New Trends in Modification of Lignins - American Chemical Society

Chapter 18

New Trends in Modification of Lignins Henryk Struszczyk

Downloaded by UNIV OF CINCINNATI on May 31, 2016 | http://pubs.acs.org Publication Date: July 31, 1989 | doi: 10.1021/bk-1989-0397.ch018

Institute of Chemical Fibres, 19 C. Sklodowska Str., 90-570 Lodz, Poland

New trends in the modification of lignins related to the formation of polymeric materials with such special properties as thermal stability, fire resistance and use as carriers for controlled release, bioactive compounds are discussed. Several properties of new polymeric materials, especially their thermal behavior, were studied. The activation energy of the thermal degradation process was found to be in the range of 21-176 k J / m o l for several derivatives. Practical agricultural tests with lignin-based carriers containing chemically bound 2,4-D demonstrated that lignin is capable of providing herbicide release over prolonged time periods. T h e w o r l d w i d e increase i n t h e price o f p e t r o l e u m a n d coal has created a n interest i n a l t e r n a t i v e sources o f r a w m a t e r i a l s . B i o m a s s is a n a t t r a c t i v e renewable r a w m a t e r i a l c o m p r i s i n g a l l types o f a g r i c u l t u r a l a n d s i l v i c u l t u r a l v e g e t a t i o n . T h e s e renewable resources have recently been considered m a j o r a l t e r n a t i v e r a w m a t e r i a l s for the c h e m i c a l i n d u s t r y . L i g n i n s represent t h e second most a b u n d a n t p o l y m e r i c c o m p o n e n t o f b i o m a s s . L i g n i n s i n spent p u l p i n g l i q u o r s o f c h e m i c a l p u l p i n g processes have so far been used as a n energy source, where they d o n o t a l w a y s live up t o their f u l l economic p o t e n t i a l . L i g n i n s , o w i n g t o their reactive sites w h i c h are m a i n l y a r o m a t i c as w e l l as a l i p h a t i c h y d r o x y l groups, have been p o t e n t i a l r a w m a t e r i a l s for the m a n u f a c t u r e o f new p o l y m e r s (1-7). T h i s p a p e r presents t w o different directions o f l i g n i n m o d i f i c a t i o n r e search: • m o d i f i c a t i o n b y at least d i f u n c t i o n a l reactive modifiers t o f o r m s p e c i a l types o f p o l y m e r i c m a t e r i a l s characterized by, a m o n g others, t h e r m a l s t a b i l i t y , fire resistance, a n d c h e m i c a l resistance; a n d 0097-6156/89A)397-0245$06.00A) © 1989 American Chemical Society

Glasser and Sarkanen; Lignin ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

246

LIGNIN: PROPERTIES AND MATERIALS

• m o d i f i c a t i o n of lignins or of l i g n i n derivatives to f o r m p o l y m e r i c carriers for c o n t r o l l e d release b i o a c t i v e substances.

Special Lignin-Based Polymeric Materials T w o m a i n l i g n i n types were used for these i n v e s t i g a t i o n s : kraft l i g n i n (Ind u l i n A T , W e s t v a c o C o . , U S A ) , a n d (a) l i g n i n sulfonates ( U l t r a B 0 0 2 , R a u m a R e p o l a O y , F i n l a n d ) w i t h a n i n t r i n s i c viscosity of 8.0 m L g , a t o t a l h y d r o x y l content of 1 4 . 5 % a n d a p h e n o l i c h y d r o x y l content of 4.7%; (b) l i g n i n sulfonates (Borresperse Ν A ) w i t h a n i n t r i n s i c v i s c o s i t y of 5.0 m L g , a t o t a l h y d r o x y l group content of 1 4 . 9 % a n d a p h e n y l i c h y d r o x y l c o n tent of 3.7%; a n d (c) l i g n i n sulfonates ( U l t r a z i n e N A S ) w i t h a n i n t r i n s i c v i s c o s i t y of 12.1 m L g " , a t o t a l h y d r o x y l group content of 1 5 . 1 % , a n d a p h e n y l i c h y d r o x y l content of 4 . 2 % ( b o t h p r o d u c e d b y B o r r e g a a r d Inc., Norway). C h l o r o p h o s p h a z e n e s ( N P C I 2 ) , i n the f o r m o f h e x a c h l o r o c y c l o t r i p h o s phazene ( m . p . 112-113°C, Inabate C o . , J a p a n ) as w e l l as cyclic oligomers ( m . p . 87-91°C, P o l a n d ) a n d t e r e p h t h a l o y l chloride ( M e r c k , F R G ) , served as reactive modifiers. T h e m o d i f i c a t i o n of l i g n i n s b y at least d i f u n c t i o n a l reactive modifiers was c a r r i e d out i n three systems: i n s o l u t i o n ( A ) , i n suspension ( B ) , a n d i n s o i l d state ( C ) i n the presence of hydrogen chloride acceptors (8-10). T h e m o d i f i c a t i o n i n s o l u t i o n ( A ) was carried out b y d i s s o l v i n g l i g n i n s (1.0 g) a n d a c o r r e s p o n d i n g a m o u n t of hydrogen chloride acceptor i n a s u i t a b l e s o l vent. D i f u n c t i o n a l reactive modifier (chlorophosphazenes or t e r e p h t h a l o y l chloride) dissolved i n a s u i t a b l e solvent was next a d d e d dropwise d u r i n g c o n t i n u o u s a g i t a t i o n . T h e m i x t u r e was allowed to react at the b o i l i n g p o i n t for 3 h . T h e r e a c t i o n m i x t u r e was p o u r e d i n t o ice w a t e r , a n d the s o l i d p r e c i p i t a t e was centrifuged at 66.6 rps for 15 m i n . It was washed sev eral t i m e s w i t h dioxane a n d water, or w i t h 5 % s o d i u m b i c a r b o n a t e s o l u t i o n a n d w a t e r , to o b t a i n a n e u t r a l reaction p r o d u c t , a n d i t was d r i e d ( 8 , 1 0 - 1 3 ) . T h e l i g n i n m o d i f i c a t i o n s i n suspension ( B ) were c a r r i e d out u s i n g lignins (1.0 g) dispersed i n a s u i t a b l e m e d i u m c o n t a i n i n g also the hydrogen chloride acceptor. D i f u n c t i o n a l reactive modifier dissolved i n a s u i t a b l e s o l vent was next added dropwise d u r i n g continuous a g i t a t i o n . T h e r e a c t i o n m i x t u r e was allowed to react at the b o i l i n g p o i n t for 3 h . T h e p u r i f i c a t i o n process was c a r r i e d out as described before (8,10-12). T h e l i g n i n m o d i f i c a t i o n s i n s o l i d ( C ) were c a r r i e d out u s i n g l i g n i n s (1.0 g) m i x e d w i t h c o r r e s p o n d i n g a m o u n t s of hydrogen chloride acceptor a n d chlorophosphazenes. T h e reaction was carried out b y h e a t i n g at a t e m p e r a t u r e of 100°C, i.e., above the m e l t i n g p o i n t of chlorophosphazene. T h e r e a c t i o n m i x t u r e was p o u r e d i n t o ice water, a n d t h e n the s o l i d p r o d u c t was p u r i f i e d as described before (9). T h e properties of the derivatives o b t a i n e d were d e t e r m i n e d b y the u s u a l a n a l y t i c a l methods (8-17). D i f f e r e n t i a l t h e r m a l a n a l y s i s ( D T A ) was p e r f o r m e d i n a i r w i t h a n O D 102 D e r i v a t o g r a p h ( M O M , H u n g a r y ) u s i n g 100 m g samples at a h e a t i n g rate of 1 0 ° C / m i n . D i f f e r e n t i a l t h e r m o g r a v i m e t r y ( D T G ) a n d t h e r m o g r a v i m e t r y - 1


- 1

1


18.

STRUSZCZYK

New Trends in Modification of Lignins

247

( T G ) were c a r r i e d o u t w i t h a D u P o n t T h e r m a l A n a l y z e r , T y p e 990, w i t h a 10 m g s a m p l e i n a i r . T h e s a m p l e weight was recorded against t e m p e r a t u r e i n a range o f 20-600°C a t a h e a t i n g rate o f 1 0 ° C / m i n . T h e h y d r o l y t i c resistance o f the p r o d u c t s w a s i n v e s t i g a t e d q u a n t i t a t i v e l y i n 0.4 Ν p o t a s s i u m h y d r o x i d e a n d 0.5 Ν s u l f u r i c a c i d s o l u t i o n s b y m i x i n g powdered m a t e r i a l s (40 m g ) i n a s u i t a b l e solvent (20 m L ) a t 5 0 ± 0 . 1 ° C for 24 h .


Modification of Lignins with

Chlorophosphazenes

T h e m o d i f i c a t i o n o f lignins w i t h chlorophosphazenes allows t h e m a n u f a c ture o f p r o d u c t s characterized b y flame resistance a n d t h e r m a l s t a b i l i t y . T h i s c a n be a t t r i b u t e d t o the a r o m a t i c s t r u c t u r e o f the l i g n i n - p h o s p h a z e n e p o l y m e r as well as t o the presence o f such flame i n h i b i t i n g elements as phos p h o r o u s , n i t r o g e n a n d s u l f u r . O t h e r useful properties m a y also result f r o m t h i s c o m b i n a t i o n . It has p r e v i o u s l y been r e p o r t e d (8-13) t h a t the m o d i f i c a t i o n provides crosslinked p r o d u c t s w i t h s u i t a b l y l o w c h l o r i n e content. T h i s is a consequence o f i n c o m p l e t e s u b s t i t u t i o n o f the phosphazenes cycles. A d d i t i o n a l m o d i f i c a t i o n o f the r e a c t i o n p r o d u c t s b y c h e m i c a l c o m p o u n d s w i t h reactive h y d r o x y l o r a m i n e groups reduces t h e u n r e a c t e d chlorine content a n d i m p r o v e s p r o d u c t properties (8-13). Some properties o f the derivatives o b t a i n e d are presented i n T a b l e I . A novel m o d i f i c a t i o n m e t h o d , i n s o l i d state, has recently been tested (9). S i m p l i c i t y as w e l l as effectiveness seem t o h o l d promise for t h i s t e c h nique (9). Some e x p e r i m e n t a l results are s u m m a r i z e d i n T a b l e I I . A n a d d i t i o n a l m o d i f i c a t i o n o f l i g n i n s w i t h h y d r o x y l or a m i n e g r o u p c o n t a i n i n g c o m p o u n d s was f o u n d t o further i m p r o v e the p r o d u c t properties (Table III). T h e results reveal t h a t U l t r a z i n e N A S lignosulfonates have the highest r e a c t i v i t y t o w a r d chlorophosphazenes. T h i s m u s t p r o b a b l y be e x p l a i n e d w i t h t h e i r s t r u c t u r e , their higher p u r i t y , their higher m o l e c u l a r weight, a n d their higher d i s p e r s i n g a b i l i t y i n contrast t o other lignosulfonates. T h e m o d i f i c a t i o n o f lignins b y chlorophosphazenes allows the f o r m u l a t i o n o f p o l y m e r i c m a t e r i a l s characterized b y : • H i g h flame resistance: T h e derivatives are d i s t i n g u i s h e d by h i g h flame resistance a n d failure t o glow completely, whereas the u n m o d i f i e d l i g n i n s i g n i t e d easily a n d sustained a flame (kraft) or glowed r a p i d l y (lignosulfonates) ; • H i g h h y d r o l y t i c resistance against aqueous a c i d a n d base: T h e m o d ified l i g n i n s were f o u n d n o t t o consume m o r e a l k a l i t h a n t h e p a r e n t l i g n i n (i.e., 50-80 m g K O H / g of derivative as c o m p a r e d t o 85 m g K O H / g o f parent l i g n i n ) ; • C h e m i c a l resistance t o t h e a c t i o n o f o r g a n i c solvents; • L o w m a n u f a c t u r i n g costs i n c o m p a r i s o n t o other types o f phosphazene polymers; a n d • C o n t i n u o u s i m p r o v e m e n t s o f chlorophosphazene-modified l i g n i n s , a l l o w i n g the e v a l u a t i o n o f a wide range o f a p p l i c a t i o n s .

American Chemical Society Library 1155 St.,Lignin N.W. Glasser and16th Sarkanen; ACS Symposium Series; American Chemical Society: Washington, DC, 1989. Washington. O.C. 20036


Ultra

Ultra

Borresperse NA

Ultrazine NAS

Ultrazine NAS

3/B

4/B

5/B

6/B

6a/B

2

trimer

olig.

olig.

trimer

olig.

olig. trimer

NPC1 2

6.085

12.160

12.160

2.146

8.584

12.208 3.052

NPC1

13.746

27.492

7.492

4.848

19.392

24.364 6.091

Pyridine

0.038

0.192

0.185

0.035

1.003

1.033 0.600

3

Y i e l d of Product (g)

3.86

8.76

5.90

1.01

2.55

6.76 1.20

Ρ

2.60

3.43

3.90

S

Cl

1.10

1.31

1.46

--

0.44

1.35 --

Chemical Content. %

1250 1200 1200

1210 1030

1260 1210 1212

1260 1210

P=N

1160 1025 1170 1045

1170

1155 1030 1165 1030

1158 1025

POC

Infrared Frequency of Units . cm"

A l l reactions were c a r r i e d out on l i g n i n s (1.0 g) at the b o i l i n g point i n dioxane as a solvent (A) or i n suspension (B).

a

Indulin Indulin

Lignin

Type of

1/A 2/A

Symbol of Sample

Reagents amount, nuno 1

Table I. Properties of the Lignin Modification Products


Glasser and Sarkanen; Lignin ACS Symposium Series; American Chemical Society: Washington, DC, 1989. 2

3 .06 4,.40 5,.61

0,.99

13 .75

6.09

3

Ρ

Ultrazine NAS

10

a

Ρ * pyridine. A l l reactions were c a r r i e d out on l i g n i n s (1.0 g) using oligomers of NPC1 .

4..90 4..10

5,.62 0..15

182,.20

12.16

3

NaOH

Borresperse ΝΑ

9

2.,19 3.,43

6.,83 0.,81

27,.49 *

12.16

6

Ρ

Borresperse ΝΑ

8

2.,64 3.,96 4.,40

0.,79

27,.49

Cl

S

Ρ

3

12.16

Acceptor

Content,

3

2

%

Ρ

NPC1

Reaction Time, h

Acceptor Type

Chemical Y i e l d of Product , g

Borresperse ΝΑ

Type of Lignin

Reagent Amount, mmol

7

Symbol of Sample

Table I I . Modification Parameters and Derivative Properties Using S o l i d State Reaction



1

5

12

13

Borresperse NA

Indulin AT

Indulin AT

Type of Lignin Used

diethylamine

diethylamine

n-propanol

Type of Modifying Compound

0.142

0.612

1.097

3

Y i e l d of Product , g

4.10

7.42

5.82

Ρ

4.73

S

Chemical Content. %

0.65

1.00

1.22

Cl

Reactions were c a r r i e d out using 0.145 mol of diethylamine or 0.0213 mol of n-propanol.

1

11

a

Symbol of Initial Product

Symbol of Sample

Table I I I . Properties of A d d i t i o n a l l y Modified Products


1240,1220

1260,1210

1255,1210

Infrared Frequency of P-N Unit, cm

-1

18.

STRUSZCZYK


251

T h e m o d i f i c a t i o n of l i g n i n s b y chlorophosphazenes d i s t i n c t l y increases h y d r o g e n b o n d i n g energy of the p r o d u c t s o b t a i n e d , i.e., 17-23 k J / m o l as c o m p a r e d to 14-20 k J / m o l for the parent l i g n i n . T h i s p h e n o m e n o n , w h i c h was a d d i t i o n a l l y confirmed b y X - r a y d a t a ( 1 0 , 1 2 ) , shows the a u g m e n t a t i o n of the p r o b a b l e f o r m a t i o n of regions w i t h increased degree of s u p e r m o l e c u l a r order.


Thermal Behavior of Lignins Modified by

Chlorophosphazenes

T h e t h e r m o g r a v i m e t r i c ( T G ) as w e l l as difference t h e r m o g r a v i m e t r i c ( D T G ) analysis d a t a are s u m m a r i z e d i n T a b l e I V . T h e t h e r m o g r a m s of selected derivatives are presented i n F i g u r e 1. T h e T G as w e l l as D T G d a t a (Table I V ) show a higher t h e r m a l s t a b i l i t y of lignosulfonates. T h e derivatives o b t a i n e d are d i s t i n g u i s h e d by higher t h e r m a l s t a b i l i t y i n c o m p a r i s o n w i t h the parent l i g n i n s , p a r t i c u l a r l y i n the case o f a d d i t i o n a l m o d i f i c a t i o n s b y n - p r o p o n o l or d i e t h y l a m i n e ( T a b l e I V , S a m p l e s 11 a n d 13). T h e increase i n t h e r m a l s t a b i l i t y m u s t be e x p l a i n e d w i t h the cross-linked s t r u c t u r e as w e l l as the s a t u r a t i o n w i t h such a r o m a t i c groups as p h e n y l p r o p a n e a n d phosphazene. T h e increased phosphorous content increases at the same t i m e the flame resistance. I n a l l cases, low a m o u n t s of v o l a t i l e p r o d u c t s f o r m e d i n the e x o t h e r m i c d e g r a d a t i o n process effectively stifled flame development ( T a b l e I V ) . T h e r m a l b e h a v i o r studies of the lignin-phosphazene derivatives show t h a t their d e g r a d a t i o n process results i n v o l a t i l e a n d n o n - v o l a t i l e p r o d u c t s . A s s u m i n g first-order r e a c t i o n k i n e t i c s for the t h e r m a l d e g r a d a t i o n , r e a c t i o n constant (k) a n d a c t i v a t i o n energy ( E ) c a n be c a l c u l a t e d b y d y n a m i c T G A ( 1 8 , 1 9 ) . T h e Ε-value can thus be c a l c u l a t e d f r o m the leastsquare slope of the p l o t of log k versus r e c i p r o c a l absolute t e m p e r a t u r e as s h o w n i n F i g u r e 2. T h e a c t i v a t i o n en ergy values for the t h e r m a l d e g r a d a t i o n of selected derivatives as w e l l as u n m o d i f i e d l i g n i n s are s u m m a r i z e d i n T a b l e V . A s c a n be seen f r o m F i g u r e 2, a d u a l segment a p p r o x i m a t i o n was nec essary i n the case of some l i g n i n s as well as derivatives. T h i s p h e n o m e n o n indicates t h a t p y r o l y s i s takes place b y two m e c h a n i s m s i n the t e m p e r a t u r e range s t u d i e d w h i l e the d e g r a d a t i o n of, for e x a m p l e , U l t r a z i n e N A S c o u l d be e x p l a i n e d b y a single m e c h a n i s m . T h e k r a f t l i g n i n as w e l l as U l t r a B 0 0 2 have a higher value of Ε as c o m p a r e d to other l i g n i n sulfonates. T h i s m a y result f r o m differences i n the l i g n i n s t r u c t u r e . T h e m o d i f i c a t i o n of l i g n i n s w i t h chlorophosphazenes results i n changes of Ε t h a t correspond to the degree of s u b s t i t u t i o n a n d the phosphorous content (Table V ) . L i g n i n m o d i f i c a t i o n w i t h chlorophosphazenes is a n e x a m p l e of h o w t h i s renewable resource m a y be u t i l i z e d i n s p e c i a l p o l y m e r i c m a t e r i a l s .

Lignin Modification with Terephthaloyl Chloride A n o t h e r p o t e n t i a l l i g n i n m o d i f i c a t i o n m e t h o d concerns the r e a c t i o n w i t h d i f u n c t i o n a l a c i d chlorides, especially t e r e p h t h a l o y l chloride, to f o r m crossl i n k e d p o l y m e r i c m a t e r i a l s ( 1 , 1 0 , 1 4 , 2 0 ) . Several studies have dealt w i t h



a

325 280,370

--

Borresperse NA Ultrazine NAS

300-398 250-495 472-495 250-350 240-430

250-300

250-300

280 280,289

270-310 270-330

275 300

225-300

— 235-350

— 305 250,570

— 350

—

4 .5 3 .5

1,.8 3 .4

4,.0

11,.0 8,.0 6,.0 12,.0

4.,2

3 .5 6,.7 5,.8 2..0

7..1 5..0

4..1 4..0

8..0

15.,0 14.,0 9.,0 20..0

5.,5

7..0 9,.3 8,.5 3..3

28,.2 12 .1

13,.0 22,.6

29,.0

25..0 20..0 10..0 27..0

16.,2

12,.5 18..0 12..8 11..8

44,.9 26 .1

76,.3 29 .8

35,.0

30,.0 45,.0 13,.0 33,.0

24.,0

22,.2 26,.1 22,.4 22..0

51 .3 31 .5

86 .1 63 .1

46,.0

41,.0 56,.0 16,.0 42,.0

32..8

30,.8 45,.2 32,.4 28,.4

Range of Percentage of Mass Loss at Temp, of Max. Different Temperatures Rate of Mass Loss, °C 100°C 200°C 300°C 400°C 500°C

492

393 292,489

5,.61

4..40 5,.02 5..90 6,.83

2..55

1,.20 6,.76 5..82 7,.42

Ρ Content, %

Temperature of Maximum Rate of Mass Loss, °C

Indulin AT U l t r a B002

Ultrazine NAS

NA NA NA NA

Modified by n-propanol. ^Modified by diethylamine.

--

10

Borresperse Borresperse Borresperse Borresperse

7 9 5 8

AT AT AT AT

U l t r a B002

b

a

Indulin Indulin Indulin Indulin

Type of l i g n i n

3

1 2 ll 13

Symbol of Sample

Table IV. TG and DTG Analysis of the Products of Modification by Chlorophosphazenes


45 .0

88,.1 64,.4

56,.0

48,.1 75..0 20,.0 51,.0

50.,1

43,.5 61,.3 40..7 34..1

600°C

S

S

Β

£5

STRUSZCZYK


253


18.

F i g u r e 1. T h e r m o g r a m s o f u n m o d i f i e d (parent) l i g n i n s : k r a f t l i g n i n (a); U l t r a B 0 0 2 (b); Borresperse Ν A (c); a n d U l t r a z i n e N A S (d), as w e l l as t h e i r derivatives: l ( a i ) ; 2 ( a ) ; l l ( a ) ; 1 2 ( a ) ; 3 ( b i ) ; 1 3 ( c i ) ; 1 0 ( d i ) . 2

3

4




254

' 1A

1,5

16

t)

1,8

1,4

2p

1.

1 0

3

(°K'«')

F i g u r e 2. A r r h e n i u s plot for selected l i g n i n s a n d their derivatives f r o m d y n a m i c T G A d a t a : kraft l i g n i n ( 1 , φ ) ; Borresperse Ν A (2, 0 ) ; U l t r a z i n e N A S (3, x ) ; Borresperse N A derivatives of s y m b o l # 7 ( 4 , d ) ; Borresperse Ν A derivatives of s y m b o l # 9 (5, Δ ) ; a n d U l t r a z i n e N A S derivatives of s y m b o l # 1 0 (6, © ) .

Table V. A c t i v a t i o n Energy of the Thermal Degradation Process.

Sample

Type of Lignins

--

Borresperse NA Ultrazine NAS U l t r a B002 Indulin AT

7 9 8

10

Borresperse NA Borresperse NA Borresperse NA Ultrazine NAS

Ρ Content, %

4.40 5.62 6.83 5.61

kJ/mol

Temperature Range, °C

46.0 33.3 162.4 176.7

250-350 250-350 250-350 350-400

70.0 44.0 34.8 41.0

250-350 250-350 250-350 250-350



18.

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t h i s r e a c t i o n a n d r e p o r t e d o n l i m i t e d success. A recent r e i n v e s t i g a t i o n of this r e a c t i o n has p r o d u c e d m e l t a b l e a r o m a t i c ester-like p o l y m e r i c m a t e r i als. T h e m o d i f i c a t i o n of l i g n i n sulfonates w i t h t e r e p h t h a l o y l chloride i n solvent or suspension (10) p e r m i t s the f o r m a t i o n of l i g n i n - b a s e d p o l y m e r s w i t h ester groups. T h e p r o d u c t s are characterized b y several advantages: m e l t i n g p o i n t is observed between 290 a n d 330° C ; h y d r o l y t i c a n d c h e m i c a l resistance is good; t h e r m a l s t a b i l i t y is increased; color is w h i t e to yellow; the p r o d u c t can be m i x e d i n the m e l t w i t h other p o l y m e r s ; the presence of such f u n c t i o n a l groups as sulfonates p e r m i t s the a p p l i c a t i o n as additives to m o d i f y other p o l y m e r properties. S o m e results of the m o d i f i c a t i o n of l i g n i n sulfonate U l t r a B 0 0 2 b y r e a c t i o n w i t h t e r e p h t h a l o y l chloride are s u m m a r i z e d i n T a b l e V I . T h e t o t a l h y d r o x y l content of the lignosulfonates as well as t h e i r derivatives are presented i n T a b l e V I I . T h e h y d r o l y t i c resistance of selected p r o d u c t s is e v a l u a t e d i n T a b l e V I I I . T h e results presented i n Tables V I - V I I I stress sev eral advantages of the derivatives w i t h t e r e p h t h a l o y l chloride. T h e m o d i fied l i g n i n sulfonates were i n s o l u b l e , or o n l y very s l i g h t l y soluble, i n o r g a n i c solvents. T h e y were, however, soluble i n d i m e t h y l sulfoxide. O r d e r e d s t r u c tures were identified b y X - r a y studies ( 1 6 , 1 7 ) . T h e m o d i f i c a t i o n of lignins w i t h t e r e p h t h a l o y l chloride is of interest to the t h e r m a l properties of the derivatives (15). These are presented i n T a b l e I X . T h e results reveal t h a t a n e x o t h e r m i c t e m p e r a t u r e event is shifted to higher t e m p e r a t u r e as a consequence of m o d i f i c a t i o n . T h e e n d o t h e r m i c t e m p e r a t u r e event can be a t t r i b u t e d to the glass t r a n s i t i o n a n d the m e l t i n g process of the derivatives. T h e a c t i v a t i o n energy of the d e g r a d a t i o n process was c a l c u l a t e d for several samples based o n the results of d y n a m i c T G studies ( T a b l e X ) . A d i s t i n c t decrease i n a c t i v a t i o n energy is observed i n the case of U l t r a B 0 0 2 . A t the same t i m e , the Ε values seem t o correspond w i t h the higher t e m p e r a t u r e of the m o d i f i c a t i o n . T h e m o d i f i c a t i o n of l i g n i n sulfonates w i t h t e r e p h t h a l o y l chloride p r o duces new p o l y m e r i c m a t e r i a l s c o n t a i n i n g ester groups. T h i s m o d i f i c a t i o n can be used to u t i l i z e lignins also for i m p r o v e m e n t of c h e m i c a l fiber p r o p erties. T h i s is presently under i n v e s t i g a t i o n .

Modified Lignins as the Carriers for Controlled Release Prepara tions In the hope of finding large m a r k e t s for l i g n i n s , a review of p o t e n t i a l a g r i c u l t u r a l a p p l i c a t i o n s has been c o n d u c t e d ( 1 , 6 , 1 4 ) . M o d i f i c a t i o n of l i g n i n s w i t h bioactive c o m p o u n d s c o n t a i n i n g s u i t a b l e reactive groups p e r m i t s the f o r m a t i o n o f various derivatives characterized b y a w i d e range o f release rate of active c o m p o n e n t . 2 , 4 - d i c h l o r o p h e n o x y a c e t i c a c i d ( 2 , 4 - D ) as a s t a n d a r d herbicide c o n t a i n i n g reactive c a r b o x y l i c f u n c t i o n a l i t y was used i n the present s t u d y . A d d i t i o n a l l y , the l i g n i n sulfonates of " K l u t a n " ( N i e d o m i c e , P o l a n d ) a n d the r e a c t i o n residues f r o m v a n i l l i n p r o d u c t i o n ( L S - W , W l o c l a w e k , P o l a n d ) were also used. T h e carriers c o n t a i n i n g c h e m i c a l b o u n d 2 , 4 - D used the f o l l o w i n g preparations:



256

Table VI. E f f e c t of Modification with Terephthaloyl Chloride on the Properties of the U l t r a B002 Product.

Reagent Molar Ratio

Color of Product

Dioxane

1:1.10 1:1.65 1:2.20

yellow yellow yellow

Water

1:0.55 1:1.10 1:1.65 1:2.20


Reaction Medium

It.yellow It.yellow It.yellow It.yellow

Yield of Product

Chemical Content, 3

C

H

M.p. °C

S

0.419 0.359 0.399

53..8 55..3 58..5

3.95 4.17 4.20

0.95 0.84 0.75

310-316 318-321 327-331

0.250 0.475 0.576 1.038

54..0 45..3 51..5 56..8

4.09 3.95 3.87 4.10

0.76 1.36 1.00 0.79

298-311 306-314 311-320 309-322

a

A l l reactions were c a r r i e d out on a l i g n i n (1.0 g) at 30°C f o r 15 min.

Table VII. Total Hydroxyl Content of Lignin Sulfonates and Their Derivatives with Terephthaloyl Chloride.

Symbol of Sample

Tvpe of Lignin

Total Hydroxyl Content. %

.. NA-2-20 NA-2-70

Borresperse NA Borresperse NA Borresperse NA

14.9 1.9 1.5

R-2-10 R-2-70

U l t r a B002 U l t r a B002 U l t r a B002

14.5 0.1 0.1


18.

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257

L D : l i g n i n sulfonates m o d i f i e d b y 2 , 4 - D (21) L S D : l i g n i n sulfonates modified by t e r e p h t h a l o y l chloride a n d subse q u e n t l y b y 2 , 4 - D (22) L F : l i g n i n sulfonates m o d i f i e d b y p h e n o l a n d f o r m a l d e h y d e a n d t h e n b y 2 , 4 - D (23). Table VIII. Hydrolytic Resistance of the Lignins Modified with Terephthaloyl Chloride Average Amount of H S 0 (g) Consumed by 1 g of Product (χ 10" )


2

Type of Product

4

3

Average Amount of KOH Consumed by 1 g of Product (χ 10" ) 3

Modified Borresperse NA

50-200

10-50

Modified U l t r a B002

50-300

10-50

Borresperse NA

450

85

U l t r a B002

450

85

A p p l i c a t i o n o f several types o f l i g n i n sulfonates as carriers i n connec t i o n w i t h reactive herbicides (21-23) p e r m i t s t h e development o f effective c o n t r o l l e d release ( C R ) p r e p a r a t i o n s . T h e properties o f c h e m i c a l l y b o u n d l i g n i n 2 , 4 - D - b a s e d herbicides are s u m m a r i z e d i n T a b l e X I . Several p r e p a r a t i o n s were subjected t o s t a n d a r d release a n a l y s i s i n a n aqueous m e d i u m (14). T h e release d a t a are s h o w n i n F i g u r e 3. T h e s e d a t a suggest t h a t the l i g n i n sulfonate 2 , 4 - D - b a s e d p r e p a r a t i o n s have the c a p a c i t y for releasing herbicide a c t i v i t y over a prolonged t i m e p e r i o d . T h e most i m p o r t a n t v e r i f i c a t i o n o f C R p r e p a r a t i o n s is t h e i r p r a c t i c a l test u n d e r a g r i c u l t u r a l c o n d i t i o n s . S u c h a performance test was c a r r i e d out at t h e P l a n t P r o t e c t i o n I n s t i t u t e ( P o z n a n , P o l a n d ) u s i n g t w o doses of Pielik, a P o l i s h 2 , 4 - D p r e p a r a t i o n i n 8 5 % p u r i t y : " a " dose o f 1 k g o f Pielik per 1 h a , a n d " b " dose o f 2 k g o f Pielik per 1 h a . E p i p h y f i c p r e p a r a t i o n s were a p p l i e d at three stages: d i r e c t l y after g e r m i n a t i o n o f three types o f test plants (sunflower, wetch a n d w h i t e m u s t a r d ) (I); one week after g e r m i n a t i o n (II); a n d t w o weeks after g e r m i n a t i o n (III). T h e weight loss o f t h e p l a n t s was d e t e r m i n e d u n t i l 30 days following a p p l i c a t i o n . T h e test results are summarized i n Table X I I . T h e s e results reveal t h a t L S D - 6 ( W ) was the most effective p r e p a r a t i o n w h e n a p p l i e d i n the higher dose (b). T h e other p r e p a r a t i o n s were c h a r a c terized b y a lower p r a c t i c a l a c t i o n w i t h i n the test p e r i o d . A t t h e same t i m e these p r e p a r a t i o n s have effectively acted for a longer p e r i o d t h a n t h a t s t u d i e d i n the test o f T a b l e X I I . It c a n be concluded t h a t l i g n i n sulfonates m o d i f i e d b y r e a c t i o n w i t h herbicide f u n c t i o n a l i t y (21-23) c a n be used as p o t e n t i a l carriers for c o n t r o l l e d release herbicides. T h i s a p p l i c a t i o n o f l i g n i n sulfonates offers several advantages b o t h for a g r i c u l t u r e a n d for t h e e n v i r o n m e n t .



Borresperse NA

Borresperse NA

U l t r a B002

U l t r a B002

Na-2-70

R-2-10

R-2-70

Borresperse NA U l t r a B002

Tvpe of Lienin

NA-2-20

Symbol of Sample

355 410

348 420

355

380 435

200 185

370 450

370 450

375

405 462

322 330

400 470

400 470

400

425 470

425 450

Temperature of exothermic °C Event Start Max. End

100 250

100 250

100 250

100 250

120 342

120 330

122 340

122 358

—

130 355

125 345

130 350

130 367

Temperature of endothermic °C Event Start Max End

Table IX. Thermal Properties of Lignosulfonates Modified by Terephthaloyl Chloride.


STRUSZCZYK

18.

259



Table X. A c t i v a t i o n Energy of the Degradation Process of Selected Lignin Sulfonates as well as t h e i r Derivatives with Terephthaloyl Chloride

Type of Lignins

Ε kJ/mol

Temperature Range, °C

Borresperse NA U l t r a B002

46.0 162.4

250-350 250-350

NA-2-10 NA-2-70

Borresperse NA Borresperse NA

49.0 95.0

250-350 250-350

R-2-10 R-2-70

U l t r a B002 U l t r a B002

21.4 48.1

250-350 250-350

Type of Sample

Table XI. Properties of 2,4-D Modified Lignin Sulfonates

Chemical Content. %

Symbol of Sample

Tvpe of Lignin

LD-3 LD-3(W) LD-3(K)

Borresperse NA LS-W Klutan

57..1 46..5 41,.2

LSD-6(W) LSD-6

LS-W Borresperse NA

52..3 57,.1

LF-2

Borresperse NA

-·

a

a

C

S

Cl

2,4-D Content. %

4.38 3.43 3.28

4.14 4.52 5.35

6 .38 7 .97 7 .14

19.,2 24.,8 22.,2

4.11 3.99

2.38 1.43

0 .73 0 .74

Η

4 .53

2.,24 2.,31 14.,1

The reaction conditions were reported previously (21-23).



260


RelQase substance amount, in relation to initial amount

0

10

20

30

40 Τ

[days]

Figure 3. Release curves of 2, 4-D from preparations of: L S D - 6 (a); L F - 2 (b); L D - 3 (c); and standard 2, 4-D (d).

Table XII. Test Results of the E f f e c t of 2,4-D Containing Preparations on Plant Growth.

Average Wt. Loss. % Type of Preparation

Dose

I

II

III

Average Weight Loss from 3 Stages, %

LD-3

a b

41.8 53.7

60.8 57.7

43.4 63.7

48.7 58.4

LD-3(W)

a b

36.8 70.0

50.5 51.7

35.7 61.2

41.0 60.9

LD-3(K)

a b

61.5 55.8

49.8 59.8

58.5 79.3

56.6 64.9

LSD-6(W)

a b

54.0 63.7

56.0 82.5

59.2 73.7

56.4 73.3

LSD-6

a b

55.8 59.0

63.2 60.5

49.7 65.3

56.2 61.6

a b

70.3 72.7

81.2 69.3

49.3 72.7

66.9 71.6

Standard 2,4-D (Pielik)


18.

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261

L i g n i n u t i l i z a t i o n studies have been c o n d u c t e d i n several fields. H o w ever, n o p r a c t i c a l , c o m m e r c i a l process has yet emerged for the m a n u f a c t u r e o f l i g n i n - b a s e d p o l y m e r i c m a t e r i a l s . T h i s is u n d o u b t e d l y related t o such factors as p r o d u c t inhomogeneity, r e a c t i v i t y differences, a n d also w i t h lack of f a m i l i a r i t y w i t h t h i s t y p e o f r a w m a t e r i a l . It s h o u l d be also stressed t h a t l i g n i n s are o n l y b y - p r o d u c t s f r o m p u l p m a n u f a c t u r e . However, t h e u t i l i z a t i o n o f l i g n i n s i n p o l y m e r i c m a t e r i a l s seems t o b e possible. Acknowledgment


It i s a pleasure t o acknowledge the c o n t r i b u t i o n o f m y assistant, M r s . K . W r z e s n i e w s k a - T o s i k , for her continued c o o p e r a t i o n . Literature C i t e d 1. Sarkanen, Κ. V.; Ludwig, C . H., Eds. Lignins; Wiley-Interscience: New York, 1971. 2. Simonescu, C . I. Cell. Chem. Technol. 1978, 12, 577. 3. Naraian, H . Indian Chem. Manuf. 1981, 19(6), 11. 4. Lindberg, J. J.; Melartin, J. Kem. Kemi 1982, 9(11), 736. 5. Glasser, W . G . ; Hsu, Ο. H . ; Reed, D. L . ; Forte, R. C . 1979 Cana dian Wood Chemistry Symposium Proceedings; Harrison Hot Springs, Canada. 6. Allan, G . G . ; Balaba, W.; Dutkiewicz, J.; Struszczyk, H . Chemicals from Western Hardwoods and Agricultural Residues; Semi-Annual Re port, April 1979, NSE-7708979; Univ. of Washington, Seattle, U S A . 7. Chen, R.; Kokta, Β . V . ; Valade, J. L . J. Appl. Polym. Sci. 1979, 24, 1609. 8. Struszczyk, H.; Laine, J. E . Polish Patent 125877, 1981. 9. Struszczyk, H . Polish Patent Appl. P-265167, 1987. 10. Struszczyk, H.; Krajewski, K . Polish Patent 134256, 1982. 11. Struszczyk, H . ; Laine, J. E . J. Macromol. Sci.-Chem. 1982, A17(8), 1193. 12. Struszczyk, H . Fire and Materials 1982, 6(1), 7. 13. Struszczyk, H . J. Macromol Sci.-Chem. 1986, A23(8), 973. 14. Struszczyk, H . ; Wrześniewska-Tosik, K . Proc. Inter. Symp. on Fibre Sci. and Technol.; Hakone, Japan, 1985, p. 336. 15. Struszczyk, H . ; Allan, G . G . ; Balaba, W . Proc. of Euchem '80 Conf.; Helsinki, Finland, 1980. 16. Struszczyk, H . Proc. Hungarian Symp. on Thermal Analysis; Budapest, Hungary, 1981. 17. Struszczyk, H . Proc. of 31st IUPAC Conf. Macro '87; Merseburg, Ger. Dem. Rep., 1987. 18. Ramian, M . V . J. Appl. Polym. Sci. 1970, 14, 1323. 19. Tang, W . G . U.S. For. Serv. Res. Pap. FPL 71, 1967. 20. Van der Klashort, G . H.; Forbes, C . P.; Psotta, K . Holzforschung 1983, 37(6), 279. 21. Struszczyk, H.; Wrześniewska-Tosik, K . Polish Patent 141253, 1985. 22. Struszczyk, H.; Wrześniewska-Tosik, K . Polish Patent 141254, 1985. 23. Struszczyk, H.; Wrześniewska-Tosik, K . Polish Patent 141255, 1985. RECEIVED April 18,1989


New Trends in Modification of Lignins - American Chemical Society

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