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Molecular rheology of coniferous wood tissues Chow, Sue-Zone 1969

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MOLECULAR RHEOLOGY OF CONIFEROUS WOOD TISSUES by SUE-ZONE CHOW B . S c . N a t i o n a l Taiwan U n i v e r s i t y 1959 M . F . U n i v e r s i t y o f B r i t i s h Columbia 1966 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department o f F o r e s t r y We a c c e p t t h i s t h e s i s as con fo rming t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA December 1969 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree tha p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f p 0 P Q S t y y (Wood and Pu lp Science) The U n i v e r s i t y o f B r i t i s h Co lumbia V a n c o u v e r 8, Canada Date M a y . ?h% Supervisor: Professor J . W. Wilson ABSTRACT The time dependent molecular motions of wood components at s t r a i n i n g p a r a l l e l to f i b r e d i r e c t i o n were observed by i n f r a r e d p o l a r i z a t i o n technique. A two-stage molecular motion i n v o l v i n g three wood components, c e l l u l o s e , h e m i c e l l u l o s e and l i g n i n i s suggested as the course of wood molecular r e l a x a t i o n . The f i r s t stage begins at e q u i l i b r i u m , when the specimen i s not s t r e s s e d , and extends Immediately to a minimum d i c h r o i c r a t i o (4^ ) of carbo-hydrate components represented by l l 6 0 cm""* and 1730 cm"* bands, and the maximum dichroism of l i g n i n (1500 cm"^-). The second stage s t a r t s at the end of the f i r s t stage and extends to ; e q u i l i b r i u m recovery. Regardless of the form of e x t e r n a l e x c i t a t i o n (creep or s t r e s s r e l a x a t i o n ) , and the time of e x c i t a t i o n (ramp- or st e p - l o a d i n g ) , the b a s i c p a t t e r n of the two-stage molecular motion was fo l l o w e d , while damping of the molecules accompanied the whole r h e o l o g i c a l process. Thus, the wood macromolecular s t r u c t u r e maintains an " i n t e r n a l s t a t e " of e q u i l i b r i u m on r e c e i v i n g e x t e r n a l e x c i t a t i o n . This e q u i l i b r i u m s t a t e i s achieved by moving the carbohydrate and l i g n i n components i n opposite d i r e c t i o n s . The described p a t t e r n of molecular motion f o r a, component i n wood i s a compensatory r e s u l t from the i n t e r f e r e n c e i i i of other components. Removing one or more components from wood changes the motion patterns of the remaining components. The conformation of c e l l u l o s e i n the specimen without the presence of l i g n i n and h e m i c e l l u l o s e i s comparable to that of other s y n t h e t i c l i n e a r polymers. Energy t r a n s f e r system of wood was pos t u l a t e d as being due to the d i r e c t i o n a l movement of molecular components, which r e s u l t s l n a s s o c i a t i o n and high s t e r i c i n t e r f e r e n c e between carbohydrates and l i g n i n , s i m i l a r to c r o s s - l i n k e d chains of l i g n i n and carbohydrates. This energy t r a n s f e r system of wood i s f u r t h e r ^  f a c i l i t a t e d by the existence of a systematic s t r u c t u r e of wood m i c r o f i b r i l s which permits a zone of gradual t r a n s i t i o n from high c r y s t a l l i n i t y to a d i f f u s e s t a t e . The l i g n i n network of the system may do more than t r a n s f e r energy, I t may act a l s o as an "energy si n k " and thereby f u n c t i o n to maintain the memory of the e x c i t a t i o n . i v TABLE OF CONTENTS PAGE T ITLE PAGE i ABSTRACT i i TABLE OF CONTENTS i v L IST OF TABLES v i L IST OF FIGURES v i i ACKNOWLEDGEMENTS x INTRODUCTION 1 LITERATURE REVIEW 5 I. C o n i f e r o u s Wood M o r p h o l o g i c a l S t r u c t u r e 5 I I . Chemica l O r g a n i z a t i o n o f C o n i f e r o u s Wood 7 1. T r a c h e i d Wal l and Growth Zone Chemica l C o m p o s i t i o n . . 7 2. C e l l u l o s e L a t t i c e S t r u c t u r e 9 A . F r i n g e d - M i c e l l e Model 10 B. F r i n g e d - F i b r i l Model • 11 C . L a m e l l a r Model 12 3. The U n i t C e l l S t r u c t u r e and Hydrogen Bonding o f C e l l u l o s e 13 A . U n i t C e l l S t r u c t u r e . . . . . . . . . . 13 B. Hydrogen Bonding 13 4. O r i e n t a t i o n o f H e m i c e l l u l o s e s 15 A . A r a b i n o-4-0 - m e t h y l g l u c u r o n o - x y l a n 15 B. O - A c e t y l - g a l a c t o g l u c o m a n n a n s 17 5. O r i e n t a t i o n o f L i g n i n . . . . . . . 18 PAGE I I I . R h e o l o g i c a l B e h a v i o u r o f Wood 22 IV. I n f r a r e d S p e c t r o p h o t o m e t r i c Study o f W o o d . . . . . . 27 MATERIALS AND METHODS 33 I. Wood Specimens 33 I I . Chemica l Treatments 0 . 3^ I I I . M i c r o - m e c h a n i c a l Techn iques 35 IV. O p t i c a l Techn iques 4Q RESULTS 5^ DISCUSSION „ 5.1 I. O r i e n t a t i o n , C r y s t a l l i n i t y and S y s t e m a t i c S t r u c t u r e o f Wood 5 l I I . Wood M o l e c u l a r R e l a x a t i o n 58 1. P a t t e r n s o f Wood M o l e c u l a r R e l a x a t i o n 58 2. V a r y i n g M o l e c u l a r R e l a x a t i o n A c r o s s A Annua l Increments 59 3 . The Wood M o l e c u l a r R e l a x a t i o n M e c h a n i s m . . . . . 60 I I I . R e l a t i o n s h i p Between Wood M o l e c u l a r R e l a x a t i o n and S t r e s s R e l a x a t i o n 63 1. D e l i g n i f i c a t i o n and Wood F i n e S t r u c t u r e 63 2. M o l e c u l a r R e l a x a t i o n 65 3 . S t r e s s R e l a x a t i o n , 66 IV. Proposed Mechanism f o r the M o l e c u l a r Mot ion i n Wood Under S t r e s s 70 CONCLUSIONS .' 74 LITERATURE CITED 7? v i L IST OF TABLES PAGE TABLE 1. THE CHEMICAL COMPOSITION OF CELL WALT. LAYERS ACCORDING TO MEIER (117, 118) 9^ TABLE 2 . THE CHEMICAL COMPOSITION OF GROWTH ZONES (Pinus s y l v e s t r i s ( L . ) ACCORDING TO MEIER (118) 9k TABLE 3 . THE UNIT CELL STRUCTURE OF CELLULOSES . . . . . . 95 TABLE k. THE BRIDGING ANGLE FOR 1 , k - O - p - Q - L I N K A G E OF CELLULOSIC MATERIALS 95 TABLE 5. THE UNIT CELL STRUCTURE OF XYLAN ( 1 0 8 ) . 96 TABLE 6. THE UNIT CELL DIMENSIONS OF XYLAN HYDRATE AND CELLULOSE II (108) 96 TABLE 7 . BAND ASSIGNMENTS IN WOOD INFRARED S P E C T R A . . . 97 TABLE 8. WOOD TISSUE SAMPLING PROCEDURE 100 TABLE 9. DICHROISM OF WOOD COMPONENTS OBSERVED AT 1160, 1500 and 1730 CM-1 WAVE NUMBERS 101 TABLE 10. INTRA-INCREMENTAL RELAXATION OF THE ll60 C M " 1 COMPONENT (CELLULOSE) IN DOUGLAS FIR WOOD... 102 TABLE 11 . INTRA-INCREMENTAL RELAXATION OF THE 1730 C M " 1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR WOOD 103 TABLE 12. INTRA-INCREMENTAL RELAXATION OF THE 1 5 0 0 C M " 1 COMPONENT(LIGNIN) IN DOUGLAS FIR WOOD 10^ TABLE 13. INTRA-INCREMENTAL RELAXATION OF THE ll60 C M " 1 COMPONENT (CELLULOSE)IN BALSAM FIR WOOD 105 TABLE l * * . INTRA-INCREMENTAL RELAXATION OF THE 1730 C M " 1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR WOOD 106 TABLE 15 . INTRA-INCREMENTAL RELAXATION OF THE 1 5 0 0 C M " 1 COMPONENT (LIGNIN) IN BALSAM FIR WOOD 107 TABLE 16. EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON RELAXATION OF THE ll60 C M " 1 COMPONENT (CELLULOSE) IN DOUGLAS FIR EARLYWOOD 108 v i i PAGE TABLE 17. EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 C M - 1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR EARLYWOOD 109 TABLE 18. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON RELAXATION OF THE 1160 C M " 1 COMPONENT (CELLULOSE) IN DOUGLAS FIR LATEWOOD 110 TABLE 19. EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM-1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR LATEWOOD I l l TABLE 20. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON RELAXATION OF THE l l 6 0 C M " 1 COMPONENT (CELLULOSE) IN BALSAM FIR EARLYWOOD 112 TABLE 21. EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM-1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR EARLYWOOD 113 TABLE 22. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON RELAXATION OF THE l l 6 0 CM""1 COMPONENT (CELLULOSE) IN BALSAM FIR LATEWOOD 114 TABLE 23. EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 C M " 1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR LATEWOOD 115 TABLE 24. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON STRESS DECREMENT OF DOUGLAS FIR EARLYWOOD DURING RELAXATION 116 TABLE 25. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON STRESS DECREMENT OF DOUGLAS FIR LATEWOOD DURING RELAXATION 118 TABLE 26. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON STRESS DECREMENT OF BALSAM FIR EARLYWOOD DURING RELAXATION 120 TABLE 27. EFFECTS OF REMOVING LIGNIN, THEN HEMI-CELLULOSE ON STRESS DECREMENT OF BALSAM FIR LATEWOOD DURING RELAXATION 122 v i i i FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 4. FIGURE 5. FIGURE 6. FIGURE 7. FIGURE 8. FIGURE 9. FIGURE 10. LIST OF FIGURES PAGE PHOTOGRAPHS SHOWING THE RAMP-LOADING APPARATUS (A) AND ITS POSITION IN THE INSTRUMENT (B), AND THE STEP-LOADING APPARATUS .(C) AND ITS POSITION IN THE INSTRUMENT (D) 124 INFRARED POLARIZATION SPECTRA ( II AND 1 ) OF DOUGLAS FIR "REGULAR " AND COMPRESSION WOOD TISSUES (ARROW INDICATES THE 1160 CM_1BAND)... 125 RELATIONSHIP BETWEEN LIGNIN (1500 CM""1) AND CELLULOSE (1160 CM".1..).. ORIENTATION FOR VARIOUS WOOD TISSUES 126 ELECTRON PHOTOMICROGRAPHS OF BALSAM FIR LATEWOOD CROSSSECTION FOLLOWING DELIGNIFICATION (a,Q MIN; b,60 MIN; AND c,2k0 MIN) AND FAILURE-IN TENSION PARALLEL TO GRAIN. CELL WALL LAYERS(P. S-, S 2 AND S3) AND MIDDLE LAMELLA (ML) 127 DEPENDENCE OF DICHROIC RATIOS AT l l 6 0 AND 1730 CM-1 ON LIGNIN CONTENT OF DOUGLAS FIR AND BALSAM FIR WOOD TISSUES 128: X-RAY DIFFRACTION PATTERNS OF DOUGLAS FIR WOOD TISSUES FOLLOWING DIFFERENT LEVELS OF CHLORITE DELIGNIFICATION 129 EFFECT OF DELIGNIFICATION LEVEL ON CRYSTALLINITY OF WOOD TISSUES 130 RELATIONSHIP BETWEEN X-RAY TOTAL CRYSTAL-LINITY AND ORIENTATION-ANGLE OF THE WOOD CELLULOSE, 1,4-0-p-D-LINKAGE 131 INTRA-INCREMENTAL RELAXATION OF THE 1160 CM"1 COMPONENT (CELLULOSE) IN DOUGLAS FIR WOOD TISSUES 132 INTRA-INCREMENTAL RELAXATION OF THE 1730 CM"1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR WOOD TISSUES 133 Ix PAGE FIGURE 11. INTRA-INCREMENTAL RELAXATION OF THE 1500 CM-1 COMPONENT (LIGNIN) IN DOUGLAS FIR WOOD T I S S U E S . . . 13 4 FIGURE 12. MOLECULAR MOTION OF WOOD CARBOHYDRATE COMPONENTS DURING CREEP TEST OF BALSAM FIR WOOD TISSUES 13 5 FIGURE 13. EXCITATION TIME EFFECTS ON THE MOLECULAR RELAXATION OF THE 1730 CM-1 COMPONENT IN BALSAM FIR WOOD TISSUES 13 6 FIGURE 14. THE EFFECT OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON RELAXATION OF THE 1160 CM-1 COMPONENT (CELLULOSE) IN DOUGLAS FIR EARLYWOOD TISSUES 137 FIGURE 15. THE EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM-1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR EARLYWOOD TISSUES 13 8 FIGURE 16. THE EFFECT OF REMOVING LIGNIN, THEN HEMICELLULOSE ON RELAXATION OF THE 1160 CM-1 COMPONENT (CELLULOSE) IN DOUGLAS FIR LATEWOOD T I S S U E S . . 13 9 FIGURE 17. THE EFFECT OF REMOVING LIGNIN ON RELAXATION * * OF THE 1730 CM-1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR LATEWOOD T I S S U E S . . 140 FIGURE 18. EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON PHYSICAL STRESS RELAXATION OF DOUGLAS FIR EARLYWOOD TISSUES 141 FIGURE 19. EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON PHYSICAL RELAXATION OF DOUGLAS FIR LATEWOOD TISSUES 142 X ACKNOWLEDGEMENTS The author wishes to express h i s g r a t i t u d e to Dr. J.W. Wilson, Professor, F a c u l t y of F o r e s t r y , U n i v e r s i t y of B r i t i s h Columbia, under whose d i r e c t i o n t h i s t h e s i s was accomplished. A p p r e c i a t i o n i s a l s o due the author's committee f o r t h e i r c o n s t r u c t i v e c r i t i c i s m and review of t h i s t h e s i s , and to Dr. R.E. Foster, D i r e c t o r , and colleagues of the Forest Products Laboratory, Department of F i s h e r i e s and Fo r e s t r y , Vancouver, f o r p r o v i d i n g e d u c a t i o n a l leave and f o r use of lab o r a t o r y f a c i l i t i e s and equipment. S p e c i a l thanks are due Dr. L. Bach, Department of C i v i l Engineering, Technical U n i v e r s i t y , Copenhagen, f o r h i s valuable c r i t i c i s m and suggestions during the progress of the experiments, to Dr. R.T. L i n , School of Fo r e s t r y , Oregon State U n i v e r s i t y , f o r s e r v i n g as e x t e r n a l examiner of the t h e s i s , and to Dr. R.W. Meyer, Forest Products Laboratory, Vancouver, f o r p r o v i d i n g e l e c t r o n photomicrographs. Thanks are a l s o due to Dr. K.B. Harvey, Prof e s s o r , Department of Chemistry, ; f o r h i s generous permission to use the Perkin-Elmer 421 I n f r a r e d spectrophotometer f o r primary experiments of the t h e s i s , and to Dr. J.A. Gower, Ass o c i a t e Professor, Department of Geology, f o r a s s i s t a n c e i n X-ray spectrophotometry. G r a t e f u l a p p r e c i a t i o n i s a l s o due the author's parents f o r t h e i r c o n t i n u i n g encouragement, and to my w i f e , Nobu, f o r as s i s t a n c e i n p r e p a r a t i o n of the manuscript, and handling the noise of my young son, Gordon. INTRODUCTION I t may be t h e o r i z e d t h a t p h y s i c a l m e c h a n i c a l c h a r a c t e r i s t i c s o f p o l y m e r i c m a t e r i a l s a r e the combined m o l e c u l a r response t o e x t e r n a l e x c i t a t i o n . C l a s s i c a l e l a s t i c i t y and v i s c o s i t y t h e o r i e s , which I n t e r p r e t m e c h a n i c a l b e h a v i o u r s as i d e a l i z e d s o l i d s and p e r f e c t f l u i d s , do not a d e q u a t e l y e x p l a i n t h e s e e v e n t s . M o l e c u l e s a r e kept from f l o w i n g I n d e f i n i t e l y th rough f o r m a t i o n o f t h r e e -d i m e n s i o n a l networks e i t h e r by c h e m i c a l bond ing o r by growth o f c r y s t a l l i n e r e g i o n s (133). T h e r e b y , m o l e c u l a r p a c k i n g r e p r e s e n t s an e q u i l i b r i u m c o n d i t i o n a p p r o a c h i n g s t a b i l i t y . . When e x t e r n a l e x c i t a t i o n i s a p p l i e d , the system undergoes d e f o r m a t i o n o r f l o w . Mot ion of m o l e c u l e s depends on t h e i r -c o m p o s i t i o n and h i s t o r y , as w e l l as magnitude and n a t u r e o f the e x t e r n a l f o r c e . Rheology i s the s c i e n c e d e a l i n g w i t h d e f o r m a t i o n and f low o f m a t t e r , e s p e c i a l l y as c h a r a c t e r i z e d by i n t e r d e p e n d e n c e o f s t r e s s , s t r a i n and t i m e . S e v e r a l means may be used f o r o b s e r v i n g m o l e c u l a r r h e o l o g y , such as b i r e f r i n g e n c e , n u c l e a r magnet ic r e s o n a n c e , d i e l e c t r i c c o n s t a n t and more r e c e n t l y , ; i n f r a r e d d i c h r o i s m . , B i r e f r i n g e n c e has been the most w i d e l y used method. I t s a p p l i c a t i o n t o i l l u s t r a t e dynamic m o l e c u l a r r e l a x a t i o n has been s u c c e s s f u l l y per formed w i t h some s i m p l e polymers (155» 169, 171, 1 9 0 ) . One r e c e n t example i s the b i r e f r i n g e n c e s tudy of p o l y v i n y l c h l o r i d e r e l a x a t i o n by Utsuo and S t e i n ( 1 9 0 ) . T h e i r r e s u l t s show the development o f n e g a t i v e b i r e f r i n g e n c e as polymer f i l m s were s u b j e c t e d t o t e n s i l e s t r a i n . Dur ing - 2 -r e l a x a t i o n the n e g a t i v e b i r e f r i n g e n c e g r a d u a l l y r e d u c e d , w h i l e the s u s t a i n e d s t r e s s d e c r e a s e d a t a s i m i l a r r a t e . Both b i r e f r i n g e n c e and d i e l e c t r i c c o n s t a n t t e c h n i q u e s s u f f e r from a f a c t o f g r o s s n e s s , i n t h a t they r e p r e s e n t compos i te sample p r o p e r t i e s and thereby do not r e f l e c t b e h a v i o u r s o f i d e n t i f i a b l e m o l e c u l e s o r c h e m i c a l groups (179). w h i l e n u c l e a r magnet ic resonance 1 Q 1 3 i s l i m i t e d to the o b s e r v a t i o n o f p r o t o n , F , C and a few o t h e r n u c l e i , and i s d i f f i c u l t t o a p p l y t o s o l i d s . In c o n t r a s t , d i c h r o i s m o b t a i n e d by p o l a r i z e d I n f r a r e d methods may be made ; s p e c i f i c f o r g i v e n f u n c t i o n a l g r o u p s . Thereby , d i c h r o i s m r e p r e s e n t s t r a n s i t i o n a l moment d i r e c t i o n s w i t h r e s p e c t t o the m o l e c u l a r c h a i n a x i s and i s u s e f u l f o r a p p r o x i m a t i o n s w i t h many a b s o r p t i o n bands (33,149 ,205). * The f i r s t o b s e r v a t i o n on d i c h r o i s m o f polymers w i t h p o l a r i z e d i n f r a r e d r a d i a t i o n was made by Bath and E l l i s i n ; 1940* (7. 3 4 ) . Because of equipment l i m i t a t i o n s , however, the use of I n f r a r e d d i c h r o i s m f o r dynamic s tudy of polymer r e l a x a t i o n was on ly r e p o r t e d a f t e r 1965 (48, 49, 92, 135), f i v e y e a r s a f t e r development o f the w i re g r i d p o l a r i z e r (11, 33)• In t h i s r e c e n t p e r i o d , Gotoh et a l .(48, 49) r e p o r t e d t h a t s t r e t c h i n g o f v u l c a n i z e d n a t u r a l rubber s u b j e c t e d t o , t e n s i l e s t r a i n gave r i s e t o i n s t a n t a n e o u s d i c h r o i s m o f some i n f r a r e d bands. They f u r t h e r n o t e d c o r r e s p o n d e n c e between change o f d i c h r o i s m f o r amorphous bands, and s t r e s s r e l a x a t i o n . The c r y s t a l l i n e band (844 cm""l), on the o t h e r hand, comple ted o r i e n t a t i o n a lmost immediate ly a f t e r e l o n g a t i o n . S t r e s s r e l a x a t i o n was thus a t t r i b u t e d to m o l e c u l a r r e o r i e n t a t i o n i n - 3 -amorphous regions. A d i c h r o i s m - s t r e s s behaviour has been reported a l s o during r e l a x a t i o n of phenyl methyl s i l i c o n e polymer ( 9 2 ) . Further, Onogi and Asada (135) a l s o demonstrated w i t h polyethylene that i n f r a r e d a b s o r p t i o n bands a t 720 cm*"i (amorphous) and 730 cm" 1 ( c r y s t a l l i n e ) a t t a i n an e q u i l i b r i u m s t a t e about one second a f t e r t e n s i l e s t r e s s i n g of specimens. There are a few s t u d i e s on polymers which describe changes of i n f r a r e d dichroism a t d i f f e r e n t r a t e s of el o n g a t i o n . Polymers examined i n t h i s way have been polyethylene (83, 85, 1 4 9 , 1 7 0 ) , polypropylene ( 1 5 5 ) t polyethylene t e r e p h t h a l a t e ( 8 4 ) and p o l y v i n y l c h l o r i d e (172). In no instance have wood or wood products been stud i e d i n these ways. Wood i s an extremely complex m a t e r i a l . I t s main components are macromolecular systems known as c e l l u l o s e , h e m i -c e l l u l o s e and l i g n i n . These may occur as separated or con-tinuous arrangements i n the wood matrix, and may be permeated p a r t l y w i t h extraneous m a t e r i a l s . The comprehensive study of wood molecular dynamics r e q u i r e s d e t e c t i o n techniques not a v a i l a b l e w i t h b i r e f r i n g e n c e , nuclear magnetic resonance or d i e l e c t r i c constant methods. I d e a l l y , the approach should enable s e l e c t i v e study of f u n c t i o n a l group a c t i v i t i e s w i t h the nat i v e or t r e a t e d wood matrix. The p o l a r i z e d i n f r a r e d technique could provide such an approach. Three hypotheses were set f o r examination i n the present study. F i r s t , t h a t wood molecular a c t i v i t y accompanies p h y s i c a l -mechanical e x c i t a t i o n , t h a t t h i s may be observed by s u i t a b l e technique, and when observed w i l l be found t o be time dependent. Second, t h a t each major wood component has an i n d i v i d u a l time dependent p a t t e r n of molecular motion, and t h a t some major component must d i f f e r d i r e c t l o n a l l y from the others i n order to provide the unique property of damping i n wood. T h i r d , t h a t energy t r a n s f e r i n wood r e q u i r e s the p a r t i c i p a t i o n of a l l major components, and that the mechanism i s s e r i o u s l y modified by adjustment of the system. - 5 -LITERATURE REVIEW I. C o n i f e r o u s Wood M o r p h o l o g i c a l S t r u c t u r e Two s p a t i a l systems o f t i s s u e o r g a n i z a t i o n e x i s t i n the wood o f c o n i f e r o u s s tems. The a x i a l system c o n s i s t s m o s t l y o f l o n g i t u d i n a l t r a c h e i d s , w h i c h compr ise up to 9 0 p e r cen t o f the wood volume and over 9 5 p e r cent o f the wood weight ( 1 1 3 i 136, l 4 l ) . The r a d i a l system l i e s p e r p e n d i c u l a r t o the stem a x i s and i n c l u d e s m o s t l y ray parenchyma c e l l s . Depending on s p e c i e s , o t h e r minor c e l l t ypes may o c c u r i n v a r y i n g amounts. Wood m o r p h o l o g i c a l u n i t s a r e h e l d as a m a t r i x by l i g n i n . The l i g n i n r i c h i n t e r - c e l l u l a r l a y e r i s c a l l e d the m i d d l e l a m e l l a (M). The c e l l w a l l i t s e l f was observed e a r l y ( 7 8 ) as h a v i n g a l a y e r e d s t r u c t u r e . These l a y e r s a r e known as the pr imary w a l l (P) which i s t h i n and a d j o i n s the m idd le l a m e l l a (M), and the t h i c k secondary w a l l which i s f u r t h e r s u b d i v i d e d as an o u t e r ( S ^ ) , c e n t r a l (S2) and sometimes i n n e r (S3) l a y e r . As e x a m p l e , c e l l w a l l l a y e r t h i c k n e s s o f Japanese r e d p i n e (Pinus d e n s l f l o r a S i e b . e t Z u c c . ) ear lywood t r a c h e i d s a r e r e p o r t e d ( 5 3 ) as 0 . 6 u ( P ) , 0 . 3 1 }x ( S 1 ) , 1 . 9 3 u ( S 2 ) and 0 . 1 7 P-(S3). D i f f e r e n c e s i n t h i c k n e s s and p r o p o r t i o n i n g o f l a y e r s appear i n the a s s o c i a t e d l a t e w o o d . M i c r o f i b r i l o r i e n t a t i o n w i t h i n c e l l w a l l s v a r i e s w i t h the c e l l l a y e r s and has been e x t e n s i v e l y s t u d i e d as r e g a r d s m e c h a n i c a l and p h y s i c a l importance ( 5 3 » 1 * * 5 . 1 9 * 0 . M i c r o f i b r i l s i n the pr imary w a l l a r e thought to be randomly a r r a n g e d and much permeated w i t h l i g n i n ( 2 7 , 5 3 ) . The pr imary w a l l , h o w e v e r , has been r e p o r t e d as a two l a y e r e d s t r u c t u r e ( 1 2 6 , 1 9 4 ) . - 6 -M i c r o f i ' b r i l s of the S i l a y e r a r e o r i e n t e d a t h i g h a n g l e s to the t r a c h e i d a x i s , p r o v i d i n g f l a t h e l i c a l p a t t e r n s ( 5 3 ) . Dunning (27) found t h a t t h e r e were a t l e a s t t h r e e l a m e l l a e i n the S i l a y e r . These l a m e l l a e appeared as a l e f t o r r i g h t hand h e l i x w i t h m i c r o -f i b r i l s a t a n g l e s o f 65 to 75 degrees to the f i b r e a x i s . The dominant S 2 l a y e r shows a s teep h e l i c a l s t r u c t u r e , o r i e n t e d a t a n g l e s o f 20 t o 30 degrees to ear lywood t r a c h e i d axes and 5 t o 10 degrees w i t h la tewood t r a c h e i d axes i n Japanese c e d a r [Cryptomer la j a p o n l c a (Linnaeus f i l . ) Don.] and Hondo spruce ( P i c e a j e z o e n s l s Maxim.) ( 5 3 ) . A c c o r d i n g to e s t i m a t e s o f Harada (53) and Jayme and Pengel (68, 69) t h i s l a y e r o c c u p i e s about 78/6 o f the whole w a l l t h i c k n e s s . In l o n g l e a f p i n e (P inus  p a l u s t r i s M.) l a tewood , the m i c r o f i b r i l a l ignment appeared to be very u n i f o r m ( 2 7 ) . The p e r f e c t i o n o f S 2 p a r a l l e l i s m . i s g r e a t e r f o r la tewood than ear lywood ( 5 3 ) . The S3 l a y e r has a f l a t h e l i c a l p a t t e r n s i m i l a r t o . t h e S i l a y e r (53) and a l t e r n a t i n g l a m e l l a e w i t h d i f f e r e n t o r i e n t a t i o n s o c c u r i n the l a y e r . Prom the above , i t i s apparent t h a t m i c r o f i b r i l o r g a n i z a t i o n i n the c e l l w a l l v a r i e s c o n s i d e r a b l y between the d i f f e r e n t c e l l w a l l l a y e r s , as w e l l as between d i f f e r e n t c e l l s i n the same growth i n c r e m e n t . The h i g h p a r a l l e l i s m o f the S 2 l a y e r , wh ich o c c u p i e s t h r e e - q u a r t e r s o r more of the t o t a l c e l l w a l l a r e a , a n d the g r a d u a l t r a n s i t i o n from the S 2 m i c r o f i b r i l p a t t e r n to t h a t o f S i and S3 l a y e r s through l a m e l l a r system g i v e s the Impress ion t h a t wood i s o r g a n i z e d w i t h purpose a t the u l t r a c e l l u l a r l e v e l . These b i o l o g i c a l p r o v i s i o n s c o u l d r e l a t e i n some impor tant ways to wood r h e o l o g l c a l b e h a v i o r . I I . C h e m i c a l O r g a n i z a t i o n o f C o n i f e r o u s Wood ! • T r a c h e i d Wal l and Growth Zone Chemica l C o m p o s i t i o n C o n i f e r o u s wood i s composed o f c a r b o h y d r a t e s , l i g n i n and l e s s e r amounts o f v a r i o u s ex t raneous s u b s t a n c e s . R i t t e r (151). f i r s t r e p o r t e d t h a t 75$ o f the c o n i f e r o u s wood l i g n i n i s l o c a t e d i n the m i d d l e l a m e l l a . T h i s concept was extended by Bai]ey (5).who found by a n a l y s i s f o l l o w i n g m i c r o - d i s s e c t i o n t h a t the midd le l a m e l l a o f Douglas f i r [ P s e u d o t s u g a m e n z i e s i i (Mirb) Franco) i s compr ised o f 70% l i g n i n and \h% p e n t o s a n s . T h i s l i g n i n c o n c e n t r a t i o n was l a t e r c o n f i r m e d by u l t r a v i o l e t a b s o r p t i o n s t u d i e s o f Lange (90) , who c o n c l u d e d a l s o t h a t t h e r e was i n c r e a s i n g l l g n i f i c a t i o n i n the o u t e r l a y e r s o f the secondary w a l l and i n the p r imary w a l l toward a maxima l n the m idd le l a m e l l a . R e c e n t l y , B e r l y n and Mark (10) rev iewed e a r l i e r d a t a and c a l c u l a t e d l i g n i n d i s t r i b u t i o n i n the c e l l w a l l by c o n s i d e r i n g thai; the compound midd le l a m e l l a c o m p r i s e s a p p r o x i m a t e l y 10 t o 12 pe r cen t o f the volume i n c o n i f e r o u s wood. T h e r e b y , l i g n i n c o n t e n t o f the secondary w a l l appears t o be about 8 6 . 4 p e r cen t o f the t o t a l l i g n i n l n compar ison w i t h 13.6 p e r c e n t i n the compound midd le l a m e l l a . T h i s p o s t u l a t i o n i s v e r i f i e d by S c o t t et a l . ( l 6 0 ) i n a r e c e n t exper iment . E l e c t r o n : m i c r o s c o p i c o b s e r v a t i o n s of Sachs et a l .(153) have demonstrated u n i f o r m d i s t r i b u t i o n o f l i g n i n i n the S 2 l a y e r a c o n t i n u o u s network i n the c e l l w a l l . The p a t t e r n o f l i g n i n d i s t r i b u t i o n i n c o n i f e r o u s woods can be a l t e r e d by c o n d i t i o n s o f t r e e g rowth . A good example - 8 -i s c o m p r e s s i o n wood,which has h i g h e r l i g n i n c o n t e n t than the a s s o c i a t e d r e g u l a r wood ( 2 1 ) . Compress ion wood t r a c h e i d s a r e found a l s o t o have an a d j u s t e d o r g a n i z a t i o n o f w a l l l a y e r s , i n t h a t an i s o t r o p i c l a y e r w i t h h i g h l i g n i n c o n c e n t r a t i o n o c c u r s Immediately i n s i d e the S^ l a y e r ( 2 2 ) . The d i s t r i b u t i o n o f p o l y s a c c h a r i d e s i n c o n i f e r o u s wood c e l l w a l l l a y e r s was s t u d i e d by Me ie r ( 1 1 7 t 1 1 8 ) arid M e i e r and W i l k i e ( 1 1 9 ) • T h e i r r e s u l t s w i t h S c o t s p i n e [ p i n u s s y l v e s t r i s (L.) ) and European spruce £ P i c e a a b l e s (L.) a r e summarized i n T a b l e 1 . They c o n c l u d e d t h a t maximum amounts< o f c e l l u l o s e and glucomannan o c c u r i n the S 2 l a y e r , w h i l e the S^ l a y e r has the h i g h e s t v a l u e s o f g l u c u r o n o a r a b i n o x y l a n . The r a d i a l d i s t r i b u t i o n o f h e m i c e l l u l o s e s i n c e l l w a l l s was demonstrated a l s o by Luce ( 1 0 2 ) , w h o employed a c h e m i c a l p e e l i n g t e c h n i q u e . R e s i d u a l x y l a n and mannan o f unb leached and b l e a c h e d p u l p s were found t o be h i g h l y c o n c e n t r a t e d a t the f i b r e s u r f a c e i n the pr imary w a l l and midd le l a m e l l a r e g i o n s and to d e c r e a s e toward the lumen. A r a d i a l d i s t r i b u t i o n f o r c e l l u l o s e degree o f p o l y m e r i -z a t i o n (DP) i n c e l l w a l l s was proposed by Jayme and Von Koppen ( 7 0 ) , where the pr imary w a l l DP has lowest and the S^ l a y e r maximum v a l u e s . T h i s p a t t e r n o f DP d i s t r i b u t i o n i s s u p p o r t e d by e x p e r i m e n t a l d a t a o f L u c e ( 1 0 2 ) . The uneven d i s t r i b u t i o n o f t r a c h e i d w a l l c h e m i c a l c o n s t i t u e n t s has been advanced as e x p l a n a t i o n o f c h e m i c a l d i f f e r e n c e s between ear lywood and l a t e w o o d , m o s t l y as a r e s u l t o f the t h i c k e r la tewood S 2 l a y e r ( 1 1 8 , 1 8 3 ) . The r e l a t i v e percen tages o f c a r b o h y d r a t e c o n s t i t u e n t s i s o l a t e d from S c o t s p i n e ear lywood and la tewood by Me ier (118) a r e shown i n T a b l e 2 . In c o n t r a s t t o M e i e r ' s v a l u e s , I f j u (65) showed t h a t Douglas f i r ear lywood c o n t a i n e d more a r a b a n and x y l a n than l a t e w o o d , w h i l e the la tewood had more g a l a c t a n than e a r l y w o o d . The l l g n i n - c a r b o h y d r a t e r a t i o i n wood has been a s u b j e c t o f s t u d y . Three t o f i v e p e r c e n t h i g h e r l i g n i n c o n t e n t o f r ear lywood i n c o n t r a s t to the a s s o c i a t e d la tewood has been ; r e p o r t e d by many r e s e a r c h e r s ( 2 0 , 5 0 , 8 9 , 9 4 , 9 5 . 1 9 8 , 2 0 1 ) . In a d d i t i o n , W u and W i l s o n (201) and Chow (20) u s i n g u l t r a v i o l e t and i n f r a r e d s p e c t r o p h o t o m e t r i c methods i n d e p e n d e n t l y showed t h a t minimum l i g n i n c o n t e n t o c c u r s r e g u l a r l y i n the l a s t - f o r m e d la tewood w h i l e maximum l i g n i n c o n t e n t i s not found u s u a l l y i n the f i r s t formed e a r l y w o o d , b u t more o f t e n somewhat l a t e r i n the growth s e a s o n . T h i s p a t t e r n o f l i g n i n v a r i a t i o n l e d t o the p o s t u l a t i o n (201) t h a t the i n i t i a l ear lywood t i s s u e a r i s i n g from " o v e r w i n t e r e d " x y l a r y mother c e l l s has some "memory" f a c t o r as c h e m i c a l p r e d i s p o s i t i o n towards the p r e c e d i n g s e a s o n ' s g rowth . In more r e c e n t work on l i g n l n - c a r b o h y d r a t e b a l a n c e . w i t h i n growth i n c r e m e n t s , S q u i r e (168) p o s t u l a t e d t h a t p r o p o r t i o n i n g o f wood a l p h a - c e l l u l o s e and l i g n i n i s m a n i p u l a t e d by a m u t u a l l y e x c l u s i v e p r i n c i p l e . 2 . C e l l u l o s e L a t t i c e S t r u c t u r e The c e l l u l o s e c r y s t a l u n i t c e l l , i s c e l l o b i o s e which i s formed from two g l u c o s e r e s i d u e s l i n k e d by the 1 ,4-0-^3-D-gly cos i d l e b o n d . Length o f the (po ly ) g l u c o s e o r c e l l u l o s e macromolecule i s g i v e n by degree o f p o l y m e r i z a t i o n (DP) measurements. C e l l u l o s e DP e s t i m a t e s va ry w i th the - 1 0 -source of m a t e r i a l s , methods of i s o l a t i o n and means used f o r measuring and c a l c u l a t i n g data. The DP of wood c e l l u l o s e s has been reported by Goring and T i m e l l (47) to be 7 5 0 0 f o r jack pine (Pinus bankslana Lamb.), and 8 0 0 0 f o r Engelmann spruce [ P i c e a engelmannll (Parry) Engelm.) . A d i f f e r e n c e between earlywood and latewood c e l l u l o s e DP of Douglas f i r was reported by I f j u ( 6 5 ) as 5 2 5 0 and 5 6 6 0 , r e s p e c t i v e l y . I f length of the c e l l o b i o s e u n i t i s accepted as 1 0 . 3 A ( l 6 7 ) , t h e o wood c e l l u l o s e c h a i n l e n g t h appears to range up t o 80,000 A, thereby transcending numerous areas of supermolecular order. The long c e l l u l o s e chains are thought to be arranged according to some supermolecular order, the exact nature of : which has been the subject of much argument, and remains a current i s s u e . Pine l a t t i c e s t r u c t u r e s are proposed as amorphous, p a r a c r y s t a l l l n e , p e r f e c t c r y s t a l , c r y s t a l defect model, f r i n g e d m i c e l l e , f r i n g e d f i b r i l and a l a m e l l a r model (57). In a d d i t i o n , a p r o t o f i b r i l concept has been Introduced r e c e n t l y (104,175). Three of the most used explanations have been the f r i n g e d - m l c e l l e , f r i n g e d - f i b r i l and l a m e l l a r models. A. F r l n g e d - M l c e l l e Model This i s an e a r l y model proposed by Herrmann et a l . ; i n 1930 ( 5 9 ) to account f o r observations of polymer molecules and t h e i r behaviour. The long molecule Is considered as threading through s e v e r a l adjacent c r y s t a l l i n e and n o n c r y s t a l l i n e ( f r i n g e ) regions (14). A c c o r d i n g l y , amorphous and c r y s t a l l i n e regions c o e x i s t , i n t e r a c t and r e s i s t s e paration (14). For wood c e l l u l o s e , Frey-Wyssling (4l) f u r t h e r proposed a gradual t r a n s i t i o n between the c r y s t a l l i n e and amorphous - 1 1 - ;• s t a t e s . The c r y s t a l l i n e r e g i o n s a r e a r r a n g e d a t r e g u l a r i n t e r v a l s but s c a t t e r e d a l o n g the a x i s a t random. T h i s concept o f c e l l u l o s e f i n e s t r u c t u r e i s suppor ted by M a r c h e s s a u l t (108) and Mark (113) w i t h some m o d i f i c a t i o n s . M a r c h e s s a u l t (108) suggested t h a t c r y s t a l l i z e d c e l l u l o s e r e g i o n s a r e segrega ted as f i b r i l s , w h i l e o r i e n t e d h e m i c e l l u l o s e s occupy the i n t e r f i b r l l l a r s p a c e . Mark (113), w i t h h i s concept o f s t r e s s a n a l y s i s , p roposed t h a t the s h o r t c r y s t a l l i n e c e l l u l o s e r e g i o n i s e n d - c o u p l e d w i t h h e m i c e l l u l o s e d u r i n g the s y n t h e s i s o f m l c r o f i b e r s , w h i l e the n o n - c r y s t a l l i n e c e l l u l o s e i s d e p o s i t e d between c r y s t a l l i n e r e g i o n s a t a l a t e r s t a g e . B. F r i n g e d - F i b r l l Model T h i s model was i n t r o d u c e d by H e a r l e (55. 56, 57) because the f r i n g e d - m i c e l l e concept does not e x p l a i n s a t i s f a c t o r i l y the a p p a r e n t l y i n f i n i t e l e n g t h o f m i c r o f i b r i l s observed w i t h e l e c t r o n m l c r o s c o p y (56, 166) and the p r o c e s s o f p o l y m o l e c u l a r growth by s p h e r u l l t i c a r rangement . T h i s concept p e r m i t s s u c c e s s i v e growth o f c r y s t a l l i t e s g i v i n g a c o n t i n u o u s d e n d r i t i c network. In t h i s mode l , the f i b r i l s a r e assumed to be l o n g , 3 i m p e r f e c t , p o s s i b l y branched c r y s t a l s made up o f c o m p a r a t i v e l y s h o r t segments o f c e l l u l o s e c h a i n s packed t o g e t h e r . Any one l o n g - c h a i n m o l e c u l e p a s s e s a l t e r n a t e l y th rough a number o f c r y s t a l l i n e f i b r i l s and through the n o n - c r y s t a l l i n e r e g i o n s between them. T h i s theory a p p l i e d to c o t t o n c e l l u l o s e s t r u c t u r e r e c e i v e d the suppor t o f T r i p p et a l . (186) . However, the model has been c r i t i c i z e d by M i c h i e e_t a l . (122) i n a p p l i c a t i o n to r a y o n , and by Mark (113) and Cowdrey and P r e s t o n (23) i n -12-a p p l i c a t i o n t o wood t r a c h e i d s . D isagreements a r e based on i n a b i l i t y o f the model to e x p l a i n observed f i b r e m e c h a n i c a l p r o p e r t i e s . A c c o r d i n g t o H e a r l e ( 5 6 , 57) . the f r i n g e d - m l c e l l e s t r u c t u r e i s p a r t o f a l a r g e r f r i n g e d - f i b r i l s t r u c t u r e h a v i n g ve ry s h o r t f i b r i l l a r l e n g t h . C . L a m e l l a r Model The I n d i v i d u a l c e l l u l o s e c h a i n s o f t h i s m o d e l , a s suggested by K e l l e r (77 ) # a r e c o n s i d e r e d t o f o l d back on themse lves w i t h r e g u l a r i t y p r o v i d i n g a form t h a t i s much t h i n n e r i n the d i r e c t i o n o f the c h a i n than the l e n g t h o f the c h a i n I t s e l f . S t r u c t u r e s o f t h i s type a r e p roven f o r v a r i o u s m a t e r i a l s I n c l u d i n g c e l l u l o s e d e r i v a t i v e s , as by Manley ( 1 0 4 ) , who used e l e c t r o n d i f f r a c t i o n t e c h n i q u e s . Man ley*s f i n d i n g was r e c e n t l y suppor ted by S u l l i v a n ( 1 7 5 ) f o r c e l l u l o s e s from s i x p i n e s and"two pored woods. T h i s mode l , however, has been c r i t i c i z e d by Mark ( 1 1 3 ) because i t does not s a t i s f y the observed p h y s i c a l and m e c h a n i c a l b e h a v i o u r s o f wood c e l l w a l l s , which a r e c h a r a c t e r i z e d by low e x t e n s i b i l i t y , ve ry h i g h s t r e n g t h , and l a c k o f g l a s s t r a n s i t i o n b e h a v i o u r which i s a l s o t y p i c a l ; o f s y n t h e t i c p o l y m e r s . I t i s b e l i e v e d t h a t none o f the above t h r e e models : c o m p l e t e l y e x p l a i n the p h y s i c a l and m e c h a n i c a l b e h a v i o u r o f wood, which Is not f u l l y u n d e r s t o o d a t t h i s s t a g e . Lack * i o f b e t t e r u n d e r s t a n d i n g r e l a t e s to v a r i a t i o n s i n n a t i v e c e l l w a l l s t r u c t u r e , c o m p l i c a t i o n s i n t r o d u c e d by the p r e s e n c e o f l i g n i n and h e m l c e l l u l o s e s and d i f f i c u l t i e s In i s o l a t i o n of] pure sys tems . - 1 3 -3. The U n i t C e l l S t r u c t u r e and Hydrogen Bonding o f C e l l u l o s e A . U n i t C e l l S t r u c t u r e The c r y s t a l l i n e n a t u r e o f c e l l u l o s e was f i r s t demonstra ted by Nishikawa and Ono i n 1913 (129). T h e i r d i s c o v e r y opened a new f i e l d f o r s t u d y i n g c e l l u l o s e s t r u c t u r e . In 1921, P o l a n y i ( 1 6 7 } *pub l i shed the f i r s t u n i t c e l l d imens ions and p o s t u l a t e d t h a t a u n i t c e l l o f the o b s e r v e d d imens ions c o u l d accommodate f o u r g l u c o s e r e s i d u e s . S p o n s e l e r (167 f r e v i s e d P o l a n y i ' s concept , a d d i n g t h a t two g l u c o s e u n i t s c o m p r i s e d the u n i t c e l l ( b - a x i s o f the c e l l ) . R e s u l t s o f v a r i o u s s t u d i e s on u n i t c e l l d imens ions a r e r e c o r d e d i n T a b l e 3 . The l i t e r a t u r e on u n i t c e l l d imens ions f o r c e l l u l o s e s t r e a t e d by a c i d , amine and s a l t has been summarized by Rydholm ( 1 5 2 ) . Values o f u n i t c e l l d imens ions as l i s t e d i n t h e s e s o u r c e s va ry g r e a t l y . In a d d i t i o n , g r e a t v a r i a t i o n i n m i c r o f i b r i l w i d t h i s " r e p o r t e d , i . e . , r a n g i n g between 30 t o 300 £ ( 1 2 3 ) . A n g u l a r arrangement of the b r i d g i n g 1,4-0-^3-D-linkage a l s o . v a r i e s a c c o r d i n g to d i f f e r e n t a u t h o r s as shown i n T a b l e 4, B. Hydrogen Bonding The na tu re o f f o r c e s which h o l d the u n i t c e l l s t r u c t u r e l n s p a t i a l form has been rev iewed up t o 19^0 by Mark (112). Whi le the concept o f hydrogen bonding i s i n t r o d u c e d , d e t a i l e d u n d e r s t a n d i n g o f bonding mechanisms i s l a c k i n g . F u r t h e r examina t ion o f c e l l u l o s e hydrogen bonding has been f a c i l i t a t e d by p r o g r e s s w i t h i n f r a r e d s p e c t r o m e t r y , whereby M a r r i n a n and Mann (106, 114, 115) d e s c r i b e d i n a ; s e r i e s o f papers the p o s s i b l e na ture o f hydrogen bondings w i t h i n the c e l l u l o s e u n i t c e l l as deduced from i n f r a r e d * O r i g i n a l not s e e n . C i t e d from l i t e r a t u r e (167). - In-spec t r a i n the 3300 cm~* wave number (3 wavelength) r e g i o n . A l l c e l l u l o s e h y d r o x y l groups were found to engage i n hydrogen bonding (114), a l t h o u g h the u n i t c e l l s t r u c t u r e s f o r c e l l u l o s e s I, II and I I I were d i f f e r e n t (106, 115). A l l t h r e e c r y s t a l l i n e m o d i f i c a t i o n s showed tha t some h y d r o x y l groups make a r e l a t i v e l y s m a l l a n g l e w i t h the c h a i n d i r e c t i o n , whereas o t h e r s show; a n g l e s g r e a t e r than 55 degrees (106). S i n c e o n l y h y d r o x y l groups which form i n t r a m o l e c u l a r hydrogen bonds cause s m a l l , a n g l e s w i t h the c h a i n d i r e c t i o n (73), the p o s s i b l e i n t r a m o l e c u l a r bonds which l i n k s u c c e s s i v e g l u c o s e u n i t s i n c e l l u l o s e c h a i n s were i n f e r r e d as 0-3. . . •> 0-5 and 0-2. . . ^0-6 (where dashed l i n e s r e f e r to a d j a c e n t r e s i d u e s o f the same c h a i n and the number noted r e p r e s e n t s the p o s i t i o n o f oxygen i n the pyranose u n i t ) (73). A f u r t h e r s tudy by Jones (74) on c e l l o t e t r a o s e s i n g l e c r y s t a l s , which a r e s i m i l a r to c e l l u l o s e II , showed the l i k e l i h o o d o f f a u l t s and d i s t o r t i o n s i n the c e l l u l o s e c r y s t a l . T h i s o b s e r v a t i o n on d i s o r d e r i n the c e l l u l o s e c r y s t a l l i n e s t r u c t u r e was c o n f i r m e d by P o p p l e t o n and Math ieson (143). The i n f r a r e d s p e c t r a o f n a t i v e c e l l u l o s e i n the 3300 cm""1 wave number r e g i o n was a l s o examined by L i a n g and M a r c h e s s a u l t (98). From d i f f e r e n c e i n p o l a r i z a t i o n o f OH s t r e t c h i n g b a n d s , a s l i g h t l y m o d i f i e d system o f hydrogen bond ing was proposed f o r the c r y s t a l s t r u c t u r e o f c e l l u l o s e I. I t seems t h a t ; c o n f o r m a t i o n o f the c e l l o b i o s e u n i t p e r m i t s i n t r a m o l e c u l a r hydrogen bonding between the C-3 h y d r o x y l and the r i n g oxygen o f a c o n t i g u o u s g l u c o s e u n i t . I n t e r m o l e c u l a r hydrogen bonds i n the 101 p l ane were proposed between the C-6 h y d r o x y l s o f a n t i p a r a l l e l c h a i n s and the b r i d g e oxygens o f a d j a c e n t p a r a l l e l c h a i n s . The C5 h y d r o x y l s o f the p a r a l l e l c h a i n s were thought t o be hydrogen-bonded t o the b r i d g e oxygens o f a d j a c e n t a n t i p a r a l l e l c h a i n s i n the 101 p l a n e . Hydrogen bonds i n the 101 p lane were e x p l a i n e d as s h o r t e r t h a n those i n the 101 p l a n e . S i m i l a r r e s u l t s were observed by the same a u t h o r s w i t h m e r c e r i z e d c e l l u l o s e (110) . The i n t r a m o l e c u l a r hydrogen 1b o n d i n g between 0 - 3 of one r e s i d u e and the r i n g oxygen o f the a d j a c e n t r e s i d u e i s suggested by J a c o b s o n e t a l . ( 6 6 ) as the b a s i c f a c t o r c o n t r o l l i n g r e l a t i v e o r i e n t a t i o n o f the c e l l o b i o s e u n i t . 4 . O r i e n t a t i o n o f H e m l c e l l u l o s e s A . A r a b i n o - 4 - 0 - m e t h y l g l u c u r o n o - x y l a n X y l a n was the f i r s t h e m i c e l l u l o s e f r a c t i o n r e p o r t e d a s o r i e n t e d w i t h i n wood t i s s u e s (96, 108, 111). In the n a t i v e s t a t e A t h i s p o l y s a c c h a r i d e i s b e l i e v e d to sur round c e l l u l o s e m i c r o f i b r i l s as a somewhat amorphous m a t r i x (108, 19^, 1 9 6 ) . The x y l a n o f c o n i f e r o u s woods was f i r s t r e p o r t e d by Dut ton and Smith (29, 30) as a backbone o f D - x y l o s e u n i t s , j o i n t e i b y 1 , 4 - 0 - p - D - H n k a g e , t o which u n i t s o f 4 - O - m e t h y l - D -g l u c u r o n l c a c i d a r e a t t a c h e d a t G - 2 , and o c c a s i o n a l L - a r a b i n o f u r a n o s e r e s i d u e s o c c u r a t the x y l a n C - 3 . Separa ted c o n i f e r o u s x y l a n s have a DP o f about 120 u n i t s , and c o n t a i n one a c i d s i d e c h a i n p e r f i v e o r s i x x y l o s e r e s i d u e s , w h i l e one a r a b i n o s e o c c u r s p e r seven to e i g h t x y l o s e u n i t s (182) . The e x i s t e n c e o f 0 - a c e t y l g roups i n n a t i v e 4 - 0 - m e t h y l g l u c u r o n o a r a b l n o - x y l a n s have been shown to be a t t a c h e d t o x y l o s e r e s i d u e s , but t h e i r d i s t r i b u t i o n has not been e s t a b l i s h e d as ye t ( 1 5 ) . - 1 6 -Th e X - r a y d iagram o f an o r i e n t e d x y l a n sample has been shown t o be e n t i r e l y d i f f e r e n t from t h a t o f c e l l u l o s e (108) . The backbone c o n f o r m a t i o n was p o s t u l a t e d as c o r r e s p o n d i n g t o a t h r e e f o l d screw symmetry w i t h an advance of 5 A* Per o r e s i d u e ( " f i b r e r e p e a t " be ing 15 A) and r o t a t i o n o f 1 2 0 ° . The i n f r a r e d spectrum of s e p a r a t e d x y l a n has r e v e a l e d a h i g h e r f requency o f OH bands a s s o c i a t e d w i t h i n t r a m o l e c u l a r b o n d i n g , than found w i t h c e l l u l o s e II , i n d i c a t i n g a l o n g e r 0 - 3 . . 0 - 5 d i s t a n c e . I t was c o n c l u d e d t h a t a c o n f o r m a t i o n I n c l u d i n g . a t h r e e f o l d screw symmetry o c c u r s i n the x y l a n m o l e c u l e . In f u r t h e r work, S e t t i n e r i and M a r c h e s s a u l t (164) r e p o r t e d t h a t the l e f t - h a n d e d h e l i x o f the s e p a r a t e d x y l a n was a more p r o b a b l e c o n f o r m a t i o n f o r lf 4 - a n h y d r o - ^ 3 - D - x y l o s e . C a l c u l a t e d parameters f o r x y l a n c h a i n s w i t h 0 - 3 . . . 0 - 5 d i s t a n c e a t 3.0 A* a r e r e c o r d e d i n T a b l e 5 (108) . D i r e c t d r y i n g o f x y l a n h y d r a t e f i l m s , w h e n x y l a n c o n t a i n e d 4 - 0 - m e t h y l g l u c u r o n l c a c i d , w a s found to p r o v i d e p a t t e r n s o f i low c r y s t a l l i n l t y (204) . No l a y e r l i n e s t r u c t u r e was observed In the X - r a y d iagram (108) , p o s s i b l y due t o a more compact l a t t i c e which would not accommodate the u r o n i c a c i d w i thout d e f o r m a t i o n . U n i t c e l l d imens ions f o r the x y l a n h y d r a t e as compared w i t h C e l l u l o s e II by M a r c h e s s a u l t (108) a r e shown i n T a b l e 6 . Based on these u n i t c e l l d imens ions a c o -c r y s t a l l i z a t i o n has been p o s t u l a t e d (108) between x y l a n and c e l l u l o s e which forms a low o r d e r l a t t i c e . T h i s i s c o n s i s t e n t w i t h the v iew of A s t b u r y e t a l . ( l ) , but has been q u e s t i o n e d by C a u l f i e l d (19) . D e a c e t y l a t i o n and m i l d h y d r o l y s i s s t u d i e s on n a t i v e x y l a n , show an o v e r a l l s h a r p e n i n g o f X - r a y diagrams and the - re -f o r m a t i o n o f a new t y p i c a l x y l a n r e f l e c t i o n . M a r c h e s s a u l t e t a l . (108, 109) argued t h a t x y l a n i s c r y s t a l l i z e d i n s i d e the f i b r e c e l l w a l l s f o l l o w i n g o r i e n t a t i o n o f the main a x i s , i . e . p r e f e r e n t i a l l y p a r a l l e l t o t h a t o f the c e l l u l o s e . T h i s p o s t u l a t i o n i s c o n s i s t e n t w i t h the concept o f Cowdry and P r e s t o n ( 2 3 ) . I t s h o u l d be n o t e d , however, t h a t the h i g h l y branched s t r u c t u r e o f c o n i f e r o u s x y l a n s c o u l d p reven t c r y s t a l f o r m a t i o n i n the c e l l w a l l (93. 127). In c o n i f e r o u s wood, the r a y c e l l s have been r e p o r t e d to c o n t a i n more x y l a n t h a n t r a c h e i d s ( l 4 l ) . S i n c e by v o l u m e . t h e s e ray c e l l s account f o r o n l y 5 t o 10% o f the t o t a l wood volume a.nd the s t r u c t u r e o f r a y c e l l x y l a n s has not been r e p o r t e d , the e f f e c t o f t h i s x y l a n on wood p r o p e r t i e s may be o n l y of secondary i m p o r t a n c e . B. O - A c e t y l - g a l a c t o g l u c o m a n n a n s The O - a c e t y l - g a l a c t o g l u c o m a n n a n s a r e the predominant h e m i c e l l u l o s e o f c o n i f e r o u s woods. T h i s h e m i c e l l u l o s e was f i r s t r e p o r t e d by Hami l ton e t a l . i n 1956 ( 5 1 . 5 2 ) . The m o l e c u l a r b a c k -bone c o n s i s t s o f / 3 -D -g lucopyranose and j3-D-mannopyranose r e s i d u e s , (1-4) l i n k e d , and p r o b a b l y d i s t r i b u t e d a t random. Some u n i t s have an oi - D - g a l a c t o p y r a n o s e r e s i d u e d i r e c t l y a t t a c h e d t o G - 6 , w h i l e the 0 - a c e t y l groups a r e d i s t r i b u t e d a t G-2 and C-3of the mannose u n i t s w i t h about the same number o f groups i n each o f t h e s e p o s i t i o n s (100 ,101) . The DP o f s e p a r a t e d glucomannans has been measured a t 60 t o 140 hexose r e s i d u e s (118, 181, 182, 183) . A f t e r d e a c e t y l a t l o n , the s e p a r a t e d ga lac tog lucomannan c a n be c r y s t a l l i z e d (101, 204) . X-Ray diagrams have shown t h a t g l u c o -mannans may be c l o s e l y a s s o c i a t e d w i t h c e l l u l o s e m i c r o f i b r i l s ± as between the c e l l u l o s e c h a i n s (127). Removal o f the m a n n a n - r i c h h e m i c e l l u l o s e f r a c t i o n -18-sharpens the 002 d i f f r a c t i o n peak, which indicates greater packing perfection for the c e l l u l o s e c r y s t a l l i n e m i c r o f i b r i l structure. The l i n e a r molecular chains of glucomannan are believed to be deposited i n p a r a l l e l with the c e l l u l o s e m i c r o f i b r i l surface ( 2 3 , 147). 5. Orientation of Lignin Lignin,which i s comprised mainly of phenylpropane , units (17), has been considered as the encrusting substance of the woody plant c e l l matrix. The detailed structure of poly-molecular l i g n i n ln_ s i t u i s complex and partly obscure at the present time. Lignin i s generally believed to be a three-dimensional macromolecule. It i s f i r s t recognized a f t e r completion of the c e l l u l o s e skeleton (193» 195)• During wood maturation l i g n i n i s f i r s t observed at c e l l primary wall corners, and subsquently i t appears to extend to the i n t e r c e l l u l a r layer and among various layers of the secondary wall i n association with hemicellulose. L i g n i f i c a t i o n l i m i t s further surface enlargement of the c e l l s by immobilizing those components of the matrix which permit surface growth to take place (194). Consequently, the c e l l wall becomes r i g i d , strong and somewhat fixe d . Because of the highly branched nature of polymolecular l i g n i n , It has not been anticipated as having a c r y s t a l l i n e structure i n wood. Orientation of l i g n i n i n the c e l l wall, however, has been the subject of some argument. Prey (39) i n 1928 found that the incrustation of c e l l wall l i g n i n did not change the birefringence of c e l l walls and concluded that l i g n i n occurs i n an amorphous state, with incorporation In -19-th e c e l l wall representing a swelling phenomenon. The discovery of u l t r a v i o l e t (UV) dichroism (-j£=1.2 or 4=f.=0.83) at 280 mu f o r l i g n l f i e d wood c e l l walls by Lange (90) suggested that l i g n i n was oriented inside the c e l l wall, since native wood carbohydrates do not absorbe UV l i g h t at t h i s wave length. The dichroism found was explained as "intrinsic".meaning a true e f f e c t of l i g n i n o rientation. This discovery prompted Frey-Wyssllng (40) to further investigation of the problem with u l t r a v i o l e t and fluorescent dichroism. Frey-Wyssling stated that Lange's view of l i g n i n orientation seemed plausible, since a , l a t t i c e of graphite-like layers was shown in isolated cuprpxam l i g n i n by Jodl (71) and the monomeric molecules of polymeric l i g n i n are in part c o n i f e r y l alcohol. These units show a system of conjugated double bonds which cause absorption of UV l i g h t . The amount -of absorbed l i g h t d i f f e r s in p a r a l l e l and perpendicular p o l a r i z a t i o n according to alignment with the aromatic ring,of the molecule. Thus, a s u f f i c i e n t number of equally oriented molecules should y i e l d a dichrolc e f f e c t v i s i b l e in the p o l a r i z i n g microscope. This coincides with the observation of Pearl pn experimental r e s u l t s of Kringstad and E l l e f s e n (88), who studied, lignin-carbohydrate bonding by comparison of polysaccharide molecular weight d i s t r i b u t i o n following stepwise d e l l g n i f i c a t i o n of holocelluloses. Pearl (138) explained that l i g n i n In the holocellulose occurs in the form of short, non-crosslinked: branches in the polysaccharide chain which could be e a s i l y accommodated and oriented Inside the carbohydrate l a t t i c e . Although the r e s u l t s of Frey-Wyssling show also a , -20-s l i g h t " i n t r i n s i c " dichroism, he d e c l a r e d the UV dichroism observed w i t h i n l l g n i f i e d c e l l w a l l s to be "form""anisotropy due to a r o d l e t composite body, which m i r r o r s the ordered c e l l u l o s i c supermolecular s t r u c t u r e . C a r e f u l examination of i n f r a r e d p o l a r i z a t i o n s p e c t r a on t h i n wood s e c t i o n s recorded by Liang et a l . (96) c l e a r l y shows dichroism f o r the 1500 cm""* l i g n i n band of western red cedar (Thuja p l i c a t a Donn),although the o r i g i n a l authors deny p o l a r i z a t i o n e f f e c t s f o r l i g n i n . This i s an important p o i n t , s i n c e p o l a r i z a t i o n i s p r e r e q u i s i t e to dichroism. The p h y s i c a l a s s o c i a t i o n between l i g n i n and c e l l u l o s e has beea e x t e n s i v e l y i n v e s t i g a t e d * Preston and. a s s o c i a t e s (1, 1^4) examined the e f f e c t of d e l i g n i f i c a t i o n on X-ray patterns f o r p l a n t t i s s u e s and found that the treatments produced l i t t l e change. This l e d to the c o n c l u s i o n t h a t l i g n i n d i d not penetrate the c e l l u l o s e m i c e l l e s t r u c t u r e (1, 144, 1 9 6 ) . On the other hand, Wardrop-(191, 193) and Wardrop and Preston (196) showed th a t wood d e l i g n i f i c a t i o n changed the l i n e breadth corresponding to the 002 planes i n X-ray diagramsof mountain ash (Eucalyptus regnans E ) . The c a l c u l a t e d apparent c r y s t a l s i z e f o r wood c e l l u l o s e and h o l o c e l l u l o s e i n d i c a t e d an increase of 18,8% i n c r y s t a l l i n i t y , which was c o n s i s t e n t w i t h values obtained f o r h y d r o l i z e d c e l l u l o s e c r y s t a l s . In f u r t h e r experiments, Wardrop (192, 193) reported t h a t h y d r o l y s i s during d e l i g n i f i c a t i o n and subsequent h y d r o l y s i s of h o l o c e l l u l o s e products produced aggregated clumps of m i c r o f i b r i l s v i s i b l e i n e l e c t r o n microscopy. This was a t t r i b u t e d to c r y s t a l l i z a t i o n of the l e s s ordered para-c r y s t a l l i n e s t r u c t u r e surrounding the m i c r o f i b r i l s , which had been prevented from c r y s t a l l i z a t i o n i n the o r i g i n a l specimens - 2 1 -by l i g n i n i n f i l t r a t i o n . Thereby , the change i n m i c r o f i b r i l o r d e r was suggested as ana logous to changes between m i c e l l e s w i t h i n the m i c r o f i b r i l s t h a t cause s h a r p e n i n g o f d i f f r a c t i o n l i n e s . Wardrop (193) a rgued t h a t some o f the c e l l w a l l l i g n i n must be a s s o c i a t e d w i t h the p a r a c r y s t a l l i n e phase o f c e l l u l o s e . The e f f e c t s on X - r a y d i f f r a c t i o n p a t t e r n s o f c h l o r i t e d e l i g n i f i c a t i o n and a l k a l i n e e x t r a c t i o n o f h e m l c e l l u l o s e s i w i t h s l a s h p i n e (Pinus c a r i b a e a M.) was s t u d i e d by Ne lson (127). The r e s u l t s showed t h a t the 101 p l u s 101 peak I n t e n s i t i e s , r e m a i n e d r e l a t i v e l y c o n s t a n t , w h i l e the 002 peak i n t e n s i t y i n c r e a s e d g r e a t l y . The 002 peak change, however, may o r may not have r e p r e s e n t e d an i n c r e a s e i n c r y s t a l l i t e w i d t h . The changes were e x p l a i n e d ass (1) l a t e r a l u n i o n o f c r y s t a l l i t e s which had been m a i n t a i n e d as s e p a r a t e s t r u c t u r e s by l i g n i n i n the whole wood; (I I) r e d u c t i o n o f l i q u i d type l i g n i n s c a t t e r i n g , a l l o w i n g , c r y s t a l l i t e p o r t i o n s to d i f f r a c t a g r e a t e r share o f energy d u r i n g a n a l y s e s ; o r ( i l l ) r e l i e f o f minor s t r a i n s o r d i s t o r t i o n s i n the c e l l u l o s e framework imposed by c e l l w a l l g rowth , the presence o f l i g n i n o r d r y i n g . F o r these r e a s o n s , l i g n i n was p o s t u l a t e d as e x t r a c r y s t a l l i n e . L a t e r , Sachs et a l . ( 1 5 3 ) showed o r i e n t a t i o n o f l i g n i n around the S j c e l l w a l l l a y e r o f l o b l o l l y p i n e (P inus taeda L. ) and whi te spruce by e l e c t r o n m i c r o s c o p y . T h i s f i n d i n g a g r e e s w i t h the e a r l i e r o b s e r v a t i o n o f Jayme and Fenge l (69), Sachs et a l . ( 1 5 3 ) f u r t h e r r e p o r t e d the p r e s e n c e o f h i g h d e n s i t y ; l i g n i n i n the compound midd le l a m e l l a , where a l a y e r e d l i g n i n s t r u c t u r e appears t o e x i s t . -22-S i n c e t h e r e has been l i t t l e r e s e a r c h d e a l i n g d i r e c t l y w i th l i g n i n o r i e n t a t i o n , i t i s ex t remely d i f f i c u l t t o d e f i n e the exact c o n t r o v e r s i a l c o n c e p t s o f t h i s t o p i c . I I I . R h e o l o g l c a l B e h a v i o u r o f Wood L i t e r a t u r e on wood r h e o l o g y , p u b l i s h e d b e f o r e 1962* was rev iewed by K i n g s t o n (79) , Pentoney (139)t and Pentoney a n d . Dav idson ( l 4 0 ) . L i t e r a t u r e p u b l i s h e d between 1957 and e a r l y 1968 was rev iewed r e c e n t l y by Schnlewlnd (158). Only some p o i n t s r e l e v a n t t o the p r e s e n t s tudy a r e d i s c u s s e d h e r e . , Creep and s t r e s s r e l a x a t i o n t e s t s a r e two approaches used i n s tudy o f wood r h e o l o g l c a l b e h a v i o u r . The c r e e p t e s t i s c h a r a c t e r i z e d by a c o n s t a n t l o a d w i t h changes i n s t r a i n o r d e f o r m a t i o n measured o v e r t i m e . In the s t r e s s r e l a x a t i o n t e s t , on the o t h e r hand, the s t r a i n i s kept c o n s t a n t and the change o f s t r e s s a r i s i n g w i t h l a p s e d t ime i s observed (31» I 6 5 ) . Creep compl iance and s t r e s s r e l a x a t i o n appear t o be r e l a t e d f o r m a t e r i a l s which approx imate l i n e a r v i s c o e l a s t i c i t y (2). T h i s has been d e s c r i b e d a s , " the same a n i m a l , . b u t : i t s s k i n i s s t a i n e d a d i f f e r e n t c o l o u r " (4). Thereby , i t Is p o s s i b l e . t h a t one response f u n c t i o n can be c a l c u l a t e d from the o t h e r , a t convergence o f the known f u n c t i o n (2). S t r e s s r e l a x a t i o n o f wood was f i r s t s t u d i e d twenty, y e a r s ago by K i tazawa (80) , who examined g r o s s wood c o m p r e s s i o n p e r p e n d i c u l a r t o the g r a i n . R e l a x a t i o n t ime was o b s e r v e d o v e r the t ime range o f one to one thousand m i n u t e s . H i s e m p i r i c a l e q u a t i o n f o r s t r e s s decay was : - 2 3 -S(f) 61 = 1 - m l o g t &(f) Si = f r a c t i o n a l s t r e s s r e l a x a t i o n t b a s e d on s t r e s s a t one m i n u t e . t = t ime m = c o n s t a n t ; a r e l a x a t i o n c o e f f i c i e n t . From these r e s u l t s w i t h a v a r i e t y o f s p e c i e s a l i n e a r v i s c o e l a s t i c b e h a v i o u r was i n d i c a t e d . L i n e a r v i s c o e l a s t i c i t y f o r s t r e s s r e l a x a t i o n i n c o m p r e s s i o n and t e n s i o n p e r p e n d i c u l a r to the g r a i n was found a l s o by Young (203) i n b e n d i n g , and i n t e n s i o n p a r a l l e l t o the g r a i n by Johnson ( 7 2 ) . I t s h o u l d be no ted t h a t i n v e s t i g a t o r s have d i s r e g a r d e d the wood r e l a x a t i o n response w i t h i n the f i r s t m i n u t e . Thekr r e s u l t s o f t e n show a n o n - l i n e a r b e h a v i o u r a t h i g h s t r a i n . As Bach (2) p o i n t e d o u t , "The v i s c o e l a s t i c m e c h a n i c a l b e h a v i o u r o f hard maple i s shown to be c l e a r l y n o n - l i n e a r . However, as a f i r s t a p p r o x i m a t i o n , the response o f wood ( to l o n g i t u d i n a l , t e n s i l e s t r e s s ) may be c o n s i d e r e d e l a s t i c f o r ambient c o n d i t i o n s o f low m o i s t u r e c o n t e n t and room t e m p e r a t u r e , and as l i n e a r v i s c o e l a s t i c f o r low s t r e s s " . T h e r e f o r e , the l i n e a r v i s c o -e l a s t i c behav iour o f wood i s i n doubt a c c o r d i n g t o systems t h a t have been u s e d . I g n o r i n g wood response w i t h i n the f i r s t minute o f t e s t , which has been found to be impor tant f o r s y n t h e s i z e d polymers (135. 169) , c o u l d be a s e r i o u s m i s t a k e o f wood r h . e o l o g i s t s which l i m i t s i n t e r p r e t a t i o n o f t h e i r r e s u l t s . Recent s t u d i e s i n Japan on wood r h e o l o g i c a l b e h a v i o u r p r o v i d e some i n t e r e s t i n g i n f o r m a t i o n . Norimoto e t a l . ( 1 3 1 » . 132) - 2 4 -examined the s t r e s s r e l a x a t i o n of J a p a n e s e cypress (Chamaecyparls obtusa Endl.) i n bending and t o r s i o n creep. The authors found a peak which appeared i n the r e l a x a t i o n spectrum or retarded spectrum of every specimen a t 10 J to 10 seconds, (17 to 160 min)i The peak moved to sh o r t e r time as r e l a t i v e humidity was Increased. Consequently, the time-temperature or time-humidity s u p e r p o s i t i o n p r i n c i p l e d i d not apply to wood* This i s c o n s i s t e n t w i t h r e s u l t s of Goldsmith and Grossman (46) and the Schniewind (158) i n t e r p r e t a t i o n of r e s u l t s from Davidson (25) which i n d i c a t e that wood r h e o l o g l c a l behaviour i s not simply governed by the Boltzman p r i n c i p l e (184). Instead , i t i s proposed (91) as s i m i l a r to the s t r e t c h i n g of rayon, s i l k and Nylon 6 6 , where c r y s t a l l i n e r e o r i e n t a t i o n occurs during l o a d i n g . The t r a n s i t o r y nature of wood c r y s t a l l i t e s during load a p p l i c a t i o n has been observed by a few researchers (124, 177). Murphey (124) found that there was an Increase of wood c r y s t a l l i n l t y as measured by X-ray d i f f r a c t i o n immediately a f t e r l o a d i n g . A change i n d i e l e c t r i c constant during s t r e s s r e l a x a t i o n was a l s o observed by Suzuki (177). The d i e l e c t r i c constant decreased at time of l o a d i n g , returned to the o r i g i n a l value a f t e r about 10 minutes, and then s t a b i l i z e d at s l i g h t l y lower values between 10 to 100 minutes. An increase i n c r y s t a l l i n e o r i e n t a t i o n of h o l o c e l l u l o s e f i b r e s during creep l o a d i n g t e s t s was observed by H i l l ( 6 l ) . A c o r r e l a t i o n between Young's modulus and the c e l l u l o s e h e l i c a l angle obtained by 002 plane measurements on S i t k a spruce (Picea s l t c h e n s i s (BongJCarK) wood was shown hv Cowdrey * I t i s a l s o probable t h a t a p p l i e d s t r e s s causes changes i n wood e q u i l i b r i u m moisture content. - 2 5 -and Preston ( 2 3 ) . An attempt to i l l u s t r a t e wood creep behaviour through molecular s t r u c t u r e s t u d i e s was made by Yamada et a l . (202). Wood sec t i o n s c o n t a i n i n g n u j o l were str e t c h e d at 20 and 60% of t h e i r u l t i m a t e s t r e s s l e v e l s and t h e i r I n f r a r e d transmittance and p o l a r i z a t i o n spectra were recorded. Results reported ,by the authors showed the appearance,of a very weak 1495 cm"! wave number band* and o c c a s i o n a l l y another band a t 1115 cm"*. Their p o l a r i z a t i o n r e s u l t s provided l i t t l e a d d i t i o n a l i n f o r - , mation. In most cases the spectra were poorly r e s o l v e d and the noise to s i g n a l r a t i o was too l a r g e f o r reading meaningful r e s u l t s . The r h e o l o g i c a l behaviour of d e l i g n i f l e d wood was • i n v e s t i g a t e d r e c e n t l y by E r i k s s o n (35. 36) and P u s h i t a n i (42, 43, 44), E r i k s s o n (35. 36) s t u d i e d the e f f e c t of sodium c h l o r i t e d e l i g n i f i c a t i o n on creep p a r a l l e l to g r a i n with Scots pine. He found that no noteworthy changes occurred by removing up to 10.5# of the sample. L i g n i n was thought to c o n t r i b u t e to wood mechanical p r o p e r t i e s i n d i r e c t l y . The l i g n i n i n c e l l w a l l s , due to the hydrophobic nature, was proposed as preventing the f i b r e s from absorbing l a r g e q u a n t i t i e s of water. The f i b r e s would have otherwise s u f f e r e d a r a d i c a l strength r e d u c t i o n . P u s h i t a n i (42, 43, 44) i n a s e r i e s of experiments stud i e d s t r e s s r e l a x a t i o n i n bending t e s t s on d e l i g n i f i e d * We have observed a s p l i t band i n the 1500±10 cm"1 r e g i o n on t a n g e n t i a l wood sec t i o n s of coniferous woods without s t r e t c h i n g . -26-H i n o k i and found t h a t : ( i ) The amount o f s t r e s s r e l a x a t i o n w i t h a i r - d r i e d specimens I n c r e a s e d l i t t l e w i t h d e c r e a s e d l i g n i n c o n t e n t , w h i l e a s i g n i f i c a n t Inc rease i n amount o f r e l a x a t i o n was observed w i t h w a t e r - s a t u r a t e d spec imens; ( i i ) the t i m e - t e m p e r a t u r e s u p e r p o s i t i o n r e l a t i o n s h i p d i d not a p p l y to e i t h e r d e l i g n i f i e d o r a c e t y l a t e d wood even when t e s t e d , under w a t e r - s a t u r a t e d c o n d i t i o n s ; and ( i i i ) the r e l a x a t i o n spectrum o f u n t r e a t e d wood showed a b road peak between 10^*5 t o 10^ sec w h i l e t h a t f o r d e l i g n i f i e d wood was r e l a t i v e l y f l a t a c r o s s the same t ime and the spectrum peak f o r a c e t y l a t e d specimens s h i f t e d t o l o n g e r t i m e s . The i n f l u e n c e o f m o i s t u r e c o n t e n t a s s o c i a t e d w i t h d e c r e a s e d l i g n i n c o n t e n t was thought to c o n t r i b u t e o n l y minor e f f e c t s . The h i g h l i g n i n c o n t e n t o f i n i t i a l specimens was c o n s i d e r e d as h i n d e r i n g hydrogen bonding o f h o l o c e l l u l o s e . Sarkanen e t al.(157) p roposed a r o l e f o r l i g n i n l n r e g u l a t i n g wood r h e o l o g i c a l b e h a v i o u r , as due t o l i g n i n e s t e r g r o u p s , whereby: "The e s t e r groups may e x e r t a k i n d of p l a s t i c i z i n g e f f e c t upon the l i g n i n by r e d u c i n g the o p p o r -t u n i t y f o r i n t e r n a l hydrogen b o n d i n g . F u r t h e r m o r e , the c o n j u g a t e d e s t e r g r o u p s , i f connec ted w i t h the ot -carbon i n l i g n i n as presumed, reduced the number of s i t e s t h a t o t h e r -wise may p a r t i c i p a t e i n l i g n i n - l i g n i n bonds o r l i g n i n -p o l y s a c c h a r i d e bonds. C o n s e q u e n t l y , e s t e r groups may a c t as r e g u l a t o r s o f the r h e o l o g i c a l p r o p e r t i e s o f the wood t i s s u e as a who le . The f a c t t h a t l i g n i n e s t e r groups are ; prominent i n j u v e n i l e p inewood, which i s q u i t e f l e x i b l e , but a lmost absent i n the r i g i d c o m p r e s s i o n wood, s u p p o r t s - 2 7 -such a s u p p o s i t i o n " . IV. I n f r a r e d S p e c t r o p h o t o m e t r i c Study o f Wood Wood i s an aggrega te of c e l l u l o s e , h e m i c e l l u l o s e , l i g n i n and v a r i o u s ex t raneous components. The ex t raneous complex Is not d i s c u s s e d h e r e . L i g n i n s p e c t r a l s t r u c t u r e s have been e x t e n s i v e l y s t u d i e d s i n c e f i r s t examined i n 1948 by Jones ( 7 5 ) . I t i s b e l i e v e d t h a t i n f r a r e d s t u d i e s on c e l l u l o s e s t r u c t u r e s began p r i o r t o t h i s p e r i o d . The i n f r a r e d spectrum of whole wood was f i r s t r e c o r d e d by K r a t z l and Tschamler (87) i n 1952, w i t h the a i d o f p a r a f f i n o i l ( n u j o l ) . S i n c e n u j o l a b s o r b s i n the 2940 and 1470 c m - 1 r e g i o n s , t h e i r s p e c t r a d i d not c o v e r the whole range o f wood a b s o r p t i o n . A t about the same t Alme, Brauns (16) r e c o r d e d the I n f r a r e d s p e c t r a o f c o l l o i d a l homogenized c o n i f e r o u s wood between 3570 and 900 c m " 1 . L a t e r , Tschamler et a l . (187) o b t a i n e d wood i n f r a r e d s p e c t r a u s i n g r a d i a l m i c r o s c o p i c s e c t i o n s about f i v e m ic rons t h i c k . T h e i r r e s u l t s enab led d i f f e r e n t i a t i o n between c o n i f e r o u s woods and pored woods. D i f f i c u l t i e s i n p r e p a r i n g the ve ry t h i n wood s e c t i o n s r e q u i r e d f o r i n s t r u m e n -t a t i o n o f the t ime seems t o have d e l a y e d use of the method. R e c e n t l y , H a r r i n g t o n et a l . (5*0 r e c o r d e d the s p e c t r a of mountain ash and Monterey p i n e (P inus r a d l a t a D. Don) sapwoods and a s s i g n e d the v a r i o u s a b s o r p t i o n bands t o wood c o n s t i t u e n t s . It was found tha t b e t t e r s p e c t r a were o b t a i n e d from wood s e c t i o n s than from p e l l e t i z e d m i l l e d woods. - 2 8 -A number of s e c t i o n s p r e s s e d as a sandwich i n a po tass ium c h l o r i d e p e l l e t gave a s h a r p e r spectrum t h a n a s i n g l e s e c t i o n , s i m i l a r l y p r e p a r e d . The s u p e r i o r i t y o f non-Imbedded wood s e c t i o n s p e c t r a i s r e p o r t e d by Chow ( 2 0 ) . T a n i g u c h i e t a l . (180) a l s o found b e t t e r band r e s o l u t i o n e s p e c i a l l y i n the 1000 to 1200 c m " 1 r e g i o n . T h e i r o b j e c t i v e , however, was to r e l a t e bands a t 1110, 1060 and 1040 c m " 1 to wood c e l l u l o s e c r y s t a l l i n i t y . The i n f r a r e d s p e c t r a o f t a n g e n t i a l wood s e c t i o n s o b t a i n e d from v a r i o u s p o s i t i o n s w i t h i n growth increments of f o u r wes te rn and e a s t e r n Canad ian c o n i f e r o u s woods were examined by Chow ( 2 0 ) . The s p e c t r a l s t r u c t u r e s o f e x t r a c t i v e -f r e e wood f o r the d i f f e r e n t s p e c i e s were s i m i l a r , bu t the r e l a t i v e i n t e n s i t i e s between v a r i o u s bands w i t h i n one spectrum d i f f e r e d between s p e c i e s , and from the i n i t i a t i o n o f ear lywood t o the l a s t - f o r m e d la tewood w i t h i n s i n g l e annua l i n c rements . One impor tant method of i n f r a r e d s p e c t r o m e t r y i s the use of p o l a r i z a t i o n f o r ass ignment of a b s o r p t i o n bands based on known m o l e c u l a r o r i e n t a t i o n of the p o l y m e r s . E l l i s and Bath (34) s t u d i e d ramie f i b r e s by the t e c h n i q u e as e a r l y as 19-40. They observed a b s o r p t i o n bands c h a r a c t e r i s t i c o f h y d r o x y l groups i n the 6060 to 5000 c m " 1 wave number (1.5 and 2 . 0 / 0 r e g i o n , w i th r e s u l t s s u g g e s t i n g t h a t hydrogen b r i d g e s of v a r i a b l e d i s t a n c e s and v a r i a b l e bond a n g l e s o c c u r between h y d r o x y l groups o f a d j a c e n t c e l l u l o s e c h a i n s . - 2 9 -The f i r s t wood c e l l u l o s e spectrum r e c o r d e d a c r o s s the r e g i o n from 36OO c m " 1 to 750 c m " 1 u s i n g p o l a r i z e d i n f r a r e d r a d i a t i o n was r e p o r t e d i n 1950 by Darmon and R u d a l l (24) . A number of s t r o n g l y p o l a r i z e d bands were observed i n the 1250 c m " 1 to 950 c m " 1 r e g i o n . These f r e q u e n c i e s were expec ted t o o r i g i n a t e m a i n l y from C - 0 ( s i n g l e bond) l i n k a g e s such as C - O - C and C-OH groups of the pyranose r i n g , and the g l u c o s l d i c C - O - C l i n k a g e . The g l u c o s i d i c b r i d g e f requency s h o u l d g i v e h i g h p a r a l l e l d i c h r o i s m t o the r e g i o n . F u r t h e r s tudy by T s u b o i (188) p r o v i d e d some means f o r i n t e r p r e t i n g bands on the b a s i s of s p a t i a l m o l e c u l a r o r i e n t a t i o n o f c e l l u l o s e . S t rong p a r a l l e l d i c h r o i s m o f the 1160 c m " 1 band was noted among the s p e c t r a r e c o r d e d . The s t u d i e s of L i a n g and M a r c h e s s a u l t (97.98) on b l e a c h e d ramie and b a c t e r i a l c e l l u l o s e s gave g r e a t d e t a i l on the na tu re of c e l l u l o s e p o l a r i z a t i o n . B e s i d e s l l l u s - ,.. t r a t i n g hydrogen bonding phenomenon a t 3300 c m " 1 wave number ( 3 / < r e g i o n ) , the d i c h r o i s m o f bands from 1700 to 690 c m " 1 were t h o r o u g h l y s t u d i e d . The s t r o n g and h i g h l y p a r a l l e l p o l a r i z e d band a t 1160 c m " 1 was a s s i g n e d t o the a n t i s y m m e t r i c b r i d g e C ^ - O - C ^ s t r e t c h i n g mode. The weak p a r a l l e l band near 895 c m " 1 , which had been a s s i g n e d e a r l i e r by Barker et a l . (6) t o the C^-H bending mode o f the j B - l i n k a g e , was r e a s s i g n e d to a n t i s y m m e t r i c o u t - o f - p h a s e r i n g s t r e t c h i n g . T h i s ass ignment was l a t e r adapted to wood s p e c t r a ( 9 6 , 1 0 7 ) . - 3 0 -In wood s p e c t r a , the 1730 cm*" 1 band and i t s p e r p e n -d i c u l a r p o l a r i z a t i o n have been a s s i g n e d to h e m i c e l l u l o s e c a r b o x y l o r a c e t y l g r o u p s . T h i s ass ignment by M a r c h e s s a u l t was suppor ted by Sumlya e t a l . ( I 7 6 ) , who found a l s o t h a t the i n f r a r e d band i n t e n s i t i e s a t 1160 and 895 c m " 1 d e c r e a s e d w i t h wood decay by f u n g i which were c a p a b l e of h y d r o l y z i n g the c e l l u l o s e 1 , 4 - O - ^ B - D - l i n k a g e . The i n f r a r e d band of o t h e r wood components i s a l s o a s s i g n e d by Maekawa and K i t a o (103). A s s o c i a t i o n of the 1160 c m " 1 band w i t h the wood s t r u c t u r e w i l l be f u r t h e r d e s c r i b e d . The v a r i o u s band ass ignments r e c o r d e d f o r c o n i f e r o u s wood s p e c t r a a r e l i s t e d l n T a b l e 7 . M o s t l y the a b s o r p t i o n band above 3000 c m " 1 i s r e p o r t e d to r e s u l t from 0 -H v a l e n c e v i b r a t i o n s ( 9 ) . Water vapour i s thought t o account f o r 3652 c m " 1 symmetric s t r e t c h i n g , 1595 c m " 1 bending and 3756 c m " 1 a n t i s y m m e t r i c s t r e t c h i n g bands , whereas water i n l i q u i d form a b s o r b s a t 3450, 1640 and 3615 c m " 1 (163). Water a b s o r p t i o n i n f l u e n c e s i n f r a r e d s p e c t r a l q u a l i t y by chang ing hydrogen b o n d i n g , the reby c a u s i n g a s h i f t to lower f r e q u e n c y and i n c r e a s i n g w id th and i n t e n s i t y o f the a b s o r p t i o n bands ( 6 2 ) . The energy of hydrogen bonding i s r e p o r t e d t o be 3«7 - 4 . 5 K c a l per mole f o r l i q u i d water ( 6 2 ) , w h i l e magnitude o f the a b s o r p t i o n band s h i f t due t o f o r m a t i o n of hydrogen bonds i s about 35 cm 1 per' K c a l ( 9 ) . P o l y m e r i c a s s o c i a t i o n s , such as n o r m a l l y found i n h y d r o x y l i c compounds, g i v e r i s e t o a b s o r p t i o n bands i n the 3400-3200 c m " 1 range ( 9 , 1 4 8 ) . The e f f e c t o f s o l v e n t s on •; - 3 1 -s t r e t c h i n g v i b r a t i o n s of f r e e and i n t r a - m o l e c u l a r l y bonded l i g n i n hydroxyl groups may give a b s o r p t i o n bands as high as 3550 cm 1 (120), as recorded i n Table 7 , In c e l l u l o s e , a l l hydroxyl groups have been reported to engage i n hydrogen bonding (114). Marchessault and Liang (110) a t t r i b u t e d the 3440 to 3480 cm" 1 band to i n t r a - m o l e c u l a r hydrogen bonding and the other lower wave numbers to 3000 cm"1 to i n t e r - m o l e c u l a r hydrogen bonding of c e l l u l o s e . This complexity ; i s shown i n Table 7 , where band l o c a t i o n s f o r 0-H a b s o r p t i o n appear to vary g r e a t l y with the m a t e r i a l s used. D i f f e r e n t i a t i o n of compounds based on these p a r t i c u l a r a b s o r p t i o n frequencies i s d i f f i c u l t or perhaps impossible. Absorption bands i n the 3000 cm"1 r e g i o n are assigned to C-H s t r e t c h i n g v i b r a t i o n s . In c o n t r a s t , alkane groups e x h i b i t C-H s t r e t c h i n g at frequencies lower than 3000 cm" 1 (9, 148). In a complex organic polymer s t a t e such as wood, abs o r p t i o n by C-H s t r e t c h i n g may c o n t a i n c o n t r i b u t i o n s from l i g n i n , c e l l u l o s e and h e m i c e l l u l o s e , w i t h a l l absorbing at almost the same frequency (9. 28, 107. 111. 1 5 6 ) . No absorbing species has been found f o r n a t i v e wood spectra between 2800 cm"1 to 1900 cm"1. Deuterium exchange of c e l l u l o s l c -OH groups, however, reduces abs o r p t i o n frequencies by approximately l//2~~ (105, 1 2 5 ) . which provides a new band at 2300 - 2600 cm" 1 w i t h wood spectra ( 2 0 ) . Compounds c o n t a i n i n g carbonyl and c a r b o x y l groups give r i s e to strong absorptions at 1900 - 1550 cm"1, -32-which i s a s c r i b e d to s t r e t c h i n g of the C-0 bond. In a d d i t i o n , groups p to the benzene r i n g absorb i n the t y p i c a l 1730cm - 1 r e g i o n of carboxyl groups (13, 32, 58, 87, 107). In wood, the perpen-d i c u l a r dichroism at t h i s frequency has been assigned to the a b s o r p t i o n of h e m i c e l l u l o s e carbonyl or a c e t y l groups (96, 103, 107, 111). For separated l i g n i n , the 1715 and 1735 cm 1 bands have been assigned to aromatic e s t e r and acetate groups, r e s p e c t i v e l y (157). The bands from 1700- , 1550 cm"1 are due mainly to absorptions of other carbonyl groups (32, 86, 107, I87) . In t h i s r e g i o n , atmospheric moisture a l s o absorbs at 1650 to 1630 cm - 1 (9, 20, 107, 163), which f u r t h e r complicates matters. L i g n i n double bonds absorb a t 1640 cm" 1 (I87), and t y p i c a l aromatic s k e l e t a l v i b r a t i o n s are shown between 1600-1400 cm" 1 (28, 75, 87, 156). For both wood and i s o l a t e d l i g n i n s p e c t r a the absorptions a t 1600 and 1500 cm"1 appear to be r e l a t i v e l y independent f u n c t i o n s . Absorption bands below 1500 cm" 1 are considered to be i n the complicated " f i n g e r p r i n t " r e g i o n . For example, l i g n i n a b s o r p t i o n bands found at 1493 cm" 1 appear to represent double bonds (187), while methylene and methoxyl. C-H deformations seem to absorb at 1470-1420 cm"1. These, too, may be mixed w i t h c o n t r i b u t i o n s from s i m i l a r carbohy-drate groups (9, 28, 58, 87, 120, 121, 206). Assignment of wood abs o r p t i o n bands between 1400 to 450 cm""1 wave numbers i s complicated by the m u l t i p l i c i t y of wood component absorptions which appear at s i m i l a r wave numbers. Obviously, the many problems of band assignment n e c e s s i t a t e f u r t h e r study. -33-MATERIALS AND METHODS I. Wood Specimens Wood t i s s u e s from f o u r Canad ian c o n i f e r o u s s p e c i e s were used i n the e x p e r i m e n t s . S i t k a spruce [ p i c e a s l t c h e n s l s (Bong.) Carr.J, Douglas f i r [Pseudotsuga menzfesll ( M i r b . ) Franco) and grand f i r [ A b i e s grand i s (Doug l . ) L i n d l . ] mature stems were from Vancouver , B . C . , w h i l e the balsam f i r [ A b i e s balsamea (L . ) M i l l . ] sample o r i g i n a t e d from S t . M i c h e l s des S a i n t s , P . Q . and was s u p p l i e d by the P u l p and Paper Research I n s t i t u t e o f Canada. Immediately a f t e r f e l l i n g , stem s e c t i o n s were taken a t b r e a s t h e i g h t , wrapped i n p o l y e t h y l e n e sheet and t r a n s p o r t e d t o the l a b o r a t o r y where they were s t o r e d i n the c o l d under; c o n d i t i o n s m a i n t a i n i n g o r i g i n a l t r e e m o i s t u r e . In a d d i t i o n t o taxonomic v a r i a t i o n , stems were s e l e c t e d to .meet o t h e r e x p e r i m e n t a l n e e d s , such as s u i t a b l e growth c h a r a c t e r i s t i c s for p r o v i d i n g a c c e p t a b l e m i c r o s e c t i o n s . Sapwood zones were used f o r reasons of m i n i m i z i n g s p e c t r o p h o t o m e t r i c i n t e r f e r e n c e from e x t r a c t i v e s ( 2 0 ) , and because o f g r e a t e r , a s s u r a n c e i n p r e p a r i n g q u a l i t y m i c r o s e c t i o n s (26, 7 6 ) . To f u r t h e r e x p l o r e wood zone d i f f e r e n c e s , a Douglas f i r sapwood :, s e c t o r c o n t a i n i n g c o m p r e s s i o n wood was examined. S i n c e d e h y d r a t i n g e x t r a c t i v e t rea tments were not u s e d , r e s u l t s a r e thought t o r e p r e s e n t n a t i v e wood p r o p e r t i e s . S e r i a l t a n g e n t i a l m i c r o s e c t i o n s (0.5 x 2- I n . s u r f a c e a r e a ) were o b t a i n e d i n the u s u a l manner from water s a t u r a t e d , but o therw ise u n t r e a t e d , wood b l o c k s . A l t e r n a t e 20*5 m i c r o n - 3 4 -and 100+10 m i c r o n m i c r o s e c t i o n b lanks were p r e p a r e d , which p r o v i d e d 15 t o 18 s e c t i o n s of b o t h t h i c k n e s s e s f o r each growth increment examined. T h i n s e c t i o n s were used f o r e x p -e r iments t o be d e s c r i b e d , w h i l e the t h i c k e r s e c t i o n s were examined i n o t h e r work. Compress ion wood was e s p e c i a l l y ; d i f f i c u l t t o manufacture t o a c c e p t a b l e t h i c k n e s s e s . In a l l c a s e s , c a r e was taken to i n s u r e exact a l ignment between g r a i n d i r e c t i o n and the k n i f e c u t t i n g edge . The sampl ing p l a n w i t h i n two growth increments each of Douglas f i r and balsam f i r , the woods most s t u d i e d , i s * shown i n T a b l e 8. I I . C h e m i c a l Treatments A l t h o u g h many t e s t s were done w i t h u n t r e a t e d wood s p e c i m e n s , i t seemed u s e f u l a l s o t o a l t e r some f e a t u r e s of wood c o m p o s i t i o n . Thereby , requ i rements f o r m a i n t a i n i n g o r i g i n a l energy t r a n s f e r p a t t e r n s were b r i e f l y examined, and the v a l i d i t y o f c e r t a i n i n f r a r e d band ass ignments was v e r i f i e d . D e l i g n i f i c a t i o n t o v a r i o u s l e v e l s was done a c c o r d i n g t o the c h l o r i t e method as m o d i f i e d by Wise et a l . (199, 200) , and U p r i c h a r d (189) . Wood m i c r o s e c t i o n b lanks c o n t a i n e d i n 50 ml f l a s k s were immersed i n 10 ml o f b u f f e r s o l u t i o n (48 g sodium h y d r o x i d e , 144 g a c e t i c a c i d , 1920 ml w a t e r ) , then 1 ml o f 27# (w/v) aq c h l o r i t e s o l u t i o n was a d d e d . The l o o s e l y s topped f l a s k s were heated i n a water b a t h a t 76±1°C w i t h g e n t l e m i x i n g a t 1/2 h r i n t e r v a l s , a t which t imes a d d i t i o n a l 1 ml amounts o f c h l o r i t e s o l u t i o n were a d d e d . • A t each o f s i x t rea tment t imes up to 4 h r one f l a s k was removed, c o o l e d i n an i c e ba th f o r 5 min and 15 ml o f c o l d , d i s t i l l e d water - 3 5 -was added. The samples were then washed w i t h ten-10 ml por t i o n s of aq 1% a c e t i c a c i d and f i n a l l y two-5 ml p o r t i o n s of acetone. Samples were a i r - d r i e d and made ready f o r t e s t i n g . A companion set of wood se c t i o n s processed 4 hr by the method described was f u r t h e r t r e a t e d w i t h 1, 5 or 17.5% sodium hydroxide s o l u t i o n . The f r a g i l e nature of t h i n wood sec t i o n s n e c e s s i t a t e d s p e c i a l handling. I n d i v i d u a l sections, were l a i d f l a t on g l a s s m i c r o s l i d e s w i t h ends beneath cover g l a s s e s , but w i t h mid-sections exposed. The assembly was immersed i n the base f o r 45 min a t 25°C. Samples were washed while on the g l a s s w i t h 100 ml of d i s t i l l e d water, 10 ml of aq 10$ a c e t i c a c i d , 200 ml of d i s t i l l e d water and f i n a l l y 50 ml of acetone. F i l t e r paper was placed over the s e c t i o n s , m i c r o s l i d e s were l a i d over the surface and a i r -dryi n g was continued f o r at l e a s t three days before the t r e a t e d samples were recovered and t e s t e d . Wood microsections provide too l i t t l e m a t e r i a l for, determining l i g n i n by conventional means. A technique (20) employing r a t i o s of s p e c i f i c i n f r a r e d absorbance bands, such as 1500/2880 or 1420/2880 cm*"1 or other wave numbers, was used wi t h untreated samples. Comparative absorbance at 1500 cm~l wave number of matched samples was used f o r a s s e s s i n g percentage r e s i d u a l l i g n i n of d e l i g n i f i e d samples. I I I . Micro-mechanical Techniques M i c r o t e n s i l e t e s t s (65) were done to determine wood t i s s u e u l t i m a t e strengths. Specimens were prepared from 20±5 micron t a n g e n t i a l m i c r o s e c t i o n blanks. G r a i n d i r e c t i o n was defined and l o n g i t u d i n a l 2.5 x 220 mm re c t a n g u l a r s t r i p s - 3 6 -were cut by a s p e c i a l l y machined d i e f i x e d to a l / 2 - t o n arbor press. In order to avoid f a i l u r e at g r i p s , t e s t specimen ends, but not the mid-section, were saturated w i t h p o l y v i n y l a c e t a t e and r e i n f o r c i n g papers were a p p l i e d to the t a n g e n t i a l f a c e s . Testing was done on a r e c o r d i n g , t a b l e model In s t r o n housed i n a standard conditioned room (72±1°F dry bulb and 65!tl°F wet b u l b ) . Specimens were gripped a t e x a c t l y 0 . 5 -in jaw spacing, while 30 and 50 foot-pound torques were a p p l i e d to t i g h t e n g r i p s w i t h earlywood and latewood specimens. Load was a p p l i e d w i t h constant r a t e of s t r a i n at 0 . 4 5 -in /min, chart speed-was 1-in /min and s e n s i t i v i t y of chart reading was 2 g. Two ;> r e p l i c a t i o n s c o n s t i t u t e d a determination. Ultimate t e n s i l e s t r a i n was read d i r e c t l y from recorder c h a r t s , and p o r t i o n a l , s t r a i n and a s s o c i a t e d s t r e s s values f o r t e s t s t o be described were determined from these data. This assumes a r e l a t i o n s h i p between s t r e s s - s t r a i n behaviour l n t h i s customary t e s t and that occurring at more r a p i d r a t e of l o a d i n g . Some comparative s t r e s s r e l a x a t i o n t e s t s were done;with the system described and at r a t e of s t r a i n of 0 . 4 5 -in /min. This required approximately 2 sec f o r l o a d i n g to 50% of u l t i m a t e s t r a i n . The machine was stopped a t t h i s p o s i t i o n (to) and the load r e q u i r e d to maintain constant deformation was recorded a u t o m a t i c a l l y over a p e r i o d of 40 min. F r a c t i o n a l s t r e s s r e l a x a t i o n i s expressed as S(0) where <5(t) i s s tress at any t ime, t ; and <S(0) i s i n i t i a l stress at i n i t i a l time, t Q . This d i f f e r s from the conventional expression -37-<S(t) as i n t r o d u c e d f o r mathemat ica l c o n v e n i e n c e by K i tazawa (80) , where $(1) r e f e r s t o s t r e s s a t e x p i r a t i o n of one minute f o l l o w i n g c o m p l e t i o n of l o a d i n g . The na tu re of I n f r a r e d r e c o r d i n g s p e c t r o p h o t o m e t e r s i s such t h a t space i s not a v a i l a b l e f o r accommodating specimens h e l d i n c o n v e n t i o n a l t e s t e n g i n e s . New systems were needed to a p p l y c o n t r o l l e d l o a d s f o r wood t i s s u e r e l a x a t i o n s t u d i e s . E a r l y t r i a l s were done w i t h an a p p a r a t u s p r o v i d i n g ramp- ; f u n c t i o n e x c i t a t i o n , w h i l e the main exper iments as r e p o r t e d here i n c l u d e d s i m u l a t e d s t e p - f u n c t i o n e x c i t a t i o n as d e r i v e d from a second a p p a r a t u s . F o r c o m p l e t e n e s s , b o t h i n s t r u m e n t s a r e d e s c r i b e d and some compara t ive r e s u l t s a r e g i v e n . I t was not the purpose o f the p r e s e n t s tudy , however, t o examine e f f e c t s o f l o a d i n g h i s t o r y . In a d d i t i o n , a r e l a t i v e l y s i m p l e t h i r d system was d e v i s e d f o r d o i n g c r e e p s t u d i e s w i t h wood microspec imens exposed to the i n f r a r e d f i e l d . The p r o t o t y p e appara tus f o r examining e f f e c t s under c o n s t a n t d e f o r m a t i o n i s shown i n d e t a i l as F i g . l - A and mounted i n t e s t p o s i t i o n i n F i g . l - B . The p r i n c i p l e i n v o l v e s c o n t r o l l e d thermal e x p a n s i o n o f meta l h o l d e r s (A ^ ) which t r a n s m i t p r e s e l e c t e d s p a t i a l ad jus tments th rough a g u i d e d (A-g) rodjftA^) t o s e p a r a t e d s u r f a c e s (A^) on which the specimen (A^) i s a f f i x e d . The f l a n k i n g h o l d e r s (A^) a r e h o l l o w copper tubes h e l d as : ! a s t r u c t u r e by welded i r o n end p l a t e s . Tube i n s i d e d iamete r i s 1 /2 i n * and l e n g t h i s 1 f t . The bottom tube ends a r e s e a l e d and q u a r t z r a d i a n t h e a t e r rods ( A Q ) a r e i n s e r t e d . The tube s u r f a c e s a r e i n s u l a t e d w i t h a s b e s t o s and f u r t h e r wrapped w i t h -38-c o t t o n to l i m i t r a d i a n t heat e f f e c t s . An aluminium rod (A3) i s fastened to the top p l a t e and kept i n alignment by guides ( A ^ ) * Hard maple blocks are f i x e d to the assembly w i t h spacing of 1 / 2 - i n . at 2 5 i l ° C , which i s the i n i t i a l span l e n g t h f o r specimens (A^ ). L i n e a r expansion over the span was t c a l c u l a t e d according to s e t t i n g of a powerstat used to c o n t r o l heating of the rods (AQ). Amount and r a t e of s t r a i n were examined by mounting a Budd m e t a l f i l m s t r a i n gauge on a specimen put under t e s t . The method was shown to provide uniform, ramp-function e x c i t a t i o n r e q u i r i n g 10 to 12 min to reach 1% s t r a i n by r a i s i n g the system from 25 to 45°C. A second apparatus was designed f o r observing r e l a x a t i o n e f f e c t s f o l l o w i n g short-time l o a d i n g , which approaches s t e p - f u n c t i o n e x c i t a t i o n ( F i g . IC and ID). In p r i n c i p l e , s t r e s s e d springs (C 0) released by a c l u t c h (C]_) a c t i v a t e a s l i d i n g p l a t e (C2) f o r r a p i d t r a n s m i s s i o n of c o n t r o l l e d (C^) extension to a mounted specimen (C4). The d o v e - t a i l , s l i d i n g p l a t e (C2) i s l i n k e d to the upper part of the supporting body by two strong springs (Cg). A micro-meter (G3) with accuracy of ± 0 . 0 0 0 1 i n . i s attached to the supporting body and used to preset the de:sired deformation. The s l i d i n g p l a t e performs before a window w i t h motion c o n t r o l l e d by two mechanisms; the micrometer c l u t c h and the release c l u t c h (Qj). In operation, both c l u t c h e s are released before mounting the specimen. Distance between : the s l i d i n g upper p l a t e (C 2) and f i x e d lower p l a t e Is adjusted to 0 . 5 * 0 . 0 0 0 5 i n . by t u r n i n g the micrometer and - 3 9 -f o r c i n g i t s p i s t o n f o r w a r d . Both c l u t c h e s a r e t h e n engaged and the sample i s mounted a c r o s s the t e s t s p a n . The micrometer c l u t c h i s r e l e a s e d , the p i s t o n i s r e t r a c t e d a c c o r d i n g t o s e t t i n g on the micrometer and the micrometer c l u t c h i s r e - e n g a g e d . The t e s t i s executed by t r i g g e r i n g the r e l e a s e c l u t c h , the s l i d i n g p l a t e moves to the p o s i t i o n l i m i t e d by the p i s t o n and the r e l e a s e c l u t c h i s then r e - e n g a g e d to h o l d the specimen i n the s p a t i a l ad justment a t t a i n e d . Exper iments employ ing a l i n e a r v a r i a b l e d i f f e r e n t i a l t r a n s r former have shown t h a t a p p r o x i m a t e l y 10"" ^  sec i s r e q u i r e d to a t t a i n 1% s t r a i n w i t h the method. The t h i r d appara tus was d e s i g n e d f o r r a p i d a p p l i c a t i o n o f c o n s t a n t l o a d s , and t h e r e b y o b s e r v a t i o n o f c r e e p e f f e c t s . The mechanism i s s i m p l y a bored p l a t e f i t t e d t o the ins t rument h o l d e r , w i t h s p a c e r s f i x e d above and below the a p e r t u r e . In o p e r a t i o n , the specimen i s mounted between the upper s p a c e r and a f r e e - h a n g i n g t h i n , t r i a n g u l a r c o p p e r sheet w i t h s m a l l h o l e a t the apex . The assembly i s p l a c e d i n «., p o s i t i o n and a known weight i s added w i t h i n s t a n t r e l e a s e . With a l l t e s t sys tems , specimen f i b r e d i r e c t i o n was found by t e a r i n g the edge and t h i s was c a r e f u l l y a l i g n e d w i t h the l o a d i n g d i r e c t i o n . Thereby , l o n g i t u d i n a l wood t i s s u e f e a t u r e s s e r v e d as r e f e r e n c e f o r I n f r a r e d p o l a r i z a t i o n measurements. T h i s c o i n c i d e n c e of b i o l o g i c a l a l ignment w i t h d i r e c t i o n o f l o a d i n g i s a power fu l p o i n t o f the exper iment , as c o n t r a s t e d t o randomly o r d e r e d m o l e c u l a r ( p l a s t i c ) and p a r t i c l e (paper) s t r u c t u r e s where -40-the p o l a r i z a t i o n r e f e r e n c e o n l y r e l a t e s t o l o a d i n g d i r e c t i o n . Q u i c k - s e t t i n g Budd GA-1 s t r a i n - g u a g e cement was found to be a s u i t a b l e a d h e s i v e f o r f i x i n g specimens t o sample h o l d e r s . Three s t r a i n l e v e l s , 30, 5 0 , and Q0% o f u l t i m a t e s t r a i n , were examined i n p r e l i m i n a r y m o l e c u l a r s t r e s s r e l a x a t i o n exper iments w i t h balsam f i r wood t i s s u e s . These s t r a i n s were chosen t o r e p r e s e n t e l a s t i c , i n t e r m e d i a t e and p l a s t i c r e g i o n s as shown by t y p i c a l s t r e s s - s t r a i n c u r v e s deve loped i n s t a t i c t e s t i n g . The 50% s t r a i n l e v e l was s e l e c t e d f o r the main exper iment , s i n c e d i c h r o i s m , w h i l e s i m i l a r , w a s not a lways as w e l l d i s t i n g u i s h e d a t the lower ; s t r a i n l e v e l and specimens d i d not a lways s u r v i v e f o r r e q u i r e d t imes a t the h i g h e r s t r a i n l e v e l . Bach (3) d e s -c r i b e d t h i s e f f e c t o f s t a t i c f a t i g u e under c o n s t a n t t e n s i l e s t r a i n f o r t h i c k e r wood t i s s u e s , and p r e d i c t e d s u r v i v a l w i t h l o a d i n g a t 90# of e s t i m a t e d u l t i m a t e s t r a i n . M o l e c u l a r c r e e p t e s t s were done o n l y on balsam f i r t i s s u e s w i t h s t r e s s l o a d s c a l c u l a t e d t o p r o v i d e 50% o f s t r a i n to f a i l u r e . E f f e c t s o f temperature and m o i s t u r e were not examined as v a r i a b l e s o f the p r e s e n t exper iment . Measurements on wood t i s s u e s exposed to the i n f r a r e d f i e l d showed t h a t temperature was 40 + 0 . 5 ° C and m o i s t u r e c o n t e n t 6 + \ % ( m o i s t u r e - f r e e b a s i s ) when d i c h r o i s m was d e t e r m i n e d . IV. O p t i c a l Techniques A c r i t i c a l f e a t u r e o f the p r e s e n t s tudy i s a c c u r a t e measurement o f changes i n d i c h r o i s m . The p r o p e r t y c h a r a c t e r i z e s o f m a t e r i a l s , i n c l u d i n g s o l i d o r g a n i c macromolecu la r c o n f o r m a t i o n s , - 4 1 -which p r e f e r e n t i a l l y a b s o r b energy a c c o r d i n g to - : c o i n c i d e n c e w i t h s t r u c t u r e o r i e n t a t i o n . O b s e r v a t i o n s may be made when random f i e l d energy v e c t o r s a r e r e s o l v e d i n a p lane. , as by p o l a r i z a t i o n , and super imposed on the m a t e r i a l s t r u c t u r e . At a p a r t i c u l a r f requency the p r o b a b i l i t y f o r maximum energy t r a n s f e r o c c u r s when the d i r e c t e d energy p lane Is a l i g n e d , w i th the f i x e d v i b r a t i n g moment d i r e c t i o n o f the s t r u c t u r e . C o n v e r s e l y , minimum energy t r a n s f e r o c c u r s when the two d i r e c t i o n s a r e p e r p e n d i c u l a r . A l t h o u g h the p r o p e r t y s h o u l d appear a t numerous p o i n t s o f the e l e c t r o m a g n e t i c spec t rum, i t s study has been a lmost e n t i r e l y r e s t r i c t e d to the I n f r a r e d r e g i o n . I n f r a r e d measurements were made w i t h a P e r k i n - E l m e r 521 g r a t i n g spec t rophotomete r equipped with l i n e a r absorbance at tachment and Honeywel l E l e c t r o n i k 19 e x t e r n a l - s t r i p c h a r t r e c o r d e r . A tmospher ic m o i s t u r e e f f e c t s were removed by c o n t i n u o u s p u r g i n g w i th dry a i r . A P e r k i n - E l m e r Wire G r i d P o l a r i z e r was used to r e s o l v e the sample beam. P o l a r i z a t i o n e r r o r s a r e thought to be n e g l i g i b l e , s i n c e 35# o f the i n c i d e n t r a d i a t i o n i s t r a n s m i t t e d a t 99# e f f i c i e n c y a c r o s s the range s t u d i e d . To compensate f o r l o s s o f sample beam i n t e n s i t y , an a t t e n u a t o r was used to reduce i n t e n s i t y o f the r e f e r e n c e beam. P o s s i b l e e r r o r s due to sample b i r e f r i n g e n c e (99. 149, 205) were e l i m i n a t e d by p a s s i n g the sample beam through the specimen b e f o r e p o l a r i z a t i o n . Machine p o l a r i z a t i o n and d e c l i n e o f ; base l i n e were c o r r e c t e d by p o s i t i o n i n g both p o l a r i z a t i o n -42-and specimen axes at 4 5 ° to the spectrophotometer s l i t ( P i g . l ) f o r o b t a i n i n g the p a r a l l e l component. The p e r p e n d i c u l a r measurement was obtained by s e t t i n g the p o l a r i z e r d i a l a t 90° to the specimen a x i s . By coincidence, the p o l a r i z e r arrangement i n our technique i s a l s o that published r e c e n t l y by Read and S t e i n (149), who examined p o l y v i n y l c h l o r i d e f i l m s . The apparatus w i t h specimen mounted i s . p o s i t i o n e d i n the instrument as shown i n F i g . l . In operation,the-mechanical l o a d i n g mechanism i s a c t i v a t e d and spectrophotometry scanning i s s t a r t e d . By automatic s e t t i n g , regions of i n t e r e s t are recorded at 120 cm"l/mln while the speed suppression switch i s o p e r a t i n g . The drum i s set to r e t u r n a u t o m a t i c a l l y t o the s t a r t i n g p o i n t p o l a r i z a t i o n angle i s changed and a second t r a c e i s recorded. Thereby, data f o r c a l c u l a t i n g a s i n g l e d i c h r o i c r a t i o may be obtained a t one to three minute i n t e r v a l s . This time r e q u i r e d f o r o b t a i n i n g measurements i s a l i m i t a t i o n of the technique, e s p e c i a l l y f o r studying e f f e c t s immediately f o l l o w i n g mechanical e x c i t a t i o n . The d i c h r o i c r a t i o (D) i s expressed (205) as D = Al/Aii [3] where Ax i s absorbance perpendicular and An absorbance p a r a l l e l to the l o a d i n g d i r e c t i o n which,by specimen arrangement, c o i n c i d e s with the f i b r e a x i s . Thus, d i c h r o i c r a t i o and o r i e n t a t i o n angle (0) f o r molecular t r a n s i t i o n moments r e l a t e to the f i b r e a x i s as D = A J . / A I I = 0 . 5 t a n 2 9 (4] * D=l 9 no o r i e n t a t i o n . D <1, p a r a l l e l o r i e n t a t i o n . D > 1 , perpendicular o r i e n t a t i o n . - 4 3 -Equation [4] provides means f o r comparing between s p e c t r a l molecular motion a c t i v i t i e s ( 9 ) and mechanical s t r e s s r e l a x a t i o n (S(t)/<5 ( 0 ) , [2] ) observed under the same experimental c o n d i t i o n s . A second technique, X-ray d i f f r a c t i o n , was employed i n the study f o r a s s e s s i n g treatment e f f e c t s on the n a t i v e wood s t r u c t u r e . A P h i l l i p s Eindhoven X-Hay d i f f r a c t o m e t e r was us which generates a CuKot beam at 1 . 5 4 A* wave l e n g t h . The d i f f r a c t e d ray i s f i l t e r e d , passed through a s l i t to a goniometer and i n t e n s i t y i s recorded a u t o m a t i c a l l y . Measurements were made on matched, a i r - d r y specimens mounted on g l a s s p l a t e s f i t t e d Into the sample post. D i f f r a c t i o n patterns were recorded f o r 20 angles between 5 and 3 5 ° , w i t h scanning speed a t l°/min. Estimates of c r y s t a l l i n e f r a c t i o n were obtained by a n a l y z i n g X-ray diagrams according to the method of Jayme and K n o l l e (67). B r i e f l y , the area subtended by a t r i a n g l e formed between the interpeak minima and base l i n e i s considered background i n t e n s i t y a r i s i n g from disordered d i f f r a c t i o n (d). S u b t r a c t i n g t h i s amount from t o t a l area under the curve provides an i n t e n s i t y measurement for ordered d i f f r a c t i o n (o). Specimen c r y s t a l l i n i t y , termed t o t a l c r y s t a l l i n i t y per cent (C,%), i s obtained by the simple c a l c u l a t i o n G,% = o/(o+d)xl00 [5] Means are a v a i l a b l e a l s o f o r e s t i m a t i n g c o n t r i b u t i o n s from the various planes. E l e c t r o n microscopy was used to examine l i g n i n d i s t r i -b u t i o n patterns i n wood t i s s u e s f o l l o w i n g v arious periods -44-o o f d e l i g n i f I c a t i o n . C r o s s s e c t i o n s o f 8 0 0 A t h i c k n e s s were p repared from t e s t specimen f ragments embedded i n 8 0 : 2 0 methy l and b u t y l m e t h a c r y l a t e and s t a i n e d w i t h 1% aq po tass ium permanganate. A H i t a c h i - H u - l l - e l e c t r o n m i c r o s c o p e was used a t m a g n i f i c a t i o n o f 6000 x . - 4 5 -RESULTS D i c h r o i s m i n the i n f r a r e d r e g i o n was used t o d e r i v e i n f o r m a t i o n on wood m o l e c u l a r s t r u c t u r e , such as i n i t i a l b i o l o g i c a l c o n f o r m a t i o n and r e o r i e n t a t i o n ad jus tments d u r i n g accommodation o f e x t e r n a l m e c h a n i c a l e x c i t a t i o n . T h i s In t roduces " m o l e c u l a r r h e o l o g y " t o wood s c i e n c e . P r e s e n t l y , band ass ignments a r e a c c e p t e d as e s t a b l i s h e d by o t h e r means, whereby i n t e r p r e t a t i o n s a r e o n l y as v a l i d as c e r t a i n t y of a s s i g n m e n t . A second use o f d i c h r o i s m i s f o r reexamin ing ass ignments a l r e a d y g i v e n p a r t i c u l a r a b s o r p t i o n f r e q u e n c i e s . T h i s use i s examined b r i e f l y , s i n c e wood " m o l e c u l a r r h e o l p g y " may c o n t a i n new means f o r more r i g o r o u s p r o o f s o f s t r u c t u r e . . C o n i f e r o u s wood t i s s u e s y i e l d more than twenty d i s t i n c t a b s o r p t i o n bands between 3530 and 450 c m " 1 wave number (2.8 to 21 .0 u wave l e n g t h ) as summarized i n T a b l e 7 . About o n e - h a l f , e s p e c i a l l y f r e q u e n c i e s a s s i g n e d t o c e r t a i n c a r b o h y d r a t e v i b r a t i o n s , a r e d e s c r i b e d as p o l a r i z e d (96, 97)» e i t h e r p a r a l l e l o r p e r p e n d i c u l a r t o the major b i o l o g i c a l a x i s . The p r e s e n t s tudy does not a t tempt to f o l l o w a l l j ;. these o p p o r t u n i t i e s , but does aim a t i n c l u d i n g s p e c i f i c f u n c t i o n a l groups f o r r e p r e s e n t i n g each o f the t h r e e major -46-wood components; c e l l u l o s e , l i g n i n and some he m i c e l l u l o s e f r a c t i o n s . Absorption at 1730 cm"*! wave number (5«8 j i ) was used to c h a r a c t e r i z e a h e m i c e l l u l o s e a c t i v i t y . The frequency i s as s o c i a t e d w i t h 0=0 s t r e t c h i n g v i b r a t i o n s of a c e t y l and/or c a r b o x y l i c a c i d groups (32, 87, 9 8 ) , but may c o n t a i n minor c o n t r i b u t i o n s from l i g n i n ^3-keto s t r u c t u r e s (13» 32, 58) or other groups (32) as demonstrated f o r l i g n i n i s o l a t e s . The assignment f o r wood t i s s u e s of the present study r e f e r s to C=0 of -C00H and -COOCH3 groups i n 4 - 0-methylglucuronoacetyl x y l a n . I f the x y l a n a x i s p a r a l l e l s wood u l t r a s t r u c t u r e and the parent f u n c t i o n a l body i s o r i e n t e d perpendicular to the xy l a n c h a i n , p o l a r i z a t i o n perpendicular to the b i o l o g i c a l a x i s would be p r e d i c t e d f o r the 1730 cm"* mode. This has been .shown p r e v i o u s l y w i t h wood t i s s u e s (96) , and i s r e a f f i r m e d by st u d i e s of wood x y l a n f ilms ( 1 1 1 ) . L i g n i n a c t i v i t y was observed at 1500 cm""* wave number (6.6 p.). This c h a r a c t e r i s t i c C=C s t r e t c h i n g v i b r a t i o n i s unequivocally assigned to l i g n i n aromatic s k e l e t o n s , i n c l u d i n g those of the coniferous wood matrix (107, 156) . Other l i g n i n a b s o r p t i o n bands do not appear as a t t r a c t i v e , due to i n t e r f e r e n c e by water and polyphenolic e x t r a c t i v e s or l a c k of s p e c i f i c i t y . E i t h e r i n i t i a l or induced p o l a r i z a t i o n i s p r e r e q u i s i t e to . dichroism, and p o l a r i z a t i o n of the 1500 cm*"l l i g n i n mode i s , denied (5^»107). As w i l l be shown, l i g n i n o r i e n t a t i o n e f f e c t s do occur. i A second carbohydrate a c t i v i t y was studied by observations at l l 6 0 cm""* wave number (8.6 )i). This strong absorption?. frequency appears to be c l o s e l y a s s o c i a t e d w i t h polysaccharide main chain s t r u c t u r e . Exact assignments are c o n t r o v e r s i a l , while r e g i o n a l masking from complex i n t e r r e l a t e d v i b r a t i o n modes has r a i s e d questions on v a l i d i t y f o r any s p e c i f i c assignment ( 6 0 ) . According to v a r i o u s i n t e r p r e t a t i o n s the frequency represents G-O-C bridge asymmetric s t r e t c h i n g . v i b r a t i o n s (107), or bending f o r the C-OH group (206) . Since i n t e r p r e t a t i o n s p a r a l l e l main carbohydrate chains which f o l l o w the b i o l o g i c a l a x i s , i t i s not s u r p r i s i n g that the band shows strong p a r a l l e l p o l a r i z a t i o n (107). For reasons to be described, we p r e f e r the bridge s t r e t c h i n g assignment which has been given f o r coniferous wood t i s s u e polysaccharides (96, 107) . < The i n f r a r e d p o l a r i z a t i o n s p e c t r a of regular wood and compression wood of Douglas f i r are shown i n F i g . 2. * The range i n o r i e n t a t i o n of the chemical components of four n a t i v e woods, earlywood and latewood only and Douglas f i r compression wood i s i n d i c a t e d i n Table 9. From the data, the r e l a t i o n s h i p between o r i e n t a t i o n angles c a l c u l a t e d from 1500 and l l 6 0 cm"1 d i c h r o i c r a t i o s i s l i n e a r as shown i n ; F i g . 3 and s i g n i f i c a n t at the 1% l e v e l as Y E = 47.95 + 0.15 x e [6] r = 0 . 7 5 * * N= 38 SEg = 1.43 where YQ i s the o r i e n t a t i o n angle at 1500 cm"! (degree) X e i s the o r i e n t a t i o n angle at 1160 cm"1 (degree). The r e l a t i o n s h i p between o r i e n t a t i o n angles at 1500 and 1730 cm-l i s a l s o l i n e a r and h i g h l y s i g n i f i c a n t at the V% l e v e l as -48-Y 0 = 100.25 - 0 . 7 9 XQ [7] r = 0 . 7 3 * * N = 37 SE E = 1.48 where YQ i s the o r i e n t a t i o n angle at 1500 cm"1 (degree) XQ i s the o r i e n t a t i o n angle at 1730 cm"1 (degree). For t r e a t e d specimens, the l i g n i n contents are expressed as per cent of o r i g i n a l l i g n i n i n non-treated specimens and are shown i n most of the l a t e r f i g u r e s and t a b l e s d e s c r i b i n g the r e l a t i o n s h i p between d e l i g n i f i c a t i o n and molecular a c t i v i t i e s . These l i g n i n contents seem reasonable and compare favourably-w i t h values reported on wood t i s s u e s by Stone and Clayton (174). E l e c t r o n photomicrographs f o r c o n t r o l and d e l i g n i f i e d specimens of balsam f i r latewood as shown i n F i g . 4 i n d i c a t e that the * d e l i g n i f i c a t i o n was r a t h e r m i l d . A f t e r 60 min treatment, the l i g n i n was not s i g n i f i c a n t l y removed from c e l l w a l l s . Even a f t e r 240 min, l i g n i n s t i l l remained i n the wood t i s s u e , w i t h ordered o r g a n i z a t i o n s t i l l r e t a i n e d . The e l e c t r o n photomicrographs show that the l i g n i n was removed uniformly from the c e l l w a l l and middle l a m e l l a . T e n s i l e f a i l u r e patterns f o r wood c r o s s s e c t i o n s f o l l o w i n g 240 min treatment show ; rupture across the f i b e r s , not i n the middle l a m e l l a r e g i o n . D e l i g n i f i c a t i o n appears to change dichroism of 1160 and 1730 cm"1 bands. The r e l a t i o n s h i p between these d l c h r o i c r a t i o s and the l i g n i n content of specimens i s shown f o r earlywood and latewood of Douglas f i r and balsam f i r i n F i g . 5» The X-ray d i f f r a c t i o n patterns f o r Douglas f i r earlywood and latewood are shown i n F i g . 6 . The d i f f r a c t i o n patterns f o r both earlywood and latewood of balsam fir» which are not presented, were s i m i l a r to those of Douglas f i r latewood. -49-D e l i g n i f i c a t i o n of Douglas f i r specimens changed the X-ray d i f f r a c t i o n p a t t e r n based on the r e l a t i v e i n t e n s i t y of 002 and (101 + 101) peaks as shown i n F i g . 6, w h i l e the same treatment d i d not s i g n i f i c a n t l y change the d i f f r a c t i o n p a t t e r n of balsam f i r . The per cent c r y s t a l l i n i t y i n respect to the l i g n i n content of Douglas f i r and balsam f i r wood t i s s u e s i s shown i n F i g . 7 . When the per cent t o t a l c r y s t a l l i n i t y of the Douglas f i r and balsam f i r specimens i s p l o t t e d a g a i n s t the i n i t i a l o r i e n t a t i o n angle derived from the d i c h r o i c r a t i o at l l 6 0 cm"'1, a h i g h l y s i g n i f i c a n t l i n e a r r e l a t i o n s h i p i s obtained as "shown i n F i g . 8 and expressed as f o l l o w s Y = 87.6 - 0.91 X Q [8] r = - 0 . 9 0 N = 23 S E E = 3 .59 where Y i s the per cent t o t a l c r y s t a l l i n i t y Xg i s the o r i e n t a t i o n angle at 1160 cm-1 (degree) Results of molecular motions of 1160 cm-1, 1730 cm"l and 1500 cm-1 components of Douglas f i r across an annual increment during s t r e s s r e l a x a t i o n are shown l n Tables 10, 11, 12 and F i g . 9, 10, 1 1 , r e s p e c t i v e l y . The r e s u l t s f o r balsam f i r , although not presented i n f i g u r e s , are shown i n Tables 13, 14 and 15 f o r 1160 cm"1,,1730 cm"1 and 1500 cm" 1 components, r e s p e c t i v e l y . The comparison of the r e s u l t s on the molecular motions f o r wood components during creep and s t r e s s r e l a x a t i o n of balsam f i r i s shown i n Fig. 1 2 . E f f e c t s of e x c i t a t i o n - t i m e on molecular r e l a x a t i o n of the 1730 cm"1 component i s shown i n Fig. 1 3 . The experimental re s u l t s on the eff e c t of removing l i g n i n and hemicellulose on the molecular relaxation of Douglas f i r earlywood are shown i n Tables 16, 17 and Pig. 14, 15 for the l l 6 0 cm"l and 1730 cm~l components, respectively. Tables 18,19 and Pig. 16, 17 show the molecular relaxation of l l 6 p cm"l and 1730 cm""1 components of Douglas f i r latewood. The results f o r the molecular relaxation of 1160 cm-l and 1730 cm~l components f o r treated balsam f i r earlywood are shown i n Tables 20 and 2 1/respectlvely. The res u l t s for latewood of the same species are shown i n Tables 22 and 2 3 , respectively, f o r l l 6 0 cm"l and 1730 cm-l components. The trends f o r the stress relaxation of the d e l i g n i f i e d wood specimens, regardless of earlywood or latewood, are si m i l a r . The difference between the tree species i s also small. The results on physical-mechanical stress relaxation of Douglas f i r earlywood and latewood are shown i n Tables 24, 25 and Pigs, 18. 19 respectively, while those for balsam f i r earlywood and latewood are shown i n Tables 26 and 27. -51-DISCUSSION D e s p i t e i t s c o m p l e x i t y , wood i s a n a t u r a l l y o r d e r e d polymer complex . The main c h a i n s o f c e l l u l o s e and h e m i c e l l u l o s e i n the c e l l w a l l s p r e f e r e n t i a l l y a l i g n p a r a l l e l t o the f i b r i l d i r e c t i o n . T h e r e f o r e , wood c a r b o h y d r a t e s c a n be t r e a t e d as polymers o f n e a r l y p e r f e c t , but v a r y i n g a x i a l o r i e n t a t i o n ( 2 0 5 ) . T h i s b i o - o r i e n t a t i o n ^ p l u s the h i g h degree o f c a r b o h y d r a t e l i n e a r p o l y m e r i z a t i o n , m a k e s wood an i d e a l subs tance f o r examining m o l e c u l a r r e o r i e n t a t i o n e f f e c t s . In a d d i t i o n , some wood c h e m i c a l components c a n be removed i n s tepwise f a s h i o n w i thout s e r i o u s l y i m p a i r i n g the b a s i c c e l l w a l l o r g a n i z a t i o n . T h i s p r o v i d e s means f o r examining i n d i v i d u a l m o l e c u l a r mot ions o f c e r t a i n wood c h e m i c a l c o n s t i t u e n t s . These advantages do not e x i s t w i t h o t h e r polymers examined e a r l i e r (48, 83, 84, 85, 92, 133, 135. 149, 170, 171. 172). Because the na tu re and t e c h n i q u e s o f t h i s work a r e new t o wood s c i e n c e r e s e a r c h , some r e s u l t s which r e l a t e d i r e c t l y t o wood f i n e s t r u c t u r e but i n d i r e c t l y t o the t o p i c , r e q u i r e e x p l a n a t i o n . T h e r e f o r e , t h i s d i s c u s s i o n b e g i n s w i t h e x p l o r a t i o n o f the f i n e s t r u c t u r e and o r i e n t a t i o n o f wood components, and then examines the t ime dependent m o l e c u l a r b e h a v i o u r observed i n s t r e s s r e l a x a t i o n . F i n a l l y , t h i s m o l e c u l a r b e h a v i o u r i s r e l a t e d t o the energy t r a n s f e r mechanism i n wood. I. O r i e n t a t i o n , C r y s t a l l i n i t y and S y s t e m a t i c S t r u c t u r e o f Wood One o f the major c h e m i c a l components o f wood, l i g n i n i s g e n e r a l l y b e l i e v e d to be a t h r e e - d i m e n s i o n a l po lymer (199) wi thout apparent c r y s t a l l i n i t y o r o r i e n t a t i o n . E x p e r i m e n t a l r e s u l t s g i v e n i n Tab le 9 demonstrate l i g n i n d i c h r o i s m a t - 5 2 -1500 c m " 1 . L i g n i n d i c h r o i c r a t i o s range from 0 .7 t o 1.3 f o r the v a r i o u s u n t r e a t e d , u n s t r e s s e d wood t i s s u e s o f f o u r c o n i f e r o u s woods i n c l u d i n g specimens from d i f f e r e n t seasons o f g rowth . Thus , the l i g n i n p o r t i o n o f the n a t i v e wood m a t r i x i s proven t o be o r i e n t e d to some d e g r e e . T h i s f i n d i n g a g r e e s w i t h t h a t o f Lange ( 9 0 ) , who observed u l t r a v i o l e t d i c h r o i s m o f l i g n i n f o r European s p r u c e , bu t d i s a g r e e s w i t h l a t e r i n t e r p r e t a t i o n s o f P r e y - W y s s l i n g (40) , H a r r i n g t o n et a l . ( 5 4 ) and M a r c h e s s a u l t (10?) who c l a i m t h a t l i g n i n i s not o r i e n t e d w i t h i n wood. The c o n t r o v e r s i a l f i n d i n g on l i g n i n o r i e n t a t i o n i n wood can be p a r t l y e x p l a i n e d by d i s s i m i l a r i t y o f the e x p e r i m e n t a l m a t e r i a l s u s e d . T a n g e n t i a l s e c t i o n s , as used i n t h i s exper iment , a l l o w s e q u e n t i a l i n v e s t i g a t i o n a c r o s s growth z o n e s . T h i s approach maximizes the o p p o r t u n i t i e s f o r f i n d i n g d i f f e r e n c e s , s i n c e most p r o p e r t i e s o f wood vary more r a d i a l l y than t a n g e n t l a l l y . As shown i n T a b l e 9, the average 1500 cm~l d i c h r o i s m o f a n n u a l increments i n v e s t i g a t e d were 0 . 9 1 , 0 . 9 8 , 1.09 and 0 . 9 3 f o r S i t k a s p r u c e , Douglas f i r , ba lsam f i r and grand f i r woods, r e s p e c t i v e l y . The grand average f o r t h e s e f o u r v a l u e s i s 0 . 9 8 , which i s c o n s i s t e n t w i t h p r o v i n g an amorphous s t r u c t u r e by i n f r a r e d d i c h r o i s m ( 2 0 5 ) . These average v a l u e s o b t a i n e d on ear lywood and la tewood t a n g e n t i a l s e c t i o n s h o u l d be s i m i l a r t o those o b t a i n e d by exposure o f r a d i a l s e c t i o n s . T h e r e f o r e , s ta tements 0 0 l i g n i n n o n - o r i e n t a t i o n by M a r c h e s s a u l t (1Q7) and H a r r i n g t o n ( 5 4 ) , who used r a d i a l s e c t i o n s as e x p e r i m e n t a l m a t e r i a l s , a r e u n d e r s t a n d a b l e . As shown a l s o i n T a b l e 9, the average l i g n i n d i c h r o i s m - 5 3 -d i f f e r s f o r earlywood, latewood and compression wood. This suggests that l i g n i n o r i e n t a t i o n i n wood depends g r e a t l y on tre e species, p o r t i o n of growth zone examined and perhaps other e f f e c t s of growth. Besides the aforementioned phenomena t l i g n i n o r i e n t a t i o n i n woody p l a n t s was found to be l i n e a r l y a s s o c i a t e d w i t h the carbohydrate s t r u c t u r e at the 1% l e v e l of s i g n i f i c a n c e ( see Formulae 6 and 7» and F i g . 3 ) . This i s the only evidence a v a i l a b l e to date that r e l a t e s l i g n i n and carbohydrate o r i e n -t a t i o n systems i n wood. The X-ray d i f f r a c t i o n patterns shown i n Fi g .6 present other new info r m a t i o n . Although the d i f f r a c t i o n p a t t e r n f o r compression wood Is not given i n the same f i g u r e , the (101+101) i n t e n s i t y i n n a t i v e Douglas f i r wood t i s s u e specimens decreased i n the f o l l o w i n g order, compression wood, earlywood and latewood. This order i n d i c a t e s that the wood X-ray d i f f r a c t i o n p a t t e r n i s r e l a t e d t o l i g n i n content. The qu a n t i t y of l i g n i n i n wpod specimens has been shown (21, 22) to f o l l o w the same order as I n t e n s i t y of d i f f r a c t i o n (101+101) found i n t h i s I n v e s t i g a t i o n . The (101+101) peak i n the X-ray d i f f r a c t i o n p a t t e r n was assigned to the d i f f r a c t i o n of c r y s t a l l i n e c e l l u l o s e as found i n the t a n g e n t i a l plane, while the 002 peak r e l a t e s to c r y s t a l l i n e d i f f r a c t i o n corresponding to the plane p a r a l l e l i n g the f i b r e a x i s (123, 150, 159). Hence the c r y s t a l l i n e s t r u c t u r e of wood must be d i f f e r e n t i n the three t i s s u e s mentioned. The stronger the peak i n the (101+101) plane, the g r e a t e r the amount of c r y s t a l l i n e c e l l u l o s e i n the t a n g e n t i a l d i r e c t i o n . This agrees w i t h r e s u l t s of Kocon (82), who reported t h a t the crys- : - 5 4 -t a l l i n e c e l l u l o s e of spruce and l a r c h compression wood i s pre-f e r e n t i a l l y o r i e n t e d t a n g e n t i a l to the f i b r e a x i s . Furthermore, c r y s t a l l i n e c e l l u l o s e from narrow annual r i n g s has been found to be o r i e n t e d more p a r a l l e l to the f i b r e a x i s than that from wide annual r i n g s of the same pinewood l o g (81). These r e s u l t s are a l s o supported by Okano (134), who mathematically c h a r a c t e r i z e d the o r i e n t a t i o n of c r y s t a l l i n e c e l l u l o s e i n four Japanese , coniferous species by 002 plane d i f f r a c t i o n . C r y s t a l l i n e substances i n the c e l l w a l l were found to be d i s t r i b u t e d non-uniformly around the f i b r e a x i s . Based on the above observation, i t seems reasonable to conclude that wood X-ray d i f f r a c t i o n shows the same dependence on t r e e species, growth zone p o r t i o n (earlywood or latewood) and tr e e response, as found f o r wood i n f r a r e d dichroism. „ ..When l i g n i n i s removed stepwise from wood t i s s u e s , the X-ray d i f f r a c t i o n patterns f o r Douglas f i r , as presented In F i g .6 , show a s i g n i f i c a n t decrease of (101+101) peak i n t e n s i t y i n comparison to the corresponding 002 peak. Decrease of the (101+101) peak i s c o n s i s t e n t w i t h d i f f r a c t i o n patterns of sodium c h l o r i t e d e l i g n i f l e d woods as shown e a r l i e r by Maekawa and. Kita o (103) and Pew and Weyna (142). A c c o r d i n g l y , the (101+101) plane c r y s t a l l i n e c e l l u l o s e must be p a r t i a l l y penetrated by l i g n i n . This supports r e s u l t s on i n f r a r e d dichroism of untreated wood t i s s u e specimens, which suggest t h a t o r i e n t a t i o n of l i g n i n and c e l l u l o s e i s l i n e a r l y r e l a t e d as shown i n F i g . 3 . while d e l i g n i f i c a t i o n changed the 1160 cm"*l and 1730 cm - 1 o r i e n t a t i o n ( F i g . 5 ) . Therefore packing distances between l i g n i n and carbohydrates i n the p a r a c r y s t a l l i n e to c r y s t a l l i n e regions - 5 5 -must be very short. These f i n d i n g s provide the a s s o c i a t i o n necessary f o r e s t a b l i s h i n g the much p o s t u l a t e d l l g n i n - c a r b o -hydrate bonding. The b i o l o g i c a l suggestion i s an overlapping period f o r formation of c e l l u l o s e and l i g n i n , or as suggested by M a r x - P i g i n i (116) c r y s t a l l i z a t i o n and b i o s y n t h e s i s of c e l l u l o s e need not take place simultaneously. Thus even i f l i g n i n i s formed a f t e r c e l l u l o s e , the coexistence of l i g n i n and c e l l u l o s e i n c r y s t a l l i n e regions i s h i g h l y p o s s i b l e . This reasoning i s a l s o i n d i r e c t l y supported by the most recent f i n d i n g of Scott et a l . ( l 6 0 ) that the secondary w a l l of spruce earlywood t r a c h e i d s contains over 70% of the wood l i g n i n . Based on the above evidence, i t i s reasonable to p o s t u l a t e two c r y s t a l l i n e s t r u c t u r e s w i t h d i f f e r e n t o r i e n t a t i o n s i n wood t i s s u e . One i s the basic model which a l i g n s a x i a l l y and d i f f r a c t s i n the ^002 plane. The other i s the c r y s t a l l i n e c e l l u l o s e which i s o r i e n t e d t a n g e n t l a l l y l n the f i b r e a x i s and d i f f r a c t s In the (101+101) plane. Thus, the c r y s t a l l i n e s t r u c t u r e of wood can be considered as having an 002 c r y s t a l l i n e core which i s surrounded by p a r a c r y s t a l l i n e l a y e r s which y i e l d the (101+101) plane, p o s s i b l y r i c h i n l i g n i n . This c o n s i d e r a t i o n i s c o n s i s t e n t w i t h wood u l t r a s t r u c t u r e as demonstrated by e l e c t r o n microscopy ( 6 8 , 7 0 ) . Mann's(105) explanation of the d i f f e r e n c e between i n f r a r e d and X-ray c r y s t a l l i n i t i e s obtained from'the same c e l l u l o s i c m a t e r i a l s supports the existence of a p a r a c r y s t a l l i n e phase. X-ray c r y s t a l l i n i t y i s higher than i n f r a r e d c r y s t a l l i n i t y because the former a l s o measures the b l u r r e d c r y s t a l v e rsions -56-which are amorphous to the i n f r a r e d , i . e . , more e a s i l y a c c e s s i b l e during deuterium oxide exchange. Thus the q u a n t i t y of hydroxyl groups revealed by i n f r a r e d c r y s t a l l i n i t y are hydrogen bonded i n the r e g u l a r c r y s t a l l i n e manner which could be a r e f l e c t i o n of the 002 i n t e n s i t y l n the X-ray d i f f r a c t i o n curve. On the other hand, a c c e s s i b l e hydroxyl groups i n c l u d e d l n X-ray c r y s -t a l l i n i t y are r e f l e c t e d i n the (101+101) peak i n t e n s i t y . Keeping Mann's i n t e r p r e t a t i o n i n mind, and c o n s i d e r i n g that the magnitude of the (101+101) peak from wood t i s s u e s v a r i e s from species to species and t i s s u e to t i s s u e (Fig. 6 and 7 ) , the conclusions of Nelson (127) and Preston and'Allosopp (144) are not s u r p r i s i n g , as only l i t t l e change i n the X-ray d i f f r a c t i o n diagram was observed on wood d e l i g n i f i c a t i o n . S i m i l a r r e s u l t s were found on d e l i g n i f i c a t i o n of balsam f i r wood i n t h i s experiment ( F i g . 7 ) . The increase of 002 peak i n t e n s i t y of d e l i g n i f i e d specimens i s a l s o observed i n t h i s experiment (Fig. 6 and 7 ) . Probably t h i s i s caused by a c r y s t a l l i z a t i o n of the p a r a c r y s t a l l i n e c e l l u l o s e surrounding the m i c e l l e (64, 191. 193. 195) . However, the I n t e r p r e t a t i o n of Nelson (127) as mentioned e a r l i e r should be kept i n mind. In a d d i t i o n , hindrance of the (101+101) p a r a c r y s t a l l i n e l a y e r to d i f f r a c t i o n from the 002 core i n wood should not be passed over. The presence of t h i s hindrance i s i n d i c a t e d by the f a c t that the X-ray wavelength used i s only 1 . 54 8, which i s much s h o r t e r than t h a t expected f o r (101+10T) p a r a c r y s t a l l i n e c e l l u l o s e . Thus a specimen which has a t h i c k p a r a c r y s t a l l i n e zone (101+101) i n plane, such as Douglas f i r - 5 7 -earlywood, w i l l greatly mask d i f f r a c t i o n from the .002 core. D e l i g n i f I c a t i o n removes t h i s hindrance and by so doing exposes more 002 core f o r r e f l e c t i o n . The evidence mentioned above proves the penetration of l i g n i n into at least surface layers of the commonly accepted c r y s t a l l i n e structure, thereby forming the so c a l l e d para-c r y s t a l l i n e zone. The l i g n i n which exists inside t h i s zone must be mainly oriented i n the same d i r e c t i o n as the c e l l u l o s e and hemicellulose. Association between l i g n i n and carbohydrate provides a systematic structure for wood substance i n transverse d i r e c t i o n to the m i c r o f i b r i l s . This suggests a new ;structure f o r wood m i c r o f i b r i l s . The wood m i c r o f i b r i l centre could be a c r y s t a l l i n e core capsulated- by pa r a c r y s t a l l i n e layers which are amorphous with pa r t l y ordered to completely random organization. The c r y s t a l l i n e core could be a pure c e l l u l o s e structure of c r y s t a l l i n e perfection (56, 104) or a fringed-micelle system (4l), while the para-c r y s t a l l i n e layers may contain imperfections as less ordered c r y s t a l l i n e c e l l u l o s e i n admixture with oriented hemicellulose and l i g n i n . The ordered amorphous zone consists mainly of oriented c e l l u l o s e , hemicellulose and l i g n i n while the completely amorphous region i s dominated by non-oriented l i g n i n . This systematic structure would permit a zone of gradual t r a n s i t i o n from high c r y s t a l l i n i t y to a di f f u s e state. This also provides a zone for physical association or bonding between carbohydrate-carbohydrate, carbohydrate-lignin and l i g n i n - l i g n i n . Such an i n t e r f a c i a l system could be^  important to energy transfer i n wood. - 5 8 -II. Wood Molecular Relaxation 1. Patterns of Wood Molecular Relaxation It i s understood that although single infrared functions are not e n t i r e l y descriptive of wood chemical components, as a matter of convenience hemicellulose, l i g n i n and c e l l u l o s e w i l l hereafter be referred to as components absorbing at 1730, 1500 and l l 6 0 cm"*l wave numbers, respectively. Since these chemical components are l i k e l y arranged systematically i n ,wood, t h e i r time dependent molecular motions are apt to be i n t e r -dependent. The experimental re s u l t s of t h i s work show d i f f e r e n t patterns of molecular relaxation f o r wood l i g n i n and carbohydrate fr a c t i o n s . In the course of stress relaxation, the carbohydrate components represented by 1160 cm"1 and 1730 cm"1 bands show i n i t i a l l y a marked reduction of dlchroic r a t i o to the p a r a l l e l position, followed by recovery to the equilibrium l e v e l a f t e r about 20 min relaxation time according to experimental conditions used in the present study. The two-stage motion observed with carbohydrates i s .-. suggested as the course of molecular relaxation. The f i r s t ; stage begins at equilibrium, before the specimen i s stressed j and extends immediately to a minimum dichroic r a t i o . The second stage starts at the end of the f i r s t stage and extends to recovery of equilibrium. The continuing presence of numerous small i r r e g u l a r peaks i n the relaxation curve i s considered to be - 5 9 -a damping e f f e c t which w i l l be discussed l a t e r . On the other hand, the l i g n i n d i c h r o i c r a t i o c a l c u l a t e d -1 at 1500 cm (Fig.11).moves immediately tothe perpendicular p o s i t i o n upon the a p p l i c a t i o n of an e x t e r n a l f o r c e . The maximum d i c h r o i c r a t i o of l i g n i n , l n most cases, c o i n c i d e s w i t h t e r m i n a t i o n of the f i r s t stage described above, i . e . , the time at which the other two components a t t a i n minimum dichroism. In the second 1 stage, the l i g n i n component returns to the e q u i l i b r i u m p o s i t i o n w i t h i n about 20 min. This motion p a t t e r n i s strong evidence r e f u t i n g previous concepts that l i g n i n i s a r i g i d , component s t r u c t u r e incapable of deformation (79). I t i s f u r t h e r suggested that at l e a s t some wood l i g n i n must have a b i l i t y f o r r e o r i e n t -a t i o n complementary to that of carbohydrates, or i t s conformation as shown i n F i g . 11 would be u n l i k e l y to occur. Above a l l , , t h e results, suggest t h a t l i g n i n plays an important r o l e i n modifying wood s t r e s s r e l a x a t i o n . This suggests that removing l i g n i n should a l t e r r e l a x a t i o n p a t t e r n s . Although i t i s not the prime purpose of t h i s experiment, the molecular motion p a t t e r n measured as dichroism at 1160.CM"1 does provide f u r t h e r evidence confirming correctness of the band assignment to the c e l l u l o s e 1 ,4-0-jJ-D-linkage as reported by Marchessault (107). 2. Varying Molecular R e l a x a t i o n Across Annual Increments Intra-incremental d i f f e r e n t i a t i o n of 1160 and 1730jCm"1 r e l a x a t i o n i s d i f f i c u l t , since patterns are very s i m i l a r ( F i g . 9 and .10). Examination of the data show, however, the main d i f f e r e n c e to be l n the time required to r e g a i n e q u i l i b r i u m . The l l 6 0 cm-1 component reaches e q u i l i b r i u m e a r l i e r than the -- 6 0 -companion 1730 cm"*1. This observation i n d i c a t e s t h a t the motion patterns f o r 1730 and 1160 cm"1 components are d i f f e r e n t . Consequently, h e m i c e l l u l o s e could prevent c e l l u l o s e from f a s t recovery of e q u i l i b r i u m . This p o s s i b i l i t y w i l l be examined f u r t h e r In a l a t e r s e c t i o n . The v a r i a t i o n of molecular motion patterns across annual increments suggests some b i o l o g i c a l i m p l i c a t i o n . S i m i l a r i t y i n conformational spectra of the 1160 cm""1 and 1730 cm"1 i components (Tables 10, 11, 13 and 14, F i g . 9 and-10) f o r specimens of the f i r s t formed earlywood and the preceeding l a s t formed latewood suggests that these wood t i s s u e s o r i g i n a t e d from same cambial c e l l s as po s t u l a t e d by Wilson and a s s o c i a t e s ( 1 9 8 , 2 0 1).Also s i m i l a r i t y i n the conformational spectra of l l 6 0 cm"1 and 1730 cm-*1 components i n the apparent t r a n s i t i o n wood (about 50% to 60% p o s i t i o n ) i s noteworthy. The r a p i d r a t e of decrease In dichroism f o r "the f i r s t stage and short e q u i l i b r a t i o n p e r i o d suggest : that the two species studied have molecular s i m i l a r i t i e s i n t r a n s i t i o n zones. • In the case of the 1500 cm"1 component (Tables 12 and; 15» Fig. 1 1 ) , the f i r s t stage r a t e of d i c h r o l c r a t i o increase to the perpendicular p o s i t i o n i s slower f o r earlywood specimens than f o r latewood specimens. These r e s u l t s lend strong support to the p o s t u l a t i o n that d i f f e r e n c e s w i t h i n wood zones l i e at a molecular l e v e l . 3.The Wood Molecular Relaxation_Mecnanism Based on r e s u l t s discussed thus f a r , a t e n t a t i v e mechanism may be described f o r molecular r e l a x a t i o n of wood specimens. The mechanism involves two stages of molecular motions - 6 1 -i n c l u d i n g a l l three major wood components. In the f i r s t stage, the two carbohydrate components as represented by l l 6 0 and 1730 cm""1 band a c t i v i t i e s , independent of t h e i r s t a t e of c r y s -t a l l i z a t i o n , promptly y i e l d i n the d i r e c t i o n of s t r e s s as shown by attainment of d i c h r o i c minima, while the l i g n i n component (1500 cm""l) r o t a t e s to a p o s i t i o n perpendicular to the d i r e c t i o n of s t r e s s as evidenced by maximum, d i c h r o i c r a t i o . At s t a r t of the second stage, the l i g n i n component begins y i e l d i n g i n the s t r e s s d i r e c t i o n and regains e q u i l i b r i u m . The two carbohydrate components, on the other hand, move again s t the s t r e s s d i r e c t i o n with decreasing damping amplitudes and e v e n t u a l l y r e e s t a b l i s h e q u i l i b r i u m . On r e c e i v i n g e x t e r n a l e x c i t a t i o n the wood macromolecular s t r u c t u r e maintains an " i n t e r n a l s t a t e of e q u i l i b r i u m " . This\ e q u i l i b r i u m s t a t e i s achieved by short and long term molecular events through movements of the carbohydrate and l i g n i n components i n opposite d i r e c t i o n s . Over prolonged time, a l l molecular s t r u c t u r e has r e a t t a l n e d a s t a b l e s t a t e . r This mechanism of molecular r e l a x a t i o n questions the -p o s t u l a t i o n of Nissan (130), that the r h e o l o g i c a l behaviour of c e l l u l o s i c m a t e r i a l s i s s o l e l y due to a c t i v i t y of hydrogen bonds which are proposed as s t o r i n g a l l energy i n the system. Experimental r e s u l t s of t h i s t h e s i s show that s t r e t c h i n g of the l,4-0-J3-D-linkage.(covalent bond) i s a l s o ' i n v o l v e d , i f the usual assignment of the l l 6 0 cm - 1 band i s accepted. Other evidence a r i s e s from the apparent a c t i v a t i o n energy of wood and d e l i g n i f i e d wood i n s t r e s s r e l a x a t i o n , which i s found to be 35 to 56 and 17 to 53 K c a l / m o l e , r e s p e c t i v e l y (42). This i s f a r higher than -62-hydrogen bonding energies (137). I t appears that Nissan's p o s t u l a t i o n i s an o v e r s i m p l i f i c a t i o n of complex phenomena. Furthermore, since the s t r e t c h i n g of 1,4-0-/3-D-linkage i s i n v o l v e d , the 10.3 A* spacing of c e l l o b i o s e u n i t s must be considered to a r i s e only under one c o n d i t i o n of s t r e s s , s t r a i n and time of e x c i t a t i o n . When the above mechanism de r i v e d from s t r e s s r e l a x a t i o n s t u d i e s i s compared w i t h creep phenomenon, i t i s i n t e r e s t i n g to note that molecular motions of the creep specimen are e s s e n t i a l l y the same as those of s t r e s s r e l a x a t i o n . This molecular mechanism f o r creep behaviour i s c o n s i s t e n t w i t h the e l e c t r o n microscopic observation made by Senft (162), who found t h a t long-term e f f e c t s of a creep-inducing s t r e s s a p p l i e d along the g r a i n are not r e g i s t e r e d by any changes In m i c r o f i b r i l l a r angle. These experimental r e s u l t s suggest that the basic molecular mechanism of wood r h e o l o g l c a l behaviour i s s i m i l a r ( F i g . 12) f o r e x t e r n a l forces a p p l i e d as constant s t r a i n or constant s t r e s s . In a d d i t i o n , experiments on the e f f e c t of l o a d i n g time on the molecular r e l a x a t i o n of wood gave i n t e r e s t i n g r e s u l t s . As shown i n F i g . l 3 t the d i c h r o i c r a t i o decreased to a p a r a l l e l p o s i t i o n a f t e r l o a d i n g by a ramp f u n c t i o n system. This terminated e i t h e r at the end of l o a d i n g (earlywood) or s e v e r a l minutes a f t e r the end of l o a d i n g (latewood), then the d i c h r o i c r a t i o increased to n e a r l y the o r i g i n a l value. I d e n t i c a l molecular motion curve*were found f o r step-l o a d i n g experiments w i t h both earlywood and latewood. This evidence suggests that wood i s an e x c e l l e n t m a t e r i a l f o r d i s s i p a t i n g energy from e x t e r n a l e x c i t a t i o n . Regardless of the e x c i t a t i o n time, the process of d i s s i p a t i o n - 6 3 -i s not d i s t u r b e d , but l o a d i n g h i s t o r y may be confused w i t h r e l a x a t i o n . I I I . R e l a t i o n s h i p Between Wood Molecular R e l a x a t i o n and Stress  R e l a x a t i o n In the previous d i s c u s s i o n , the compensating molecular motions of d i f f e r e n t wood components are suggested as means f o r maintaining i n t e r n a l e q u i l i b r i u m . These motions are expected to r e s u l t i n l o s s of energy by I n t e r n a l work, which should be observed as phenomenological r e l a x a t i o n . P h y s i c a l s t r e s s r e l a x a t i o n i s one phenomenological. observation of r e l a x a t i o n . A means f o r studying molecular r e l a x a t i o n i s to t e s t and compare r e s u l t s w i t h wood t i s s u e , specimens modified i n var y i n g ways. Thereby, d e l i g n i f i c a t i o n provides a gradual m o d i f i c a t i o n of the three-component wood system.to a two component body which can be examined f o r molecular motion. Further removal of he m i c e l l u l o s e from the two-component body allows examination of an approximate one-component system, the c e l l u l o s e alone. This approach f o r examining molecular behaviour i s be l i e v e d to be the f i r s t attempt of i t s type w i t h complex polymeric systems, 1. D e l i g n i f i c a t i o n and Wood Fine S t r u c t u r e As described under R e s u l t s , wood specimen dichroism v a r i e s w i t h the wood t i s s u e examined, Latewoods, regardl e s s , of species, had lower 1160 cm"1 d i c h r o i c r a t i o s than corresponding earlywoods. This means that the alignment of 1 ,4-0-p-D-linkage in latewoods i s more p a r a l l e l to the f i b r e a x i s than that of earlywoods. As d e l i g n i f i c a t i o n proceeded ( F i g . 5 ) . the l l 6 0 cm""1 latewood dichroism increased l i n e a r l y . This i s - 6 4 -supported by other observations that d e l i g n i f i c a t i o n causes an increase of wood s e c t i o n shrinkage ( 1 5 * 0 and the bending of m i c r o f i b r i l s ( 6 8 , 7 0 ) . The l l 6 0 cm"1 d i c h r o i c r a t i o f o r Douglas f i r earlywood decreased s l i g h t l y on d e l i g n i f I c a t i o n , w h i l e that f o r balsam f i r remained r e l a t i v e l y constant. The 1160 cm-1 dichroism i n l i g n i n - f r e e specimens was s i m i l a r f o r earlywood and latewood of the same species, but v a r i e d between species. This suggests i n d i r e c t l y that the u n i t c e l l l e n g t h of n a t i v e wood c e l l u l o s e can vary as discussed i n a previous s e c t i o n . The value of 10.3 as g e n e r a l l y accepted (167) f o r the c e l l u l o s e l b a x i s , t h e r e f o r e deserves reexamination under v a r y i n g c o n d i t i o n of s t r e s s , s t r a i n and time. The l l 6 0 cm"1 d i c h r o i c r a t i o s f o r d e l i g n i f l e d specimens were l i n e a r l y c o r r e l a t e d to t o t a l c r y s t a l l i n i t y as measured f o r the same specimens ( F i g . 8 ) . Because the c o r r e l a t i o n . c o e f f i c i e n t (slope) i s negative, t h i s experiment supports the previous statement that l i g n i n e x i s t s i n s i d e at l e a s t part of the supposed wood c r y s t a l l i n e s t r u c t u r e . D e l i g n i f i c a t i o n appears to have destroyed the c r y s t a l l i n i t y to some extent, perhaps by d i s t u r b i n g p a r a l l e l c e l l u l o s e o r i e n t a t i o n . ; The e f f e c t of d e l i g n i f i c a t i o n on 1730 cm"1 d i c h r o i c r a t i o s i s s i m i l a r f o r both species examined ( F i g . 5 ) . The; l a t e -wood dichroism was s l i g h t l y decreased or remained constant, while earlywood showed a marked increase when the l i g n i n content was lowered to l e s s than 60^ of that i n o r i g i n a l t i s s u e s . The cause f o r t h i s Increase of dichroism i n earlywood,although not known, i s presumably due to adjustments caused by d e l i g n i f i c a t i o n , - 6 5 -or to the o x i d a t i o n of t e r m i n a l reducing groups to carboxyl groups (128). The above r e s u l t s show c o n c l u s i v e l y the c l o s e a s s o c i a t i o n between l i g n i n and c e l l u l o s e and r e s t r a i n i n g e f f e c t s of l i g n i n on the carbohydrate components. Removing l i g n i n t h e r e f o r e : l i b e r a t e s a carbohydrate which i s l e s s r e s t r a i n e d i n molecular motion. 2. Molecular R e l a x a t i o n During e a r l y stages of d e l i g n i f i c a t i o n , when the specimen r e s i d u a l l i g n i n i s more than one-half of the o r i g i n a l amount, — 1 1 elements as represented by 1730 cm and l l 6 0 cm""1 bands show numerous peaks i n the r e l a x a t i o n curve (Tables 16, 17, 18, 19, 20, 21, 22 and 23, and F i g . 14, 15, 16 and 17). These peak i n t e n s i t i e s decrease with lapsed time. This decay p a t t e r n may be due to a molecular pendulum motion during the course of e q u i l i b r i u m recovery. The phenomena w i l l be c a l l e d "damping" herein. Magnitude of the damping e f f e c t i s d i r e c t l y r e l a t e d to the amount of l i g n i n present. As shown i n F i g . 14 and 15. when the l i g n i n content of specimens was l e s s than one-half the o r i g i n a l amount (before the removal of h e m i c e l l u l o s e ) , earlywood r e l a x a t i o n curves were of simpler form. This was s i m i l a r to the molecular r e l a x a t i o n of t r a n s i t i o n wood ( F i g . 9 and 1 0 ) . The r a t e of decrease i n d i c h r o i c r a t i o i n the f i r s t phase was l a r g e , while the time r e q u i r e d to reach e q u i l i b r i u m i n the second phase was shortened. A l s o , the o s c i l l a t i o n s w i t h i n curves were not as s i g n i f i c a n t as during r e l a x a t i o n of specimens having i n i t i a l l y high r e s i d u a l l i g n i n contents. Among i n d i v i d u a l - 6 6 -a b s o r p t i o n bands, the 1160 cm _l component reached t h i s simpler form at a higher r e s i d u a l l i g n i n l e v e l than the 1730 cm-l component. This suggests more intimacy between l i g n i n and h e m i c e l l u l o s e , than between c e l l u l o s e and the other two components. On the other hand, the latewood r e l a x a t i o n curves were markedly d i f f e r e n t from those of earlywood ( P i g . 16 and 17) . The l l 6 0 cm-l component showed a simpler form of r e l a x a t i o n when part of the l i g n i n was removed. As specimen l i g n i n contents approached one-half the o r i g i n a l amount, the r e l a x a t i o n curve became a s t r a i g h t l i n e . This could be due t o the f a s t e q u i l i b r i u m recovery of the 1160 cm""l component which i s s i m i l a r to the d e s c r i p t i o n s of Gotoh and coworkers (48, 49) , Onogi and Asada(135) and S t e i n (169) on the experimental r e s u l t s of other simple polymers by d i f f e r e n t means. The latewood r e l a x a t i o n curves of 1730 cm components, are s i m i l a r to t h e i r counterparts i n earlywood ( F i g . 15 and 17) . These r e s u l t s suggest that there i s a time d i f f e r e n c e In r e l a x a t i o n of 1160 cm"l and 1730 cm"1 components. The reason f o r the small d i f f e r e n c e i n the wood specimen could be due to the i n f l u e n c e of l i g n i n , D e l i g n i f i c a t i o n ap-pears to increase d i f f e r e n t i a t i o n . The 1730 cm"l component may r e t a r d r a p i d recovery of l l 6 0 cra-1 component when e x t e r n a l e x c i t a t i o n i s r e c e i v e d . In such a system, the main s t r e s s flow passes along the long c e l l u l o s e chains, w h i l e l i g n i n and he m i c e l l u l o s e d i s s i p a t e the force e i t h e r d i r e c t i o n a l l y or by out of phase motions, and thus r e t a r d the c e l l u l o s e recovery. 3. Stress R e l a x a t i o n Stress i s a form of energy which i n d i c a t e s the r e s i s t a n c e - 6 7 -of m a t e r i a l t o y i e l d ( 1 8 4 ) . D e l i g n i f i c a t i o n , a s shown i n Tables 24, 25, 26 and 27, and Figs. 1 8 and 19,induces change of shape i n s t r e s s r e l a x a t i o n curves. The s t r e s s r e l a x a t i o n curves f o r specimens which have l i g n i n content more than one-half the o r i g i n a l amount are almost i d e n t i c a l to the molecular r e l a x a t i o n curves of 1160 cm - 1 and 1730 cm""1 components e i t h e r i n shape or t i m i n g of damping.This i s the f i r s t evidence showing c o n c l u s i v e l y t h a t the wood r h e o l o g i c a l behaviour i s a composite expression of the molecular motions of the wood components. The s t r e s s r e l a x a t i o n curves of the present study u s i n g t h i n wood s e c t i o n s are c o n s i s t e n t w i t h curves observed by Norimoto et a l (131, 132) on macrospecimens examined i n t o r s i o n bending t e s t s , and by Takemura et a l . ( 1 7 8 ) i n bending t e s t s . A r i s i n g peak was found i n t h e i r r e l a x a t i o n spectra (continuous p l o t of slope f o r s t r e s s r e l a x a t i o n curve against time) between l p ^ to 10^ seconds of r e l a x a t i o n time w i t h almost every specimen t e s t e d , even under d i f f e r e n t humidity c o n d i t i o n s . As the r e l a t i v e humidity increased, t h i s peak shifted, to s h o r t e r times. S i m i l a r l y , a peak has been observed i n the s t r e s s r e l a x a t i o n spectra of wood swollen w i t h a l i p h a t i c a l c o h o l s of various c h a i n lengths and t e s t e d i n the a l c o h o l s o l u t i o n s ( 4 5 ) . The r e s u l t s i n d i c a t e d that the s h o r t e r the c h a i n l e n g t h ( i . e . , t h e g r e a t e r the s w e l l i n g ) , the s h o r t e r the time f o r appearance pf the peak. When the l i g n i n content of specimens i n the present experiment was l e s s than one-half the o r i g i n a l amount, the damping of r e l a x a t i o n curves became simpler and peaks moved to s h o r t e r -68-times. The tendency of the relaxation curve to damp les s i s sim i l a r to that of molecular relaxation. As shown i n Pig. 18 and 19* the physical-mechanical curves of wood tissues can he separated into two stages according to molecular relaxation. The f i r s t stage extends from the zero time decrement to a curve d e f l e c t i o n point. The second stage begins from t h i s point and appears to extend to i n f i n i t e time. In the f i r s t stage, the magnitude and rate of stress decrement increases rapidly as the l i g n i n content of specimens is decreased. In other words, the relaxation time to reach the end of t h i s f i r s t stage i s shortened. When the f i r s t and second stages are compared, the amount of stress decrement i n the f i r s t stages i s much greater than that of the second stage. In the second stage, i t i s intere s t i n g to note that the p r o f i l e of stress decrement at 40 min relaxation time (Pig. 18 and 19) coincides with per cent (101+101) c r y s t a l l i n i t y , as defined e a r l i e r , for both woods examined ( Fig.7). This suggests that the stress decrement of wood could relate to part of the (101+loT) c r y s t a l l i n e structure which i s penetrated by l i g n i n . This phenomenon i s s i m i l a r to effects of swelling solutions on wood stress relaxation (45),where only the paracrystalline region * A curve d e f l e c t i o n point Is either (1) the point where the stress, instead of continuing to decrease, begins to increase thus causing the stress curve to change i t s o r i g i n a l d i r e c t i o n ; and (2) the point where the rate of stress decrement becomes very small. -69-i s supposedly swollen. This l i n e of exp l a n a t i o n , however, i s not c o n s i s t e n t w i t h t h a t of P u s h i t a n i (42). I t does, agree, however, w i t h the viewpoint of E r i k s s o n , (35, 36) who considered t h a t the f u n c t i o n of l i g n i n i n the r e l a x a t i o n modulus i s to reduce carbohydrate m o b i l i t y . This observation a l s o agrees wi t h the hypothesis of Mark (113) t h a t hydrogen bonds l y i n g i n the (101+101) c r y s t a l plane of c e l l u l o s e are r e l a t e d to the wood shear modulus. The r e l a t i v e increase of h e m i c e l l u l o s e i n d e l i g n i f i e d specimens should be a l s o taken i n t o c o n s i d e r a t i o n . As described p r e v i o u s l y , the 1500 cm"1 and 1730 cm - 1 components of l i g n i n and h e m i c e l l u l o s e ^ r e s p e c t i v e l y , are capable of r e t a r d i n g the c e l l u l o s e r e l a x a t i o n component as measured by ll60 cm"1 a c t i v i t y . Hence, the d i s p r o p o r t i o n of components p r o v i d i n g the 1500 cm" 1 and 1730 cm" 1 a c t i v i t y due t o d e l i g n i f i c a t i o n i s equivalent to tKe removal of one while adding the other. Therefore, the s t r e s s decrements l n d e l i g n i f i e d specimens may depend on the d i f f e r e n c e between the e f f e c t of 1160 and 1730 cm"1 components. The r e l a t i o n s h i p between s t r u c t u r a l components and s t r e s s r e l a x a t i o n can be explained a l s o according t o the systematic s t r u c t u r e of wood substance. D e l i g n i f i c a t i o n and hem i c e l l u l o s e removal are approaches used to destroy the wood "memory system". The higher the order of b i o - s t r u c t u r e r e t a i n e d , the stronger the wood "memory system" w i l l be. During l a t e r stages of d e l i g n i f I c a t i o n , the l i g n i n p o r t i o n of the paracrys-t a l l i n e s t r u c t u r e , which i s r e l a t e d to energy storage and ( t r a n s f e r , w i l l be removed. Therefore, removal of l i g n i n from • amorphous zones provides m a t e r i a l s showing d i f f e r e n c e s i n s t r e s s decrement, but the e f f e c t becomes more pronounced i n -70-l a t e r stages of d e l i g n i f i c a t i o n . Probably, the l i g n i n a s s o c i a t e d w i t h c r y s t a l l i n e c e l l u l o s e i s removed and thus the system i s g r e a t l y impaired. When he m i c e l l u l o s e s are removed, the systematic s t r u c t u r e of wood i s no longer present and the s t r e s s decreases g r e a t l y . S i m i l a r i l y , the low r e s i s t a n c e of wood to fo r c e per-p e n d i c u l a r to the g r a i n d i r e c t i o n i s e x p l a i n a b l e on the decrease i n f u n c t i o n a l i t y of the wood "memory system" due to lessened opportunity to t r a n s f e r energy. IV. Proposed Mechanism f o r the Molecular Motion i n Wood  Under Stress The consistency of i n f r a r e d dichroism and s t r e s s r e l a x a t i o n demonstrated above agrees w i t h the theory of T r e l o a r (185), i n that the d i f f e r e n c e between any two p r i n c i p a l r e f r a c t i v e i n d i c e s i s p r o p o r t i o n a l to the d i f f e r e n c e between the corresponding p r i n c i p a l s t r e s s e s . This i s a l s o supported by the p o s t u l a t i o n of S t e i n and Tobolsky (173) and Tobolsky ( 184), the s t r e s s - b i r e f r i n g e n c e r e l a t i o n s h i p as f o l l o w s ; entropy, i n t e r n a l energy * f r e e energy d i s t r i b u t i o n f u n c t i o n s t r e s s il b i r e f r i n g e n c e . This diagram i s c o n s i s t e n t w i t h recent Russian l i t e r a t u r e as surveyed by B i r s h t e l n and P t i t s y n (12), i n that not only entropy, but a l s o the energy of chains, change during polymer deformation. -71-A c c o r d i n g l y , the time-dependent behaviour of wood polymers can be re s o l v e d i n t o one or more processes by c o n s i d e r i n g o p t i c a l s t r e s s c o e f f i c i e n t s * (12, 173. 184). Motions of l i g n i n i n the wood matrix appear to f o l l o w viscous flow or d i f f u s i o n behaviour, while those of the carbohydrates (1730 cm"1 and,: l l 6 0 cm"1) seem to undergo processes r e p r e s e n t a t i v e of c r y s -t a l l i z a t i o n and o r i e n t a t i o n of c r y s t a l l i n e s t r u c t u r e s . This i s supported by r e s u l t s of Murphey(124) and Suzuki (177). L i g n i n i n wood, t h e r e f o r e , may be considered as a Newtonian body , (dashpot i n a t y p i c a l mechanical model). The r e l a t i o n s h i p , of c e l l u l o s e and/or h e m i c e l l u l o s e to a s p r i n g as described by;the Maxwell body (31, 37. 165) i s not proper, since l i n e a r v i s c o -e l a s t i c behaviour of polymers i s not a p p l i c a b l e under c o n d i t i o n s where the polymer c r y s t a l l i n e c h aracter i s changing during a v i s c o e l a s t i c experiment (184). Recognition of the two-stage mechanism f o r molecular . motion of wood c o n s t i t u e n t s f i t s the argument. According to t h i s mechanism, motions of i n d i v i d u a l components r e t a i n wood s t a b i l i t y a t the macromolecular l e v e l when e x t e r n a l e x c i t a t i o n i s r e c e i v e d . In the f i r s t stage of motion or immediate response, the development of p a r a l l e l dichroism f o r the carbohydrates i n d i c a t e s the p o s s i b i l i t y of c r y s t a l l i z a t i o n w hile at the same time l i g n i n attempts to d i f f u s e Into the carbohydrate 1 l a t t i c e . This behaviour of polymers r e s u l t s i n high s t e r i c i n t e r f e r e n c e through a s s o c i a t i o n , which a c t s i n a manner; s i m i l a r to c r o s s - l i n k e d chains of l i g n i n and carbohydrates, * The o p t i c a l c o e f f i c i e n t i s the r a t i o between s t r e s s and dichroism. Each polymer has i t s own c o e f f i c i e n t which depends only on l o c a l s t r u c t u r e of the polymer c h a i n . -72-even i f there i s no l i g n i n - c a r b o h y d r a t e bonding present. Conse-quently, as the wood re c e i v e s t e n s i l e e x c i t a t i o n , the p r e f e r r e d flow of for c e which i s i n the c e l l u l o s e (or t o t a l carbohydrate) chain d i r e c t i o n w i l l be tr a n s m i t t e d to the l i g n i n network through a s s o c i a t i o n or s t e r i c i n t e r f e r e n c e . Therefore, although the e x c i t a t i o n w i l l induce a heterogeneous d i s t r i b u t i o n of st r e s s e s i n the wood during the i n i t i a l stage ( f i r s t stage), the immediate r e a c t i o n of l i g n i n to the a p p l i e d f o r c e reduces the burden on the carbohydrate. The forc e i s then t r a n s m i t t e d through the l i g n i n matrix from the p a r a c r y s t a l l i n e to the amorphous regions of the whole wood. During fo r c e transmittance, each succeeding set of l l g n i n - l i g n l n , or h e m i c e l l u l o s e - l i g n i n a s s o c i a t i o n , responds l e s s r a p i d l y because of the l a r g e r amount of l i g n i n a v a i l a b l e f o r ab s o r p t i o n of energy and f r i c t i o n a s s o c i a t e d w i t h each group, and the response of the more d i s t a n t chains i s delayed. With t h i s i n t e r p r e t a t i o n , the prolonged recovery time r e q u i r e d f o r the dichroism of the carbohydrates, i n the presence of l i g n i n , to reach e q u i l i b r i u m w i t h the damping a c t i o n i n the second stage of r e l a x a t i o n i s reasonably-explained. The c r y s t a l l i n e r e o r i e n t a t i o n process i s t h e r e f o r e expected t o occur only i n the f i r s t stage. The l i g n i n network of the system may do more than t r a n s f e r energy;with i t s l a r g e percentage of benzene n u c l e i i t may act a l s o as an energy sink and thereby f u n c t i o n to,; maintain the memory of the e x c i t a t i o n . B i o p h y s i c a l m o d i f i c a t i o n s which could r e l a t e t o t h i s are high l i g n i n content and abnormal l i g n i n d i s t r i b u t i o n i n latewood c e l l w a l l s of compression wood(21). -73-higher l i g n i n content of earlywood than latewood (20, 198, 201) and f i n a l l y existence of a mutually e x c l u s i v e r e l a t i o n s h i p between a l p h a - c e l l u l o s e and l i g n i n i n c oniferous woods (168). -74-G0NCLUSI0N3 I . The time dependent molecular a c t i v i t i e s of wood components at s t r a i n i n g can be observed by I n f r a r e d p o l a r i z a t i o n techniques. I I . A two-stage molecular motion I n v o l v i n g three wood components i s suggested as the course of molecular r e l a x a t i o n . The f i r s t stage begins at e q u i l i b r i u m , when the specimen i s not st r e s s e d , and extends immediately to a minimum d i c h r o i c r a t i o of carbohydrate components represented by l l 6 0 cm"1 ; and 1730 cm"! bands, and the maximum dichroism of l i g n i n ( 1 5 0 0 cm-l). rp^ Q s e c o n d stage s t a r t s at the end of the. f i r s t stage and extends to e q u i l i b r i u m recovery. Thus , on r e c e i v i n g e x t e r n a l e x c i t a t i o n the wood macromolecular s t r u c t u r e can maintain an " i n t e r n a l s t a t e " of e q u i l i b r i u m . This e q u i l i b r i u m s t a t e i s achieved by moving the carbohydrate and l i g n i n components i n opposite d i r e c t i o n s . Regardless of the form of e x c i t a t i o n ( s t r e s s r e l a x a t i o n or creep), and the time of e x c i t a t i o n , the basic p a t t e r n of two-stage motion w i l l not be d i s t u r b e d , while damping of the molecules accompanies the whole r h e o l o g l c a l process. III.The molecular motion of wood components i s environment dependent. The observed p a t t e r n of the motion f o r each component i n the wood macromolecular system i s a compensatory r e s u l t from the i n t e r f e r e n c e of other components. The stepwise removal of l i g n i n from wood specimens a l t e r e d the motional patter n of carbohydrates. The motion of c e l l u l o s e , w i t h o u t the i n t e r f e r e n c e of l i g n i n and h e m i c e l l u l o s e , i s comparable - 7 5 -to that of the other high polymers ( 1 3 5 . 1 6 9 ) . IV. Rheological behaviour of wood, as represented by the s t r e s s r e l a x a t i o n process, i s shown to be a composite expression of the molecular motions of wood components as evidenced by the consistency of the f l u c t u a t i o n of curves f o r s t r e s s r e l a x a t i o n and molecular motions of carbohydrate components. V. Energy t r a n s f e r system of wood was thus explained on the c o n s i d e r a t i o n that the motion of each chemical component i s f o r a c h i e v i n g s t a b i l i t y of the wood macromolecular system when e x t e r n a l e x c i t a t i o n i s re c e i v e d . The d i f f e r e n c e i n d i r e c t i o n a l movement i n carbohydrate ;and l i g n i n molecules r e s u l t s l n a high s t e r i c Interference and, a s s o c i a t i o n which ac t s i n a manner s i m i l a r to c r o s s - l i n k e d chains of l i g n i n and carbohydrates, even i f there i s no lig n i n - c a r b o h y d r a t e bonding present. Consequently, as the wood rec e i v e s t e n s i l e e x c i t a t i o n , the p r e f e r r e d flow of,, force which i s i n the carbohydrate chain d i r e c t i o n w i l l . b e transmitted to the l i g n i n network by the a s s o c i a t i o n or s t e r i c i n t e r f e r e n c e . Therefore, although the e x c i t a t i o n w i l l induce a heterogeneous d i s t r i b u t i o n of s t r e s s e s i n the wood during the i n i t i a l stage, the immediate r e a c t i o n of l i g n i n to a p p l i e d force reduces the burden on the carbohydrate. The force i s then t r a n s m i t t e d through the l i g n i n matrix to the whole wood. During force transmittance, each succeeding set of l i g n i n , or h e m i c e l l u l o s e a s s o c i a t e d w i t h l i g n i n , responds l e s s r a p i d l y - 7 6 -because of the f r i c t i o n s a s s o c i a t e d w i t h each group and the la r g e percentage of benzene n u c l e i i n l i g n i n f o r a b s o r p t i o n of energy, the response of the more d i s t a n t chains i s delayed. Thus, damping motion accompanies the molecular r e l a x a t i o n process f o r chemical components to reach e q u i l i b r i u m . VI.For f u l f i l l m e n t of the r h e o l o g i c a l p r o p e r t i e s described, a systematic s t r u c t u r e of wood m i c r o f i b r i l s , based on the evidences found by X-ray and i n f r a r e d spectrophotometers, Is proposed. The wood m i c r o f i b r i l center could be c r y s t a l l i n e core capsulated by p a r a c r y s t a l l i n e l a y e r s which are amorphous with p a r t l y ordered to completely random o r g a n i z a t i o n . The c r y s t a l l i n e core could be a pure c e l l u l o s e s t r u c t u r e of c r y s t a l l i n e p e r f e c t i o n or a f r l n g e d - m l c e l l e system, while the p a r a c r y s t a l l i n e l a y e r s may c o n t a i n imperfections as l e s s ordered c r y s t a l l i n e c e l l u l o s e i n admixture w i t h o r i e n t e d h e m i c e l l u l o s e and l i g n i n . The orde'uJamorphous zone c o n s i s t s mainly of o r i e n t e d c e l l u l o s e , h e m i c e l l u l o s e and l i g n i n while the completely amorphous reg i o n i s dominated by non-oriented l i g n i n . This systematic s t r u c t u r e would permit a zone of gradual t r a n s i t i o n from high c r y s t a l l i n i t y to a d i f f u s e s t a t e . This a l s o provides a zone f o r p h y s i c a l a s s o c i a t i o n or bonding between carbohydrate-carbohydrate, c a r b o h y d r a t e - l l g n i n and. l i g n i n - l i g n i n . -77 -LITERATURE CITED 1. Astbury, W.T., Preston, R.D. and A.G. Norman. 1935. X-ray examination of the e f f e c t of removing non-c e l l u l o s i c c o n s t i t u e n t s from vegetable f i b r e s . Nature 136:391-392. 2. Bach, L. 1965. Non-linear mechanical behaviour of wood In l o n g i t u d i n a l t e n s i o n . Ph.D. T h e s i s , College of F o r e s t r y , State Univ. of New York, Syracuse, pp .283. 3. . 1967. S t a t i c f a t i g u e of wood under constant s t r a i n . Information Report VP-X-24, Forest Prod. Lab., Vancouver. Pp.4. 4. . 1968. Personal communication. 5 . B a i l e y , A.J. 1 9 3 6 . L i g n i n i n D o u g l a s - f i r : Composition of the middle l a m e l l a . Ind. Eng. Chem. (Anal. Ed.) 8 : 5 2 - 5 5 . 6 . Barker, S.A., Bourne, E.J., Stephens, M. and D.H. 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THE CHEMICAL COMPOSITION OF CELL WALL LAYERS ACCORDING TO MEIER (117. 118) Layer of c e l l w a l l M+P S« S- outer So inner + S-, % r 2 % d % 3 Pinus s y l v e s t r l s ( L . ) Galactan 20.1 5.2 1.6 3.2 C e l l u l o s e 35.5 6 l . 5 6 6 . 5 47.5 Glucomannan 7.7 16.9 24 .6 27.2 Arabinan 29 .4 0 . 6 0 . 0 2 . 4 Glue u ro noarab i no- 7.3 15.7 7 . 4 1 9 . 4 x y l a n Picea Abies (L.) Karst Galactan 16.4 8 .0 0 . 0 0 . 0 C e l l u l o s e 3 3 . 4 55.2 64 .3 6 3 . 6 Glue omannan 7 . 9 18.1 24 . 4 23.7 Arabinan 29.3 1.1 0.8 0 . 0 Glucuronoarabino- 13.0 17.6 10.7 12.7 x y l a n TABLE 2. THE CHEMICAL COMPOSITION OF GROWTH ZONES (Pinus s y l v e s t r l s (L.) ACCORDING TO MEIER ( 118 ) Polysaccharide Earlywood Latewood % % Galactan 3.4 3.1 C e l l u l o s e 56.7 56.2 Glucomannan 20.3 24.8 Arabinan 1.0 1.8 Glucuronoarabinoxylan 18.6 14.1 TABLE 3. THE UNIT CELL STRUCTURE OP CELLULOSES Type of c e l l u l o s e Monoclinlc o dimenslon(A) Cellulose I Monoclinic angle(degrees) Author a b c 7.90 10.20 8.45 PolanyK 167 ) * # 12.20 10.25 10.80 - Sponsler(1 6 7 ) * 8.35 10.30 7.90 84.0 Meyer and Mark(l67) 6 0 . 0 Meyer and Mlsch( i 6 7 ) 15.80 10.30 12.50 Sen and Roy( 161) 8.70 10.34 7.85 83.6 Jones (74) 8.20 10,3k 7.84 82.0 Fisher and Mann(38) 8 . 3 9 10.58 7 . 9 ^ 82.0 Honjo and 7.76 Watanabe(63) . 8.20 10.34 82.0 Honjo and Watanabe 8.20 10.3** 96.0 ( 6 3 ) . ( 3 8 ) * * 7 . 8 9 Wellard(i97) Cellulose II 8.10 16.30 7.92 8.97 10.30 10.30 1 0 . 3 ^ 10.3*+ 9.10 9.00 9.08 7.31 Andress(167)* 64.0 Sen and Roy ( l 6 l ) 6 2 . 7 Jones(74) 99.*+ Poppleton and Mathieson(l43) * The o r i g i n a l s were not seen,cited from reference (167) i ** These dimensions were calculated from Honjo and Watanabe's data 0 by Fisher and Mann(38) who considered that t h e i r value b=10.58 A was too large, and used instead 10.34 A for calculation.. TABLE 4.THE BRIDGING ANGLE FOR 1,4-0-^-D-LINKAGE OP CELLULOSIC MATERIALS Author Angle(degree) 117.0 116.7 116.0 111.6 to 118.8 108.0 108.0 to 113.0 Ramachandran e_t al^i46) Brown (18) Beevers et al.( 8 ) S e t t l n e r i and Marchessault(164) Jacobson et al.( 66) Jones(73 T~ -96-TABLE 5 . THE UNIT CELL STRUCTURE OF XYLAN (108) F i b e r r e p e a t % A n g l e , d e g r e e s D is tance ,X C^-O-Cjj, T r a n s . moment H - i . . . H-4 0 - 5 . . . Q.3 0 - 2 . . . H-4 15.00 118.8 89 2.47 3 . 0 4 . 5 14.84 116.5 88 2.43 3 . 0 4 . 5 14.50 111.6 86 2.32 3.0 4 . 5 • D e f i n e s o r i e n t a t i o n o f the t r a n s i t i o n moment f o r the CH2 group a t C<j i n the r i n g . TABLE 6 . THE UNIT CELL DIMENSIONS OF XYLAN HYDRATE AND CELLULOSE 11(108) 0 Dimens ions ,A Angle a b c (degrees) X y l a n h y d r a t e 9.16 14.84 9.16 60 C e l l u l o s e II 8 .14 10.30 9 . 14 62 - 9 7 -TABLE 7.BAND ASSIGNMENTS IN WOOD INFRARED SPECTRA Wave Wave P o l a r i - Assignment  leng t h number z a t i o n ft n number Tcrn-H" 2.82 3550 0-H stretching ( 4-methyl gualcaol)( 1 5 6 ) 3545 0-H s t r e t c h i n g ( g u a i a c y l g l y e r o l model)(156) 35^0 O-H stretching(4-methyl s y r l n g o l model)(156) 3525 0-H s t r e t c h i n g ( m i l l e d wood l i g n i n i n C H 2 C I 2 ) ( 1 2 0 ) ( a l s o methanol l i g n i n i n C HgC^ipulp Halse l i g n i n , p u l p Klason l i g n i n (120) 2.84 3520 0-H s t r e t c h i n g ( K r a f t l i g n i n ) ( 1 2 0 ) 3510 0-H stretching(methanol l i g n i n i n butan-2-one) (120) ; 3490 0-H s t r e t c h i n g ( m i l l e d wood l i g n i n , p u l p Halse l i g n i n i n dioxan ) ( 1 2 0 ) 2 .87 3485 0-H stretching(methanol l i g n i n , p u l p Klason l i g n i n i n p y r i d i n e ) (120 ) 3480 0-H s t r e t c h i n g ( K r a f t l i g n i n ) (120 ) 2 .92 3425 0-H s t r e t c h i n g ( m i l l e d wood l i g n i n , K r a f t l i g n i n , pulp Halse l i g n i n , p u l p Klason l i g n i n - i n butan-2-one)(120 ) 3420 0-H s t r e t c h i n g ( m i l l e d wood l i g n i n , s o l i d methanol l i g n i n ) (120 ) 2 .93 .3415 0-H s t r e t c h i n g ( m i l l e d wood l i g n i n in: p y r i d i n e ) (120) 3410 0-H s t r e t c h i n g ( K r a f t l i g n i n , p u l p Halse l i g n i n , s o l i d Klason l i g n i n and pulp Halse l i g n i n i n p y r i d i n e ) ( 1 2 0 ) * 3400 -L 0-H s t r e t c h i n g ( 188 ) 0-H s t r e t c h i n g ( i n t e r - m o l e c u l a r hydrogen bonds i n l O l plane( 98 ) 3350 || 0-H s t r e t c h i n g ( i n t r a - m o l e c u l a r hydrogen bonds) ( 98 ) * 3305 -L 0-H s t r e t c h i n g ( i n t e r - m o l e c u l a r hydrogen bonds i n 101 p l a n e ) ( 9 8 ) * 3300 'I 0-H s t r e t c h i n g ( 1 8 8 ) * 3.33 3000 C-H s t r e t c h i n g ( 9 8 ) 3.37 2970 'I C-H s t r e t c h i n g ( 9 8 ) (188)* 2945 J- CH2 antisymmetrical s t r e t c h i n g ( 9 8 ) * 2914 to 2870 ± C-H s t r e t c h i n g ( 9 8 ) * 3.52 2850 II CH2 s t r e t c h i n g ( 98 ) * 5.78 1730 to _L C=0 s t r e t c h i n g ofyB-keto groups (13,32,58 ) 1725 C=0 s t r e t c h i n g of a c e t y l or c a r b o x y l i c acid ( 3 2 , 8 7 , 9 8 ) ( 9 8 ) * 5 . 9 9 1670 to C=0 s t r e t c h i n g of s y r i n g y l aldehyde and 1660 v a n i l l i n ( l 8 7 ) , l i g n i n ( 9 8 ) 6.06 1650 t o H0H bending of water and due to l i g n i n 1635 carbonyl band(21,32,163 ) C=C bond (187) 6.21 1610 to Guaiacyl and s y r i n g y l models, aromatic 1600 s k e l e t a l v i b r a t i o n s ( 1 5 6 ) -98-Wave Wave Polar1-l e n g t h number z a t l o n Assignment (cm-J-) 6.23 1605 Aromatic s k e l e t a l vibrations( 1 5 6 ) 6.27 1595 A/ Lignln ( l 0 7 )*, aromatic s k e l e t a l v i b r a -t i o n s (156) 6.33 1580 Lignin ( 1 0 7 ) 6.58 1520 to Aromatic s k e l e t a l v i b r a t i o n s ( 1 5 6 ) , 1500 g u a l a c y l and s y r i n g y l models (156) 6.62 1510 to /V Lignin ( 5 4 a 0 7 )•* 1500 6.85 1460 _L L i g n i n and CH 2 symmetrical bending In the pyran r i n g ( 1 0 7 ) * 6 . 8 7 1455 to J_ 0-H bending(107) (188 )* 1400 6 . 9 0 1450 to Gua i c y l and s y r i n g y l models(156) 1420 7 . 0 0 1430 to || CH 2 symmetrical bending mode, hydroxymethyl 1425 (107)*. aromatic s k e l e t a l v i b r a t i o n s ( 1 5 6 ) * C-H bending v i b r a t i o n In methoxyl groups (13.28) 7.24 1380 II C-H bending(107)* 7.35 1360 || 0»H in-plane bending(13,86) C-H deformation(188)* 7 . 4 9 1335 _L 0-H in-plane deformation(188)* r i n g b r e a t h i n g w i t h C-0 s t r e t c h i n g , s y r i n g y l type (with 1245 cm" 1,1125 cm-l)(156) 7.42 1330 Ring breathing w i t h C=0 s t r e t c h i n g , g u a l a c y l type (with 1240 cm"*l, 1110 cm - 1) (156) 7.61 1315 J_ CH 2 wagging(107 )*, C-H d e f o r m a t l o n ( l 8 8 ) * 7085 1270 to || Cll? wagging ( 1 8 8 ) * 1275 L i g n i n ( 1 0 7 ) r i n g breathing w i t h C-0 s t r e t c h i n g , g u a l a c y l type(with 1240 cm-l, 1130 cm-l) (156) 7.91 1265 C°0-C symmetric s t r e t c h i n g v i b r a t i o n of a r y l ether l i n k a g e ( 2 8 ) , lignin ( 1 2 1 ) 8 . 0 0 1250 to Phenolic OH(156), syringln(hardwood), 1150 c o n i f e r l n and v a n i l l i n ( s o f t w o c d ) C=0 s t r e t c h i n g of aromatic ethers (187) 8 . 0 7 1240 -L C-0 of a c e t y l ( 1 0 7 ) , C-0 s t r e t c h i n g v i b r a t i o n i n glucuronoxylan(mainly a c e t y l , some car b o x y l ( 9 6 , 1 0 7 ) , CH ? wagging or CH and OH d e f o r m a t l o n d 88)* 8.13 1230 II CT>0-C asymmetrical s t r e t c h i n g v i b r a t i o n of a r y l - a l k y l ether l i n k a g e ( 2 8 ) , l i g n i n ( 1 2 1 ) CH 2 wagging or CH and OH d e f o r m a t i o n ( l 8 8 ) * 8.20 1220 to J. 0-H bending w i t h r i n g s t r e t c h i n g character 1205 (156) Band In c e l l u l o s e and h e m i c e l l u l o s e (unasslgned(121), (188)* - 9 9 -Wave Wave P o l a r i -l e n g t h number z a t i o n (cm-1) 8.62 1160 II 8 . 8 9 1125 t o 895 8.93 1120 9.01 1110 II 9.05 1105 II 9.52 1050 9.72 1020 II 11.17 895 II 11.43 ' '875 II 11.97 835 1250 800 J. 13.02 768 _L 15.38 700 t o II 18 .86 650 530 21.27 470 Assignment C - O - C a n t i s y m m e t r i c b r i d g e s t r e t c h i n g v i b r a t i o n i n c e l l u l o s e ( 6 0 , 9 6 , 9 7 , 1 0 3 ) ( 1 0 7 ) * C-H i n - p l a n e bend ing i n g u a i a c y l com-pounds (156) C - 0 s t r e t c h i n g and r i n g v i b r a t i o n a l modes(107) C - O - C a s y m m e t r i c a l s t r e t c h i n g v i b r a t i o n i n d i a l k y l e t h e r l i n k a g e (13 ) 0 -H a s s o c i a t i o n band i n c e l l u l o s e and h e m i c e l l u l o s e ( m i n o r l i g n i n c o n t r i b u t i o n ) (60)(l88)* C r y s t a l l i n e band(i8o) C - O - C ( a l i p h a t i c e t h e r ) methy l e t h e r o f v a n i l l y l a l c o h o l ( 1 5 6 ) C H 2 wagging or CH and OH d e f o r m a t l o n ( 188)* C-6 s t r e t c h i n g v i b r a t i o n i n c e l l u l o s e and h e m i c e l l u l o s e (60,96,97) C-H i n - p l a n e bend ing o f g u a i a c y l group(156) C r y s t a l l i n e band(180) CH2 wagging or CH and OH deformation(188)* C r y s t a l l i n e band(180) C h a r a c t e r i s t i c o f j3-linkage(6,103;206) anomer ic c a r b o n group f r e q u e n c y i n c e l l u l o s e and xylan(107)* Mode due t o glucomannan(107)* Lignin(121) CH o u t - o f - p l a n e bend ing v i b r a t i o n ( 9 ) Mode due t o glucomannan(107 )* Mode due t o arabinogalactan(107 )* OH o u t - o f - p l a n e bending(107)* C - O - C bend ing v i b r a t i o n ( 9 ) Deformat ion o f a r o m a t i c ring(121) Remark: * - p o l a r i z a t i o n ass ignment || - p a r a l l e l p o l a r i z a t i o n 1 - p e r p e n d i c u l a r p o l a r i z a t i o n / V - n o n - p o l a r i z i n g 100-TABLE 8 . WOOD TISSUE SAMPLING PROCEDURE BALSAM FIR (Abies b a l s a m e a ( L . ) M i l l . ) Increment No. Ear lywood Latewood S e c t i o n No. 31 1 2 3 4 5 6 ? 8 9 10 11 12 13 14 15 16 17 18 N N N N N N P P P N P N N N N N 32 D D D D D N P P P P P N D D D D D i i 1 i 1 c i c i i 1 i i i * 32 D D D D D N P P P P P N D D D D D D s s s s s i t i t s s s s s s DOUGLAS FIR (Pseudotsuga m e n z i e s i i ( M i r b . ) F ranco) Increment No. Ear lywood Latewood S e c t i o n No. 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 N N N N N P P N P N N N N N N N 47 D D D D D D P P P P D D D D D D D i i i s s s s s s i i 1 i * 47 D D D D D D P P P P D D D D D D i 1 i i s s s s s i i i REMARKS * The same increment o b t a i n e d from a matched t a n g e n t i a l b l o c k . N Unt rea ted specimen used to s tudy i n t r a - i n c r e m e n t a l i n f r a r e d d i c h r o i s m d u r i n g r e l a x a t i o n . D Sample d e l i g n i f i e d and then s t u d i e d as r e g a r d s i n f r a r e d 1 d i c h r o i s m d u r i n g r e l a x a t i o n . D Sample d e l i g n i f i e d and then s t u d i e d as r e g a r d s s t r e s s r e l a x a t i o n . w Unt rea ted specimen used t o s tudy I n f r a r e d d i c h r o i s m ^ d u r i n g c r e e p t e s t N Unt rea ted specimen used t o s tudy the e x c i t a t i o n t ime e f f e c t i t on i n f r a r e d d i c h r o i s m d u r i n g r e l a x a t i o n . P Sample used i n p r e l i m a r y exper iments o r f o r o t h e r -purposes . - 1 0 1 -TABLE 9.DICHROISM OP WOOD COMPONENTS OBSERVED AT 1160,1500 and 1730 C M " 1 WAVE NUMBERS S p e c i e s and D i c h r o i c r a t i o t i s s u e 1160 c m " 1 1500 c m " 1 1730 c m " 1 Range Average Range Average Range Average S i t k a spruce ( P i c e a s l t o h e n s l s (Bong.) C a r r ) 0 . 2 4 0 .91 1.36 Ear lywood 0 *18* 0 * 4 3 0.27 0 . 7 9 - 1 . 0 4 0 . 93 1 . 0 5 - 1 . 6 0 1.27 Latewood 0 . 1 5 - 0 . 3 3 0.21 0 . 7 1 - 0 . 8 8 0.87 1 . 39 - 1 . 5 8 1.49 Douglas f i r (Pseudotsuga  m e n z i e s i i ( M l r b . ) Franco) 0 .50 0.98 1.33 Ear lywood 0 . 5 9 - 0 . 7 0 O .63 1 . 0 3 - 1 . 3 2 1.15 1 .15-1.25 1.20 Latewood 0 . 2 4 - 0 . 4 4 0 . 3 3 0 . 7 0 - 0 . 8 7 0 . 8 5 1 . 3 6 - 1 , 5 3 1.45 Compress ion wood 1 . 81 - 2 . 5 2 2.32 1 . 0 0 - 1 . 3 7 1.22 0 . 8 0 - 1 . 0 0 0.86 Balsam f i r (Abies balsamea (LTTMIITT 0.56 1.09 1.33 Ear lywood 0 . 4 7 - 0 . 6 7 0.57 1 .07-1 .28 1 .14 1 . 2 6 - 1 . 3 0 1 .28 Latewood 0 . 4 7 - 0 . 6 6 0 . 5 4 1 . 0 0 - 1 . 0 5 1 .02 1 . 28 - 1 . 4 5 I.36 Grand f i r (Abies g r a n d i s (Doug l . ) L i n d l . Ear lywood 0 Latewood 0 ) 0.31 . 2 7 - 0 . 5 5 0 .44 . 2 5 - 0 . 1 8 0 .22 0 . 9 3 1 . 0 0 - 1 . 0 9 1.01 0 . 7 7 - 1 . 0 0 0.86 1.28 1 . 0 6 - 1 . 2 0 1.14 1 .19 -1 . 5 7 1.36 REMARKS i D i c h r o i c r a t i o =1 D i c h r o i c r a t i o <1 D i c h r o i c r a t i o >1 no o r i e n t a t i o n p a r a l l e l o r i e n t a t i o n p e r p e n d i c u l a r o r i e n t a t i o n - 1 0 2 -TABLE 10. INTRA-INCREMENTAL RELAXATION OF THE 1160 CM"1 COMPONENT ( CELLULOSE ) IN DOUGLAS FIR WOOD Re l a t i v e p o s i t i o n w i t h i n increment, % at Ion 7 28 49 70 91 Time, L i g n i n content , ** •min. '• 24.7 25.3 24 .6 2 5 . 4 24 .2 0 0.70 0 . 5 9 0.42 0 . 4 4 0.24 1 0.68 0 . 5 4 0.32 0.40 0.18 3 O.65 0 . 5 0 0.31 0 . 2 9 0 . 1 9 6 0.66 0.48 0 . 3 3 0.40 O.30 9 0.65 0 . 5 9 0.42 0.50 0.32 12 0.70 0.57 0.36 0.47 0 . 2 0 15 0.73 0.56 0 . 2 0 0.50 0.19 18 O.76 0.55 0 . 4 0 0.35 0 . 2 2 21 0 . 6 8 0.47 0.40 0 . 4 4 0.23 24 O.63 0.47 0 . 3 8 0 . 3 9 0.25 27 0.60 0.49 0.42 0.32 0 . 3 0 3 0 0 . 5 9 0.52 0.36 0.40 0.32 33 O.76 0.52 0 . 3 3 0.32 0 . 2 0 36 0.68 0 . 4 9 0.36 0.32 0 . 2 3 3 9 0.72 0.61 0.36 0.35 0 . 2 9 42 0 . 7 4 0.72 0.42 0.40 0.22 *+5 0 . 7 4 0.70 0.40 0.46 0.36 48 O.76 0 . 6 8 0.35 0 . 3 8 0.27 51 0.80 O.63 0 . 3 8 0.40 0.27 54 0.78 0.56 0.37 0.46 0.24 57 0.81 0.5*+ 0.40 0.47 0 . 2 0 60 0.75 0.58 0.42 0 . 4 4 0.28 63 0 . 7 4 O.61 0.37 0 . 4 3 0.24 66 0 . 7 4 0.57 O.36 0 . 4 3 0.26 69 0.71 0.57 0 . 3 3 O.36 0 . 3 0 72 0.72 0.61 0 . 3 2 0.38 0 . 3 3 75 0.71 0 . 6 2 0.32 0 . 3 3 0 . 3 3 78 0,58 0 . 3 2 0.42 0.25 * Determined according to reference ( 20) - 1 0 3 -TABLE 11. INTRA-INCREMENTAL RELAXATION OF THE 1730 CM"1 COMPONENT ( HEMICELLULOSE ) IN DOUGLAS FIR WOOD Re l a t i v e p o s i t i o n w i t h i n increment • % a t i o n 7 28 49 70 91 time , L i g n i n content * %* min. 1 24.7 25.3 24.6 25.4 24.2 0 1.25 1.15 1.36 1 . 3 3 1.37 1 1 .03 1.02 . 1.18 1 . 3 2 1.33 3 1 .03 0.94 1.07 l . 2 i 1.36 6 1 .06 0.96 1.02 1.26 1.46 9 1.00 0.97 1.21 1.21 1.39 12 1.00 0.92 1.31 1.23 1.24 15 1.15 1.10 1.42 1.48 1.20 18 1.15 1.00 1.36 I . 3 0 1.21 21 1.11 1.11 1.31 1.35 1.24 24 1.00 1.20 1.34 1 .26 1.42 27 1.00 1.00 1.28 1.11 1.30 30 0.96 1.19 1.30 1.14 1.40 33 1.02 1.01 1.26 1.29 1.49 36 1.15 1.20 1 .36 1 .26 1.36 39 0.95 1.15 1.31 1.39 1.30 42 1 .06 1.04 1.32 1.26 1.28 45 0.94 1.10 1.34 1.36 1.33 48 1.02 1.22 1.28 1.50 1.40 51 1.00 1 .23 1.30 1.28 1.29 54 1.14 1 .05 1,30 1.34 1 .32 57 1 .03 1.01 1.30 1 .30 1.48 60 0.97 1 .07 1.34 1.18 1 .36 63 1.08 1.20 1.37 1.37 66 1.14 1.12 1.27 1.39 69 1.00 1.10 1.24 1.35 72 1.23 1.15 1.27 1.45 75 1.15 1.04 1.34 1.50 78 1.10 1.14 1.28 1.48 81 1.30 1.41 * Determined according to reference ( 20 ) -104-TABLE 12.INTRA-INCREMENTAL RELAXATION OF THE 1500 CM COMPONENT (LIGNIN) IN DOUGLAS FIR WOOD -1 R e l a t i v e p o s i t i o n w i t h i n increment,. Relax- 7 21 28 , 5 6 80 100 a t i o n L i g n i n content , time , 24.7 2 6 . 8 25.3 23.7 25.2 24 .0 min. 0 1.11 1.31 1.03 0.87 0.70 0.86 1 1.31 1.40 1.08 1.30 0 . 7 9 1.45 3 1.25 1.26 1.20 1.20 0.91 1.35 6 1.27 1.36 1.21 1.45 0.97 1.32 9 1.33 1.32 1.12 1.30 0.84 1.50 " 12 1.48 1.27 1.19 1.32 0.84 1.44 15 1.31 1.24 1.10 1.06 0.81 1.45 18 1.24 1.17 1.13 0 . 9 5 0.64 1.43 21 1.31 1.3*+ 1.15 1.00 0 . 6 6 1.28 24 1.30 1.20 0 . 9 0 1.04 0.68- 1.27 * 27 ' 1.29 1.28 0.84 1.04 0.64 1.18 30 1.3*+ 1.13 0 . 7 4 1.00 0.61 1.10 33 1.20 1.10 0.78 0 . 9 5 0.68 1.12 36 1.26 1.24 0.80 0 . 9 6 O.67 1.11 39 1.31 1.17 0.86 0 . 6 2 0.61 1.18 42 1.12 1.24 0.80 0 . 6 9 0.70 1.11 *+5 1.26 1.03 0.67 0.91 0 . 6 0 1.20 48 1.21 1.24 0.63 0 . 5 3 0.78 1.10 51 1.33 1.17 0.68 0.75 0.66 1.10 5*+ 1.25 1.22 0.64 0.64 0.71 0.9*+ 57 1.14 1.12 0.62 0 . 9 3 0.65 0.90 60 1.12 1.08 0.70 0.64 0.65 O.87 63 1.18 1.18 0.64 0.84 0.72 0 . 8 9 66 1.22 1.16 0.72 0 . 8 6 0.70 0.68 69 1.18 1.18 0 . 8 6 0.64 0.64 1.04 71 1.08 0.93 0.76 0.78 0.82 0.77 74 1.08 1.00 0.68 0.75 0.70 0.75 77 1.08 0.77 80 1.03 0.64 * Determined according to reference ( 20) - 1 0 5 -TABLE 13. INTRA-INCREMENTAL RELAXATION OF THE 1160 CM COMPONENT (CELLULOSE) IN BALSAM FIR WOOD Relax- R e l a t i v e p o s i t i o n w i t h i n increment. % a t i o n *8 38 50 64 74 92 time , 34.0 L i g n i n content , % min. 32.8 32.2 33.0 33.2 33.5 0 0.58 0.47 O.67 0.50 0.47 0.66 1 0 .50 0.38 0.33 0.42 0.45 0.64 3 0.46 0.35 0 .30 0.40 0.44 0 .60 6 0.48 0.33 0.48 0 .39 0.45 0.47 9 0.4l 0.38 0 .60 0.43 O.38 0 .50 . 12 0.43 O.36 0 .70 0 . 3 9 0.37 0.5*+ 15 0.40 0.35 0 .70 0.40 0.39 0 .52 18 0 .50 O.36 0.53 0.40 0.33 0.57 21 0 .50 0.33 O.67 0 . 3 9 O.56 0.5*+ 24 0.47 0 .32 0 .70 0.45 0 .50 0 .50 27 0.48 0.33 0 .60 0.45 0.45 0 .50 30 0 .50 0.37 0 .60 0.44 0.40 0 .50 33 0.46 0.44 O.67 0.45 0.38 0.47 36 0 .50 0.40 0.62 0.37 0.44 0.5*+ 39 0.48 0.46 0 .60 0.41 0.42 0 .50 42 0.46 0.48 0.53 0.40 0.4l 0.64 *+5 0.48 0.46 0.55 0*42 0.44 0.5*+ 48 0.45 0 .52 0.60 0.42 0 .50 0.46 '51 0.48 0 .50 O.67 0.55 0 .50 0.48 5*+ 0 .50 0.55 O.63 0.48 0.46 0.57 57 0.45 0.48 0 .50 0.48 0 .50 0.64 60 0.48 0 .50 0 .52 0 . 4 9 0.5*+ 0.62 63 0 .50 0.48 0.56 0.46 0 .50 0.59 66 0 .52 0.45 0.5*+ 0.40 0.48 0.55 69 0.55 0.48 0 .52 0 . 3 9 0 .50 0 .60 72 0.58 0 .50 0.58 0.46 0 .50 0.55 75 0.5*+ 0 .52 0.56 0.48 0.47 0.56 78 0.58 0 .50 0.50 0.55 0.44 0.64 81 0 .52 0.42 0.62 0.64 * Determined according to reference ( 20 ) -106-TABLE 14. INTRA-INCREMENTAL RELAXATION OF THE 1730 CM"1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR WOOD Relax- R e l a t i v e p o s i t i o n w i t h i n increment, % a t l o n 6 24 50 64 87 100 time, L i g n i n content * min.' 35.2 34.1 32.2 33.0 33.4 33.3 0 1.27 1.30 1.26 1.28 1.24 1.45 1 1.24 1.25 1.14 1.16 1.12 1.42 3 1.24 1.16 1.10 1.18 1.10 1.38 6 1.14 1.21 0.98 1.14 1 .06 1 .38 9 1.15 1.18 1.10 1.22 1.16 1.30 12 1.04 1.22 1.06 1.30 1.25 1.35 15 1.12 1.28 1.22 1.18 1.16 1.36 18 1.14 1.19 1.22 0.98 1.18 1.45 21 1.31 1.18 1.26 1.02 1.02 1.42 24 1.18 1.14 1.42 1.00 1.06 1.48 27 1.09 1.22 1.38 1.12 1.04 1.32 30 1.00 1.24 1 .36 U'18 1.20 I . 3 6 33 1.08 1.30 1.30 1.18 1.28 1.22 36 1.17 1.26 1.38 1.14 1.22 1.18 39 1.29 1.28 1.28 1.14 1.28 1.30 42 1.11 1.34 1.38 1.20 1.20 1.18 45 1.17 1.28 1.30 1.20 1 .25 1.40 48 1.20 1.34 1 .32 1.22 1.28 1.30 51 ' ' 1.18 1.30 1.30 1.18 1.31 1.38 54 1.20 1.40 1.28 1.14 1.31 1.38 57 1.20 1.38 1.37 1.14 1.28 1.48 60 1.16 1.30 1.26 1.19 1.28 1.45 63 1.20 1.35 1 .32 1.19 1.32 1.48 66 1.24 1.32 1 .36 1.16 1.26 1.40 69 1.16 1.30 1.28 1.16 1.22 1.50 72 1.18 1.34 1.28 1.25 1.34 1.42 75 1.20 1.30 1.36 1.16 1.22 1.40 78 1.20 1.34 1.26 1.20 1.30 1.42 81 1.17 1.30 1.34 1 .25 1.26 1.42 * Determined according to reference ( 20 ) - 1 0 7 -TABLE 15. INTRA-INCREMENTAL RELAXATION OP THE 1500 CM - 1 COMPONENT (LIGNIN) IN BALSAM FIR WOOD ^ e ^ a x R e l a t i v e p o s i t i o n w i t h i n increment, % at ion"" 18 38 50 64 87 100 time t L i g n i n content,1% * m i n - 3^.0 32.3 32.2 33.0 33.4- 3 3 . 3 0 1.28 1.07 1.07 1.05 1.00 1.05 1 1.46 1.08 1.23 1.05 1.07 1.05 3 1.40 1.10 1.25 1.08 1.20 1.08 6 1.3^ 1.08 1.20 1.10 1.17 1.11 9 1.25 1.10 1.26 1.04 1.16 1.13 12 1.18 1.00 1.10 1.10 1.27 1.02 15 1.20 1.02 1.08 1.18 1.20 1.10 18 1.21 1.00 1.00 1.15 1.08 0 . 9 4 21 1.07 1.03 1.12 1.15 1.14 0 . 8 9 24 1.23 1.03 1.00 1.10 1.10 0 . 9 0 27 1.21 1.00 1.10 1.15 1.10 0 . 9 0 30 1.14 1.00 1.08 1.10 1.14 0 . 9 5 33 1.14 1.02 1.00 1.15 1.08 0 . 8 5 36, . > 3 9 1.23 1.01 1.03 1.10 1.00 1.00 1.20 1.00 1.12 1.00 1.07 1.00 41 1.25 0 . 9 8 1.05 1.10 1.00 1.00 44 1.23 1.00 1.00 1.05 1.00 0 . 9 ^ ^7 1.18 0 . 9 8 1.00 1.05 0 . 9 8 0 . 9 4 50 1.15 0.96 1.06 1.00 0 . 9 ^ 1.00 53 1.14 1.00 1.06 1.05 1.00 0 . 9 4 56 1.21 0 . 9 4 1.04 0 . 9 6 1.02 1.06 59 1.18 0.95 1.10 1.00 0 . 9 5 1.00 61 1.16 0.96 1.00 1.06 0 . 9 3 0 . 9 5 64 1.08 0 . 9 ^ 1.10 1.04 1.00 0 . 9 ^ 67 1.10 0.98 1.08 1.05 1.05 0 . 9 5 70 1.14 0 . 9 ^ 1.08 1.05 1.00 0 . 9 4 73 1.15 1.00 1.00 1.05 1.00 1.05 76 1.21 0 . 9 ^ 1.01 1.00 1.06 1.00 79 1.15 0.90 1.00 1.00 1.00 0 . 9 5 82 1.23 0 . 9 2 0 . 9 5 1.00 0 . 9 4 •Determined according tp reference ( 20 ) TABLE 16.EFFECTS OF REMOVING LIGNIN.THEN HEMICELLULOSE,ON RELAXATION OF THE 1160 CM COMPONENT (CELLULOSE) IN DOUGLAS FIR EARLYWOOD Relax-60 DelignifIcation time , min. 240(l£)240(5^)240(17.5%) ation 0 30 90 120 180 240 time , 68 Lignin content. % ** min. 100 78 52 30 23 0 0 0 0 0.70 :- 0 . 7 8 0.71 0 .59 0.6-5 O.56 0.62 0.52 0.49 0.53 1 0.68 0 . 7 0 0.68 0.38 0 . 6 5 0.62 0.61 0.51 0.48 0.50 3 O .65 0 . 6 2 O .65 0.44 0.62 0.64 0.58 0.51 0.48 0.55 6 0.66 0.80 O .67 0.56 0.59 0.55 O.60 0.50 0.46 0.47 9 O .65 0.85 O.67 0.58 0.60 0 . 6 3 O .63 0.49 0.48 0.53 12 0.70 0.89 0.5^ O .63 0.64 0.58 O.60 0.5*+ 0.48 0.64 15 0.73 0.71 0.66 0.58 O .69 0.52 0.53 0.56 0.44 0.5*+ 18 Q.76 s 0.70 0.77 0.60 O .65 0.59 O.60 0.44 0.47 0.49 21 0.68 0.71 0.70 0.58 0.62 O .60 0.58 0.46 0.48 0.49 24 O.63,; 0.70 0.64 O .63 O .65 0.62 0.57 0.46 0.45 0.5*+ 27 0.60 ?, 0 . 7 3 0.66 O .69 0.62 0.57 O.65 0.51 0.46 O.56 30 0 .59 ; : 0 .72 O.67 0.62 0.68 0.60 0.56 0.47 0.48 0.55 33 O .76 0.80 0.72 0.58 0.66 0 .59 0.62 0.50 0.50 0 . 5 2 36 0.68 0.82 0.79 0.57 0.71 0.56 0.59 0.48 0.46 0.56 39 0.72 i : 0 . 6 7 0.75 0.72 O .65 0.60 0.55 0.50 0.46 0.53 42 0.74 0.76 0.72 O.56 O.65 0.50 0.5*+ 0.52 0.44 0.52 45 0.74 v 0.82 O.76 0.55 0.57 0.66 0.62 0.56 0.45 0.47 48 ; O .76 , 0.80 O .67 0.55 0.66 0.63 0.62 0.55 0.44 0.48 51 0.80 !' 0.71 0.80 0.55 0.61 O .63 0.59 0.53 0.45 0.5*+ 54 O .78 0 . 7 2 0.75 0.55 0.62 0.60 0.57 0.51 0.45 0.5*+ 57 -0.81 i 0.77 0.72 0.5*+ O.60 O .63 0.54 0.50 0.47 O .61 60 0.75 I 0 .70 0.75 0.57 0.59 0.60 0.59 0.50 0.44 O .60 63 0.74 0.80 0.75 0.50 0.53 0.61 0.62 0.53 0.47 0.51 66 i .0.74 il 0.75 0.81 0.65 0 . 6 5 0.50 O.60 0.47 0.48 0.55 69 0.71 0.85 0.81 0.60 0 . 6 3 0.57 0.61 0.55 0.47 0.58 72 0.72 0.78 0.74 0.5^ O.67 0.55 0.59 0.53 0.50 0.55 75 0.71 0.7^ 0.73 0.58 O.61 0 .59 0 . 6 0 0.49 0.45 0.55 78 i 0.7 6.. 0.7-5 O .56 - 0.53 0.57 0.64 , 0.5Q 0.45 0.53 81 0.73 0.80 0.64 0.62 0.49 0.50 0 . 5 0 * Caustic treatments a t 25°C *• Based on 1500 cm"1 band i n t e n s i t y -10 9-TABLE 17 . EFFECT . OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM"COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR EARLYWOOD Relax-a t i o n time min.' 0 30 100 ?8 D e l i g n i f i c a t i o n time min. 60 90 120 180 240 L i g n i n content % 68 56 43 30 23 0 1 3 6 9 12 15 18 21 •24 27 30 33 36 :39 42 45 48 51 54. 57 60 63 66 6,9 72 75 78 81 1.25 1.03 ,1.0 3 1.06 1.00 1.00 1.15 l . l l 1.00 i . o o 0 ; 96 1.02 1,15 o , 9 5 1.06 0 . 9 4 1.02 1.00 1.14 1>03 0. 97 1.08 1.14 lfQO 1. f?3 1,15 1.10 1.40 1.21 1.36 1.31 1.65 1.68 1.35 1.06 1.35 1.10 1.66 1.61 1.35 1.12 1.17 1.18 1.54 1.28 1.32 1.08 1.09 1.20 1.30 1.33 1.21 1.05 1.19 1.16 1.29 1.48 1.12 1.11 1.09 1.15 1.47 I . 6 3 1.42 1.06 1.05 1.14 1.31 1 .44 1.32 1.08 1.20 1.18 1.41 1.38 1.38 1.19 1.21 1.14 1.68 1.59 1.20 1.20 1.30 1.17 1 . 6 l 1.46 1.16 1.16 1.44 1.07 1.60 1.48 1.35 1.12 1.40 0 . 9 0 I . 6 9 1.59 1.29 0 . 9 8 1.21 1.06 I . 6 3 1.52 1.25 1.01 1.21 1.19 1.51 1 .44 1.24 1.18 1.20 1.10 1.00 1.45 1.26 1.20 1.09 1.05 1.53 1.54 1.28 1.27 1.12 1.27 1.56 1.48 1.20 1.17 1.20 1.10 1.58 1.58 1.12 1.21 1.22 1.15 1.58 1.43 1.30 1.26 1.16 1.13 1.69 1.52 1.26 1.18 1.28 1.27 1.62 1.51 1.18 1.10 1.26 1.05 1.56 1.48 1.39 1.28 1.20 1.12 1.56 1.52 1.26 1.16 1.10 1.14 1.54 1.37 1.07 1.07 1.21 1.50 1.25 1.20 1.14 1.54 1.21 1.02 1.22 1.48 1.36 1.08 1.17 1.28 1.16 * Based on the 1500 Cm"1 band i n t e n s i t y V TABLE 18. EFFECTS OF REMOVING LIGNIN,THEN HEMICELLULOSE ON RELAXATION OF THE l l 6 0 CM"1 COMPONENT (CELLULOSE) IN DOUGLAS FIR LATEWOOD D e l i g n i f i c a t i o n time, min. Relax-a t i o n 0 30 60 90 120 180 240 240 (1%) 240 {5%) 240 (17 . 5%) time , L i g n i n content, % min. 100 97 86 72 60 46 20 0 0 0 0 0 . 2 4 0.18 0 . 37 0 . 3 2 0 . 33 0 .31 0.38 0 .38 0 . 4 i 0.50 1 0.21 0 .17 0 . 3 4 0 . 2 9 0 . 3 4 O.29 0.36 0 .37 0 .4o 0.52 3 0 . 2 0 0 . 18 0 . 3 5 0 . 2 9 0.35 0 . 3 4 0 .48 0 . 3 9 0 . 39 0 . 55 6 0 . 2 4 0 . 1 9 0 . 3 6 0 . 28 0 . 3 4 0 . 2 9 0 . 4 4 0 .37 0 . 4 4 0 . 4 9 9 0.27 0 . 1 9 0 .37 0 . 2 9 0 . 3 4 0 .30 0 .37 0 . 3 9 0 . 4 4 0 . 4 5 12 0 .29 0 . 18 0 . 3 4 0 . 3 5 0 .32 0 .28 0 . 4 i 0 . 3 4 0 . 39 0 . 4 4 15 0 . 28 0 . 18 0 . 31 O.29 0 . 33 0 . 3 4 0 .4o 0 . 38 0 . 39 0.50 18 0 . 2 0 0.15 0 . 3 0 0 . 3 2 0 .31 0.32 0 .41 O.36 0 . 39 0 . 5 4 21 0 . 1 9 •0.16 0 . 3 9 0 . 3 3 0 . 33 0.30 0 .46 • O.36 0 .47 0.47 24 0 . 2 5 0 . 1 9 O.36 0 . 3 9 0 .34 0 .28 0 .47 0 . 3 4 0 .42 0 . 53 21 0 . 3 0 0 .25 0 . 36 0 . 38 0.35 0 .28 0 .40 O.36 0 . 39 O.67 30 0 . 31 0 . 2 5 0 . 40 0.33 O.36 0 . 2 9 0 .41 0 .40 0 .40 0.51 33 0.26 0 .20 0 . 26 0 . 3 9 0.35 0 . 2 9 0.50 0.35 0 .43 0 . 6 l 36 0 . 2 9 0 . 2 5 0 . 3 4 0 . 4 2 0 . 3 4 0.25 , 0 . 4 5 0 . 3 9 0 .41 0 . 5 4 39 0 . 26 0 . 1 9 0 . 38 0 . 3 5 0.32 0 . 33 0 . 45 O.38 0 .42 0.50 42 0 . 3 4 0 . 2 0 0 . 38 0 . 3 4 O.36 0 .28 0 . 43 0 . 35 0 .41 0 . 53 45 0 . 3 0 0.21 0 . 36 0 . 2 9 0 . 3 2 0.32 0 .41 0 . 4 l 0 .41 0 . 4 9 48 0 . 31 0 . 1 9 0 . 3 0 0 . 40 0 . 33 0 .31 0 . 4 9 0 . 33 0 .33 0 .56 51 0 . 2 9 0 . 2 5 0 . 3 9 0 . 3 5 0 . 3 2 0 . 31 0 .41 0 . 35 0 . 4 l 0 .47 54 0 . 26 0 .21 0.36 0 . 3 4 0.32 0 .26 0 .48 0.41 0 .41 0 .56 57 0 . 3 2 0 . 18 0 . 3 8 0 . 37 0 .31 0.27 0 .45 0 . 35 0 .35 0 .68 60 0.26 0 . 2 4 0 . 3 8 0 . 4 l 0 .37 0.31 0 .47 0 . 3 9 0.44 O.61 63 0 . 28 0 . 2 2 0 . 38 0 . 2 9 0 . 35 0 .32 0 .46 0 .40 0 .49 0 .56 66 0.35 0 . 1 9 0 . 3 4 0 . 38 0 . 40 0.32 0 . 45 0 .34 0.43 0 . 53 69 0 . 30 0.21 0 . 3 4 0 . 3 4 0 . 35 0 .32 0.'4o O.36 0 .45 0 . 56 72 0.33 0 . 2 1 0 . 31 0 . 41 0 . 35 0.32 0 .46 O.36 0 .47 0 . 5 4 75 0 . 3 4 0 .21 0 . 37 0 . 4 i 0 . 3 4 0 . 2 9 0 .40 0 .35 0 .42 0 .48 78 0 . 28 0 . 35 0 .29 0 . 43 O.36 0 .47 0 . 4 9 81 0 . 3 2 0 .30 0 . 31 0 . 43 ' 0 . 35 0 . 45 0 . 58 •Caustic treatments a t 25°C ** Based on 1500 cm"1 band i n t e n s i t y - I l l -TABLE 1 9 . EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 C M " 1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR LATEWOOD D e l i g n i f i c a t i o n t i m e , m i n . a t i o n 0 30 60 90 120 180 240 t ime ... •» L i g n i n c o n t e n t % m i n . , 100 97 86 72 60 46 20 0 1.53 1.26 1.38 1.33 1.24 1.40 1.31 1 1 .52 1.21 1.10 1 .30 1.20 1.20 1 .23 3 1 . 4 l 1.20 1.03 1.21 1.21 1.16 1.16 6 1.46 1.15 1.24 1.43 1.41 1 .30 1.13 9 1 . 4 l 1.17 1.39 1.26 1.57 1.24 1 .25 12 1.43 1.15 1.28 1 .30 1.44 1 .05 1 !.36 15 1.68 1.10 1.13 • 1.08 1.48 1.20 1.40 18 1.50 1 .30 1.17 1.15 1.28 1.14 1 .30 21 1.35 1.44 1.26 1.17 1.38 1.20 1.27 24 1.26 1 .50 1.21 1.21 1.24 1.20 1.24 27 1.11 1.44 1.38 1.25 1.27 .1.20 1.28 30 1.14 1.47 1.28 1.20 1 .30 1.20 1.17 33 1 .26 1.26 1.43 1.16 1.46 1.20 1.20 .36- - 1 .26 1 .30 1.33 1 .26 1 .32 1 .26 1 .32 40 1.39 1.24 1 .23 1.26 1.43 1 .25 1.21 *W 1.26 1.24 1.24 1.17 1.41 ' 1.15 1 .29 46 1 .36 1.35 1.26 1.17 1.31 1 .25 1 .30 49 1.40 I . 2 3 1.20 1.24 1.28 1.20 1.21 52 1.28 1.31 1.20 1.24 1.38 1.19 1 .26 55 1.3*+ 1 .29 1.22 1.18 1.24 1.14 1.20 58 1 .30 1 .30 1.17 1.18 1.18 1.09 1.28 61 1.3^ 1.31+ l v07 1.30 1.31 1.22 1.17 64 1.37 I . 2 9 1.19 1.22 1.27 1.20 1.24 67 1.27 1.28 1.13 1.12 1 .32 1.16 1.17 70 1.24 1 .23 1.22 1.27 1.27 1 .23 1.19 73 1.27 1.20 1.21 1.28 1.24 1.24 1.27 76 1.3^ 1.24 1.13 1.21 ' 1 .30 1.13 1.31 79 1.28 1.37 1.20 1.17 1.33 1.27 1.24 81 1.30 1.28 1.17 1 • B a s e d on 1500 cm band i n t e n s i t y TABLE 2 0 . EFFECTS OF REMOVING LIGNIN,THEN HEMICELLULOSE ON RELAXATION OF THE 1160 C M " 1 COMPONENT (CELLULOSE) IN .BALSAM FIR EARLYWOOD R e l a x - D e l i g n i f i c a t i o n t ime , m i n . a t i o n 0 30 60 90 : 120 180 240 240(5,5?) 240(17 . 5 / 0 t ime f m i n . L i g n i n c o n t e n t ,% #* 100 78 62 55 52 45 30 14 0 0 0 .66 0 .70 0.68 0.68 0.68 O.65 0.68 ! 0.70 0.68 1 0 . 6 2 0 .61 0.58 0 .52 0 .54 0.58 0.5*+ i 0 .66 0 . 6 6 3 0.48 0 .50 0 .54 0.48 0 .50 0.48 0 .50 ! 0 .66 0 .64 • 6 0 .47 0.45 0.46 0.48 0 .52 0.45 0.48 0.68 0.68 9 0 .50 0 .55 0.48 0 .49 0 .50 0.35 0.40 0.68 0.68 12 0 . 5 4 0.57 0.50 0.48 0.68 0.46 0 .39 0.72 0 .70 15 O.56 0 .70 0.53 0 .50 0.62 0.42 0 .50 0.68 0 .66 18 0 .61 0.78 0 . 5 2 0.48 0.68 0 .60 0 .52 0.72 0.68 21 0 .57 O.67 0.62 0 .52 0 .64 0.58 0.47 ,: 0 .66 0.71 24 0 .50 0.60 0 .50 0.58 0.71 O.56 0.46 i O.70 0.68 27 0 .51 0 .55 0.43 0.62 0.71 0.45 0.50 1 0 .73 0.70 s 30 0 .57 0.67 0.48 0.60 0.68 0 .50 0 .52 0.68 0 .72 33 0.64 0 . 6 5 0.60 0 .60 0.68 0.5*+ 0.44 0 .72 0.70 36 . 0 . 5 8 0.57 O.63 0 .60 O.67 0.46 0 .50 ; 0 . 6 8 0 .74 39 0 .57 0 . 6 9 0.58 0.56 0 .64 0.42 0.5*+ ; 0.70 0.68 42 0.5*+ 0.68 0 . 6 6 0.5*+ 0.57 0 .54 0.42 ; 0 . 6 9 0 . 6 6 *+5 O.61 0 . 5 5 0.57 0 .55 0 . 6 0 0 .55 0.46 0.72 0.70 49 0 .60 0.58 0 .54 0.52 O.56 0.47 0 . 4 4 0.70 0 .70 51 O.56 0 .54 0 .54 0.5*+ 0.71 O.61 0.48 0.72 0 .72 5*+ O.63 O.56 0.56 0.53 0 .60 0.56 0 .50 0.73 0.70 57 0 . 6 l 0.57 O.56 0.53 0.58 0 .64 0.46 0.70 0 .70 60 0.58 O.67 0.57 0.5*+ O.69 0.62 0.48 0.70 0.68 63 0.56 0 .73 0 .49 0.51 0 .66 0 .66 0 .50 0.68 0 . 6 6 66 0 .60 O.71 0.57 0.56 O.71 0 .52 0 .52 0.73 0 .72 69 0.58 O.65 0 .55 0 . 5 5 0.68 0 .50 0 .52 0.70 0 . 6 9 72 " ' 0.60 * 0.^53 0 .53 0 .55 0;67 J 0.64 0 .52 0.68 0.68 '.' 75 0.56 0.67~, 0 . 4 9 0 .53 0.57 0 .52 0 .50 j 0 .72 0.70 78 O.63 0.5*+ 0 . 6 0 0 .52 O.58 0.62 0.51 ! 0.68 0 .72 81 O.63 0.73 0.58 0.52 0 .64 0.57 0.53 1 0.71 0 .70 - • C a u s t i c t r e a t m e n t s a t 25°C • • B a s e d on 1500 c m " 1 band I n t e n s i t y -113-TABLE 21. EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 C M " 1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR EARLY-WOOD Relax- D e l i g n i f i c a t i o n time, min. a t i o n 2 30 60 90 120 180 240 time , min. 100 78 62 L i g n i n 55 content, 52 %* 45 30 0 1.18 1.16 1.26 1.28 1.26 1.37 1.34 1 1.06 1.08 1.17 1.13 1.19 1.21 1.24 3 1.04 1.10 1.20 1.07 1.18 1.11 1.09 6 1.08 1 .06 1.26 1.14 1.18 1.12 1 .06 9 1.10 1 .06 1.34 1.27 1.04 1.18 1 .03 12 1.12 1.08 1 .30 1.20 1.08 1.14 1.16 15 1.18 1.15 1.11 1.09 1.09 1 .23 1.28 18 1.15 1.14 1.13 1 .03 1 .23 1.35 1.20 22 1.10 1.17 1.18 1.25 1.28 1 .30 1.14 25 1 .05 1.10 1.22 1.30 1.14 1.35 1.15 28 1.04 1.12 1.30 1.33 1.15 1.38 1.20 30 1.18 1.20 1 .23 1.26 1.13 1.34 1.10 33 1.18 1.15 1.29 1.20 1.20 1 .30' 1.26 36 1.18 1.20 1.20 1.35 1.28 1.19 1.20 39 • ' 1.22 1.15 1.16 1.27 1.19 1 .30 1.26 42 1.18 1.20 1 .23 1.15 1.15 1.22 1.18 45 1.15 1.14 1.10 1.20 1.22 1.19 1.28 48 1.14 1.14 1.20 1.26 1.20 1.26 1.30 51 1.18 1.22 1 .23 1.26 1.12 1.20 1.22 54 1.16 1.13 1.15 1.17 1.16 1.18 1.19 57 1.30 1.16 1.21 1.21 1.14 1.31 1.20 60 1.18 1.18 1.20 1.17 1.15 1.22 1.22 63 1 .23 1.24 1.28 1.15 •1.16 1.27 1.19 66 1.24 1.24 1.20 1.14 1.24 1.28 1.16 69 1.20 1.22 1.30 1.21 1.20 1.24 1.26 72 1 . 2 4 1.15 1.32 1.12 1.16 1.22 1.17 75 1.20 1.20 1.28 1.24 1.22 1.20 1.24 78 1.24 U 20 1.18 1 .25 1.20 81 1.31 1.16 1.22 1.24 * Based on the 1500 cm"1 band i n t e n s i t y TABLE 22. EFFECTS OF REMOVING LIGNIN,THEN HEMICELLULOSE ON RELAXATION OF THE l l 6 0 CM - 1 COMPONENT (CELLULOSE) IN BALSAM FIR LATEWOOD Relax-a t i o n time t 30 min. . 100 0 0.48 1 0 .44 3 0.41 6 0.42 9 0.42 12 0.45 15 0.38 18 O.36 21 0 .44 24 0 .50 27 0.56 30 0.48 33 0.48 36 0.47 39 0 .49 42 0 .50 *+5 0.40 48 0.45 51 0.38 5*+ 0.40 57 O.36 60 0.40 63 O.36 66 0.42 69 0.40 72 0.46 75 0.40 78 0 .44 81 0.44 96 D e l i g n i f i c a t i o n time , min. 60 90 120 180 240 2 4 0 ( 5 # ) 2 4 0 ( 1 7 . 5 # ) » L i g n i n content, % #* 79 72 55 41 19 £3 0 0 .52 0.46 0 .50 0.48 0.45 0.42 0 .44 0 .44 0.46 0.5*+ 0 .50 O.50 0.49 0 . 3 8 0.42 0.42 0 .44 0.42 O.36 0.38 0.40 0.42 0 .44 0.40 0.42 0;42 0.45 0.46 0.45 0 . 5 6 0 . 5 2 0 . 5 2 0 . 47 0 . 4 6 0 . 4 8 0 . 46 0 . 48 0 . 48 0 . 4 8 0 , 5 0 0 . 5 2 0 . 5 6 0 . 4 8 0 . 5 0 0 . 5 5 0 . 5 2 0.5*+ 0 . 5 0 0 . 5 0 0 . 5 0 0 . 5 8 0 . 5 0 0 . 4 8 0 . 4 6 o.5*+ 0 . 4 6 0 . 5 2 0 . 5 8 * Caustic treatments a t 25°C 0 . 5 5 0.52 0.62 O.56 0 . 4 2 0 . 42 0.50 0.5*+ 0 . 4 4 0 .46 0 .58 0.50 0 . 4 4 0 .48 0.61 0.52 0 . 4 5 0 .48 0 . 6 4 0 . 5 4 0 . 48 0 . 5 4 0.57 0.52 0 . 4 3 0.50 0.58 0.52 0 . 3 9 0 .48 0 .62 0.50 0 . 46 0 .46 0 . 5 9 0 . 5 4 0 . 46 0 .48 0 .58 0.58 0 . 5 3 0.50 0 . 6 2 0.5*+ 0 . 4 9 0 .46 0 . 6 6 0 . 5 4 0 . 6 0 0 . 4 9 0.57 0.50 0 .46 0 .46 0.5*+ O.52 0 . 5 3 0 .46 0.58 0.52 0 . 5 5 0 .48 O.63 0 .48 0.58 0 . 5 9 0.57 0 .48 0 . 48 O.56 0.58 0 .48 0 . 5 3 0.57 0.58 0.50 0.50 0.51 0.56 0.52 0 . 46 0*.53 0 . 6 2 0.50 0 . 4 5 0.56 0 . 6 4 0.50 0 . 40 0.52 O.56 0.50 0 . 40 0 . 5 4 0.58 0.53 0 . 4 5 0.5*+ O.63 0.52 0 . 4 5 0/58 0 . 5 8 • 0 . 48 O.36 O.50 0.5*+ 0.50 O.36 0.5*+ 0.58 0 .48 0 . 4 5 0 . 5 4 O.58 0.50 **Based on the 1500 cm"1 0.66 0 . 6 4 0.66 0.72 0.68 0.70 0.70 O.67 O.69 0.66 0.70 O.67 0.70 O.69 O.69 O.67 0 . 6 6 0 . 6 4 0.66 O.65 0.68 O.69 0.68 O.65 O.65 O.67 O.67 O.67 0.68 0 .68 0.62 O.69 0.70 O.69 O.65 O.63 O.63 0 .68 0 .68 O.69 0 . 62 0 .68 0.61 O.69 0 .68 O.65 0 .68 0 . 68 0 .66 0 . 6 4 0 . 6 4 O.69 O.65 O.65 O.69 0.70 0 .68 0 . 6 4 band i n t e n s i t y - 1 1 5 -TABLE 2 3 . EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM"1 COMPONENT (HEMICELLULOSE) IN BALSAM FIR LATEWOOD Relax- D e l i g n i f i c a t i o n time min. a t i o n 30 60 90 120 180 240 time, L i g n i n content :% * min., 96 79 72 4.1 19 0 1.28 1.32 1.28 1.31 1.26 1.26 1 1.20 1.27 1.20 1.02 1.16 1.22 3 1 .25 1.24 1.14 1.16 1.12 1.16 6 1.16 1.20 1.15 1.04 1 .06 1.08 9 1.12 1.15 1.18 1.08 1.14 1.14 12 1.18 1.15 1.12 1.22 1.20 1.18 15 1.20 1.10 1.13 1.28 1.24 1.24 18 1.18 1.18 1.27 1.33 1.18 1 .26 21 1.16 1.17 1 .25 1.26 1.10 1.22 24 1.15 1.12 1 .30 1.30 1.12 1.18 27 1.19 1.26 1.17 1.24 1.18 1.28 30 1.18 1 .30 1.19 1.24 1.20 1 .26 33 1.26 1.31 1.10 1.30 1.14 1.18 36 1.26 1.28 1.11 1.37 1.24 1 .32 39 1.34 1.26 1.22 1.24 1.16 1.26 42 1 .30 1.30 1.18 1.35 1.18 1.22 45 - 1.26 1.24 1.26 1.22" 1.12 1.18 * 48 1.18 1.31 1 .30 1.17 1.12 1.24 51 1.18 1.30 1 .23 1.12 1.19 1.22 54 1.20 1.22 1 .25 1.18 1.20 1.20 57 1.22 1.18 1.22 1 .14 1.16 1.17 60 1.20 1.30 1.20 1.14 1.18 1.26 63. 1.13 1.16 1.26 1.16 1.20 1.17 66 1.18 1.16 1.20 1.18 1.20 1.22 69 .1.24 1.20 1.20 1.24 1.21 1.14 72 1.20 1.22 1.28 1.14 1.26 1 .25 75 1.18 1 .24 1.28 1.16 1.15 1.14 78 1.18 1.24 1.28 1.18 1.17 1.13 81 1.20 1.22 1.26 1.18 1.20 1.18 * Based on the 1500 cm"1 band I n t e n s i t y TABLE 24. EFFECTS OF REMOVING LIGNIN,THEN HEMICELLULOSE ON STRESS DECREMENT OF DOUGLAS FIR EARLYWOOD DURING RELAXATION Relax-a t i o n time , 2 9 _ 60 D e l i g n i f i c a t i o n time min. 90 120 180 240 240 (lg) 240 (5#)240 (17. 5&) min. 78 68 56 0 0 0 0 0 . 2 1 2 . 3 11.4 18.2 0 . 4 13.9 12.9 22.1 0 . 6 15.^ 14.3 24 .1 0 . 8 16.9 15.7 2 5 . 9 1.0 17.7 15.7 2 6 . 5 1. 5 18 .5 15.7 2 7 . 9 2 2 0 . 0 15.7 29.1 3 20.8 16.5 3 0 . 3 4 20.8 17.1 31.5 5 20.8 17.1 31.1 6 20.8 15.7 32.1 7 20.8 15.5 3 2 . 4 8 20.8 15.0 32.7 9 2 0 . 0 14 .5 32.7 10 2 0 . 0 14.3 3 2 . 9 11 19.2 14.3 33.2 12 19 .2 14 .3 33.2 13 2 0 . 0 14.3 33.8 14 2 0 . 0 14 .3 33.8 15 2 0 . 8 14.3 3 4 . 4 16 21.5 14.3 3 4 . 4 17 21.5 17.0 3 4 . 4 18 20.8 18.6 3 4 . 4 19 20.8 18.6 3 4 . 4 20 20.8 18.6 34.1 21* 20.8 < 18.6 • 34.1 22 2 0 . 0 18.6 34.1 23 19.2 18.6 34.1 24 18 . 4 19.5 34.1 25 18.1 20.0 33.8 43 L i g n i n content , % ** 30 23 0 0 0 0 14 .5 16.4 17.6 18 .3 18 .9 2 0 . 5 21.1 22.1 2 2 . 7 2 2 . 9 2 3 . 2 2 3 . 2 2 3 . 2 2 3 . 2 23.7 23.7 24.4 24.4 24.4 25.1 25.1 25.1 25.1 25.1 25.1 24,8 24.8 24.8 25.1 2 5 . 3 0 14.2 15.6 17.8 18.8 19.3 2 0 . 5 21.4 22.4 23.4 23-7 24.2 24.2 25.1 25.6 25.9 25.6 2 6 . 3 26.3 2 6 . 3 26.3 26.3 26.3 26.3 26.6 26.6 26.6 26.8 26.8 27.1 27.1 0 18.4 22.6 25.3 26.3 27.4 29.5 31.6 33.2 35.3 36.3 37.4 37 .9 38.4 38.4 38.9 39.5 40.0 40.5 40.5 4 l . l 41.1 41.6 41.6 42.1 42.1 42.1 42.6 42.6 42.6 43.2 0 0 0 2 1 . 4 24 .6 26.1 25.8 2 9 . 4 2 9 . 9 28 .3 31.9 32.8 30.0 33.3 34.7 31.5 3 4 . 8 35.7 33.7 37.3 3 8 . 9 35.1 38.7 40 .5 37.2 40.7 42 .8 38.6 42 . 4 44.7 40 .0 4 3 . 5 45.7 40.7 44.6 47.0 41 .8 4 5 . 5 4 7 . 9 42.5 46.1 48 .6 42 .8 46.3 4 9 . 5 43.3 46 .9 5 0 . 8 4 3 . 9 47.2 51.1 44.2 48 .0 51.8 45.1 48 .6 52.1 45.6 49.2 52.1 4 5 . 9 4 9 . 4 51.8 46.1 50.0 5 2 . 4 46 .5 50.3 52.7 46.8 50.6 5 3 . 4 47.0 5 0 . 9 5 3 . 4 47.2 5 0 . 9 54.0 4 7 . 4 • 51.1 55.0 4 7 . 4 51.1 55.3 47.5 5 1 . 4 55.6 47.7 51.4 56.3 4 7 . 9 51.7 56.6 (continuing) Relax- D e l i g n i f i c a t i o n time tmin. _ at i o n 30 60 90 120 180 240 240(lg)24b (5#)240(17. 5#) time „ L i g n i n content ..%'** min. 78 68 56 43 • 30 23 0 0 0 26 18 .5 20.0 33.8 25.3 ' 27.1 43.2 48.1 51.7 56.9 27 19.2 21.0 34.1 25.5 27.1 43„2 • 48 .3 52.0 56.9 28 20.0 21.0 33.4 25.8 27.1 43.2 48 .3 52.0 57.2 29 20.8 21.0 34.7 25.8 27.1 43.2 48 .6 52.0 57.2 30 20.8 20.0 35.0 2 5 . 5 26.8 43.2 49.0 52.0 57.2 31 20.8 20.0 3 5 . 0 25.5 26.8 43.2 49.1 52.0 57.2 32 20.0 19.1 3 5 . 0 25.5 26.8 43.7 49.3 52.2 57.6 33 20.0 18.2 3 5 . 0 25.3 27.1 43.7 4 9 . 5 52.2 57.6 34 20.0 18.2 3 5 . 0 25.3 27.1 44.2 4 9 . 5 52.5 57.6 35 18 .5 17.1 3 5 . 0 2 5 . 3 27.3 44.2 49.7 52.8 57.9 36 17.7 17.1 3 5 . 0 2 5 . 3 27.3 44.7 50.0 53.1 57.9 37 17.7 17.1 3 5 . 0 2 5 . 3 27.3 44.7 50.0 53.7 58.2 38 16.9 17.1 3 5 . 0 2 5 . 3 27.3 4 5 . 3 50.0 59.0 58.2 39 16.9 17.1 3 5 . 0 2 5 . 3 27.3 45.3 50.0 59.0 5 8 . 5 40 16.9 17.1 3 5 . 0 2 5 . 3 27.3 45.3 50.2 59.0 59.2 * Caustic treatments at 25°C ** Based on the 1500 cm~l band i n t e n s i t y TABLE 25. EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE ON STRESS DECREMENT OF DOUGLAS FIR LATEWOOD DURING RELAXATION Relax- D e l i g n i f i c a t i o n time , min. • at i o n 0 30 60 . 90 120 180 240 24-0 (1#)240 (5^)240 (17.5%Y time , L i g n i n content ,'% ** ~ 100 97 86 72 60 46 20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.2 11.2 11.2 7.3 1 0 . 4 9.9 10.0 24.1 14.0 25.7 3 0 . 4 0 . 4 13.8 14 .2 8 . 0 12.1 11.9 12.6 3 0 . 4 16.0 31.1 34.7 0 . 6 15.0 15.0 9.5 13.0 12 .9 14 .0 33.5 17.5 33.2 37.3 0 . 8 15.8 16.7 9 . 9 13.8 13.7 15.0 35.4 18.7 3 5 . 4 39.0 1.0 16.5 17.5 1 0 . 9 14 .4 l4.l\= 15.7 36.7 19.3 36.8 40 . 4 1.5 17.7 18 .3 11.7 15.5 15.4 16.8 39.2 2 0 . 8 39.3 42 .8 2 18.1 19 .2 12.4 16.3 16.0 17.5 4 l . l 22.3 4 l . l 44.7 3 18.8 2 0 . 4 14.6 17.1 16.8 18 .9 43.7 2 3 . 4 43.6 47.1 4 19.6 2 0 . 8 15.3 17.7 17.2 19 .5 4 4 . 9 24 .6 45.4 49.0 5 19 .6 21.7 15.3 18 .0 17.4 19.9 46 .8 25.8 46 .5 5 0 . 2 6 20.0 22.1 15.3 18.8 17.8 20 .4 47.5 26.4 46.8 51.7 7 20 .4 2 2 . 5 15.3 19.0 17.8 20.6 48.1 27.3 47.5 5 2 . 6 8 20 .4 2 2 . 9 15.0 19.2 18.0 20.8 48.7 28.2 47.9 53.6 9 20.8 2 3 . 3 14.6 19.4 18.0 21.4 49.4 28.5 48.6 54.1 . 10 21.2 2 3 . 8 14.4 19.4 18.0 21.5 50.0 28.8 48.9 54.6 11 21.2 2 3 . 8 14.6 19.6 18.2 21.9 50.6 28.8 49.3 5 5 . 0 12 21.2 2 3 . 8 15.0 19.6 18.2 22.2 50.6 29.1 49.3 5 5 . 3 13 21.9 2 3 . 8 15.0 19.6 18.4 22.5 51.9 29.1 50.0 55.5 14 21.9 2 3 . 3 15.0 19.6 19.0 22.6 52.5 29 .4 50.O 55.7 15 21.9 2 3 . 3 16.8 19.6 19.O 22.6 53.2 29.7 5 0 . 4 56.2 16 21.7 2 3 . 3 16.8 19.6 19.0 22.6 53.2 29.7 51.1 56.5 17 21.7 2 2 . 9 16.8 19.6 19.0 22.8 53.2 30.0 51 .4 56.7 18 21.5 2 2 . 9 16.8 19.6 19.O 22.6 53.7 30.0 51.8 57.2 19 21.5 2 2 . 9 16.8 19.6 19.O 22.6 53.8 3 0 . 3 52.1 57 .4 20 21.5 2 2 . 9 16.8 19.6 18.8. 22.6 53.8 31.2 52.5 57.7 21 21.5 2 3 . 3 16.0 19.6 18.6 22.8 53.8 31.5 52.5 58.1 22 21.5 2 3 . 8 15.3 19.6 18.6 22.8 53.8 31.8 52.5 58 .9 2T ' 21.-5 2 3 . 8 " 15.3 19.6 " 18.6 23.2 ' 54 .4- 3 2 . 6 52.1 58.9 2.4.- 21.9 2 4 . 2 , 1 5 . 3 - 1 9 . 6 , 18.6 2 3 . 3 - 54.4 32.6 52.1 58.9 25 2 2 . 3 24.2 15.3 19.8 18.6 23.5 55.1 3 2 . 4 52.5 59.1 (continuing) Relax- - D e l i g n i f i c a t i o n time t min. at ion, 0 30 60 90 120 180 240 240 (1%)240 (5$)240 (17.5%) time , ~~ " L i g n i n content t%'** min. 100 97 86 72 60 46 20 0 0 p_ 26 22.7 24 .2 16.0 2 0 . 0 18.6 23.8 55.1 33.0 52.5 59.1 27 22.7 24.2 16.8 2 0 . 2 18 .8 23.9 5 5 . 1 33.0 5 2 . 5 59.1 28 22.7 24 .2 16.8 2 0 . 3 19 .0 24.0 55.7 33.0 5 2 . 5 59.1 29 22.7 24 .2 17.5 2 0 . 3 19 .2 24.0 55.7 33.0 52.9 59.1 30 22.7 24 .2 16.8 2 0 . 3 19.2 24.0 55.7 33.0 53.2 59.1 31 22.7 24 .2 16.8 2 0 . 3 19.2 24.0 56.3 33.0 53.6 59.3 32 22.7 23.8 16.0 2 0 . 3 19.2 23.9 56.3 33.0 53.6 59.6 33 22.3 22.8 16.0 2 0 . 3 19.2 23.9 56.3 33.0 53.9 59.8 34 22.3 23.3 16.8 2 0 . 3 19.2 24.0 56.3 33.2 53.9 60.1 •35 21.9 24 .2 16.8 2 0 . 3 19.2 24.2 56.3 33.2 53.6 6 0 . 5 36 21.9 24 .2 16.8 2 0 . 3 18 .8 24 .5 56.3 33.2 53.6 6l.0 37 21.9 24 .6 16.8 2 0 . 3 18.8 24.6 56.3 3 3 . 5 53.9 61.0 38 21.9 24 .6 16.8 2 0 . 3 18.8 24.6 56.3 3 3 . 5 53.9 6 0 . 8 39 21.9 24 .6 16.8 2 0 . 3 18.8 24.9 57.0 33.5 5 3 . 9 6 0 . 8 40 21.9 24 .6 16.8 2 0 . 3 18 .8 24.9 57.0 3 3 . 5 5 3 . 9 6 0 . 8 * Caustic treatments at 25°C ** Based on the 1500 cm'1 hand i n t e n s i t y TABLE 2 6 . EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE ON STRESS DECREMENT OF BALSAM FIR EARLYWOOD DURING RELAXATION 30 Relax-at ion' ^ time , min. 100 78 60 D e l i g n i f i c a t i o n time , min. 90 -120 180 240 240(5^)240(17 .5^)* 62 L i g n i n content , %'** 52 45 30 14 0 0 0 . 2 0.4 0 . 6 0.8 1.0 1.5 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22,.. 23 24 25 0 5.8 7.6 8.5 10.3 10.8 12.2 12.6 14.3 14.7 15.2 15.6 15.9 16.1 16.8 17.0 17.5 17.9 18.9 18.9 18.2 18.4 17.9 17.9 18.2 18.4 18.2 18.2 18.2 17.9 17.9. 0 4.1 5.5 4 . 8 6.2 6.2 6.2 6 . 9 8 . 9 8 . 3 9.0 9.0 9.7 9.7 9.7 10.3 10.3 10.3 10.3 10.3 10.3 9.7 . 9.0 8.3 8.3 6 . 9 7.6 9.0 8.3 9.7 10.3 0 7.7 7.7 9.2 9.2 9.2 9.2 10.8 10.8 10.8 12.3 12.3 12.3 10.8 10.8 10.8 12.3 1 3 . 9 1 5 . 4 1 5 . 4 1 5 . 4 1 3 . 9 1 3 . 9 13.8 12.3 13.6 1 3 . 9 12.3 12.3 1 0 . 8 10.8 0 11.2 13.0 14.9 15.8 16.7 18.6 i 9 . 5 20.7 21.7 22.3 22.3 23.2 23.2 2 3 . 2 23.8 24.2 24.2 24.2 24.2 24.8 24.8 24.8 24.8 24.8 25.7 25.7 25.7 25.7 25.7 25.7 0 6.6 8.7 10.1 10.8 11.6 11.6 11.6 11.6 15.1 15.1 15.6 15.9 16.3 16.4 16.7 16.7 16.7 16.7 17.5 17.5 17.5 19.1 19.3 19.3 19.3 19.3 19.3 19.8 19.8 19.8 0 6.7 8.0 9.3 10.0 10.0 11.0 11.7 12.3 13.0 13.3 13.3 13.3 13.3 13.7 13.7 !3.7 !3.7 13.3 13.3 13.0 13.0 13.0 13.7 14.3 14.7 14.7 14.7 14.3 14.3 14.3 0 11.2 13.8 14.5 15.8 16.5 17.8 19.1 19.7 19.7 20.4 20.4 21.1 21.1 21.1 21.1 21.7 22.4 22.4 23.0 23.0 22.4 22.4 22.4 22.4 21.7 22.4 22.4 23.0 23.0 23.7 0 i 5 . 1 17.1 18.7 19.7 2 0 . 4 2 2 . 4 2 3 . 4 25.1 26.1 27.1 2 7 . 4 28.8 29.1 29.8 29.8 3 0 . 4 30.8 31.1 3 1 . 4 31.8 31.8 31.8 31.8 32.1 32.1 3 2 . 4 3 2 . 4 32.8 33.1 33.1 0 28.7 33.6 36.8 38.6 40 .4 42.6 45.3 47.9 49.8 51.1 52.0 53.8 5 4 . 3 54.7 55.2 56.1 57.0 5 8 . 3 58.7 59.2 59.2 59.2 59.6 59.6 59.6 59.6 60.1 60.1 6 0 . 5 6 1 . 4 (continuing) Relax- D e l i g n i f i c a t i o n time, min. a t i o n 0 30 60 90 ' 120 180 240 240(5^)240 (17.5£) time, ' L i g n i n content. % ** min. 100 78 62 55 52 45 30 14 0 26 17.9 10.3 10.8 25.7 19.8 14.0 23.7 34.4 61.9 2? 17.7 10.3 10.8 25.7 19.8 14.0 23.7 34.4 62.8 28 18.2 10.3 10.8 25.7 • 19.8 14.3 23.0 34.4 63.2 29 17.9 10.3 10.8 25.7 19.8 14.3 23.0 34.4 63.7 30 17.7 10.3 10.8 25.7 19.6 14.7 23.0 * 34.4 63.7 31 17.9 10.3 9.2 25.7 19.3 14.7 22.4 34.4 63.7 32 17.9 9.7 9.2 25.7 19.8 14.7 22.4 33.8 63.7 33 17.9 9.7 9.2 25.7 20.4 14.7 22.4 33.8 63.7 34 17.7 9.7 9.2 25.7 20.6 14.7 22.4 33.8 63.7 35 17.7 8.3 9.2 26.7 20.9 14.7 22.4 33.8 63.7 36 17.5 8.3 7.7 26.6 20.9 14.7 23.0 34.1 63.7 37 17.5 6.9 7.7 26.6 20.9 14.7 23.7 34.1 63.7 38 17.5 6.9 7.7 26.6 20.6 14.7 24.3 34.1 63.7 39 17.5 6.9 7.7 26.6 20.6 14.7 24.3 34.5 64.1 40 17.5 6.9 7.7 26.9 20.6 14.7 24.3 34.5 64.5 * Caustic treatments at 25 C ** Based on the 1500 cm"1 band i n t e n s i t y TABLE 27 . EFFECTS OF REMOVING LIGNIN,THEN HEMICELLULOSE ON STRESS DECREMENT OF BALSAM FIR LATEWOOD DURING RELAXATION D e l i g n i f i c a t i o n time Relax-a t i o n time, 30 60 90 120 180 min. 240 240 (1%)240 (5*)240 (17.5%) min. 100 96 79 72 0 0 0 0 . 0 0 . 2 6.7 5 .9 9.2 8.3 0.4 8.3 7 .3 11.3 9.7 0 .6 9.3 8.4 12.2 10.4 0.8 10.3 9.4 13.0 11.1 1.0 10.6 9.8 13.7 11.1 1.5 11.7 10.0 14.0 11.8 2 12.7 10.2 14.7 12.5 3 13.3 10.2 ! 5 . 5 13.9 4 13.7 11.5 15.5 14.6 5 14.0 11.8 15.8 15.3 6 15.0 11.8 15.8 15.3 7 15.0 11.8 15.5 15.3 8 15.0 11.8 15.5 15.3 9 15.0 11.8 15.1 16.7 10 15.7 12.2 15.1 16.7 11 15.7 12.2 15.1 16.7 12 15.7 11.8 16.1 16.7 13 15.7 11.8 16.1 16.7 14 16.0 11.8 17.8 16.7 15 16.0 11.8 17.8 16.7 16 16.3 11.8 17.5 16.0 17 16.3 11.8 17.5 16.0 18 16.3 11.8 17.1 15.3 19 16.3 11.8 17.1 15.3 20 16.3 11.8 16.8 16.0 21 16.3 11.8 16.4 16.0 22 - 16.. 3 . 11.8 16.1 16.0 23 16.0 11.8 15.8 15.3 24 16.0 - 11.8 - 15.5 15.3 25 16.0 11.8 15.5 16.0 L i g n i n content. % ** 55 41 19 13 8 : 0 8.6 10.7 12.1 13.0 13.7 15.2 15.9 17.2 18.1 18.7 19.1 19.1 19.1 20.0 20.2 20.2 20.9 20.9 21.2 21.2 21.5 21.7 21.7 21.7 22.2 22.2 22..2 22.3 22.4 22.6 0 7.6 10.1 11.5 12.4 13.0 14.5 15.2 16.2 17.0 17.7 17.7 17.7 18.8 19.0 19.0 19.3 19.3 19.7 19.8 15.0 20.0 20.2 20.2 20.6 20.6 20.6 20.6 21.0 21.0 21.2 0 8.8 11.1 12.5 13.2 14.0 14.5 16.0 17.2 17.9 18.6 18.9 19.0 19.1 19.1 19.1 19.0 19.0 19.0 18.9 19.1 •. 19.3 19.3 19.4 19.4 19.4 19.4 19.25 19.11 18.9 19.0 0 9.4 11.6 12.7 14.0 14.7 15.8 16.5 17.4 18.3 18.6 18.7 18.8 19.0 19.1 19.1 19.3 19.4 19.5 19.8 20.0 20.1 20.1 20.1 20.1 20.0 20.0 19.8 19.8 20.0 20.0 0 14.1 17.4 19.6 21.1 22.0 24.1 25 .9 29.1 3 0 . 4 3 0 . 9 31 .9 3 2 . 4 32.8 33.0 33.7 34.1 34.6 35.0 35.7 36 .5 36.5 36.5 36.7 36.8 37.0 37.0 37.0 37.2 0 27.3 32.11 35.6 37.1 38.7 41.2 42.6 45.3 47.2 48.9 49.9 50.9 51.3 51.9 52.6 52.8 53.2 53.6 53.8 54.7 55.3 55.5 55.9 55.9 56.7 56.7 56.7 56.9 ( continuing) Relax- D e l i g n i f i c a t i o n time . min. a t i o n 0 30 60 90 120 180 240 240 (ISO240<5#)240 (17 . 5%) time , - L i g n i n content % *• min. 100 96 79 72 . 55 41 19 13 8 0 26 16.0 11.8 15.1 15.3 22.8 21.2 19.1 20.0 37.2 56.9 27 16.0 11.8 15.1 15.3 22.8 21.2 19.1 20.0 37.2 57.1 28 16.0 11.8 15.5 15.3 23.4 21.3 19.3 20.3 37.4 57.1 29 .16.0 11.8 16.1 15.3 23.4 21.3 19.3 20.4 37.4 57.3 30 16.0 11.8 16.1 15.3 23.4 21.3 19.4 20.4 37.4 57.3 31 16.0 11.8 17.1 16.0 23.5 21.5 19.6 20.8 37.6 57.5 32 16.0 11.8 17.1 16.0 23-5 21.5 19.7 21.0 37.8 57.6 33 16.0 12.2 16.8 16.0 23.5 21.5 19.5 20.8 37.8 58.0 34 16.0 12.2 16.8 16.0 23.5 21.5" 19.4 20.; 8 38,0 58.2 35 16.3 12.2 16.4 16.7 23.6 21.7 19.2 20.8 38.0 58.6 36 16.3 12.2 15.8 16.7 23.6 21.7 19.3 20.8 38.0 58.8 37 16.3 12.2 15.5 16.7 23.6 21.7 19.4 21.0 38.3 58.8 38 16.3 12.2 15.5 16.7 23.6 21.8 19.4 20.8 38.7 58.8 39 16.3 12.2 15.5 16.7 23.6 21.8 19.3 21.0 38.9 58.9 40 16.3 12.5 15.5 16.7 23.6 21.8 19.3 20.8 39.4 59.0 * C a u s t i c treatments a t 25 C ** Based on the 1500 cm"1 band i n t e n s i t y -124-PIGURE 1. PHOTOGRAPHS SHOWING THE RAMP-LOADING APPARATUS (A) AND ITS POSITION IN THE INSTRUMENT (B) , AND THE STEP-LOADING APPARATUS (C) AND ITS POSITION IN THE INSTRUMENT (D). PIGURE 2 . INFRARED POLARIZATION SPECTRA ( || AND J.) OF DOUGLAS FIR "REGULAR" AND COMPRESSION WOOD TISSUES (ARROW INDICATES THE l l 6 0 CM"1 BAND). l/> L U LU OC O LU e u o o m < L U I o z < z o z LU Qi o 64 62 60 58 56 54 52 50 48 Y = 4 7 . 9 5 + 0 .15 X -e e = 0 . 7 5 S E E = 1.43 N .= 38 X D O U G L A S FIR A B A L S A M FIR O G R A N D F I R • S I T K A S P R U C E 0 ' V . . . . t 4 . * . J 1 U . • 1 . . * 0 24 28 32 36 40 44 48 52 56 60 64 68 72 76 O R I E N T A T I O N A N G L E ( X © ) A T 1 1 6 0 c m 1 , D E G R E E S PIGURE 3. RELATIONSHIP BETWEEN LIGNIN (1500 CM"1) AND CELLULOSE (1160 CM"1) ORIENTATION FOR VARIOUS WOOD TISSUES. -127-FIGURE 4. ELECTRON PHOTOMICROGRAPHS OF BALSAM FIR LATEWOOD CROSSSECTION FOLLOWING DELIGNIFICATION (a, 0 MIN; b, 60 MIN; AND c, 2k0 MIN ) AND FAILURE IN TENSION PARALLEL TO GRAIN. CELL WALL LAYERS (P. S. . So AND S3) AND MIDDLE LAMELLA (ML). D O U G L A S F I R B A L S A M F I R 1.81 o ° E A R L Y W O O D l.8i 1.6-L A T E W O O D 100 80 60 1.4 1.2-1.0 0.8 0.6 0.4 02 1730 cm' >. -© - O - O O -O J160 cm' i . . . i i i i i i 100 80 60 40 20 0 L I G N I N C O N T E N T (%) . L I G N I N C O N T E N T FIGURE 5 . DEPENDENCE OF DICHROIC RATIOS AT l l 6 0 AND 1730 CM"1 ABS0RBANCES ON LIGNIN CONTENT OF DOUGLAS FIR AND BALSAM FIR WOOD TISSUES. E A R L Y W O O D L A T E W O O D R E S I D U A L L I G N I N 1 0 0 7 8 23 002 00 2 101 101 101 101 R E S I D U A L L I G N I N GO 1 o o 8 6 3b" l l % l , , W . . , , V s l , . V i b l M 5 M:m'2m5t'2V't'tt'trott" 5 , 2 9 2 9 FIGURE 6A X-RAY DIFFRACTION PATTERNS OF DOUGLAS FIR WOOD TISSUES FOLLOWING DIFFERENT LEVELS OF CHLORITE DELIGNIFICATION. -130-• • T O T A L C R Y S T A L L I N I T Y A A 002 P L A N E C R Y S T A L L I N I T Y O o ( 101-4-10T) P L A N E C R Y S T A L L I N I T Y E A R L Y W O O D L A T E W O O D D O U G L A S FIR 60t L I G N I N C O N T E N T (%) PIGURE 7 . EFFECT OF DELIGNIFICATION LEVEL ON CRYSTALLINITY OF WOOD TISSUES. 60! • 55; • • —J 50« >• • LI NI 45:. t fALL 40« T CO 35! « i < 30: i — • vj r— 25-• C • DOUGLAS FIR A BALSAM FIR Y = 87.6 - 0.91 X n 6 0 r = -0.90 SEE=3.59 N = 23 i I 40 45 ORIENTATION 50 55 60 AN G LE (XeV AT 11 60 cnc] DEGRE ES 1 * 1 1 1 * 65 70 FIGURE 8. RELATIONSHIP BETWEEN X-RAY TOTAL CRYSTALLINITY AND ORIENTATION ANGLE OF THE WOOD CELLULOSE 1,4-0-^-D-LINKAGE. 24.2 ro i 0 10 20 30 40 50 60 70 80 RELAXATION TIME (MI N) FIGURE 9. INTRA-INCREMENTAL RELAXATION OF THE 1160 CM"1 COMPONENT (CELLULOSE) IN DOUGLAS FIR WOOD TISSUES. RELAXATION TIME (MIN) FIGURE 10. INTRA-INCREMENTAL RELAXATION OF THE 1730 CM"1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR WOOD TISSUES. PIGURE 11. 10 20 30 40 50 60 70 80 RELAXATION TIME(MIN) INTRA-INCREMENTAL RELAXATION OP THE 1500 C M " 1 COMPONENT (LIGNIN) IN DOUGLAS FIR WOOD T ISSUES. 24.0 i I L AT E WOOD EARLYWOO D 1-7-1 1 6 1 -5 1-4 — 1-2-0 l . l -i- 1 -0-1 9-•7 6-\ •5 3-•2-T 1 73 0 cm"' • "i* • • • • • • • 116 0 cm- 1 10 20 3 0 4 0 5 0 6 0 70 173 0 cm"' J • • • * U f y i 1160 cur 0 10 20 30 40 50 60 7 0 FIGURE 12. - ' ' CREEP TIME , MlN MOLECULAR MOTION OF WOOD CARBOHYDRATE COMPONENTS DURING CREEP TEST OF BALSAM FIR WOOD TISSUES. E A R L Y W O O D S T E P - L O A D I N G (l 0"2min) L A T E W O O D o ro K o 1.4 W 1.01 •8« '1 1.3 1.1 • 9 R A M P - L O A D I H(% ( l o m i n ) O at X '3 .6 •A 1.4 1.2 1.04::... 4 . . • • .8« .6' 10 20 3^ 75 50 6'0 0 2^ tfj 4^ 5b 6^  70 8"0 T I M E , M I N PIGURE 1 3 . EXCITATION TIME EFFECTS ON THE MOLECULAR RELAXATION OF THE 1 7 3 0 CM-1 COMPONENT IN BALSAM FIR WOOD TISSUES. I ON I FIGURE 14. THE EFFECT OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON RELAXATION OF THE 1160 CM-1 COMPONENT (CELLULOSE) IN DOUGLAS FIR EARLYWOOD TISSUES. o CO K §! o !< 1 . 7 4 . 1.5-U "•. O 1.3-QC X 1.1 J u Q A 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 . ; RELAXATION T IME, MIN i CO t FIGURE 1 5 . THE EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1 7 3 0 CM" 1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR EARLYWOOD TISSUES. FIGURE 16. THE EFFECT OF REMOVING LIGNIN, THEN HEMICELLULOSE ON RELAXATION OF THE 1160 CM"1 COMPONENT (CELLULOSE) IN DOUGLAS FIR LATEWOOD TISSUES. RE LAXATION TIME, MIN FIGURE 17. THE EFFECT OF REMOVING LIGNIN ON RELAXATION OF THE 1730 CM"1 COMPONENT (HEMICELLULOSE) IN DOUGLAS FIR LATEWOOD TISSUES. RELAXATION TIME, MIN PIGURE 18. EFFECTS OP REMOVING LIGNIN, THEN HEMICELLULOSE, ON PHYSICAL STRESS RELAXATION OP DOUGLAS PIR EARLYWOOD TISSUES. o o z UJ % UJ U UJ Q CO to UJ 240(17.5% NAOH) (5% NAOH) 240.(1% NAOH) ro i , 4 * — i r 0 10 20 30 40 RELAXATION TIME, MIN FIGURE 19. EFFECTS OF REMOVING LIGNIN, THEN HEMICELLULOSE, ON PHYSICAL RELAXATION OF DOUGLAS FIR LATEWOOD TISSUES. 

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