood f a i l u r e Where s i g n i f i c a n t  multiple into  o f v a r i a n c e was p e r f o r m e d  range t e s t  subsets  f o r both the  according t o type  of t e s t .  d i f f e r e n c e s were n o t i c e d , Duncan's  was u s e d  o f homogeneous  t o s e p a r a t e t h e s e t o f means means.  new  34 4.0  4.1  R E S U L T S AND D I S C U S S I O N  Wood C h a r a c t e r i z a t i o n The  specific  oven-dry weight 0.53,  gravity  and g r e e n  (G) ( a t 12% m.c.) volume,  a sample mean o f 0.52  with  v a l u e s , b a s e d on  a r e i n t h e r a n g e o f 0.52 t o and a s t a n d a r d  deviationof  0.005. T h i s mean G o f 0.52 ± 0.005 o b t a i n e d samples u s e d i n t h i s  study,  r e p o r t e d b y Bengough  (11)  pH v a l u e s , 2.96.  of five  o f 0.026.  strongly  acidic.  The  results  are  summarized  percent  o f 0.59  (Appendix I ) .  samples,  a r e i n t h e r a n g e o f 2.89 t o  i s 2.93 a n d w i t h  a standard  T h i s i n d i c a t e s t h a t camphor wood i s  oftotal  e x t r a c t i v e content  i n the Table  Weight p e r c e n t a g e one  compares w e l l t o a v a l u e  The a v e r a g e pH v a l u e  deviation  f o r camphor wood  caustic  3.  o f camphor wood m a t t e r ,  soda s o l u t i o n  moisture-free basis.  determination  This value  s o l u b l e i n hot  (NaOH) i s 2 4 . 1 ,  on t h e  i s an a v e r a g e o f t h r e e  determinations. These r e s u l t s  indicate  t h a t a h i g h p r o p o r t i o n o f camphor  wood e x t r a c t i v e s a r e s o l u b l e i n a l c o h o l - b e n z e n e , and  c o l d water.  I t s h o u l d be p o i n t e d out t h a t t h e s e  are not from s u c c e s s i v e e x t r a c t i o n s . obtained  hot water  Also these  values  results  were  f r o m a s m a l l s e t o f s a m p l e s a n d do n o t t h e r e f o r e  represent the q u a n t i t y o f e x t r a c t i v e s i n every camphor wood s p e c i e s , s i n c e t h e d i s t r i b u t i o n  sample o f  of extractives  35 is  expected t o vary considerably  among  4.2  Gluing with Polyvinyl-acetate  The  Dry T e s t :  average  (PVA) A d h e s i v e  Bond s h e a r s t r e n g t h a n d wood percent  failure  s h e a r s t r e n g t h a n d p e r c e n t a g e wood  failure  shown i n T a b l e s 4a a n d 4b.  The s t a n d a r d d e v i a t i o n ,  minimum, maximum a n d r a n g e f o r b o t h p e r c e n t a g e wood f a i l u r e the  a s i n g l e t r e e and  trees.  4.2.1  are  within  average Figure  shear s t r e n g t h and  are also presented.  o f 15 measurements p e r t r e a t m e n t . 1 r e p r e s e n t s a histogram o f t h e average  s t r e n g t h a n d p e r c e n t a g e wood f a i l u r e . Tables  w i t h ammonia g a s p r o d u c e d  As i s e v i d e n t  nitric  acid,  t h e h i g h e s t average  (14,692 k P a ) ; w h i l e t h o s e made f r o m wood, 10% s o d i u m h y d r o x i d e s o l u t i o n  p e r c e n t a g e wood f a i l u r e Alcohol-benzene for  shear from  4a,b a n d F i g u r e 1, t h e b l o c k s made w i t h wood t h a t h a d  been s u r f a c e t r e a t e d w i t h d i l u t e  with  These v a l u e s a r e  both t h e average  percentage  shear  surface  strength  treated  showed t h e h i g h e s t  (70%).  e x t r a c t e d wood showed t h e l o w e s t v a l u e s shear s t r e n g t h  (7,452 kPa) a n d  wood f a i l u r e ( 6 % ) .  One way a n a l y s i s failure  and n e u t r a l i z e d  o f v a r i a n c e f o r s h e a r s t r e n g t h a n d wood  a r e shown i n T a b l e 5.  The  statistical  r a n k i n g o f t h e means, by Duncan's  multiple  range t e s t ,  f o r b o t h t h e s h e a r s t r e n g t h a n d wood  failure  a r e p r e s e n t e d i n T a b l e 6.  36  The (Table  analysis  5a)  cantly  water  multiple  acid  strength  higher basis  than of  surface  sodium  an  bond the  does  not  with  i n f e r i o r  or  strength.  shear wood  with  with  PVA  i t s  it  Samples  surface  it  is  the  with  water,  to  with  the  while bond  On  to  wood  gluing, with  p r i o r  PVA.  gluing,  the  that  p r i o r  Treating hot  treated  s i g n i f i c a n t l y  evident  acid,  hot  having  average  (control). is  to  as  strength The  wood  p r i o r  compared  unextracted, wood  g l u a b i l i t y  alcohol-benzene,  s i g n i f i -  treated  wood  n i t r i c  are  ranks  lowest.  strength  strength  s i g n i f i c a n c e ) .  shear  treated  extracting  when  bond  the  acid  improve  joint  6)  unextracted  g l u a b i l i t y  hydroxide  wood  the  of  hydroxide  had  n i t r i c of  treating  gluing, the  of  (Table  shear  means  level  highest  extracted  that  i t s  shear  for  treatment  test  the  results  0.01  sodium  had  average  improved  the at  range  bond  alcohol-benzene shear  that  and  average  n i t r i c  variance  (i.e.,  extracted,  similar with  indicate  different  Duncan's  of  to  Extracting  resulted  unextracted  in  wood  (control).  Table The  The  analysis  of  5b  indicate  that  wood  failure  percentage treated from  wood  the  failure  wood  56%  exhibited  by  ranking  not  value by  s i g n i f i c a n t l y ,  the  failure  is  given  variance  at  the  results  treatment  in  Table  (70%)  6  the  the  0.05  acid  l e v e l ,  untreated  shows  The  not  a l l  that  the  highest  sodium at  (49%)  from it  the  in  equal.  hydroxide  0.05  percentage  However,  shown  are  with  treatment  different  wood.  failure)  different  c o n t r o l .  n i t r i c  means  obtained  s i g n i f i c a n t l y of  (wood  level wood  is  not  56%  (nitric  acid  37 treatment)  i s significantly  different  s o d i u m h y d r o x i d e t r e a t e d wood.  The p e r c e n t a g e  showed by t h e h o t w a t e r e x t r a c t e d wood b e n z e n e e x t r a c t e d wood (at  0.05 l e v e l )  those  improved  different lower  On t h e b a s i s  none o f t h e f o u r wood the g l u a b i l i t y  failure  (18%) a n d a l c o h o l -  b u t b o t h o f them a r e s i g n i f i c a n t l y  wood f a i l u r e  significantly  wood  (6%) a r e n o t s i g n i f i c a n t l y  of the other three treatments.  percentage  f r o m t h e 70% o f t h e  than  o f average  pre-treatments  o f camphor wood when  g l u e d w i t h PVA a d h e s i v e . These r e s u l t s  a r e n o t v e r y much d i f f e r e n t  from  those  o b t a i n e d b y Goto e t a l . ( 2 0 ) . They o b s e r v e d t h a t t h e r e l a t i o n s h i p between g l u e - j o i n t either  cold  cant.  The r e s u l t s  extractives solution  s t r e n g t h and p e r c e n t a g e o f  o r hot water s o l u b l e  extractives  obtained i n this  removal,  study suggest  u s i n g h o t water,  or alcohol-benzene  i s not s i g n i f i -  sodium  does n o t improve  that  hydroxide glue-joint  strength. A t t h e same t i m e t h e r e s u l t s contradiction Wellons their  e t al.  studies  with those  that  and c h e m i c a l l y .  al.  (17),  (1). Generally results  extractives  o f a g l u e bond e i t h e r p h y s i c a l l y , physically  study are i n  r e p o r t e d b y Chugg et  ( 4 7 ) , Abe e t al. suggest  of this  affect  from  the formation  chemically or both  38  4.3  and  Gluing with Casein  4.3.1  Dry T e s t :  Tables  7a a n d 7b summarize t h e a v e r a g e  percentage  casein and also  Adhesive  wood f a i l u r e  adhesive.  range v a l u e s  casein  s t r e n g t h a n d wood  bond s h e a r  f o rthe five  strength  treatment  with  maximum  i n the tables.  Figure 2  s t r e n g t h and p e r c e n t a g e combinations  wood  o f wood a n d  adhesive.  hydroxide  solution,  wood t h a t h a d b e e n t r e a t e d w i t h  produced  t h e h i g h e s t average  s t r e n g t h o f 14,297 k P a ; w h i l e t h o s e t r e a t e d wood gave t h e l o w e s t , u n t r e a t e d wood  bond shear As  made f r o m  5,911 k P a .  (78%).  shown i n T a b l e  7b, b l o c k s made f r o m  No wood f a i l u r e  The b l o c k s made f r o m  lowest  average  hot water wood  alcohol-benzene  analysis  failure  these  e x t r a c t e d wood  (15%).  developed  From t h e a n a l y s i s  wood  values are  o f v a r i a n c e t a b l e s f o r average  s t r e n g t h a n d wood f a i l u r e  from  acid prior to  t r e a t e d wood e x h i b i t e d p e r c e n t a g e  o f 51% a n d 45%, r e s p e c t i v e l y ;  8a a n d b .  acid  was n o t i c e d i n t h e b l o c k s made  higher than t h a t of the c o n t r o l The  shear  strength.  sodium h y d r o x i d e  failures  bond  nitric  wood t h a t h a d b e e n s u r f a c e t r e a t e d w i t h n i t r i c gluing.  sodium  The b l o c k s made  ( c o n t r o l ) had t h e second  e x t r a c t e d wood gave t h e h i g h e s t p e r c e n t a g e  and  failure  f o r t h e wood b l o c k s b o n d e d  are also presented  B l o c k s made f r o m  from  shear  The s t a n d a r d d e v i a t i o n , minimum,  d e p i c t s average  failure  Bond s h e a r percent  are presented  of variance results  shear i n Tables i t is  39 evident cantly  that  the shear  different  strength treatment  a t 0.01  Duncan's M u l t i p l e hydroxide,  level.  Range t e s t  T h i s means  that  mean o f s o d i u m h y d r o x i d e t r e a t e d  (14,297 kPa) i s h i g h e r t h a n t h a t  of alcohol-benzene  wood  treated  (12,955 kPa) t h e two means a r e n o t s i g n i f i c a n t l y  different, that  a t 0.05 l e v e l .  t h e average  alcohol-benzene are  means f o r s h e a r  i n t h e same g r o u p .  although the treatment  wood  ( T a b l e 9) r a n k s t h e s o d i u m  and a l c o h o l - b e n z e n e t r e a t m e n t  s t r e n g t h development  means a r e s i g n i f i -  from t h a t  different,  a t 0.05 l e v e l .  mean i s s i g n i f i c a n t l y  The n i t r i c  (5,911 kPa) i s t h e l o w e s t  and i s a l s o  from t h e o t h e r f o u r treatment i t i s evident that  w i t h sodium h y d r o x i d e , to gluing  Adhesion  means.  significantly  surface treating  i t s gluability  I t seems t h a t  with n i t r i c  acid,  alcohol-benzene  with casein  adhesive.  surface treating  to gluing,  different  o f camphor wood  i n camphor wood i s n o t s i g n i f i c a n t l y  operation.  mean  From t h e s h e a r s t r e n g t h  e x t r a c t i n g t h e wood w i t h h o t w a t e r i . e . , p r i o r  casein  ( a t 0.05  The c o n t r o l  a c i d treatment  and e x t r a c t i n g w i t h  improves  prior  However, t h e  means a r e n o t s i g n i f i c a n t l y  a t 0.05 l e v e l .  prior  indicates  different  o f sodium h y d r o x i d e t r e a t m e n t .  and h o t w a t e r t r e a t m e n t  results  further  e x t r a c t e d wood, a n d h o t w a t e r e x t r a c t e d wood  hot water treatment  different,  test  s h e a r s t r e n g t h s f o r b l o c k s made w i t h  not s i g n i f i c a n t l y  level)  The r a n g e  lowers  adhesive.  improved  by  to the gluing  o f camphor wood i t s gluability  with  40 As for  i n d i c a t e d by a n a l y s i s  percentage  significantly treatment  wood f a i l u r e , equal.  mean  produced  ments,  not  adhesive  extracting  to gluing.  nitric  casein (sodium that  i t with  sodium  alcohol-benzene  o b t a i n e d by  strengthened  of caustic  casein glue  are joined with t h i s  as t h e wood f a i l u r e .  the quality of  s p e c i e s w i t h animal and  with a s o l u t i o n  as w e l l  Laboratory,  when wood s u r f a c e s were  on s e v e r a l  o f treatment  with  on a d h e s i o n .  done a t F o r e s t P r o d u c t s  This type  study.  i t can  o f camphor wood w i t h c a s e i n  culty.  this  results,  solutions before gluing,  Treatment  wood  treatment.  i t w i t h h o t w a t e r and  In t e s t s  hydroxide)  ordinarily  acid  by s u r f a c e t r e a t i n g  was i m p r o v e d  glues.  at the  e x h i b i t e d by t h e c o n t r o l i s  wood f a i l u r e  ( 4 ) , i t was shown t h a t  joints  treat-  different  are q u i t e s i m i l a r t o those  t r e a t e d with chemical the  and a l c o h o l - b e n z e n e  On t h e o t h e r hand, s u r f a c e t r e a t i n g  These r e s u l t s  Madison  o f 51% a n d  from t h e lowest p e r c e n t a g e  a c i d had a n e g a t i v e e f f e c t  other workers.  significantly  wood f a i l u r e s  by t h e n i t r i c  gluability  was i m p r o v e d  hydroxide, prior  different  view o f t h e percentage  stated that  8, h o t w a t e r  are not s i g n i f i c a n t l y  The 15% wood f a i l u r e  (0%) p r o d u c e d  In be  by s o d i u m h y d r o x i d e ,  significantly  failure  Percentage  (Table 8a),  means a r e n o t  (78%) i s t h e h i g h e s t and a l s o  respectively,  0.05 l e v e l .  the treatment  As shown i n T a b l e  higher than the others. 45%  of variance results  joints  g l u e w i t h some  increased the joint A similar  soda i n woods diffistrength  t r e n d was o b s e r v e d i n  According  t o Knight  (22)  i t was a t one t i m e  common  p r a c t i c e t o wipe t h e s u r f a c e s o f many hardwoods w i t h 10% sodium h y d r o x i d e ,  before  gluing with  animal  glue,  i n order t o  improve bond s t r e n g t h . Narayanamurti extractives slightly  o f Tectona  higher  about two  grandis,  i n low c o n c e n t r a t i o n s ( 2 % ) ,  of animal  glue nearly t o h a l f .  11% b u t i n c r e a s e . t h e g e l a t i o n give rise  explains the results,  failure  elata  same a u t h o r s tension  by over  200%; t h e s e  w h i c h e x h i b i t s low This  probably obtained i n  b o n d s t r e n g t h and wood  extractives.  (17) have i n d i c a t e d t h a t e x t r a c t i v e s f r o m  inhibit  the s e t t i n g  o f animal  r e p o r t t h a t e x t r a c t i v e s lower  glue.  f o r a good g l u e  On t h e o t h e r hand,  some o f t h e r e s u l t s  are i n c o n t r a d i c t i o n with  other  researchers while, Goto e t al.  between g l u e - j o i n t  Original  obtained  some r e s u l t s  i n this  o b t a i n e d by  investigating gluing of t r o p i c a l (20) p o i n t o u t t h a t t h e r e l a t i o n s h i p  s t r e n g t h and p e r c e n t a g e  not seen.  which i s  bond.  study  hardwoods.  The  the surface  o f t h e wood s u r f a c e and r e d u c e w e t t a b i l i t y ,  essential  noted  modulus b y  o f t h e hot water treatment,  removal o f hot water  Chugg a n d G r a y Afrormosia  They a l s o  o f wood f a i l u r e .  i . e . , an i n c r e a s e i n b o t h  with  time  to a starved joint  s t r e n g t h a n d low p e r c e n t a g e  study  and reduce t h e  c o n c e n t r a t i o n s reduce t h e r i g i d i t y  aspects  this  t h a t hot water  i n c r e a s e t h e modulus o f r i g i d i t y  g e l a t i o n time that  e t a l . (36) f o u n d  Cited  of either  f r o m Hancock ( 2 2 ) .  cold or  42 hot water s o l u b l e Chunsi  extractives  (16), i n t h e i r  i s not s i g n i f i c a n t .  study o f adhesion  Burmese hardwoods,  concluded that  had  relationship  no s i g n i f i c a n t  4.4  Dry t e s t :  The r e s u l t s are  glue-joint  shear s t r e n g t h  with the extractive  Both,  kPa)  as t h a t  nitric  A s c a n be s e e n alcohol-benzene  wood f a i l u r e t r e a t e d wood.  of the control.  (9,709 kPa) i s l o w e r t h a n  (12,924 k P a ) .  t h e lowest  average  Again,  nitric  acid  bond s t r e n g t h .  i n T a b l e 10b, t h e p e r c e n t a g e e x t r a c t e d wood i s t h e h i g h e s t  was o b s e r v e d  well  wood  than that  failure  (98%).  i n t h e b l o c k s made w i t h n i t r i c  B l o c k s made w i t h s o d i u m h y d r o x i d e  o f 75% a n d 60%, r e s p e c t i v e l y .  as t h a t  that  treatment  f o r alcohol-benzene  shown by t h e c o n t r o l  No acid  treated  wood, a n d h o t w a t e r e x t r a c t e d wood showed p e r c e n t a g e failures  (14,629  o f h o t w a t e r e x t r a c t e d (10,411 k P a ) ,  a c i d t r e a t e d wood  the control  for  between  i s shown i n F i g u r e  t h e bond s t r e n g t h i s h i g h e r t h a n t h a t  produced  failure  o f s o d i u m h y d r o x i d e t r e a t e d wood  On t h e o t h e r hand, t h a t and  wood  The r e l a t i o n s h i p  wood f a i l u r e  failure  i n t h e c a s e o f a l c o h o l - b e n z e n e e x t r a c t e d (14,543  as w e l l  kPa),  Adhesive  o f bond s t r e n g t h and p e r c e n t a g e  shown i n T a b l e s 10a a n d 10b.  3.  content.  Bond s h e a r s t r e n g t h a n d wood percent  bond s t r e n g t h and p e r c e n t a g e  of  strength of s i x  Gluing with Phenol-Resorcinol-Formaldehyde 4.4.1  Chow a n d  wood  T h e s e two v a l u e s , a s  e x t r a c t e d wood a r e h i g h e r  (30%).  43  In  Table  strength, puts  16, t h e s t a t i s t i c a l  treatment  alcohol-benzene  means, by Duncan's M u l t i p l e  significantly  average  shear  a t 0.05 l e v e l .  bond shear  extracting  surface treating improves  However, b o t h  o f them a r e  of the control.  strength basis,  i t c a n be  stated  camphor wood u s i n g a l c o h o l - b e n z e n e o r i t w i t h sodium h y d r o x i d e , p r i o r  i t s gluability  with phenol-resorcinol  adhesive.  Surface t r e a t i n g  extracting  i t w i t h hot water,  improve  The  a c i d t r e a t e d wood a r e n o t s i g n i f i -  lower than t h a t  On a v e r a g e that,  of the control.  means  s t r e n g t h s o f b l o c k s made w i t h h o t w a t e r  different,  significantly  hydroxide  T h e s e two t r e a t m e n t  higher than that  e x t r a c t e d wood, a n d n i t r i c cantly  Range t e s t  e x t r a c t e d wood, a n d s o d i u m  t r e a t e d wood i n t h e same g r o u p . are  ranking o f the shear  i t s gluability  to gluing, formaldehyde  t h e wood w i t h n i t r i c prior  to gluing,  with phenol-resorcinol  acid or  does n o t formaldehyde  adhesive. As  i n d i c a t e d by a n a l y s i s  the percentage different,  wood f a i l u r e  a t 0.05 l e v e l .  water treatment 0.05 l e v e l  of variance results  means a r e s i g n i f i c a n t l y Only  t h e sodium h y d r o x i d e ,  means a r e n o t s i g n i f i c a n t l y  (Table 11a).  alcohol-benzene extraction,  control. is  d i f f e r e n t , at  the treatment  h o t water e x t r a c t i o n ,  are s i g n i f i c a n t l y  lower than t h a t  means f o r  and s o d i u m  higher than that  On t h e o t h e r hand, t h e n i t r i c  significantly  and h o t  A l s o f r o m t h e r a n k i n g o f t h e means  shown i n T a b l e 16, i t i s e v i d e n t t h a t  hydroxide treatment  ( T a b l e 11a)  a c i d treatment  of the control.  of the mean  Thus, on  44 wood f a i l u r e and  basis,  sodium h y d r o x i d e  wood.  t r e a t m e n t s enhanced adhesion  On t h e c o n t r a r y ,  prior  to gluing,  formaldehyde It  t r e a t i n g t h e wood w i t h  lowers i t s g l u a b i l i t y  a n d wood f a i l u r e  benzene e x t r a c t e d  4.4.2  Cold  Results  were o b t a i n e d  soak t e s t :  shear  Bond s h e a r s t r e n g t h f a i l u r e percent  i n order  a n d wood  average shear  a r e shown i n T a b l e s  strength 12a a n d 12b,  f o r the different  o f i n c r e a s i n g m a g n i t u d e i s as f o l l o w s :  a c i d - t r e a t e d wood  (1321 k P a ) , h o t w a t e r e x t r a c t e d wood  (11,509 k P a ) , s o d i u m h y d r o x i d e  treated  (12,708 k P a ) , and a l c o h o l b e n z e n e e x t r a c t e d wood  kPa).  P e r c e n t a g e wood f a i l u r e  same o r d e r  is nitric  t r e a t e d wood (91%),  (42%),  f o r t h e c o l d soak t e s t  a c i d t r e a t e d wood control  and a l c o h o l - b e n z e n e  Analysis that  phenol-resorcinol  f o r the alcohol-  The a v e r a g e s h e a r s t r e n g t h ,  (10,421 k P a ) , c o n t r o l wood  acid,  wood.  o f t h e c o l d soak t e s t ,  respectively.  Nitric  nitric  t o note that the highest  p e r c e n t a g e wood f a i l u r e ,  treatments,  with  i n camphor  adhesive.  i s a l s o important  strength  and  i t c a n be s t a t e d t h a t b e n z e n e , h o t w a t e r ,  of variance  (60%),  (0%), sodium  i nthe hydroxide  h o t w a t e r e x t r a c t e d wood  e x t r a c t e d wood results  (14,609  (100%).  shown i n T a b l e  13a i n d i c a t e  t h e b o n d s h e a r s t r e n g t h means a r e n o t s i g n i f i c a n t l y  equal  a t 0.05 l e v e l .  f o r t h e wood f a i l u r e Statistical (Table  Similarly percent  ranking  this  observation  i s also  true  (Table 13b).  by a v e r a g e s h e a r s t r e n g t h  values  16) i n d i c a t e s t h a t none o f t h e means i s s t a t i s t i c a l l y  45 similar  t o any o t h e r .  Alcohol-benzene  treatment  means a r e s i g n i f i c a n t l y  control.  T h i s i s an i n d i c a t i o n  treatments  improved  resorcinol  formaldehyde,  concerned. adhesion,  gluability  about  9 times  Range t e s t  These r e s u l t s  adhesion;  4.4.3  Boil  indicate  glueline  decreasing  wood  a c i d treatment  that  last.  on t h e b a s i s  o f wood  treatments  and n i t r i c  acid  on a d h e s i o n .  Bond s h e a r percent  s t r e n g t h and wood  failure  shear s t r e n g t h f o r the s i x treatments  (12,926 k P a ) , s o d i u m h y d r o x i d e  sodium h y d r o x i d e ,  alcohol-  sodium  and h o t w a t e r  order i s alcohol-benzene  and n i t r i c  low b o n d  of the control.  w h i l e sodium h y d r o x i d e  test:  B l o c k s made  an e x t r e m e l y  i s ranked t h i r d ,  had a n e g a t i v e e f f e c t  lowered  as h a v i n g s i m i l a r  percent, alcohol-benzene,  treatments  kPa),  t o have  ( T a b l e 16) r a n k s  f o u r t h and n i t r i c clearly  phenol-  soak t e s t i s  appears  lower than t h a t  and h o t water t r e a t m e n t s  hydroxide treatment  The  o f camphor wood w i t h  as f a r as c o l d  f a i l u r e percent, the control  improved  t h e s e two t y p e s o f  a c i d t r e a t e d wood d e v e l o p e d  Duncan's M u l t i p l e  failure  that  although not t o a very great extent.  strength,  hydroxide  h i g h e r t h a n t h e mean o f t h e  The h o t w a t e r t r e a t m e n t  with n i t r i c  benzene,  and sodium  acid  and n i t r i c  (Table 14a).  Hot  a c i d t r e a t m e n t s have  s t r e n g t h v a l u e s lower than t h a t alcohol-benzene treatment  (13,759 k P a ) , c o n t r o l  (10,103 k P a ) , h o t w a t e r  (9,523 kPa)  in a  f o r the control.  mean i s h i g h e r  (9,920  water,  shear The  (see F i g u r e 5 ) .  46 Table  14b p r e s e n t s t h e p e r c e n t a g e  for the b o i l  test.  As c a n be s e e n  wood f a i l u r e  results  from t h e r e s u l t s ,  blocks  made w i t h a l c o h o l - b e n z e n e t r e a t e d wood showed t h e g r e a t e s t (100%) amount o f wood f a i l u r e , h o t w a t e r e x t r a c t e d wood third,  f o l l o w e d by t h o s e made  (87%).  The c o n t r o l  s o d i u m h y d r o x i d e t r e a t e d wood f o u r t h  a c i d t r e a t e d wood l a s t Analysis  s t r e n g t h and p e r c e n t a g e and b .  These r e s u l t s  treatment  failure  this  treatment  The  results  wood f a i l u r e  indicate  that  average that  shear  a t 0.05 l e v e l o f  f o r percentage  wood  bond s h e a r  p e r c e n t a r e shown i n T a b l e  are also  strength.  test  F o r wood f a i l u r e  are ranked  and  as b e i n g s i m i l a r i n  treatments  seem t o i n d i c a t e improved  adhesion,  i s concerned.  p e r c e n t , t h e range  different  showed an a v e r a g e  a c c o r d i n g t o t h e range  ranked  These r e s u l t s  benzene and hot water t r e a t m e n t s are not s i g n i f i c a n t l y  and t h e c o n t r o l  Sodium h y d r o x i d e , h o t w a t e r ,  none o f t h e f o u r d i f f e r e n t  as f a r as t h e b o i l  average  s t r e n g t h v a l u e s which are not  different.  a c i d treatments  treatments  t h e bond shear s t r e n g t h  f o r Duncan's M u l t i p l e Range t e s t ,  as h a v i n g a v e r a g e  nitric  shear  means.  The a l c o h o l - b e n z e n e t r e a t m e n t  significantly  failure.  a r e shown i n T a b l e s 15a  different  i s a l s o t h e case  s h e a r s t r e n g t h , and wood f a i l u r e 16.  (45%), and n i t r i c  f o r b o t h bond  means a r e s i g n i f i c a n t l y  significance;  (56%) i s p l a c e d  w i t h a 13 p e r c e n t wood  of variance results  from  test,  test  puts  i n t h e same g r o u p a t 0.05 l e v e l .  i . e . , they  Both  wood f a i l u r e p e r c e n t , are s i g n i f i c a n t l y  alcohol-  of these  which  higher  than  47 that  f o r the control.  treatment  The c o n t r o l  and t h e s o d i u m  hydroxide  means a r e c l a s s i f i e d as n o t s i g n i f i c a n t l y  different.  The n i t r i c  a c i d treatment  l o w e r t h a n t h e o t h e r f o u r means. the r e s u l t s treatments  suggest improved  that  mean i s s i g n i f i c a n t l y  For this particular  alcohol-benzene,  bond q u a l i t y  test,  and hot water  ( i n terms o f percentage  wood  failure).  4.6  C o m p a r i s o n o f Bond S t r e n g t h T e s t s f o r Wood B l o c k s Bonded with Phenol-Resorcinol-Formaldehyde Adhesive  As values  i s e v i d e n t from of the dry test  the c o l d  soak o r b o i l  wood l o s t water.  Table  17, t h e b o n d s h e a r s t r e n g t h  are, generally test.  11% o f t h e i r  higher than those of  B l o c k s made f r o m u n e x t r a c t e d  s h e a r s t r e n g t h due t o s o a k i n g i n c o l d  When s u b j e c t e d t o t h e b o i l  u n e x t r a c t e d wood g a i n e d a b o u t  test,  b l o c k s made  0.01% s h e a r s t r e n g t h i . e . ,  t a k i n g the dry shear  s t r e n g t h as t h e s t a n d a r d .  in  i n the cold  s t r e n g t h observed  result  of the decrease  moisture  inversely The  cold  wood f a i l u r e r e s u l t s  wood i t s e l f  Thus,  r a t h e r than  However, t h e b o i l that  instead  of t e s t i n g .  Most o f t h e  c o n t e n t o f t h e wood  o f wood v a r y (13, 2 3 ) .  support t h e above-mentioned  i t i n c r e a s e d from  soak t e s t .  c a n be assumed t o be a  and e l a s t i c c h a r a c t e r i s t i c s  with the moisture  assumptions;  test  The r e d u c t i o n  i n s t r e n g t h o f t h e wood, due t o h i g h  content a t t h e time  strength properties  from  30% ( d r y t e s t )  a r e d u c t i o n i n shear a stronger glue test  t o 60% f o r t h e  strength of the  joint.  gave some u n e x p e c t e d  results i n  o f t h e bond s t r e n g t h d e c r e a s i n g i t a c t u a l l y  48 increased.  Probably the i n c r e a s e i n bond s t r e n g t h i s due t o  a p o s t - c u r e phenomenon o f the adhesive as a r e s u l t of r a i s i n g the  temperature  (boiling).  Although, the wood f a i l u r e  percent f o r the b o i l t e s t i s lower than t h a t it  i s s l i g h t l y h i g h e r than that  o f the dry t e s t ,  f o r the c o l d soak t e s t .  Again t h i s i s c o n t r a r y t o what one would have expected.  Due  to thermal p l a s t i c i z a t i o n of wood by the hot water, the shear s t r e n g t h would be expected t o decrease. For  the b o i l t e s t the l o s s i n shear s t r e n g t h i s 5% f o r  b l o c k s made from hot water e x t r a c t e d wood.  However, b l o c k s  made from hot water e x t r a c t e d wood showed s l i g h t l y h i g h e r s t r e n g t h i n the c o l d soak t e s t than i n the dry t e s t .  The  wood f a i l u r e v a l u e s f o r the c o l d and b o i l t e s t s are h i g h e r than t h a t  of the dry t e s t .  Blocks made from wood t h a t acid p r i o r to gluing  had been t r e a t e d  showed a major l o s s  when s u b j e c t e d t o the c o l d soak t e s t .  with  nitric  (86%) i n s t r e n g t h  For the b o i l t e s t ,  b l o c k s made with n i t r i c a c i d t r e a t e d  wood showed a very  slight  The wood f a i l u r e v a l u e s  loss  (2%) i n shear s t r e n g t h .  were 0%, 0% and 13%, f o r the dry, c o l d soak t e s t and b o i l test, respectively. failure results,  C o n s i d e r i n g the shear s t r e n g t h and wood  i t can be s t a t e d  that  soaking o f the t e s t  specimens i n c o l d water p r i o r t o t e s t i n g r e s u l t e d  in a  degrade o f the glue i t s e l f r a t h e r than the wood.  B o i l i n g the  t e s t specimens seems t o have r e s u l t e d the  i n some weakening o f  wood i t s e l f ; hence the i n c r e a s e i n the amount o f wood  failure.  49 Cold  s o a k i n g and  had  been t r e a t e d w i t h  13%  and  31%  drop  boiling  o f b l o c k s made w i t h wood t h a t  sodium h y d r o x i d e  i n shear  strength,  Surprisingly,  t h e wood f a i l u r e  and  resulted  values of the  test  were l o w e r  the  drop  i n bond s t r e n g t h i s p r o b a b l y  cold  soak  that of the dry t e s t . the  t h a t m i g h t have t a k e n p l a c e i n t h e g l u e  r a t h e r than  i n the  found boil  alcohol-benzene  were l o w e r  Alcohol-benzene failure  specimen.  than  treatment  (dry t e s t  98%,  the  suggests  soak 100%  treatments most  The  and  and  boil  acid,  in  than f o r the  test.  test  sodium  100%), hydroxide failure  alcohol-benzene  as a r e s u l t  inhibitory  adhesive  soak t e s t  h i g h amount o f wood  t h a t t h e wood-glue j o i n t ,  adhesion  had  strength values  water, n i t r i c  c o n t r o l treatments.  that the  itself  showed t h e h i g h e s t amount o f wood  e x t r a c t e d wood, f a i l e d m a i n l y and  The  cold  that obtained i n the dry  cold  when compared t o t h e h o t and  of  e x t r a c t e d wood  (0.4%) s t r e n g t h i n t h e  f o r the dry t e s t test  I t seems  wood.  B l o c k s made w i t h higher  test  result  degradation  slightly  in a  respectively.  boil  that  than  solution  factors  were removed by  o f t h e wood  stress  evident with this  other  s o l v e n t system  effectively. 4.6.1  G e n e r a l d i s c u s s i o n on g l u i n g camphor wood phenol-resorcinol-formaldehyde adhesive  Over t h e y e a r s ,  attempts  r e s e a r c h e r s t o determine gluability Some o f t h e  the  have b e e n made by  from  this  many  i n f l u e n c e of e x t r a c t i v e s  o f wood w i t h p h e n o l i c r e s i n s results  with  study  (15,  18,  22,  on 47).  compare f a v o u r a b l y  with  50 their  findings reported  adhesion  i n wood.  Rapp  treatments  can  be  hardwood.  Among t h e  and  The  untreated  wood.  wood in  (Tectona  the  improve a d h e s i o n  to gluing, with  were h i g h e r  Gamble e t al.  p o r t i o n of the  grandis),  results  b e n z e n e as  are  wax  the  shear of  the removal  resulted i n a considerable  increase  r e p o r t e d by  inhibition  o f a c e t o n e and  present  strength  tropical  with  a resorcinol  Thomas  (44),  Hancock  because of e x t r a c t i v e s m i g r a t i o n  combination  wiping  c a u s t i c soda  than those  i n adhesion of oven-dried  determined that the  tropical  in a  extracting solvents.  a reduction  surface  (45) ^ have shown t h a t  glue-bond q u a l i t y obtained  Similar  10%  on  in a  i n d i c a t e d that both the  values  of acetone-soluble  literature  s u r f a c e t r e a t m e n t s u s e d was  results  wood f a i l u r e  existing  ( 4 5 ) ^ showed t h a t v a r i o u s  employed t o  wood s u r f a c e , p r i o r solution.  i n the  (22)  has  ether  and  shown t h a t  veneer i s p r i m a r i l y  to the  was  using  adhesive.  surface.  c a u s e d by  methanol/benzene  He  also  acetone or  a  extractable  fractions. E x t r a c t i v e s may polarity the  and  have an u n f a v o r a b l e  w e t t a b i l i t y o f wood  (24).  effect Chen  (15)  r e m o v a l o f e x t r a c t i v e s f r o m wood s u r f a c e s  solvents  improved the  observed that there wettability  and  w e t t a b i l i t y o f wood.  was  no  gluability  on  with  the found  various  However, he  direct  r e l a t i o n s h i p between  using  resorcinol-formaldehyde  6 C i t e d f r o m T r o o p and  Wangaard  (45).  ^ C i t e d f r o m T r o o p and  Wangaard  (45).  that  also  resin.  Jain  extracted  samples.  results  gluability  with b o i l i n g  t h a t hot  show a r e m a r k a b l e  study  this  also  findings  from  the present  sodium h y d r o x i d e  effective,  contradict  the  They r e p o r t e d t h a t e x t r a c t i o n sodium h y d r o x i d e  significantly  G l u i n g with Urea  sodium h y d r o x i d e  treatment  of Dougal et a l . (18).  o f some S.E. d i d not  Asian  hardwoods,  consistently  increase  Formaldehyde  u n e x t r a c t e d wood.  wood f a i l u r e ,  However,  values.  For t h i s p a r t of the i.e.,  adhesive.  findings  solution,  that surface  o f camphor wood b l o c k s ,  that the  4.7  hydroxide  results  solution  indicating  t h e wood f a i l u r e  improve-  results.  results,  with  findings  i s i n c l o s e agreement  glued with phenol-resorcinol-formaldehyde  was  oak  the  r e p o r t an  o f sodium  increased the wood-failure values  these  of  This c o n t r a d i c t s the  addition  b i t of t h e i r  i s evident with  with  samples.  that extraction  However, t h e y  in  trend.  water f a v o u r a b l y a f f e c t e d  study.  the  water  improvement  show a s i m i l a r  observed  of the p a r t i c l e s .  with the present  treatment  glued b e t t e r than  They f u r t h e r n o t e d  e t a l . (38)  ment i n g l u a b i l i t y  It  alcohol-benzene  i n comparison with the u n e x t r a c t e d  of the present  solution;  roxburghii  of the present  Roffael particles  indicate that  samples d i d not  bond q u a l i t y , The  (27)  s a m p l e s o f Pinus  unextracted extracted  e t al.  l e n d to the  study, The  o n l y one  results  wood l e v e l  obtained,  was  especially  used the  c o n c l u s i o n t h a t camphor wood g l u e s  52 well with urea it  essential  formaldehyde.  Hence, t h e a u t h o r d i d n o t f i n d  t o i n v e s t i g a t e t h e a d h e s i o n w i t h UF r e s i n i . e  u s i n g p r e - t r e a t e d camphor wood. 4.7.1  Dry t e s t :  Bond s h e a r  S h e a r s t r e n g t h a n d wood percent  s t r e n g t h and p e r c e n t a g e  failure  wood f a i l u r e  results  a r e shown i n t h e T a b l e s 18a and 18b. The average  u n t r e a t e d camphor wood showed a r e a s o n a b l y h i g h shear  adhesive. failure  s t r e n g t h when b o n d e d w i t h  I t also  showed a v e r y h i g h p e r c e n t a g e  which suggests t h a t  during testing, observation, with urea  rather than the adhesive.  i t c a n be s t a t e d t h a t  formaldehyde  that  From  failed,  this  camphor wood g l u e s  well  adhesive.  C o l d soak t e s t : percent  Tables  19a a n d 19b p r e s e n t t h e s h e a r s t r e n g t h a n d wood  results  The  results  f o r the cold  There  Shear  soak  s t r e n g t h a n d wood  failure  test.  show a r e d u c t i o n i n s h e a r s t r e n g t h f r o m  13,654 kPa f o r t h e d r y t e s t  from  i t s t h e wood i t s e l f  o f wood  4.7.2  failure  test.  urea-formaldehyde  i s also  t o 6,898 kPa f o r t h e c o l d  a r e d u c t i o n i n wood f a i l u r e  soak  percentage  97% t o 66%. Most a s s e m b l i e s b o n d e d w i t h u r e a - f o r m a l d e h y d e  intended  for interior  waterproof,  use because  only highly  of h i g h r e l a t i v e  the gluelines  are not f u l l y  w a t e r - r e s i s t a n t (19). A  humidity  and h i g h temperature  are  combination  deteriorates  53  urea r e s i n glue bonds i n a r e l a t i v e l y short time. to c y c l i c soaking and d r y i n g exposures  Resistance  i s reasonably good i f  the t e s t p i e c e s are plywood or t h i n members, but only moderate i f the p i e c e s are t h i c k study) (41).  ( l i k e the one used i n t h i s  54  5.0  A summary in  T a b l e 20.  results. (1)  SUMMARY AND C O N C L U S I O N  of the results F i g u r e s 6,  1, 8,  Under t h e l i g h t  obtained i n t h i s 9,  of t h i s  On b o n d s t r e n g t h b a s i s , camphor wood w i t h n i t r i c  further  study  acid,  prior  percentage  basis,  between PVA a d h e s i v e  and  significantly  to gluing,  adhesion  a n d camphor wood.  enhanced i t s g l u a b i l i t y Adhesion  of  improved  strength, surface  o f camphor wood w i t h s o d i u m  adhesive.  that:  However, on  e x t r a c t i o n with alcohol-benzene,  gluing,  these  none o f t h e f o u r  From t h e s t a n d p o i n t o f b o n d s h e a r treatment  illustrate  surface treatment  w i t h PVA.  wood f a i l u r e  i s given  i s concluded  improved i t s g l u a b i l i t y  wood p r e - t r e a t m e n t s  (2)  10  study  hydroxide, prior to  with casein  was n o t i m p r o v e d by  either  e x t r a c t i n g t h e wood w i t h h o t w a t e r o r by s u r f a c e treating casein  with n i t r i c  adhesive.  failure,  acid prior to gluing  In view o f percentage  gluability  solution,  wood  o f camphor wood w i t h c a s e i n was  i m p r o v e d by s u r f a c e t r e a t i n g hydroxide  i t with  i t with  sodium  and e x t r a c t i n g w i t h  alcohol-  benzene o r h o t water p r i o r t o g l u i n g o p e r a t i o n . Surface t r e a t i n g effect (3)  on  Extracting  with n i t r i c  a c i d had a n e g a t i v e  adhesion. camphor wood u s i n g a l c o h o l - b e n z e n e o r  surface treating  i t w i t h sodium h y d r o x i d e ,  g l u i n g w i t h PRF, i m p r o v e d a d h e s i o n .  On t h e  prior to  55 contrary,  treating  extracting  adhesion.  and h o t water e x t r a c t i o n  w h i l e sodium h y d r o x i d e  treatments (4)  acid or  i t w i t h hot water lowered  Alcohol-benzene, adhesion;  i twith n i t r i c  had a n e g a t i v e  improved  and n i t r i c  acid  effect.  C o l d w a t e r s o a k i n g o f s p e c i m e n s b o n d e d w i t h PRF specimens, reduction  prior  to testing,  resulted  ina  i n b o n d s t r e n g t h o f b l o c k s made  u n e x t r a c t e d wood, n i t r i c  acid treated  h y d r o x i d e t r e a t e d wood.  B l o c k s made w i t h  a c i d t r e a t e d wood showed a r e m a r k a b l e strength. was  But a s l i g h t  failure  There  and sodium nitric  drop  i n bond  i n c r e a s e i n bond s t r e n g t h  observed with alcohol-benzene  treatments.  from  and h o t water  was an i n c r e a s e i n p e r c e n t wood  f o r t h e h o t water,  and a l c o h o l - b e n z e n e  treatments. (5)  A drop  i n b o n d s t r e n g t h was o b s e r v e d when  s p e c i m e n s made f r o m n i t r i c  acid treated,  benzene e x t r a c t e d , and sodium h y d r o x i d e wood were b o i l e d  test alcohol  treated  i n water b e f o r e t e s t i n g .  However,  t h e b l o c k s made f r o m u n e x t r a c t e d wood g a i n e d i n bond s t r e n g t h a f t e r b o i l i n g . of  Probably,  a post-cure  t h e a d h e s i v e t o o k p l a c e as a r e s u l t o f  temperature  increase.  The b o i l  treatment  was  o b s e r v e d t o i n c r e a s e amount o f wood f a i l u r e the treatments treatment.  except  t h e sodium  hydroxide  in a l l  56 (6)  U s i n g d r y b o n d s t r e n g t h a n d p e r c e n t wood f a i l u r e as a criteria,  i t was f o u n d t h a t  w e l l with urea-formaldehyde surface treatment  camphor  wood bonds  a d h e s i v e w i t h o u t any  as s u g g e s t e d  herein.  REFERENCES  Abe, I . a n d N. A k i m o t o . 1976. The i n h i b i t o r y e f f e c t o f k a p u r wood e x t r a c t i v e s on t h e c u r i n g r e a c t i o n s o f t h e resol. J . J a p a n Wood R e s . S o c . 22 (3):191-196. Abe, I . a n d K. Ono. 1980. E f f e c t o f t h e a c i d i t y o f some t r o p i c a l wood e x t r a c t i v e s on t h e c u r i n g o f r e s o l . J . J a p a n Wood R e s . S o c . 26 (3):686-692. A n a i k e , Y., T. Nakagami, a n d T. Y o k o t a . 1974. 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Wood S c i . T e c h . 1 (1967) :253-277.  47.  W e l l o n s , J.D. a n d R.L. Krahmer. 1973. C h a r a c t e r i s t i c s o f d e l a m i n a t e d e x t e r i o r hardwood p l y w o o d . Dept. F o r . P r o d . P r o j e c t F-918, Oregon S t a t e U n i v . 8 pp.  48.  Y a t a g a i , M. a n d T. T a k a h a s h i . 1980. T r o p i c a l wood e x t r a c t i v e s ' e f f e c t s on d u r a b i l i t y , p a i n t c u r i n g t i m e , and p u l p s h e e t s p o t t i n g . Wood S c i . 12 (3):176-181.  o f wood. F o r . B u l l . No. 1512.  determa.  Table  1.  Type  of  tests  Adhesive/Test Wood  PRF  U n e x t r a c t e d wood  Dry C o l d soak Boil  Dry  Dry C o l d soak Boil  Dry  Dry C o l d soak Boil  Dry  Dry  Dry C o l d soak Boil  Dry  Dry  Dry C o l d soak Boil  Dry  Dry  Extracted  (i)  with  (i)  UF  PVA  Dry C o l d soak  Dry  wood:  alcohol-benzene  ( i i ) with hot water  Surface  Casein  treated:  with 10% NaOH  ( i i ) with d i l u t e n i t r i c  acid  _*  *No j o i n t s were made u s i n g t r e a t e d camphor wood and UF a d h e s i v e .  Dry  Table 2:  Formulation  Glue Item  Mixing r a t i o of g l u e s  Resin  o f g l u e s and g l u i n g c o n d i t i o n s  Phenol resorcinolformaldehyde  Ureaformaldehyde  100  100  Polyvinylacetate  100  Water  100 200  Hardner  Gluing conditions  Casein  15  Glue spread (g/m )  410.6  10  -  -  410.6  410.6  410.6  2  Open assembly time (min)  10  5  3  5  C l o s e d assembly  30  20  10  20  Temperature (°C)  21  21  21  21  Pressure  14  14  14  14  24  24  24  24  Time (h)  (kg/cm ) 2  to  Table 3: Total E x t r a c t i v e s Content in C a m p h o r Wood  Species  C a m p h o r wood  Hot Water Extractives (%)  9.0  Alcohol —Benzene Extractives (%)  C o l d Water Extractives (%)  10.2  * * E a c h value is an a v e r a g e of 3 d e t e r m i n a t i o n s and is on a m o i s t u r e - f r e e b a s i s .  8.8  Table 4a: Average Bond Strengtn of Blocks Bonded with PVA (DRY T E S T ) .  Mean Bond Strength (kPa)  Standard Deviation  Minimum Bond Strength (kPa)  Maximum Bond Strength (kPa)  Unextracted (Control)  13209  1992  9735  16251  6516  514  15  Hot Water Extracted  12164  1315  9839  14789  4950  340  11  Nitric acid Treated  14692  1889  11514  16968  5454  488  13  10% NaOH Treated  12745  2247  9742  16072  6330  580  18  7452  1690  3889  9818  5929  436  23  Treatments (Wood)  A.—Benzene Extracted  -  Range (kPa)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Table 4 b : Average Wood Failure of Blocks B o n d e d with PVA (DRY T E S T )  Treatments (Wood)  Mean Wood Failure (%)  Standard Deviation  Minimum Wood Failure (%).  Maximum Wood Failure (%)  Ranqe (%)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Unextracted (Control)  56  30  20  100  80  8  54  Hot Water Extracted  18  24  5  80  75  6  129  Nitric acid Treated  49  28  0  100  100  7  58  10% N a O H Treated  70  25  20  100  80  6  35  6  9  0  25  25  2  156  A-Benzene Extracted  Table 5a: A n a l y s i s of V a r i a n c e for B o n d S r e n g t h of B l o c k s B o n d e d with PVA (DRY T E S T ) .  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Wood  4  Error  70  240426625.067  Total  74  689819010.320  .  449392385.253  Mean Square  112348096.313  Computed f  32.71  3434666.072  Table 5b: A n a l y s i s of V a r i a n c e f o r Wood Failure of B l o c k s B o n d e d with PVA (DRY T E S T ) .  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  42721.333  10680.333  Error  70  41316.666  590.238  Total  74  84038.000  I Computed f 18.09  Table  6: Statistical Ranking by Duncan's Multiple Range Test for Bond Strength and Wood Failure of Blocks Bonded with PVA .  STRENGTH fkPa) RANKING OF TREATMENT MEANS Dry Test  NIT. 14692  UNX. 13209  NAO. 12745  WAT. 12164  BEN. 7452  WOOD FAILURE (%) RANKING OF TREATMENT MEANS Dry Test  NAO. 70  UNX. 56  NIT. 49  WAT. 18  BEN. 6  N.B. 1. Means underscored by the s a m e line are not significantly different at the 5% level of significance. 2. B E N . = A . - B e n z e n e extracted ; NIT.=Nitric acid t r e a t e d ; NAO.=NaOH t r e a t e d ; WAT.=Hot water extracted ;  UNX.=Unextracted(Control).  Table 7a: Average Bond Strength of Blocks Bonded with Casein (DRY  TEST).  Mean Bond Strength (kPa)  Standard Deviation  Minimum Bond Strength (kPa)  Unextracted (Control)  9933  4207  2723  - 16175  Hot W a t e r Extracted  11520  1398  9522  14493  4971  361  12  Nitric acid Treated  5911  1727  2744  8336  5592  446  29  10% NaOH Treated  14297  2523  9632  17961  8329  651  18  A-Benzene Extracted  12955  2168  8963  17078  8115  560  17  Treatments (Wood)  Maximum Bond Strength (kPa)  Range (kPa)  13452  Standard E r r o r of Mean  1086  C o e f f . of Variation (%)  42  I  Table 7b: Average Wood Failure of B i c c k s B o n d e d with C a s e i n (DRY T E S T ) .  Treatments (Wood)  Mean Wood Failye  Standard Deviation  m  Minimi) r Wood failure  M  Maximum Wood Failure i%)  Ranqe (%)  Unex t r a c t e d (Control)  15  19  Hot Water Extracted  78  30  Nitric acid Treated  0  10% N a O H Treated  51  34  10  100  90  A.—Benzene Extracted  45  23  10  90  80  Standard E r r o r of Mean  j C o e f f , ->.? Var lot ";>•"• (%) <  60  60  129  25  100  75  39  0  0  67  50  1  Table 8 a : A n a l y s i s of V a r i a n c e for B o n d S r e n g t h of B l o c k s B o n d e d with C a s e i n (DRY T E S T )  S o u r c e of Variation  Wood  D e g r e e s of Freedom  4  Error  70 .  Total  74  S u m of Squares  Mean Square  Computed f  629570759.013  157392689.753  471846902.533  6740670.036  1101417661.547  23.35  -  Table 8 b : A n a l y s i s of V a r i a n c e for Wood Failure of B l o c k s B o n d e d with C a s e i n (DRY T E S T )  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  57137.520  14284.380  Error  70  41437.600  591.966  Total  74  98575.120  Computed f  24.13  Table 9: Statistical Ranking by Duncan's Multiple Range Test for Bond Strength and Wood Failure of Blocks Bonded with Casein. STRENGTH (kPa) RANKING OF TREATMENT MEANS Dry Test  NAO. 14297  BEN. 12955  WAT. 11520  NIT. 5911  UNX. 9933  WOOD FAILURE (%)  •  RANKING OF TREATMENT MEANS Dry Test  WAT. 78  NAO. 51  BEN. 45  UNX. 15  NIT. 0  N.B. 1. Means u n d e r s c o r e d by the s a m e line are not significantly different at the 5% level of significance. 2. B E N . = A . - B e n z e n e e x t r a c t e d ; NIT.=Nitric acid t r e a t e d ; NAO.=NaOH t r e a t e d ; WAT.=Hot water extracted ; UNX.=Unextracted(Control).  Table 10a: Average Bond Strength of Blocks bonded with PRF (DRY TEST) .  Treatments (Wood)  Mean Bond Strength (kPa)  Standard Deviation  Minimum Bond Strength (kPa)  Maximum Bond Strength (kPa)  Unextracted (Control)  12924  1597  9687  15258  5571  412  12  Hot Water Extracted  10411  1866  7750  15113  7363  482  18  Nitric acid Treated  9709  2150  6385  14300  7915  555  22  10% NaOH Treated  14629  2752  10977  18719  7 742  711  19  A.-Benzene Extracted  14543  1534  12038  17037  4999  396  11  Range (kPa)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Table 10b: Average Wood Failure of Blocks B o n d e d with PRF (DRY T E S T )  Treatments (Wood)  Mean Wood Failure (%)  Standard Deviation  Minimum Wood Failure  Maximum Wood Fai lure (%)  Ranqe (%)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Unextracted (Control)  30  24  0  70  70  6  79  Hot Water Extracted  60  35  0  100  100  9  58  Nitric acid Treated  0  0  0  0  0  -  -  10% NaOH Treated  75  21  20  100  80  5  "28  A.-Benzene Extracted  98  4  90  100  10  1  4  Table 11a: A n a l y s i s of V a r i a n c e for B o n d S r e n g t h of B l o c k s B o n d e d with P R F (DRY T E S T )  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  315354452.618  78838613.153  Error  70  288109729.733  4115853.282  Total  74  603464182.347  Computed f  19.15  Table 11b: A n a l y s i s of V a r i a n c e for Wood Failure of B l o c k s B o n d e d with P R F (DRY T E S T ) .  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  88655.333  22163.833  Error  70  31243.333  446.333  Total  74  119898.667  Computed f  49.66  Table 12a: Average Bond Strength of Blocks Bonded with PRF (COLD SOAK T E S T ) .  Mean Bond Strength (kPa)  Standard Deviation  Minimum Bond Strength (kPa)  Maximum Bond Strength (kPa)  Unextracted (C o.ntrol)  11509  1164  9556  13638  4082  301  10  Hot Water Extracted  10421  856  8832  12245  3413  221  8  Nitric acid Tr e a t e d  1321  469  772  2144  1372  121  36  10% NaOH Treated  12708  2158  7398  15893  8495  557  17  A.—Benzene Extracted  14609  1570  10666  16217  5551  405  11  Treatments (Wood)  Range (kPa)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Table 12b: Average Wood Failure of Blocks Bonded with PRF  Treatments (Wood)  Mean Wood Failure (%)  Standard Deviation  Minimum Wood Failure (%)  Maximum Wood Fa i I u r e (%)  (COLD SOAK T E S T )  Range (%)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Unextracted (Control)  60  33  10  100  90  9  56  Hot Water Extracted  91  15  60  100  40  4  16  Nitric acid Treated  0  0  0  0  0  -  -  10% NaOH Treated  42  24  10  70  60  6  58  100  0  100  100  0  0  0  A.—Benzene  Extracted  Table 13a: A n a l y s i s of V a r i a n c e for B o n d S r e n g t h of B l o c k s B o n d e d with P R F (COLD S O A K T E S T )  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  1565248081.556  391312020.389  Error  70  131038117.957  1899103.159  Total  74  1696286199.514  Computed f  26.05  Table 13b: A n a l y s i s of V a r i a n c e for Wood Failure of B l o c k s B o n d e d with P R F (COLD S O A K T E S T ) .  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  Mean Square  Wood  4  97282.000  24320.500  Error  70  26766.666  382.381  Total  74  124048.667  Computed f  63.60  Table 14a: Average Bond Strength of Blocks Bonded with PRF (BOIL T E S T ) .  Mean Bond Strength (kPa)  Standard Deviation  Unextracted (Control)  12926  1840  10590  15210  4620  555  14  Hot Water Extracted  9920  1212  8157  12707  4550  366  12  Nitric acid Treated  9523  2478  5130  12411  7281  747  26  10% NaOH Treated  10103  1271  8143  12997  4854  383  13  A.-Benzene Extracted  13759  1344  11342  15961  4619  403  10  Treatments (Wood)  Minimum Bond Strength • (kPa)  Maximum Bond Strength (kPa)  Range (kPa)  Standard E r r o r of Mean  C o e f f . of Variation (%)  Table 14b: Average Wood Failure of Blocks B o n d e d with PRF (BOIL T E S T ) .  Treatments (Wood)  Mean Wood Fa i I u r e (%)  Standard Deviation  Minimum Wood Failure (%)  :  : ;  Maximum Wood Failure  Ranqe (%)  Standard' E r r o r of Mean  (%)  C o e f f . of Variation (%)  Unextracted (Control)  56  31  10  95  85  9  55  Hot Water Extracted  87  15  60  100  40  4  17  Nitric acid Treated  13  18  0  5  136  10% NaOH Treated  45.  37  5  100  0  100  A.-Benzene Extracted  :  ;  50  50  95  90  11  82  100  0  0  0  Table 15a: A n a l y s i s of V a r i a n c e f o r B o n d S r e n g t h of B l o c k s B o n d e d with P R F (BOIL T E S T )  S o u r c e of Variation  D e g r e e s of Freedom  S u m of Squares  •  149574795.732  :  Wood  4  Error  70  138824944.581 :  Total  74  288399740.315 :  Mean Square  37373698.933  Computed f  13.20  2833162.134  Table 15b: A n a l y s i s of V a r i a n c e f o r Wood Failure of B l o c k s B o n d e d with P R F (BOIL T E S T ) .  S o u r c e of Variation  S u m of Squares  D e g r e e s of Freedom  Wood  4  Error  70  Total  74  Mean Square  52548.182  13137.045  ;  28322.727  566.455  :  80870.909  Computed f  23.19  81  Table 16: Statistical Ranking by Duncan's Multiple Range Test for Bond Strength and Wood Failure of Blocks Bonded with PRF. STRENGTH (kPa) RANKING OF TREATMENT MEANS Dry Test  NAO. 14629  BEN. 14543  UNX. 12924  WAT. 10411  NIT. 9709  Cold Soak Test  BEN. 14609  NAO. 12708  UNX. 11509  WAT. 10421  NIT. 1321  BEN. 13759  UNX. 12926  NAO. 10103  WAT. 9920  NIT. 9523  Boil Test  "  WOOD FAILURE (%) RANKING OF TREATMENT MEANSDry Test  BEN. 98  NAO. 75  WAT. 60  UNX. 30  NIT. 0  Cold Soak Test  BEN. 100  WAT. 91  UNX. 60  NAO. 42  NIT. 0  Boil Test  BEN. 100  WAT. 87  UNX. 56  NAO. 45  NIT. 13  N.B. 1. Means u n d e r s c o r e d by the s a m e line are not significantly different at the 5% level of s i g n i f i c a n c e . 2. B E N . = A . - B e n z e n e e x t r a c t e d ; NIT. = Nitric acid t r e a t e d ; NAO. = NaOH t r e a t e d ; WAT. = Hot'water e x t r a c t e d ; UNX. = Unextracted(Control).  Table 17: C o m p a r i s o n of Bond Strength Test Results of blocks b o n d e d with PRF .  Treatments (Wood)  DRY T E S T Mean Mean Bond Wood Strength Failure (kPa) (%)  COLD SOAK TEST Mean Mean Bond Wood Strength Failure (kPa) (%)  BOIL T E S T Mean Bond Strength (kPa)  Mean Wood Failure  Unextracted (Control)  12924  30  11509  60  12926  56  Hot W a t e r Extracted  10411  60  10421  91  9920  87  Nitric acid Treated  9709  0  1321  0  9523  13  1 0 % NaOH Treated  14629  75  12708  42  10103  45  A.-Benzene Extracted  14543  98  14609  100  13759  100  Table 18a: Average Bond Strength of Blocks bonded with UF (DRY T E S T )  Treatments (Wood)  Unextracted (Control)  Mean Bond Strength (kPa)  Standard Deviation  Minimum Bond Strength (kPa)  Maximum Bond Strength (kPa)  13654  2409  1008  20181  Range (kPa)  10101  Standard E r r o r of Mean  622  C o e f f . of Variation (%)  18  Table 18b: Average Wood Failure of Blocks bonded with UF (DRY T E S T ) .  Treatments (Wood)  Unextracted (Control)  Mean Bond Strength (kPa)  97  Standard Deviation  6  Minimum Bond Strength (kPa)  80  Maximum Bond Strength (kPa)  100  Range (kPa)  Standard E r r o r of Mean  20  2  C o e f f . of Variation (%)  6  Table 19a: Average Bond Strength of Blocks bonded with .UF (COLD SOAK T E S T )  Treatments (Wood)  Unextracted (Control)  Mean Bond Strength (kPa)  6898  Standard Deviation  Minimum Bond Strength (kPa)  Maximum Bond Strength (kPa)  2825  1579  11569  Range (kPa)  9990  Standard E r r o r of Mean  C o e f f . of Variation (%)  41  729  Table 19b: Average Wood Failure of Blocks bonded with UF (COLD SOAK T E S T ) .  Treatments (Wood)  Unextracted (Control)  Mean Bond Strength (kPa)  66  Standard Deviation  31  Minimum Bond Strength (kPa)  15  Maximum Bond Strength (kPa)  100  Range (kPa)  85  Standard E r r o r of Mean  8  C o e f f . of Variation (%)  47  Table 2 0 : S u m m a r y of Bond Strength and Wood Failure Results. PVA Treatments (Wood)  Mean Bond Strength (kPa) . :  Mean Wood Failure (%)  Casein Mean Mean. Bond Wooa Strength Failure (kPa) (%)  PRF Mean Bond Strength Ok Pa)  UF Mean Wood Failure (%)  Unex t r a c t e d (Control)  D 13209  D 56  D 9933  D 15  D 12924 C 11509 B 12926  D 3 0 •' C 60 : B 56 :  Hot WaterExtracted  D 12164  D 18  D 11520  D 78  D 10411 C 10421 B 9920  D 6 0 '. C 91 : B 87 ;  Nitric acid Treated  D 14692  D 49  D 5911  D 0  D 9709 C 1321 B 9523  D 0 C 0 B 13  10% NaOH Treated  D 12745  D 70  D 14297  D 51  D 14629 C 12708 B 10103  D 75 C 42 B 45  D 14543 r 14609 B 13759  D 98 C 100 B 100  • A.-Benzene Extracted  N.B:  D 7452  D 6  D 12955  D 45  B = B o i l t e s t ; C = C o l d s o a k t e s t ; D = Dry t e s t  Mean Bond Strength (kPa)  D C  13654 6898  Mean Wood Failure (%)  D 97 C 66  Figure 1. Average Bond Strength and Wood Failure of Blocks bonded with PVA (DRY TEST) 16000  •100  Legend Bond Strength LZ2 Wood Failure  14000-  -80 12000  CL  10000 -60  cn c  ^_ 8000-  £ XI  CO XI O CO  -40  6000  400020 2000  UNX.  N.B  WAT.  NIT. WOOD CONDITION  NAO.  BEN.  B E N . = A l c o h o l - B e n z e n e e x t r a c t e d ; NA0. = Na0H t r e a t e d ; NIT. = Nitric acid t r e a t e d ; WAT. = Hot water e x t r a c t e d ; UNX.=Unextracted(Control).  o o  Figure 2 .  Average Bond Strength and Wood Failure of Blocks bonded with Casein (DRY  16000-  TEST) 100  Legend 14000-  Bond Strength [Z2 Wood Failure -80  12000-  CL  10000 60  cu  cn c  cu  3 8000-  ^_  "O  -«—>  (/)  O CO  &  40  6000-  o  O  4000  -20 2000  0  J  NAO.  BEN.  WOOD CONDITION N.B  B E N . = A l c o h o l - B e n z e n e e x t r a c t e d ; NA0.=Na0H t r e a t e d ; NIT.=Nitric acid t r e a t e d ; WAT.=Hot water e x t r a c t e d ; UNX.=Unextracted(Control).  00  Figure 3.  N.B  Average Bond Strength and Wood Failure of Blocks bonded with PRF (DRY TEST)  BEN = A l c o h o l - B e n z e n e e x t r a c t e d ; NAO.=NaOH t r e a t e d ; NIT.=Nitric acid t r e a t e d ; WAT.=Hot water e x t r a c t e d ; UNX.=Unextracted(Control).  Figure 4.  Average Bond Strength and Wood Failure of Blocks bonded with PRF (COLD SOAK TEST) .  UNX.  N.B  WAT.  NIT. WOOD CONDITION  NAO.  BEN.  B E N . = A l c o h o l - B e n z e n e e x t r a c t e d ; NAO.=NaOH t r e a t e d ; NIT.=Nitric acid t r e a t e d ; WAT.=Hot water e x t r a c t e d ; UNX.=Unextracted(Control).  Figure 5.  Average Bond Strength and Wood Failure of Blocks bonded with PRF (BOIL TEST) .  UNX.  N.B  WAT.  NIT. WOOD CONDITION  NAO.  BEN.  B E N . = A l c o h o l - B e n z e n e e x t r a c t e d ; NAO.=NaOH t r e a t e d ; NIT.=Nitric acid t r e a t e d ; WAT.=Hot water e x t r a c t e d ; UNX.=Unextracted(Control).  ure 6. Bond Strength and Wood Failure of Unextracted Blocks Bonded with PVA, Casein, PRF and UF Adhesives (DRY TEST) .  Figure 7. Bond Strength and  Wood Failure of Hot Water Extracted Blocks  Bonded with PVA, Casein and PRF Adhesives (DRY TEST) .  16000  100  14000-  Legend Bond Strength LZ2I Wood Failure  12000  CL  10000 60  cn c 0  8000 "D O O  CO "U c  o  K  6000-  CD  4000  2000-  PVA  CAS. ADHESIVE  PRF  Figure 8. Bond Strength and Wood Failure of Nitric Acid .Treated Blocks Bonded with PVA, Casein end PRF Adhesives (DRY TEST) .  Figure 9. Bond Strength and Wood Failure of NaOH Treated Blocks Bonded with PVA, Casein and PRF Adhesives (DRY TEST)  Figure 10. Bond Strength and Wood Failure of Alcohol-Benzene Extracted Blocks Bonded with PVA.Casein and PRF Adhesives(DRY TEST).  96  Figure 11  Form  and d i m e n s i o n  of  block  shear  test  specimen  97  A  (  i  Figu. 12.  Shearing tool  Secna*  M-A  98  APPENDIX I  Species  Description*  Botanical Local  name:  name:  Ocotea  usambarensis  Muthiti  T r a d e name:  Camphor wood  Family:  Lauraceae  Density  ( a t 12% MC):  Specific  gravity  Shrinkage  592.7 kg/m  Workability:  Moderately  Gluability:  Average  Treatability:  Extremely  Seasoning  Moderate  Uses:  (37 l b s / f t ) 3  ( a t 12% MC): 0.59  (green t o a i r d r y ) :  rate:  3  Furniture, panelling  Radial  2.5%; T a n g e n t i a l  4.0  easy  resistant  joinery,  l o r r y bodies,  and o v e r l a y  *From T i m b e r L e a f l e t No. 1 " C o m m e r c i a l Bengough, C.C. ( 1 2 ) .  boats  veneer  T i m b e r s o f Kenya",  99  APPENDIX I I .  Designation: D 905 - 49 (Reapproved 1981)"  Standard Test Method for S T R E N G T H P R O P E R T I E S O F A D H E S I V E B O N D S IN BY C O M P R E S S I O N  LOADING  SHEAR  1  T h i s standard is issued under the fixed designation D 905; the n u m b e r immediately following the designation indicates the year of original adoption or, in the case o f revision, the year o f last revision. A number in parentheses indicates the year o f last rcapproval. A superscript epsilon (<) indicates an editorial change since the last revision or reapproval. This method has been approved for use by agencies of the Department of Defense to replace method 1031 of Federal Test Method Standard No. 175a and for listing in the DoD Index of Specifications and Standards. " N O T E — S e c t i o n 2 was added editorially and subsequent sections renumbered in M a r c h  1985.  INTRODUCTION  The accuracy of the results of strength tests of adhesive bonds will depend on the conditions under which the bonding process is carried out. Unless otherwise agreed upon by the manufacturer and the purchaser, the bonding conditions shall be prescribed by the manufacturer of the adhesive. In order to ensure that complete information is available to the individual conducting the tests, the manufacturer of the adhesive shall furnish numerical values and other specific information for each of the following variables: (/) The moisture content of the wood at the time of gluing. (2) Complete mixing directions for the adhesive. (3) Conditions for applications of the adhesive including the rate of spread or thickness of film, number of coats to be applied, whether to be applied to one or both surfaces, and the conditions of drying where more than one coat is required. (4) Assembly conditions before application of pressure, including the room temperature, length of time, and whether open or closed assembly is to be used. (5) Curing conditions, including the amount of pressure to be applied, the length of time under pressure and the temperature of assembly when under pressure. It should be stated whether this temperature is that of the glue line, or of the atmosphere at which the assembly is to be maintained. (6) Conditioning procedure before testing, unless a standard procedure is specified, including the length of time, temperature, and relative humidity. A range may be prescribed for any variable by the manufacturer of the adhesive if it can be assumed by the test operator that any arbitrarily chosen value within such a range or any combination of such values for several variables will be acceptable to both the manufacturer and the purchaser of the adhesive. 1. Scope 1.1 This test method covers the determination of the comparative shear strengths of adhesive bonds used for bonding wood and other similar materials, when tested on a standard specimen under specified conditions of preparation, conditioning, and loading in compression. This test  method is intended primarily as an evaluation of adhesives for wood. T h i s test method is under the jurisdiction o f A S T M C o m mittee D-14 o n Adhesives and is the direct responsibility of Subcommittee D I 4 . 3 0 o n W o o d Adhesives. 1  Current edition approved Sept. 30. 1949. Published N o v e m ber 1949. Originally published as D 9 0 5 - 4 7 T . Last previous edition D 9 0 5 - 4 7 T .  100  D905  2. Applicable Document 2.1 ASTM Standard: D 143 Methods of Testing Small Clear Specimens of Timber 2  3. Apparatus 3.1 The testing machine shall have a capacity of not less than 6810 kg (15 000 lb) in compression and shall be fitted with a shearing tool containing a self-aligning seat to ensure uniform lateral distribution of the load. The machine shall be capable of maintaining a uniform rate of loading such that the load may be applied with a continuous motion of the movable head to maximum load at a rate of 6.35 x 10 mm/s (0.015 in./min) with a permissible variation of ±25 % . The shearing tool shown in Fig. 1 has been found satisfactory. The testing machine shall be located in an atmosphere such that the moisture content of the specimens developed under the conditions prescribed in Section 6 is not noticeably altered during testing. -3  4. Test Specimens 4.1 Test specimens shall conform to the form and dimensions shown in Fig. 2. The specimens shall be cut from test joints prepared as described in Sections 5 and 6. 4.2 At least 20 specimens shall be tested, representing at least four different joints. 5. Preparation of Test Joints 5.1 Hard maple blocks (Acer saccharum or Acer nigrum), having a minimum sp gr of 0.65 based on oven-dry weight and volume shall be selected (Note). These blocks shall be of straight grain and free from defects including knots, birdseye, short grain, decay, and any unusual discolorations within the shearing area. The blocks shall be of suitable size preferably so thatfivetest specimens may be cut from one test joint as shown in Fig. 3. Blocks approximately 19 by 63.5 by 304 mm (Vi by 2'/2 by 12 in.) have been found to be satisfactory for this purpose. The grain direction shall be parallel to the longest dimension of the block. The blocks shall be at the equilibrium moisture content recommended by the manufacturer of the adhesive. In the absence of such recommendation, the moisture content shall be from 10 to 1 2 % based on oven-dry weight as determined on representative samples in accordance with Sections 122 to 125 of Mcth-  ods D 143. The blocks shall be surfaced, just prior to gluing, preferably with a hand-feed jointer, and the blocks weighed and assembled in pairs so that blocks of approximately the same specific gravity are glued together. The surfaces shall remain unsanded and shall be free from dirt. NOTE—A method for selecting maple blocks of satisfactory specific gravity is described in the Appendix to this method. For referee tests, the specific gravity of blocks may be determined in accordance with Section 115 of Methods D 143. 5.2 The adhesive shall be prepared and applied to the blocks in accordance with the procedure recommended by the manufacturer of the adhesive. The glue-coated blocks shall then be assembled and pressed, likewise in accordance with the recommendations of the manufacturer of the adhesive. 6. Conditioning of Test Joints 6.1 The joints, upon removal from pressure shall be conditioned at a relative humidity of 50 ± 2 % and at a temperature of 23 ± 1°C (73.4 ± 2°F) either for a period of 7 days or until specimens reach equilibrium as indicated by no progressive changes in weight, whichever is the shorter period. The length of this period of conditioning may be extended beyond this limit by written agreement between the purchaser and the manufacturer of the adhesive. 7. Preparation of Specimens 7.1 Cut the specimens as shown in Fig. 3 so that the grain direction is parallel to the direction of loading during test. Take care in preparing the test specimens to make the loaded surfaces smooth and parallel to each other and perpendicular to the height. Take care also in reducing the lengths of the laminations to 44.4 mm (l /4 in.) to ensure that the saw cuts extend to, but not beyond, the glue line. Measure the width and length of the specimen at the glue line to the nearest 0.25 mm (0.010 in.) to determine the shear area. 7.2 Retain specimens in the conditioning atmosphere described in Section 6 until tested, except during the cutting operations. 3  8. Procedure 8.1 Place the test specimen in the shearing 1  Annual  Honk of ASTM  Stumlurds.  V o l 04.09.  101  #  D 905  A  i  I  Metric Equivalents in.  'A  %  IV.  mm  6J  19  44.4  FIG. 2  2 50.8  F o r m and Dimensions of Test Specimen  APPENDIX (Nonmandatory Information) XI.  M E T H O D FOK S E L E C T I N G  MAPLE  BLOCKS  X1.1 Cut the hard maple blocks into some standard size such as 19 by 63.5 by 304 m m (Vi by 2'/J by 12 in.) after conditioning. Measure the linear dimensions o f the blocks in inches, using a suitable caliper or other  OF SATISFACTORY  SPECIFIC  GRAVITY  measuring device. Determine the percentage moisture content of the blocks in accordance with Sections 122 to 125 of Methods D 143. D o not use these samples in further tests.  102  0  905  tested, including type, source, manufacturer's code numbers, form, etc. 10.1.2 Application and bonding conditions used in preparing the specimens. 10.1.3 Conditioning procedure used for the specimens. 10.1.4 Temperature and relative humidity in the test room. 9. Calculation 10.1.5 Number of specimens tested. 9.1 Calculate the shear stress at failure in 10.1.6 Number of joints represented. pounds-force per square inch (or kilopascals) 10.1.7 Maximum and minimum shear based on the glue line area between the two stresscsat failure and percentages of wood failure. laminations measured to the nearest 0.06 cm The standard deviation or all individual test val(0.01 in. ), and report for each specimen together ues, or both, for the failing load values and wood with the estimated percentage of wood failure. failure values may be included in the report al the option of either the purchaser or the manu10. Report facturer of the adhesive. tool so that the load may be applied as described in Section 3. The position of the specimen in one type of shearing tool is shown in Fig. 1. Apply the loading with a continuous motion of the movable head at a rate of 0.37 mm (0.015 in.)/ min to failure as prescribed in Section 3.  2  2  10.1 The report shall include the following: 10.1.1 Complete identification of the adhesive TABLE I  Faclors for Corrected Weight in Crams  Moisture Content. „.  . . Factor  4  10.83  5  10.88  6  10.92  7  10.96  1  8  11.00  9  11.03  10  11.08  II  11.12  12  A  10.1.8 The average shear stress at failure and the average percentage of wood failure.  11.15  13 14  11.20  15  11.27  11.23  These values arc the weights o f ! i n . ' i n sugar maple i n  grams, at the moisture content values indicated, which would have a sp gr o f 0.65 o n the oven-dry weigh! and volume basis. Weigh all blocks to be used in the test at this moisture content: do  not use those blocks having a weight less than the above  calculated value.  103  #  X1.2 nearest  Calculate I cm  1  (0.1  the  volume  of the  blocks  to  D 905  the  in.') and express the average per-  centage moisture content to the nearest whole number. Determine the numerical value of the factor for this  which were conditioned to various moisture  content  values. X U  Multiply the factor iii 1 able I by lite volume  of the block in cubic inches to obtain the weight of the  moisture content by reference to Table 1. which is based  block in grams which would have a specific gravity of  on  0.65  0.65  hard maple blocks that have a specific gravity o n the oven-dry weight  and  of  on the oven-dry weight and volume basis.  volume basis and  The American Society for Tesline and Materials takes no position resinning the validity of any paten! riehl* abseiled in connection with any item mentioned in this standard. Users oflhts slandatd arc expressly advised that determination ol the volubly ol unv such patent rights, and the risk of infringement of such rights, are finitely their own responsibility. This slumlord Is subject to revision at any lime tiy Itie responsible teclltiiciilcommittee mid must tie icvii'ncd ever\' live \cuis anil if not revised, either reapproved or wittidrawn. Your comments are invited either for revision ol this standard or tor tnlduionul standards and should be addressed to ASTM Headquarters. Your comments will receive careful considcraiion al a mcciiny ol the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards. 1916 Race St.. Philadelphia. I'A 19103.  104 APPENDIX  III.  Designation: D 1107 — 84  Technical Association ol Pulp and Paper Industry Standard Method T 204 os-76  Standard Test Method for A L C O H O L - B E N Z E N E SOLUBILITY OF  WOOD  1  T h i s standard is issued under the fixed designation D 1107; the n u m b e r immediately following the designation indicates the year of original adoption or, in the case o f revision, the year o f last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (<) indicates an editorial change since the last revision or reapproval.  more rapidly than extractors with higher siphon tubes. 1.1 This test method covers the determination 3.2.3 Condenser of the Hopkins inner-cooled of the alcohol-benzene soluble content of wood, which is a measure of the waxes, fats, resins, and type. oils, plus tannins and certain other ether-insolu4. Reagent ble components. 4.1 Alcohol-Benzene Solution—Mix 1 volume 1.2 This standard may involve hazardous maof ethyl alcohol (95 %) and 2 volumes of chemiterials, operations, and equipment. This standard cally pure benzene. does not purport to address all of the safely prob4.1.1 Caution—This method requires the use lems associated with its use. It is the responsibilof benzene, lt has been established that exposure ity of whoever uses this standard to consult and to benzene may present a serious health hazard establish appropriate safety and health practices to humans. U. S. Government regulations adand determine the applicability of regulatory limiministered by the Occupational Safety and tations prior to use. Specific precautionary' stateHealth Administration are in effect which prements are given in Section 4.1.1. scribe rules and regulations on the use of benzene. These regulations must be consulted before 2. Significance and Use experimental programs employing benzene are 2.1 The alcohol-benzene extract of wood conundertaken. sists of the soluble materials not generally considered part of the wood substance. They are pri5. Test Specimen marily the waxes, fats, resins, and some gums, as 5.1 The test specimen shall consist of 2 g of well as some water-soluble substances. The air-dried sawdust that has been ground to pass a amounts are influenced by seasoning and drying. 425-|im sieve and be retained on a 250-u.m sieve. 1. Scope  1  3. Apparatus 3.1 Filtering Crucibles—Alundum or frittedglassfilteringcrucibles of coarse porosity. 3.2 Extraction Apparatus—A compact form of Soxhlet extraction apparatus, with groundglass joints, is preferable. The apparatus shall consist of the following items: 3.2.1 Soxhlet Extraction Flask having a capacity of 250 mL. 3.2.2 Soxhlet Extraction Tube, 45 to 50 mm in inside diameter, having a capacity to the top of the siphon of approximately 100 mL and a siphon tube approximately 55 mm in height. Extraction tubes of these dimensions siphon  6. Procedure 6.1 Weigh two 2-g test specimens in tared Alundum or fritted-glass crucibles. Dry one specimen in an oven for 2 h at 100 to 105°C, then place in a loosely stoppered weighing bottle, cool in a desiccator, and weigh. Continue the drying for 1-h periods until the weight is constant. Cal-  ' T h i s test method is under the jurisdiction o f A S T M C o m mittee D-7 o n W o o d and is the direct responsibility of S u b c o m mittee D 0 7 . I 4 on C h e m i c a l Tests. Current edition approved A p r i l 27, 1984. Published June 1984. Originally published as D 1 1 0 7 - 50. Last previous edition D 1107 - 56 (1979).  105  <# culatc the proportions of moisture-free sawdust in the air-dry specimen. 6.2 Place the other specimen in a Soxhlet extraction apparatus having a tared Soxhlet extraction flask. Set a small cone of fine-mesh screen wire in the top of the crucible to prevent loss of specimen. Extract with 150 mL of alcoholbenzene solution for 6 to 8 h, keeping the liquid boiling briskly. This-should provide four to six siphonings per hour. 6.3 After evaporating the solvent from the extraction flask, dry the flask and contents in an oven for l h at 100 to 105°C, cool in a dessicator, and weigh. Continue the drying until there is no further loss in weight.  D1107 free wood, calculated as follows: Alcohol - benzene soluble matter, %  = <,Wi/W P) x 100 s  where: W = weight of dried extract, 6.3, IV, = weight of test specimen used in 6.2, and P = proportion of moisture-free wood in the air-dry specimen (7.1). 7.2 The results shall be based on the average of at least two determinations. 2  8. Precision and Bias  2  8.1 Data obtained in a round robin test involving five laboratories indicate a repeatability of 11 % and a reproducibility of 20 %. 8.2 Bias is unknown.  7. Calculation and Report 7.1 Report the results as weight percentage of alcohol-benzene soluble matter in the moisture-  Data for this section obtained by the T e c h n c i a l Association o f the P u l p and Paper Industry, P . O . Box 105113, Atlanta, G A 30348. 1  The A merican Societyfor Test inn and Materials lakes no position respecting the validity ofany patent rights asserted in connect ion villi any item mentioned in this standard. Users of this standard arc expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed everyfiveyears and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards. 1916 Race St.. Philadelphia, Pa. 19103.  106  Designation: D1110 - 84  Technical Association o( Pulp and Paper Industry Standard Method T 207 om-81  Standard Test Methods for WATER SOLUBILITY OF WOOD  1  T h i s standard is issued under the fixed designation D 1110; the n u m b e r immediately following the designation indicates the year of original adaption or, in the ca>e o f revision, the year o f Inst revision, A number In parentheses indicates the year o f last reapproval. A superscript cpsilon (<) indicates an editorial change since the last revision or reapproval.  1. Scope  5. Procedure  1.1 These test methods cover the determina5.1 Place a 2-g test specimen, the moisture tion of the water solubility of wood. Two methcontent of which has been previously deterods are given, as follows: mined, in a 400-mL beaker, and cover with 300 mL of distilled water. Let this mixture digest at 1.1.1 Method A—Cold-Water Solubility— a temperature of 23 ± 2°C, with frequent stirring, This method provides a measure of the tannins, for 48 h. gums, sugars, and coloring matter in the wood. 5.2 Filter the material on an Alundum or 1.1.2 Method B—Hot- Water Solubility—Th is fritted-glass crucible, using suction, wash with method provides a measure of the tannins, gums, sugars, coloring matter, and starches in the wood. cold distilled water, and dry to constant weight 1.2 This standard may involve hazardous ma-at 100 to 105°C. Drying usually requires approximately 4 h. Place the crucible in a loosely stopterials, operations, and equipment. This standard pered weighing bottle, cool in a desiccator, and does not purport to address all of the safety probweigh. lems associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices 6. Report and determine the applicability of regulatory limi6.1 Report the results as percentage of matter tations prior to use. soluble in cold water, on the moisture-free basis, calculated as follows: 2. Significance and Use 2  2.1 Cold water removes a part of such extraneous materials as tannins, gums, sugars, and coloring matters. Hot water removes these plus the starches. M E T H O D A — C O L D - W A T E R SOLUBILITY  3. Apparatus 3.1 Filtering Crucibles—Alundum or frittedglass crucibles of coarse porosity will be required. 3.2 Filtering Flask—A suction filtering flask, equipped with a rubber flange for the crucible and funnel, shall be provided. 4. Test Specimen 4.1 The test specimen shall consist of 2 g of air-dried sawdust that has been ground to pass a 425-u.m sieve and be retained on a 250-um sieve.  C o l d water solubility. % =  [( H ' , -  M' )/M-',] x :  100  where: W\ — weight of moisture-free specimen used in ' 5.1, and H 2 = weight of dried specimen after extraction with cold water (5.2).  These lest methods arc under the jurisdiction o f A S T M C o m m i t t e e D - 7 o n W o o d a n d are the direct responsibility of Subcommitte D 0 7 . I 4 o n C h e m i c a l Tests. Current edition approved A p r i l 27, 1984. Published June 1984. Originally published as D 1 1 1 0 - S O T . Last previous edition D 1 1 1 0 - 5 6 ( 1 9 7 7 ) . F o r further information on these test methods, the following references may be consulted: Schorger. A . W . . " C h e m i s t r y o f Cellulose a n d W o o d s , " 1926, p 506. M c G r a w - H i l l . N . Y . H a w l c y a n d Wise. " C h e m i s t r y o f W o o d . " 1926. p. 134, C h e m i c a l Catalog C o . , N . Y . 1  1  107  # M E T H O D B — H O T - W A T E R SOLUBILITY  7. Apparatus 7.1 Digestion Apparatus—A 200-mL Erlenmeyer flask provided with a reflux condenser shall be used. 7.2 Water Bath, so constructed that the water can be maintained at boiling temperature and at a conslant-level just above the solution in the flask. 7.3 Filtering Crucible and Filtering Flask— See Section 3. 8. Test Specimen 8.1 See Section 4. 9. Procedure 9.1 Place a 2-g test specimen, the moisture content of which has been previously determined, and 100 mL of distilled water in the Erlenmeyer flask and attach the reflux condenser. Place the flask in the boiling water bath, with the solution in the flask just below the level of the water in the bath, and heat gently for 3 h. 9.2 Filter the contents of the flask on a tared Alundum or fritted-glass crucible, using suction, wash with hot water, and dry to constant weight  D1110  at 100 to 105°C. Place the crucible in a loosely stoppered weighing bottle, cool in a desiccator, and weigh. 10. Report 10.1 Report the results as percentage of matter soluble in hot water, on the moisture-free basis, calculated as follows: Hot water solubility, % = \{W, - W )/W,] x 100 2  where: H', = weight of moisture-free specimen used in 9.1, and Wi = weight of dried specimen after extraction with hot water (9.2). 11. Precision and Bias* 11.1 All data obtained in one laboratory by testing 20 woods. Repeatability,  Repeatability,  as Solubility, %  % o f Solubility  C o l d (1.1 to 6.3%)  0.14  5.7  H o t (1.6 to 9.0%)  0.15  3.8  11.2 Reproducibility and bias are unknown. D a t a i n this section obtained from the T e c h n i c a l Association o f the P u l p and Paper Industry, P . O . Box 105113, Atlanta, G A 30348. 1  The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards. 1916 Race St.. Philadelphia. Pa. 19103.  108  Designation: D1109 - 84  Technical Association of Pulp and Paper Industry Standard Method T 212 os-76  Standard Test Method for 1 % SODIUM HYDROXIDE SOLUBILITY OF WOOD  1  T h i s standard is issued under the fixed designation D 1109; the n u m b e r immediately following the designation indicates the year o f original adoption or, in the case o f revision, the year o f last revision. A number in parentheses indicates the year o f last reapproval. A superscript cpsilon (i) indicates an editorial change since the last revision or reapproval.  1. Scope 1.1 This test method covers the determination of the solubility of wood in a hot dilute alkali solution. A 1 % solution of Sodium hydroxide (NaOH) is used. One application is in determining the degree of fungus decay that has taken place in a given wood sample. As the wood decays, the percentage of alkali-soluble material increases in proportion to the decrease in pulp yield caused by the decay.  nearly level with the cover of the bath. By using this type of bath the sides of the beakers arc entirely surrounded by boiling water or steam. The water level in the bath shall be maintained above the level of the liquid in the beakers. 3.2 Beakers—The beakers shall be tall-form, 200-mL, alkali-resistant glass beakers. 3.3 Filtering Crucibles—Alundum or frittedglass crucibles of medium porosity are recommended for filtering the treated sawdust. 2  1.2 This standard may involve hazardous ma4. Reagents terials, operations, and equipment. This standard does not purport to address all of the safety prob- 4.1 Sodium Hydroxide Solution (7.0 % ) — A l low a chemically pure NaOH solution (50 %) to lems associated with its use. It is the responsibilstand about 1 week in a stoppered vessel to ity of whoever uses this standard to consult and permit settling of Na C03 and other insoluble establish appropriate safety and health practices and determine the applicability of regulatory limi-impurities. Dilute the supernatant clear solution with distilled water free of C 0 and adjust to tations prior to use. between 0.9 and 1.1 % NaOH. 2. Significance and Use 4.2 Acetic Acid (70 % ) . 2  2  2.1 Hot alkali extracts low molecular weight carbohydrates consisting mainly of hemicellulose and degraded cellulose in wood. This solubility of wood is an indication of the degree of fungal decay, or degradation by heat, light, oxidation, etc. The more decay or degradation, the higher the solubility. 3. Apparatus 3.1 Water Bath—The water bath shall be designed so that the temperature of the material during treatment is uniformly maintained at 97 to lOCC. When a new bath is used the temperature shall be checked to ensure the use of proper conditions. The type of bath recommended is one that is covered and that has holes in the top of such size that beakers may be set down in the bath until they are supported by the flared rim of the beakers. The top of the beaker shall be  5. Test Specimen 5.1 The test specimen shall consist of air-dried sawdust that has been ground to pass a 425-um sieve and be retained on a 250-|im sieve. The weight of the test specimen shall be such that it will be equivalent to 2 ± 0.1 g of moisture-free wood. 6. Procedure 6.1 Place two test specimens in 200-mL, tallform beakers and add to each 100 mL of NaOH ' T h i s test method is under the jurisdiction o f A S T M C o m mittee D - 7 o n W o o d a n d is the direct responsibility o f S u b c o m mittee D07.14 o n C h e m i c a l Tests. Current edition approved A p r i l 27, 1984. Published June 1984. Originally published as D 1 1 0 9 - SOT. Last previous edition D 1 1 0 9 - 5 6 ( 1 9 7 8 ) . Borosilicate glass has been f o u n d satisfactory for this purpose. 1  109  #  solution (1 %) measured carefully with a graduate. After stirring well, place the covered beakers in the water bath, which shall be boiling steadily. Leave the beakers in the bath for exactly 1 h, stirring the contents three times, at periods of 10, 15, and 25 min after the beakers are placed in the bath. 6.2 At the end of 1 h, filter the contents of each beaker by suction on a tared crucible. Wash the sawdust with 100 mL of hot water, then with 50 mL of acetic acid (10 %), and then thoroughly with hot water. Dry the crucible and contents to constant weight at 100 to 105°C, cool in a desiccator, and weigh in a stoppered weighing bottle. 7. Calculation and Report 7.1 Report the results as weight percentage of matter soluble in 1 % sodium hydroxide solution, on the moisture-free basis, calculated as follows: Matter soluble in caustic soda, % = [ W - Hy/H'i) x 100  D1109  where: H-'i = weight of moisture-free wood in specimen prior to test (Section 5), and \V = weight of dried specimen after treatment with the NaOH solution (6.2). 7.2 Base the results on the average of at least two determinations. 2  8. Precision and Bias  1  8.1 Results obtained from an interlaboratory study by nine laboratories on four woods indicate a repeatability of 0.45 and reproducibility of 1.96. The solubility of the wood samples ranged from 11.2 to 17.0%. 8.2 Bias is unknown.  Data in this section obtained by the T e c h n i c a l Association o f the Pulp a n d Paper Industry, P . O . Box 105113. Atlanta. G A 30348. 3  The American.Society for Testing and Materials lakes no position respecting the validity ofany patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards. 1916 Race St.. Philadelphia. Pa. 19103.  

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