Reaction of Wood Pulp with Î±,Î²-Amic Acids - ACS Symposium Series

6 Reaction of W o o d Pulp with α,β-Amic Acids

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I. Synthesis of Possible Spinnable Derivatives LARRY C. WADSWORTH and JOHN A. CUCULO Fiber and Polymer Science Program, Department of Textile Chemistry, North Carolina State University, Raleigh, NC 27607

In view of the shortage of petrochemicals used for the production of synthetic fibers, i t is no surprise that renewed emphasis is being placed on cellulose chemistry, a field which has received sagging interest for the past twenty years. In the coming years, our oil reserves w i l l become increasing ly scarce, or nonexistent, but cellulose is today, and in the future w i l l remain the most abundant of raw materials. But far more important, cellulose is a continually replaceable raw material (1). Trees or other plants currently under study, can be replanted as soon as existing mature trees are consumed. The rotation cycle for pulp can be as little as 15 years or even less (2). Granted that greater use of cellulose as a source of textile fibers could mean lesser or minimal dependence upon petrochemicals, fabrics made from cellulosics such as rayon and cotton have great aes thetic appeal, primarily greater wearing comfort due to the inherent hydrophylic properties of cellulose. Yet, the production of rayon in the United States and elsewhere is decreasing largely because of the unfavor able economics of meeting pollution standards and from competition with other fibers (3). An alternative to the viscose process has been proposed by Cuculo (4) through the reaction of cellu lose with amic acids. The product envisioned is a cellulose half-acid ester. Limited solubility of the derivatives has been obtained in dilute a l k a l i . With increasing degree of substitution (DS), the solubility of the cellulose half-acid ester should go through a transition of insolubility to solubility in dilute a l k a l i , water, water-alcohol mixtures, hydrocarbon81

Arthur; Textile and Paper Chemistry and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.


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TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY

a l c o h o l m i x t u r e s , and f i n a l l y , o r g a n i c s o l v e n t s , sim i l a r t o t h e t r a n s i t i o n d e s c r i b e d b y P e t e r s (_5) f o r cellulose ethers. The e s t e r p a r t o f t h e d e r i v a t i v e , h o w e v e r , w o u l d be s u b j e c t t o s a p o n i f i c a t i o n i n aqueous a l k a l i , d e p e n d e n t upon a l k a l i c o n c e n t r a t i o n and temper a t u r e and d e r i v a t i v e s t r u c t u r e . I d e a l l y t h e c e l l u l o s e h a l f - a c i d e s t e r c o u l d be c o n v e r t e d i n t o a w a t e r s o l u b l e s a l t , and wet extruded as a f i b e r , o r f i l m i n t o an a c i d , o r o t h e r non-solvent coagulating bath. T h i s procedure o f f e r s the advan t a g e o f a l l o w i n g c o n d i t i o n s t o be c h o s e n f o r p r e v e n t i n g s a p o n i f i c a t i o n of the d e r i v a t i v e d u r i n g the solub i l i z a t i o n s t e p , t h e r e b y o p e n i n g up many p o s s i b i l i t i e s f o r producing c e l l u l o s i c f i b e r s with enhanced prop e r t i e s , s i n c e many a m i c a c i d d e r i v a t i v e s w h i c h i m p a r t d e s i r e d p r o p e r t i e s c a n be u t i l i z e d . One important a p p l i c a t i o n c o u l d be t h e p r o d u c t i o n o f i n h e r e n t l y f l a m e - r e t a r d a n t f i b e r by r e a c t i n g c e l l u l o s e w i t h a m i c a c i d d e r i v a t i v e s c o n t a i n i n g bromine or phosphorous. Y e t , t h e p r o d u c t i o n o f s u f f i c i e n t l y h i g h DS c e l l u l o s e a c i d e s t e r to produce wet-spinnable d e r i v a t i v e n e e d n o t be a l i m i t a t i o n f o r t h e r e a c t i o n . A f o u r - f o l d i n c r e a s e i n w a t e r a b s o r b e n c y (6) h a s b e e n o b t a i n e d i n the r e a c t i o n o f rayon f a b r i c with s u c c i n a m i c a c i d w i t h a DS o f 0.3. R e s e a r c h i s now i n p r o g r e s s i n which amic a c i d s c o n t a i n i n g bromine are being r e a c t e d with c e l l u l o s i c f a b r i c s f o r the produc t i o n o f f l a m e - r e t a r d a n t f a b r i c s (7) · T h i s has a l r e a d y been demonstrated i n the l a b o r a t o r y f o r the l a t t e r case. The p o t e n t i a l s f o r m o d i f y i n g nonwovens by t h i s method are a l s o q u i t e f a s c i n a t i n g . F o r e x a m p l e , wood p u l p c o u l d be r e a c t e d w i t h a m i c a c i d s p r i o r t o nonwoven f a b r i c p r o d u c t i o n t o p r o d u c e h i g h l y a b s o r b e n t p a d d i n g and b a c k i n g m a t e r i a l s . In the p r e s e n t work, d e g r e e s o f s u b s t i t u t i o n r a n g i n g f r o m 0.3 t o 0.7 w e r e o b t a i n e d i n t h e r e a c t i o n o f v a r i o u s wood p u l p s r a n g i n g f r o m h i g h t o low d e g r e e s o f p o l y m e r i z a t i o n (DP) w i t h s u c c i n a m i c a c i d , ammonium succinamate, and Ν , Ν - d i e t h y l s u c c i n a m i c a c i d i n p a d bake r e a c t i o n s . R a t h e r l o w DS v a l u e s (DS a p p r o x i m a t e l y 0.1) w e r e o b t a i n e d i n t h e B a r r a t t e - t y p e r e a c t i o n s o f d r y and " n e v e r - d r i e d " wood p u l p s w i t h s u c c i n amic a c i d . S t r u c t u r a l p r o o f o f the c e l l u l o s e hemis u c c i n a t e d e r i v a t i v e was o b t a i n e d b y i n f r a r e d a n a l y s i s . DP d e t e r m i n a t i o n s a c c o m p a n i e d a l l DS a n a l y s e s s o t h a t r e a c t i o n c o n d i t i o n s c o u l d be a p p r o p r i a t e l y v a r i e d t o o b t a i n h i g h d e g r e e o f s u b s t i t u t i o n w i t h minimum degra dation.


6.

WADSWORTH

AND

cucuLO

Wood ΡύΙρ-α,β-Amic

Acid Reactions

83


Experimental R e a c t a n t s . S u c c i n a m i c a c i d was s y n t h e s i z e d f r o m s u c c i n i c anhydride as d e s c r i b e d by A l l e n ( 8 ) . Ammonium s u c c i n a m a t e was s y n t h e s i z e d f r o m succinamic acid. S u c c i n a m i c a c i d , 500 g , was d i s p e r s e d i n acetone t o a t o t a l volume o f 2 ^ i n a 4 % beaker. T h e s u c c i n a m i c a c i d was s l i g h t l y s o l u b l e i n acetone. Ammonia g a s was s l o w l y b u b b l e d t h r o u g h t h e r e a c t i o n m e d i a f o r 2 1/2 h o u r s w i t h c o n t i n u o u s stirring. T h e r e a c t i o n was s l i g h t l y e x o t h e r m i c , b u t r e q u i r e d no e x t e r n a l c o o l i n g . The c r y s t a l s which formed were f i l t e r e d u n d e r vacuum, washed f i v e m i n u t e s w i t h a c e t o n e w i t h o u t vacuum, a n d f i l t e r e d d r y under s u c t i o n . T h e p r o c e d u r e was r e p e a t e d t w o t i m e s , and t h e c r y s t a l s were s p r e a d o u t i n a t r a y t o d r y . A 9 5 % y i e l d was o b t a i n e d . P u r i t y and i d e n t i f i c a t i o n w e r e d e t e r m i n e d by m e l t i n g p o i n t (109° t o 110°C) a n d infrared analysis. Ν , Ν - d i e t h y l s u c c i n a m i c a c i d was s y n t h e s i z e d f r o m s u c c i n i c a n h y d r i d e b y Bowman (9). Ν,N-diethylamine, 55 m l , f r o m M a t h e s o n C o . , I n c . was p u r i f i e d b y s i m p l e distillation. S u c c i n i c a n h y d r i d e was o b t a i n e d f r o m Armageddon C h e m i c a l Co. T h e a m i n e was d i s s o l v e d i n 40 m l o f a c e t o n e ( F i s h e r L a b o r a t o r y G r a d e ) a n d a d d e d t o a s u s p e n s i o n o f 100 g r a m s o f a n h y d r i d e i n 100 m l o f acetone. T h e r e a c t i o n was i n i t i a l l y e x o t h e r m i c (max imum t e m p e r a t u r e 4 0 ° C ) . T h e s o l u t i o n was e v a p o r a t e d to near dryness. T o r e m o v e t h e y e l l o w t i n t , 100 m l o f a c e t o n e a n d a p p r o x i m a t e l y 2 g o f N o r i t e B, d e c o l o r i z i n g carbon were added and t h e m i x t u r e h e a t e d t o a boil. T h e m i x t u r e was a l l o w e d t o s t e e p f o r a b o u t f i v e m i n u t e s , a n d f i l t e r e d warm t o y i e l d a c l e a r s o l u t i o n . T h e f i l t e r e d s o l u t i o n was t h e n h e a t e d t o a b o i l a n d c a r b o n t e t r a c h l o r i d e was a d d e d t o t h e p o i n t o f i n c i p i ent t u r b i d i t y . F i n a l l y t h e s o l u t i o n was c o o l e d i n t h e f r e e z e r , and t h e r e s u l t i n g c r y s t a l s were f i l t e r e d , and s p r e a d o u t i n a t r a y t o d r y . A n 8 1 % y i e l d was o b t a i n ed. P u r i t y and i d e n t i t y were d e t e r m i n e d by m e l t i n g p o i n t (82° t o 8 4 ° C ) a n d b y i n f r a r e d a n a l y s i s . C e l l u l o s e Source. The f o l l o w i n g d i s s o l v i n g p u l p s were o b t a i n e d from ITT R a y o n i e r , I n c . i n d r y s h e e t form w i t h the i n t r i n s i c v i s c o s i t i e s (I.V.) s p e c i f i e d i n d l / g : Rayocord-X-F, I.V.-9.2; C e l l u n i e r - F , I.V.3.72; R a y s e l e c t - J , I . V . - 3 . 3 2 . A l l were S o u t h e r n P i n e and p u l p e d by the S u l f i t e P r o c e s s ( 1 0 ) .


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" N e v e r - d r i e d " C e l l u n i e r - P (Hemlock) and d r i e d " C e l l u n i e r - F (Southern P i n e ) were a l s o from ITT R a y o n i e r (11).

"neverobtained

Pretreatment Conditions. The d r y p u l p s h e e t s , a s r e c e i v e d , w e r e f i r s t s h r e d d e d w i t h w a t e r i n a commer c i a l b l e n d e r a t h i g h s p e e d f o r 90 s e c o n d s . The p u l p s l u r r y was t h e n p o u r e d i n t o a B u c h n e r f u n n e l , a n d suction applied. P u l p w h i c h was n o t t o b e m e r c e r i z e d was t h e n w a s h e d f o r f i v e m i n u t e s w i t h a c e t o n e b e f o r e s u c t i o n was a p p l i e d . T h i s s t e p was r e p e a t e d t w i c e , and t h e p u l p s p r e a d o u t on aluminum f o i l , and a i r d r i e d a t room t e m p e r a t u r e . The m o i s t u r e c o n t e n t o f t h e p u l p s t o be m e r c e r i z e d w e r e d e t e r m i n e d s o t h a t t h e sodium hydroxide c o n c e n t r a t i o n (approximately 20%) c o u l d be p r e p a r e d t o r e s u l t i n an e q u i l i b r i u m v a l u e o f 17.5% t o compensate f o r t h e d i l u t i o n e f f e c t o f t h e wet p u l p . The s a m p l e s w e r e p l a c e d i n t h e r e f r i g e r a t o r a t 7 . 5 ° C f o r 24 h o u r s . The m e r c e r i z e d c e l l u l o s e was t h e n w a s h e d f r e e o f c a u s t i c a n d a c i d i f i e d w i t h 10% acetic acid. A f t e r washing free of a c i d , the c e l l u l o s e was a c e t o n e w a s h e d a n d a i r - d r i e d . B o t h the " n e v e r - d r i e d " p u l p s were s u l f i t e p u l p e d and were a c i d i c t o l i t m u s paper. As soon as r e c e i v e d , t h e p u l p s were washed w i t h w a t e r on a B u c h n e r f u n n e l . The w a s h i n g s w e r e r e p e a t e d u n t i l the f i l t r a t e was d e t e r m i n e d n e u t r a l by a y e l l o w t o b l u e c o l o r change when one d r o p o f 0.1N NaOH a n d two d r o p s o f a 0.1% s o l u t i o n o f b r o m o c r e s o l p u r p l e i n d i c a t o r were added t o 100 m l o f f i l t r a t e . P o r t i o n s o f b o t h wet, neutralized p u l p s were s e a l e d i n p o l y e t h y l e n e bags and p l a c e d i n the r e f r i g e r a t o r u n t i l ready f o r use. Portions of b o t h w e t , n e u t r a l i z e d p u l p s , 250 g r a m s (approximately 6:1 w a t e r t o p u l p c o n t e n t ) , w e r e f u r t h e r w a s h e d t h r e e times each w i t h methanol, e t h a n o l , i s o p r o p a n o l , and acetone. T h e p u l p s w e r e t h e n a i r - d r i e d a t r o o m temp erature. Nonwoven Mat F o r m a t i o n . A c y c l i n d r i c a l handsheet m o l d (6 i n χ 16 i n ) was u t i l i z e d t o make t h e c e l l u l o s e mats. A r o u n d f i b e r g l a s s s c r e e n was c u t s l i g h t l y l a r g e r than the handsheet mold d i a m e t e r and p l a c e d on t o t h e mat f o r m i n g s c r e e n o f t h e m o l d . The cylinder was f i l l e d w i t h w a t e r a n d 1 g r a m o f c e l l u l o s e w h i c h had been shredded i n a commercial b l e n d e r a t h i g h speed f o r 90 s e c o n d s , was a d d e d . The w a t e r - c e l l u l o s e s l u r r y was a g i t a t e d , t h e l o w e r w a t e r v a l v e t o t h e m o l d o p e n e d , a n d a u n i f o r m c e l l u l o s e mat was f o r m e d o n t h e f i b e r g l a s s s c r e e n w i t h a w e i g h t o f 1.62 oz/yd (707 g r n / y d ^ ) 2


6. wADswoRTH

AND CUCULO

Wood ΈύΙρ-^,β-Amic

Acid Reactions

85


A n o t h e r f i b e r g l a s s s c r e e n was p l a c e d o n t o p o f t h e c e l l u l o s e m a t t o f o r m a s a n d w i c h a n d was t h e n r e m o v e d from t h e mold. Amic A c i d T r e a t m e n t S o l u t i o n s . Succinamic acid p a d b a t h s were p r e p a r e d by d i s s o l v i n g 54% s u c c i n a m i c a c i d o n t h e w e i g h t o f t h e s o l u t i o n (o.w.s.) i n d e i o n i z e d d i s t i l l e d water. H e a t was r e q u i r e d t o m a i n t a i n s u c c i n a m i c a c i d s o l u b i l i t y (90°C + 5 ° C ) . When c a t a l y s t was u t i l i z e d , 1.62% ammonium s u l f a m a t e (o.w.s.) was a d d e d t o t h e b a t h . Succinamic acid s o l u t i o n s w e r e p r e p a r e d i n t h e same m a n n e r f o r t h e Baratte reactions. T h e a q u e o u s ammonium s u c c i n a m a t e p a d b a t h was p r e p a r e d b y d i s s o l v i n g 6 1 . 9 % ammonium s u c c i n a m a t e i n d e i o n i z e d d i s t i l l e d w a t e r , and h e a t i n g t o 85°C + 5 ° C . When s p e c i f i e d , 1.62% ammonium s u l f a m a t e c a t a l y s t (o.w.s.) was a d d e d . The m e l t b a t h s were p r e p a r e d , s i m p l y b y h e a t i n g ammonium s u c c i n a m a t e t o s l i g h t l y above i t s m e l t i n g p o i n t o f 110°C. T h e Ν , Ν - d i e t h y l s u c c i n a m i c a c i d m e l t p a d b a t h was p r e p a r e d by h e a t i n g t o s l i g h t l y above i t s m e l t i n g p o i n t o f 84°C. Pad-Bake T e c h n i q u e . The h a n d s h e e t sandwiches were s t a p l e d around t h e c i r c u m f e r e n c e t o c o n f i n e t h e c e l l u l o s e mat. A f t e r a n i m m e r s i o n t i m e o f 90 s e c o n d s a t t h e s p e c i f i e d p a d t e m p e r a t u r e , t h e h a n d s h e e t was r e m o v e d , b l o t t e d b e t w e e n two p u l p s h e e t s , a n d squeezed between pad r o l l s t o a p i c k u p r a t i o o f a p p r o x i m a t e l y 4 t o 1. The s a m p l e s were i m m e d i a t e l y p l a c e d i n a p l a s t i c bag a f t e r p a d d i n g t o keep them wet u n t i l t h e e n t i r e s e r i e s was p a d d e d ( n o t l o n g e r t h a n 20 m i n u t e s ) . The samples were t h e n suspended w i t h p a p e r c l i p s on a r i n g s t a n d w h i c h was i m m e d i a t e l y p l a c e d i n t o t h e o v e n . The b a k e o v e n was r a i s e d t o 3 ° C a b o v e t h e s p e c i f i e d b a k e temperature t o a l l o w f o r temperature drop d u r i n g t h e o p e n i n g and c l o s i n g o f t h e oven door, and t h e c o o l i n g e f f e c t c a u s e d by t h e h e a t i n g o f t h e m e t a l r i n g s t a n d . T h r o u g h o u t t h e b a k e r e a c t i o n s , t h e t e m p e r a t u r e was m a i n t a i n e d a t t h e s p e c i f i e d t e m p e r a t u r e + 3°C. The o v e n was a P r e c i s i o n S c i e n t i f i c Company 1 I s o t e m p with forced a i r draft. B a r a t t e r e a c t i o n s were p e r f o r m e d i n a B u c h i Rotavapor. T e n grams o f p u l p w e r e p l a c e d i n t o a 500 m l r o u n d b o t t o m f l a s k a n d 100 grams o f s h o r t g l a s s r o d s ( a p p r o x i m a t e l y 1.5 χ 1.0 cm) w e r e a d d e d t o t h e f l a s k t o enhance u n i f o r m t u m b l i n g o f t h e p u l p throughout t h e reaction. When B a r a t t e r e a c t i o n s w e r e p e r f o r m e d o n " n e v e r - d r i e d " p u l p s , s u f f i c i e n t w e t p u l p was u t i l i z e d


86



t o b e e q u i v a l e n t t o 10 g r a m s o f d r y p u l p . The a m i c a c i d s o l u t i o n s were t h e n added t o t h e f l a s k , and t h e f l a s k was r o t a t e d i n a s i l i c o n e o i l b a t h m a i n t a i n e d at the temperature corresponding to t h a t of the e q u i v a l e n t pad s o l u t i o n i n the pad-bake r e a c t i o n s , f o r a p e r i o d o f 15 m i n u t e s t o a l l o w f o r s u f f i c i e n t s a t u r a t i o n o f the s u b s t r a t e w i t h the amic a c i d . Than a second o i l bath at the s p e c i f i e d r e a c t i o n temperature was p l a c e d u n d e r t h e r o t a t i n g f l a s k . Experimental Analyses. The d e t e r m i n a t i o n o f p e n d e n t c a r b o x y l i c a c i d c o n t e n t by t h e i o n - e x c h a n g e r e a c t i o n between c a l c i u m a c e t a t e and t h e c a r b o x y l i c a c i d g r o u p s , and t h e d e t e r m i n a t i o n o f t o t a l c a r b o x y l c a r b o n y l and e s t e r c a r b o n y l by t h e m o d i f i e d E b e r s t a d t m e t h o d h a v e b e e n p r e v i o u s l y d e s c r i b e d (8) . In a d d i t i o n to d e t e r m i n i n g the c a r b o x y l i c a c i d c o n t e n t by t h e c a l c i u m a c e t a t e m e t h o d u s i n g C r a m e r ' s c o r r e c t i o n f a c t o r (S, 12), f r e e c a r b o x y l c o n t e n t was a l s o determined by the cation-exchange reaction between the s i l v e r c a t i o n and the c a r b o x y l p r o t o n a s d e s c r i b e d b y D a v i d s o n a n d N e v e l (13) w i t h t h e e x c e p t i o n t h a t the volume o f s i l v e r meta-nitrophenolate t r e a t m e n t s o l u t i o n was i n c r e a s e d f r o m 100 t o 300 ml. The c a l c u l a t i o n s o f f r e e , t o t a l , and c r o s s l i n k degrees o f s u b s t i t u t i o n were performed u s i n g the f o r m u l a s d e v e l o p e d by J o h n s o n , e t a l . ( 1 4 ) . I n t r i n s i c v i s c o s i t i e s were d e t e r m i n e d on t h e s a p o n i f i e d d e r i v a t i v e s u s i n g ASTM P r o c e d u r e D1795-62 (15), and degrees o f p o l y m e r i z a t i o n were c a l c u l a t e d u s i n g t h e Mark-Houwink e q u a t i o n and t h e Κ and a v a l u e s o f Newman, et. a l . (16) . N i t r o g e n a n d s u l f u r a n a l y s e s w e r e p e r f o r m e d b y an independent l a b o r a t o r y u s i n g the f l a s h combustion t e c h n i q u e a n d t h e S c h o n i g e r t e s t f o r t h e two a n a l y s e s , respectively. I n f r a r e d a n a l y s e s o f t h e wood p u l p s a n d d e r i v a t i ves were p e r f o r m e d w i t h p o t a s s i u m bromide p e l l e t s u t i l i z i n g a P e r k i n E l m e r 337 G r a t i n g I n f r a r e d S p e c t r o photometer. A W i l e y m i l l was u t i l i z e d t o d i s i n t e g r a t e t h e p u l p t o a i d i n t h e p r e p a r a t i o n o f more u n i f o r m pellets. The r e g e n e r a t e d c e l l u l o s e f i l m s w e r e s i m p l y run without f u r t h e r p r e p a r a t i o n . Results

and

Discussion

Reactants. The s t r u c t u r e s o f t h e a , 3 - a m i c a c i d s r e a c t e d w i t h wood c e l l u l o s e a r e g i v e n i n T a b l e I . D e g r a d a t i o n o f t h e c e l l u l o s e c h a i n i s shown i n t h i s


6.

WADSWORTH

AND CUCULO

Wood Pulp-afi-Amic

Acid Reactions

87

paper to occur i n the r e a c t i o n of c e l l u l o s e with succinamic a c i d , p a r t i c u l a r l y i n the presence o f ammonium s u l f a m a t e c a t a l y s t . I t was t h e o r i z e d t h a t d e g r a d a t i o n c o u l d be m i n i m i z e d by r e a c t i n g c e l l u l o s e u n d e r t h e more a l k a l i n e c o n d i t i o n s e f f e c t e d by t h e u s e o f ammonium s u c c i n a m a t e r e a c t a n t . Ν,N-diethyl s u c c i n a m i c a c i d was s e l e c t e d t o e l i m i n a t e a competing i m i d e s i d e r e a c t i o n (1J) and t h e r e b y i n c r e a s e s t h e amount o f p r o d u c t c o n v e r t e d t o c e l l u l o s e h a l f - a c i d ester.


r

Infrared Analyses of Cellulose Hemisuccinate Derivatives. The m a i n p r o d u c t o f t h e r e a c t i o n i s a c e l l u l o s e h a l f - a c i d e s t e r with the e v o l u t i o n of ammonia: ^NH Cell-OH

2

OH.

+ 0 = C

Cell

- 0 - C

.C

C - O H +

=

Ο

NH^

*

The mechanism o f t h e r e a c t i o n s w i t h a l c o h o l s i s t h o u g h t t o i n v o l v e a c y c l i c a n h y d r i d e i n t e r m e d i a t e (18, 1 9 , 20) a n d was t h e s u b j e c t o f a r e c e n t Ph.D. disser t a t i o n (Γ7) . The i n f r a r e d s p e c t r u m o f a c e l l u l o s e h e m i s u c c i n a t e produced from the r e a c t i o n o f m e r c i z e d Rayocord-X-F wood p u l p w i t h s u c c i n a m i c a c i d i s shown i n c u r v e A o f F i g u r e l a . T h e number o f s u c c i n i c a c i d g r o u p s p e r a n h y d r o g l u c o s e u n i t as e x p r e s s e d by t h e f r e e DS i s _^ 0.38. The b r o a d a b s o r p t i o n p e a k c e n t e r e d a t 3400 cm i s t y p i c a l o f t h e OH s t r e t c h i n g a s s i g n e d t o c e l l u l o s e . The s h a r p e r a b s o r p t i o n b a n d a t 2900, a l s o a s s i g n a b l e t o c e l l u l o s e , i s due t o CH s t r e t c h i n g (_21) . The s t r o n g a b s o r p t i o n p e a k a t 1720 c m " which i s not o b s e r v e d i n n a t i v e c e l l u l o s e i s due t o t h e o v e r l a p o f t h e c a r b o x y l c a r b o n y l and t h e e s t e r c a r b o n y l . If t h i s i s t r u l y the s t r u c t u r e , then c o n v e r t i n g the pendant c a r b o x y l group i n t o a c a r b o x y l a t e anion should r e s u l t i n the r e s o l u t i o n o f the s i n g l e peak i n t o two peaks w i t h the c a r b o x y l a t e anion a b s o r b i n g a t lower energy, thereby p r o v i d i n g p r o o f o f s t r u c t u r e . This i s 1


88

Table

TEXTILE

I.

A N D PAPER

CHEMISTRY

A N D TECHNOLOGY

Reactants OH

Succinamic

acid

NH

\C = 0

0 = C CH

2

- CH

2


V*)

Ammonium

ο - c

succinamate

\ CH

\C 2

- CH

2

,0H Ν,Ν-diethyl s u c c i n a m i c

acid

0

= 0

N(CH.CH,).

β=

= c C H - CH

Figure la. IR spectra: (A) cellulose hemisuccinate; (B) sample A washed with 10% sodium bicarbonate; (C) sample A saponified

3500

ο

2

3000 2500 2000 Frequency, cm" 1


1500


6.

WADSWORTH AND

3500

3000

Wood Pulp-aft-Amic Acid Reactions

cucuLO

2500

Figure lb. IR spectra of Rayselect-J pulp reacted with (D) succinamic acid, (E) ammonium succinamate, and (F) N,Ndiethyl succinamic acid

2000

Frequency, cm"

1

3500

3000

2500

2000

Frequency, cm"

1

1500

Figure lc. IR spectra of (G) mercerized, untreated Ray select-], (H) film regenerated from Rayselect-J plus succinamic acid reactant, (I) film regenerated from Rayselect-J plus ammonium succinamate



90


confirmed i n curve Β i n which the d e r i v a t i v e was w a s h e d w i t h 10 p e r c e n t s o d i u m b i c a r b o n a t e . T h i s same e f f e c t h a s b e e n shown w i t h c e l l o p h a n e r e a c t e d w i t h s u c c i n a m i c a c i d (3/7)· I n t h e c u r v e C, t h e a b s o r p t i o n s p e c t r a a f t e r s a p o n i f i c a t i o n o f t h e d e r i v a t i v e by t h e m o d i f i e d E b e r s t a d t m e t h o d i s s h o w n ( 1 2 , 22), and i s i d e n t i c a l t o t h a t of pure c e l l u l o s e . The p e a k a t 1635 i s due t o a b s o r b e d w a t e r ( 2 1 ) . C u r v e s D, E , a n d F ( F i g u r e l b ) r e p r e s e n t m e r c e r ized Rayselect-J reacted with succinamic acid with c a t a l y s t , ammonium s u c c i n a m a t e w i t h o u t c a t a l y s t , a n d Ν,Ν-diethyl succinamic a c i d r e s p e c t i v e l y . A l l three curves appear i d e n t i c a l which o f f e r s s t r o n g support t h a t the three r e a c t a n t s y i e l d t h e same c e l l u l o s e hemisuccinate derivative. C u r v e G, F i g u r e l c , i s t h e IR s p e c t r u m o f m e r c e r ized, unreacted Rayselect-J pulp. C u r v e s H and I a r e s p e c t r a o f c e l l u l o s e f i l m s f o r m e d by d i s s o l v i n g t h e c e l l u l o s e - h e m i s u c c i n a t e d e r i v a t i v e s i n 10% s o d i u m h y d r o x i d e a t - 1 0 ° C , and c o a g u l a t i n g t h e c e l l u l o s e by the a d d i t i o n of acetone. The r e a c t a n t s f r o m w h i c h the c e l l u l o s e - h e m i s u c c i n a t e d e r i v a t i v e s were formed p r i o r t o s o l u b i l i z a t i o n and s u b s e q u e n t r e g e n e r a t i o n o f c e l l u l o s e w e r e s u c c i n a m i c a c i d a n d ammonium s u c c i n a m a t e , c u r v e s H and I , r e s p e c t i v e l y . T h e s e two s p e c t r a are i d e n t i c a l t o t h a t o f pure c e l l u l o s e , c u r v e G, a n d i t i s no s u r p r i s e t h a t t h e d e r i v a t i v e s a r e s a p o n i f i e d i n t h e 10% s o d i u m h y d r o x i d e . E f f e c t o f Treatment C o n d i t i o n s . From t h e p h o t o g r a p h s i n F i g u r e 2, i t c a n b e s e e n t h a t t h e m e r c e r i z e d c e l l u l o s e h a n d s h e e t has a more o p e n t e x t u r e and i s l e s s m a t t e d down t h a n i s t h e same w e i g h t o f u n m e r c e r i z e d R a y o c o r d - X - F wood p u l p . I t was shown t h a t the mercerized c e l l u l o s e r e s u l t e d i n almost twice the d e g r e e o f s u b s t i t u t i o n as was o b t a i n e d w i t h u n m e r c e r ized cellulose. T h e e f f e c t s o f t h e v a r i o u s p r e t r e a t m e n t s t a g e s as w e l l as t h e s u b s e q u e n t b a k i n g , and s a p o n i f i c a t i o n and a c i d n e u t r a l i z a t i o n o f t h e pad-bake c o n t r o l s are depicted i n Table I I . O v e r a l l , none o f t h e p r e t r e a t m e n t s g i v e n t h e wood p u l p s h a d a n y n o t a b l e e f f e c t on I . V . , o r DP as c a l c u l a t e d f r o m I . V . Baking without r e a c t a n t a t 1 8 0 ° C f o r 15 m i n u t e s a n d s a p o n i f i c a t i o n f o l l o w e d by a c i d n e u t r a l i z a t i o n r e s u l t e d i n o n l y m i n o r r e d u c t i o n o f DP v a l u e s . T h e n e g a t i v e DS v a l u e s o b t a i n e d a r e t o b e e x p e c t ed f o r u n t r e a t e d p u l p . The f o r m u l a s u s e d i n c a l c u l a t i n g t h e DS v a l u e s make t h e a s s u m p t i o n t h a t no s u b s t i t u e n t other than c e l l u l o s e h a l f - a c i d e s t e r or the



Pad-bake controls

13 14 15 16 17 18

13 14 15 16 17 18

X X X X X X

a

-0.01

-0.01

-0.03

1184 1249 1235 1196 1070 931 547 558 559 544 520 481 633 654 730 667 589 557

3.23 3.29 3.30 3.21 3.07 2.84 3.74 3.86 4.31 3.94 3.48 3.29

DP

6.98 7.37 7.29 7.06 6.32 5.49

Experimental data Total

B.

0.02

0.00

0.00

Free

Handsheet

Conditions

Λ

C

Shredded"

I.V.,dl/g

received

A s

-0.05

-0.01

-0.01

Crosslink

Baked 180°C/15 mln

Sap on. / a c i d neut.

Shredded with water i n a commercial blender at high speed f o r 90 seconds,

d

DP calculated from Mark-Houwink equation using the k and a values of Newman, Loeb, and Conrad (16).

i n t r i n s i c v i s c o s i t y determined by ASTM Procedure 1795-62.

b

"Vy7hëëts"as received from ITT Rayonier, Inc. were prepared f o r I n t r i n s i c v i s c o s i t y determination according to ASTM Procedure D1795-62.

9 10 11 12

7 8 9 10 11 12

Sample designation Ravocord-X-F Rayselect-J Cellunler-F

Table I I .


CO

Ci

§

δι

Ci

i.

•to

Ο Ο

i

η

i

Ο

Ο

>


92


t h e c r o s s l i n k segment i s p r e s e n t on t h e s u b s t r a t e . C r o s s l i n k i n g DS was d e t e r m i n e d b y t h e a m o u n t b y w h i c h t h e t o t a l s a p o n i f i c a t i o n e q u i v a l e n t was g r e a t e r t h a n twice the pendant c a r b o x y l d e t e r m i n a t i o n (Γ4). Thus, a t v e r y l o w d e g r e e s o f r e a c t i o n , o r w i t h no r e a c t i o n a s w i t h t h e c o n t r o l s , n e g a t i v e DS v a l u e s a r e l i k e l y t o be e n c o u n t e r e d b e c a u s e any e x p e r i m e n t a l e r r o r s a r e g r e a t l y m a g n i f i e d by t h o s e b u i l t - i n a s s u m p t i o n s . The e f f e c t o f bake t i m e a t bake t e m p e r a t u r e s r a n g i n g f r o m 1 5 0 ° C t o 1 8 0 ° C i s shown i n F i g u r e 3. DS i n c r e a s e s w i t h temperature, but l e s s d r a s t i c a l l y be yond 160°C. W i t h a l l t e m p e r a t u r e s , DS a p p e a r s t o l e v e l o f f a t i n t e r m e d i a t e b a k e t i m e s o f 20 m i n u t e s f r o m 1 5 0 ° C t o 1 7 0 ° C a n d 15 m i n u t e s a t 1 8 0 ° C . A s i m i l a r l e v e l l i n g - o f f o f DS w i t h b a k e t i m e a t 1 5 0 ° C was s h o w n b y C u c u l o (6) i n the reaction of succinamic a c i d w i t h r a y o n f a b r i c , a n d b y J o h n s o n (_23) a f t e r t h r e e minutes a t 170°C. T h e e f f e c t s o f t r e a t m e n t c o n d i t i o n s o n DS a n d DP a r e g i v e n i n T a b l e I I I . T h r e e wood p u l p s w e r e u t i l i z e d a n d some e x p e r i m e n t s w e r e p e r f o r m e d i n two t o f i v e s e p a r a t e t r i a l s , e f f e c t i n g many r e p l i c a t i o n s o f t h e same c o n d i t i o n s . T h e f r e e DS v a l u e s i n s a m p l e s 19-23 d i f f e r v e r y l i t t l e ; h o w e v e r , t h e f i r s t two t o t a l DS v a l u e s a r e n o t a b l y l o w e r t h a n t h o s e o f s a m p l e s 21 t h r o u g h 23. The t o t a l s a p o n i f i c a t i o n e q u i v a l e n t s o f s a m p l e s 19 a n d 20 w e r e d e t e r m i n e d b y t h e a l c o h o l i c a l k a l i m e t h o d (22^) i n w h i c h 95% e t h a n o l was u s e d as a s w e l l i n g a g e n t t o a i d i n t h e p e n e t r a t i o n o f sodium h y d r o x i d e , but i n a l l remaining experiments w a t e r was s u b s t i t u t e d f o r t h e e t h a n o l s i n c e i t was r e p o r t e d b y A l l e n (8) t h a t w a t e r was a b e t t e r s w e l l i n g a g e n t f o r t h e c e l l u l o s e h a l f - a c i d e s t e r t h a n was e t h a n o l , a l t h o u g h h e f o u n d no d i f f e r e n c e i n DS b y t h e s u b s t i t u t i o n of water f o r ethanol. E l i m i n a t i n g t h e c a t a l y s t i n s a m p l e s 24, 30 a n d 35, h a s n o d e t e c t a b l e e f f e c t i n t o t a l DS. Catalyst has b e e n r e p o r t e d t o d e c r e a s e t h e amount o f c r o s s l i n k i n g and s h i f t more o f t h e p r o d u c t t o t h e d e s i r e d h a l f - a c i d e s t e r (8) . C u c u l o (6) has f o u n d t h a t a c i d i c c a t a l y s t i n c r e a s e s t h e e x t e n t o f r e a c t i o n when s h o r t bake t i m e s and t e m p e r a t u r e s a r e u t i l i z e d . With the b a k e c o n d i t i o n s o f 1 8 0 ° C f o r 15 m i n u t e s e m p l o y e d i n t h i s work, h o w e v e r , t h e p r e s e n c e o f c a t a l y s t had no s i g n i f i c a n t e f f e c t o n t o t a l , f r e e o r c r o s s l i n k i n g DS. S a m p l e s 25 a n d 31 w e r e b o t h b a k e d a t 1 5 0 ° C f o r 22 m i n u t e s w i t h a c i d c a t a l y s t , a n d b o t h h a d l o w e r DS v a l u e s compared t o t h e a v e r a g e o f a l l t h e e x p e r i m e n t s a t 1 8 0 ° C f o r 15 m i n u t e s . S a m p l e s 26 a n d 32 w e r e n o t m e r c e r i z e d p r i o r t o t r e a t m e n t , a n d r e s u l t e d i n DS



6.

WADSWORTH AND CUCULO

Figure

2.

Handsheets

Wood Pulp-afi-Amic

of (a) unmercerized Rayocord-X-F cord-X-F

Acid Reactions

and (b) mercerized

93

Rayo-

0.35H

Bake time, min.

Figure 3. Free DS as a function of bake time and temperature in the reaction of Rayocord-X-F with succinamic acid with ammonium sulfamate catalyst




to > iH CO C

X

X

XX

X

m C M m

Reaction of Wood Pulp with Î±,Î²-Amic Acids - ACS Symposium Series

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