High-Performance Polymers from Lignin Degradation Products

Chapter 15

High-Performance Polymers from Lignin Degradation Products Hyoe Hatakeyama , Shigeo Hirose , and Tatsuko Hatakeyama 1

1

2

Industrial Products Research Institute, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan Research Institute for Polymers and Textiles, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan

Downloaded by PENNSYLVANIA STATE UNIV on August 12, 2013 | http://pubs.acs.org Publication Date: July 31, 1989 | doi: 10.1021/bk-1989-0397.ch015

1

2

High-performance polymers having 4-hydroxyphenyl, guaiacyl and syringyl groups were synthesized from lignin degradation products. Physical properties of the polymers were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), gel permeation chromatography (GPC), viscosity measurement, etc. The relationship between the chemical structure and physical properties of polymers was analyzed from the viewpoint of molecular design. It was found that physical properties such as molecular weight, solubility for solvents, crystallinity, relaxation in glassy state, thermal decomposition temperature, etc., could be controlled by the appropriate arrangements of chemical bonds and functional groups such as phenylene group, methoxyl group, alkylene group, etc. L i g n i n is w i d e l y f o u n d i n n a t u r e a n d exists a b u n d a n t l y next to cellulose i n higher plants. T e c h n i c a l l y most of i t is o b t a i n e d as a b y - p r o d u c t o f p u l p i n g process a n d is used as fuel to o b t a i n energy to operate p u l p i n g m i l l s . I n spite of extensive research to e x p a n d the use of l i g n i n s i n t o i n d u s t r i a l m a t e r i a l s , the results o b t a i n e d have not been very successful. T o a large extent, this difficulty of efficient u t i l i z a t i o n of l i g n i n is believed t o be dep e n d e n t o n its heterogeneous a n d c o m p l e x n a t u r e . It is generally accepted t h a t l i g n i n molecules consist o f three basic u n i t s such as 4 - h y d r o x y p h e n y l , g u a i a c y l a n d / o r s y r i n g y l groups w h i c h are considered t o l i n k each other i n s t a t i s t i c a l l y different ways. Therefore, m o s t research results c o n c e r n i n g the d e g r a d a t i o n of l i g n i n have s h o w n t h a t m o n o n u c l e a r phenols h a v i n g the above basic u n i t s are m a j o r d e g r a d a t i o n p r o d u c t s (1). T h e p u r p o s e of this paper is to describe, f r o m the s t a n d p o i n t of m o l e c u l a r design, the r e l a t i o n s h i p between the c h e m i c a l structures a n d p h y s i c a l 0097-6156/89/0397-0205$06.00/0 © 1989 American Chemical Society

In Lignin; Glasser, W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

LIGNIN: PROPERTIES AND MATERIALS

206

properties of new types of high-performance p o l y m e r s w h i c h have recently been synthesized f r o m l i g n i n d e g r a d a t i o n p r o d u c t s at our l a b o r a t o r y .


Polyhydroxystyrene

Derivatives

P o l y ( 4 - h y d r o x y s t y r e n e ) [I], p o l y ( 4 - h y d r o x y - 3 - m e t h o x y s t y r e n e ) [II], p o l y ( 4 h y d r o x y - 3 , 5 - d i m e t h o x y s t y r e n e ) [III] a n d t h e i r acetates were synthesized f r o m 4 - h y d r o x y b e n z a l d e h y d e , v a n i l l i n a n d s y r i n g a l d e h y d e (2), w h i c h were synthesized as s h o w n i n Scheme 1. M o l e c u l a r weight a n d m o l e c u l a r weight d i s t r i b u t i o n s of the samples were measured b y gel p e r m e a t i o n c h r o m a t o g r a p h y ( G P C ) . T h e m o l e c u l a r weight of the p o l y m e r s was controlled b y c h a n g i n g p o l y m e r i z a t i o n c o n d i t i o n s : f r o m 6.6 χ 1 0 to 3.7 χ 1 0 (2). T h e m o l e c u l a r weight d i s t r i b u t i o n ( M / M ) was f r o m 2.2 to 4.3 (2). G l a s s t r a n s i t i o n t e m p e r a t u r e s ( T / s ) of styrene derivatives [I], [II], a n d their acetates were measured b y differential s c a n n i n g c a l o r i m e t r y ( D S C ) (2-4). F i g u r e 1 shows the r e l a t i o n s h i p between the T ^ a n d the m o l e c u l a r weight of the styrene derivatives. T h e influence of m o l e c u l a r weight o n m o l e c u l a r m o t i o n of the p o l y m e r s is clearly recognizable. A t the same t i m e , the effect of s u b s t i t u e n t groups is also noteworthy. A s seen f r o m the figure, T ^ values for [I] a n d [II] are 10-60 Κ higher t h a n those of p o l y s t y r e n e a n d the a c e t y l a t e d samples. T h i s fact seems to i n d i c a t e t h a t the i n t r o d u c t i o n of a h y d r o x y l group at the 4-position of the a r o m a t i c r i n g forms hydrogen bonds a n d restricts the m o l e c u l a r m o t i o n of the m a i n c h a i n (2-4). O n the other h a n d , i f the m e t h o x y l group is i n t r o d u c e d i n the 3-position of the a r o m a t i c r i n g , adjacent to h y d r o x y l or a c e t o x y l group at the 4 - p o s i t i o n , T ^ decreases due to the steric h i n d r a n c e caused b y the m e t h o x y l g r o u p . T h e above results i n d i c a t e t h a t the effect of s u b s t i t u e n t groups such as h y d r o x y l a n d m e t h o x y l groups o n T is more p r o m i n e n t t h a n t h a t of m o l e c u l a r weight (2,3). 3

w

5

n

g

Polyesters Having Spiro-Dioxane Rings A s i l l u s t r a t e d i n Scheme 2, 3,9-bis ( 4 - h y d r o x y - 3 - m e t h o x y p h e n y l ) - 2 , 4 , 8 , 1 0 t e t r a o x a - s p i r o [5,5] undecane, designated b i s p h e n o l [IV], was synthesized f r o m v a n i l l i n a n d p e n t a e r y t h r i t o l . Polyesters were o b t a i n e d b y the r e a c t i o n of [IV] w i t h t e r e p h t h a l o y l l chloride or sebacoyl chloride (5). T h e t h e r m a l s t a b i l i t y of the o b t a i n e d polyesters, p o l y t e r e p h t h a l a t e ( P T S ) (inherent viscosity, 77i = 1.30 d l / g ) a n d polysebacate ( P S S ) (^inh = 0.89 d l / g ) h a v i n g spiro-dioxane r i n g s , was a n a l y z e d b y t h e r m o g r a v i m e t r y ( T G ) . P T S s t a r t e d to decompose at 568 Κ a n d P S S at 527 K . T h i s shows t h a t the former is t h e r m a l l y more stable t h a n the l a t t e r . D S C studies o f the above p o l y m e r s were carried out i n a n atmosphere of n i t r o g e n at the h e a t i n g rate of 10 K / m i n f r o m r o o m t e m p e r a t u r e to a t e m p e r a t u r e a few K ' s below the t h e r m a l d e c o m p o s i t i o n t e m p e r a t u r e (T ) d e t e r m i n e d b y T G . A l t h o u g h no t r a n s i t i o n was detected i n the D S C curve of P T S , a glass t r a n s i t i o n at 363 Κ was seen i n a D S C curve of P S S . T h e X - r a y diffract o g r a m of P T S showed a c r y s t a l l i n e p a t t e r n , w h i l e t h a t of P S S showed a n amorphous halo pattern. nh

d


15.

HATAKEYAMA ET A L

High-Performance Polymers

CHO ^ OH

CH=CHC00H • CtyCOOH^

R ^ R

*

*

CH=CH

CH=CH

OH

OCOCH3

2


^ OH

R^T^R

2

-eÇH-CH ^ A» hydrolysis^ 2

A1BN

>

OCOCH3 -ÉCH-CH^ R; R : H or OCH3

OH

[11: R, R' = H [II] : R = OCri» R* = H [III] : R, R' = OCH3 Scheme 1

2 HO^-CH

• C(CH20H)a

OCH3*

X

[IV]

·

°-

CHi

^ [IV]

OCHa

CIÇ—R—CCI _„_rr, Ô

O C H >

C

H

Î

0

1

2

0

, oc8a°

IV] R : -ÎCH )e- . 2

-©"

Scheme 2


207

LIGNIN: PROPERTIES AND MATERIALS

208

O n e of the purposes of the present s t u d y is t o investigate the re l a t i o n s h i p between the properties a n d s t r u c t u r e of the p o l y m e r s s y n t h e sized. G e n e r a l l y s p e a k i n g , as values of a p o l y m e r d e p e n d o n i t s r i g i d ity, i t s h o u l d be possible t o estimate the r i g i d i t y o f the s p i r o - d i o x a n e rings i n P S S b y c o m p a r i n g the Ύ w i t h those of polysebacates f r o m other bisphenolic compounds. A m o n g the polyesters f r o m b i s p h e n o l i c c o m p o u n d s , the t h e r m a l properties of polyesters f r o m d i s u b s t i t u t e d bis(4h y d r o x y p h e n y l ) m e t h a n e ( D B H M ) (6) have been s t u d i e d i n d e t a i l . T h e r e fore, we a t t e m p t e d t o c o m p a r e T ^ o f P S S w i t h those o f a series of polyesters o b t a i n e d f r o m D B H M . T h e result of the c o m p a r i s o n showed t h a t the r i g i d i t y of the s p i r o - d i o x a n e r i n g is a l m o s t s i m i l a r t o D B H M .


9

Polyethers and Polyesters Having Methoxybenzalazine

Units

P o l y e t h e r s a n d polyesters h a v i n g m e t h o x y b e n z a l a z i n e u n i t s w i t h various a l k y l e n e groups (C4, Ce a n d C s ) i n the m a i n c h a i n were synthesized f r o m v a n i l l i n ( 7 , 8 ) . T h e condensation r e a c t i o n of 4 , 4 - a l k y l e n e d i o x y b i s ( 3 - m e t h o x y b e n z a l d e h y d e ) [VI] w i t h h y d r a z i n e m o n o h y d r a t e was a p p l i e d t o the synthesis of polyethers [VII] ( M , 7.4 χ 1 0 for C , 7.3 χ 1 0 for C a n d 4.1 χ 1 0 for C s derivatives), as s h o w n i n Scheme 3. Polyesters [IX] (r7i h> 0.35 d l / g for C , 0.38 d l / g for C a n d 0.43 d l / g for C derivatives) were synthesized f r o m 4 , 4 ' - d i h y d r o x y - 3 , 3 ' - d i m e t h o x y b e n z a l a z i n e [VIII] a n d d i c a r b o x y l i c a c i d chlorides b y c o n v e n t i o n a l low t e m p e r a t u r e s o l u t i o n p o l y c o n d e n s a t i o n , as s h o w n i n Scheme 4. T h e t h e r m a l s t a b i l i t y of the samples was s t u d i e d b y T G . A s s h o w n i n T a b l e I, the d e c o m p o s i t i o n t e m p e r a t u r e s (T

High-Performance Polymers from Lignin Degradation Products

Recommend Documents