aspects of the copolymerization of styrene with acrylonitrii,e in solution in the presence of...

8/13/2019 Aspects of the Copolymerization of Styrene With Acrylonitrii,e in Solution in the Presence of Disperse Fillers Contai

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Polymer Science U.S.S.R. Vol. 28, No: 10, pp. 2327-2335, 1986 0032*3950/86 10.00+ .lOPrinted in Poland ~ 1987 Pergamon Journals Ltd

A S P E C T S O F T H E C O P O L Y M E R I Z A T I O N O F S T Y R E N E W I T HA C R Y L O N I T R I I , E I N S O L U T I O N I N T H E P R E S E N C E O F

D I S P E R S E F I L L E R S C O N T A I N I N G S I L IC AS . S . I V A N C HEV A . V . D M I TR EN KO V . A . D EM I DOV A

and N. YE. SHA OR I N APlastpolimer Scientific and Production Unit, Okhtinsk

Received18February1985)Aspects of the copolymerization of styrene and aerylonitrile have been investigated in

solution in the presence of Aerosil and of microfibrous Sivol, both unmodified and with thesurface modified by the chemical grafting of (methacryloxymethyl) methyldiethoxysilane. Anincrease has been found in the rate of heterogeneous copolymerization, which occurs simul-taneously with an increase in the molecular mass both of the copolymers grafted to the surfaceand also the ungrafted polymers; this is related to the gel-effect created by the filler in the reac-tion system. The modified Sivol surface has been found to have a selective effect on the com-position of the styrene-acrylonitrile grafted polymer that is formed. It has been establishedthat the relative reactivity of styrene in the graft copolymerization reaction is reduced ascompared with that in the heterogeneous non-graft process and in the homogeneous process.The special features of polym:rization occurring in the presence of disperse fillers,

which has been considered as a method of obtaining filled polymeric compositions,have been widely discussed in the literature in recent times. Features of polymerizati onin the presence o f fillers modified by having (m:thacr yloxym~thyl) methylsilane group s(MES), capable of polym~.rization, grafted to them hav~ b~en discussed previously[1, 2]. In view of its simplicity and economy, there is also great interest in exploringthe possibility o f localizing polymerizatio n to the absorbed zone of filler particles usingthe natural functional groups of the filler without their surface modification. Sincethe monomer-surface interaction is determined both by the functional nature of thesurface and also by the structure of the monomer [3], it is of interest to investigatethe selective effect of the surface in the joint polymerization of monomers differingin their reactivity and polarity.

The objective of the present work has been to investigate features of the joint poly-merization of styrene and acrylonitrile in the presence of unmodified fillers containingsilica and also in the presence of such fillers modified hy the grafting of MES groupsto the surface. I t was, moreover, of interest to cons ider the effect of the specific surfacearea and the capillary structure of the filler on the occurrence of the process.

T h e application of MES groups on to the surface of Aerosil and Sivol [4l was carried out byt he method given previously [2]. The presence of MES groups on the surface was confirmed by I R

* Vysokomol. soyed. A28: No. 10, 2095-2101, 1986.2327


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2328 S .S . IVANCnEVe t a l .s p e c t r o s c o p y ( F i g . 1 ) f r o m t h e r e d u c t i o n i n t h e ~ n te n si ty o f t h e a b s o r p t i o n b a n d c o r r e s p o n d i n gt o f r e e s i la n e g r o u p s i n t h e r e g i o n o f 3 70 0 c m - ~ a n d a l s o b y t h e a p p e a r a n c e o f a n i n c r e a s e i n t h ei n t e n s it y o f t h e a b s o r p t i o n b a n d c h a r a c t e r i s t ic o f c a r b o n y l g r o u p s ( 1 70 5 c m - ~ ) . T h e c o p o l y m e r i -z a t i o n o f s t y r e n e w i t h a c r y l o n i t r i l e w a s c a r r i e d o u t i n s o l u t i o n i n D M F A i n t h e p r e s e n c e o f b e n z o y lp e r o x i d e ( 5 - 7 8 x 1 0 - 3 m o l e / L ) a s i n i t i a t o r : c o n c e n t r a t i o n o f t h e m o n o m e r m i x t u r e , 5 . 5 m o l e /L ;t e m p e r a t u r e , 7 0 C ; d u r a t i o n , 0 . 5 - 8 h r ; a c r y l o n i t r i l e c o n c e n t r a t i o n i n t h e m o n o m e r m i x t u r e v a r i e df r o m 1 0 - 9 0 m o l e 70. T h e r e a c t i o n w a s c a r r i e d o u t i n t h e p r e s e n c e o f M E S - s u b s t i t u t e d fi ll e rs a n d a l s oi n t h e p r e s e n ce o f u n m o d i f i e d fi ll e rs u s i n g t h e m e t h o d g i v e n p r e v i o u s ly [ 2 ] . C o p o l y m e r i z a t i o n w a sa l s o c a rr i e d o u t u n d e r h o m o g e n e o u s c o n d i t i o n s f o r c o m p a r i s o n . T h e s e p a r a t i o n o f th e g r a f t e d f r o mt h e u n g r a f t e d c o p o l y m e r w a s c a r r i e d o u t a s i n [ 2, 3 ]. T h e i n t r i n s i c v i s c o s it y o f t h e c o p o l y m e r s w a sm e a s u r e d i n s o l u t i o n i n M E K . T h e m o l e c u l a r m a s s o f c o p o l y m e r s w i th t h e a z e o t r o p i c c o m p o s i t i o nw a s ca l c u la t ed b y u s e o f t he M a r k - H o u w i n k e q u a t io n w i t h t h e c o n st a n ts K = 0 . 0 0 0 2 5 a n d a = 0 - 6 7[ 5] . T h e c o m p o s i t i o n s o f t h e c o p o l y m e r s g r a ft e d t o t h e s u r f a ce a n d t h o s e o f t h e u n g r a f t e d c o p o l y m e r sw e r e d e t e rm i n e d b y p y r o l y t i c g a s c h r o m a t o g r a p h y ( P G C ) i n a c u r r e n t o f h e l i u m a t a t e m p e r a t u r e,o f 600 + 10 C fo r 45 + 5 s e c . Th e a dso rp t i o n p o t e n t i a l o f t he su r fa c e wa s a s se s se d by t he po t e n t i o -me t r i c me t hod [6 ] .

~ [ fI I , l - - ' 7

38 3 4 3 0 IS

/# ~/

1I

7 vxlO ~Zcm tF i o . 1 . I R s p e c t r a o f S iv o l : 1 - i n t h e i n i t i a l c o n d i t i o n a n d 2 , 3 - M E S - s u b s t i tu t e d , t h e c o n c e n t r a t i o n

o f M ES g ro ups be i ng 0 28 (2 ) a nd 0 .98 (3 ) mm ol e / g .

A .s i s to b e e x p e c t e d , t h e p o l y m e r i z a t i o n o f s t y r e n e a n d a c r y l o n i t r i l e i n t h e p r e s e n c eo f u n m o d i f i e d f i l le r s i s n o t a c c o m p a n i e d b y t h e f o r m a t i o n o f a c o p o l y m e r g r a f t e d t ot h e f i ll e r s u r f ac e : t h e p o l y m e r i c p r o d u c t i s c o m p l e t e l y e x t r a c t e d b y b o i l in g M E K ( T a b l e1 ). D u r i n g p o l y m e r i z a t i o n i n th e p r e s e n c e o f M E S - s u b s t i t u t e d f i l le rs , c o p o l y m e r s b o t hu n g r a f t e d a n d a l s o g r a f t e d t o t h e s u r fa c e a r e f o r m e d . I t m a y b e s e e n f r o m F i g . 2 t h a tt h e g r a f t e d c o p o l y m e r is f o r m e d a t a l o w e r r a te t h a n t h e u n g r a f t e d p o l y m e r , t h e f o r m a -t i o n o f t h e g r a f t e d c o p o l y m e r s l o w i n g d o w n t o a c o n s i d e r a b l e e x t e n t w i th t im e . T h i si s c o n n e c t e d w i t h d i f f u s i o n a l r e s t r i c t io n s o n t h e M E S g r o u p s b e c a u s e o f t h e i r b e i n gf i x e d o n t h e s u r f a c e a n d a l so i t i s c o n n e c t e d w i t h th e e x h a u s t i o n o r p a r t i a l s c r e e n i n go f t h e M E S g r o u p s a s t h e g r a f t e d p o l y m e r i s f o r m e d . T h e u s e o f t h e m o r e d e v e l o p e d


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Copolymorization o f styrene with ae rylonitrile in solution 3 9S i v o l s u r f a c e l e a d s , a s is t o b e e x p e c t e d , t o a l a r g e r y i e l d o f t h e g r a f t e d c o p o l y m e ra n d t o a g r e a te r p r o p o r t i o n o f th e g r a f t e d c o p o l y m e r in t h e t o t a l y i e ld o f p o l y m e r i cp r o d u c t s t h a n i s t h e c a s e w h e n A e r o s i l i s u s e d w i t h t h e s a m e l o a d i n g o f t h e f i ll e r. T h i si s c a u s e d b y t h e h i g h e r c o n c e n t r a t i o n o f M E S g r o u p s o n t h e S i v o l p a r t i c l e s. D u r i n gt h e p r o c e s s , t h e r a t e o f a c c u m u l a t i o n o f t h e g r a f t e d c o p o l y m e r a n d t h e e f fi c ie n c y o fg r a f t i n g d e c r e a s e . W h e n t h e c o n v e r s i o n o f th e m o n o m e r s r e a c h e s a v a l u e o f a p p r o x i -m a t e l y 5 0 , t h e e f f ic i en c y o f g r a t i n g b e c o m e s a p p r o x i m a t e l y th e s a m e w h e n e i t h e rty p e o f f i ll e r i s u sed (F ig . 2, cu rv es 5 an d 6 ; T ab le 1 ). I t is im p o r t an t t o n o te th a t , i nt h e p r e s e n c e o f S iv o l m o d i f i e d w i t h M E S , w h i c h h a s t h e m o r e d e v e l o p e d s u r f a c e , th er a t e n o t o n l y o f g r a f t e d b u t a l s o o f u n g r a f t e d c o p o l y m e r i z a t i o n i s h i g h e r ( F ig . 2 ).

I t m a y b e s e e n f r o m a n a n a l y s i s o f t h e r e s u l ts o f t h e c o p o l y m e r i z a t i o n o f s t y r e n e -a c r y l o n i t r i le m i x t u r e s h a v i n g t h e a z e o t ~o p i c c o m p o s i t i o n ( T a b l e 1 ) a n d w i t h v a r i o u sr a t i o s b e t w e e n t h e m o n o m e r s ( F i g . 3 ) t h a t , i n t h e i n it i al p e r i o d o f t h e r e a c t i o n , t h eo v e r a l l r a t e i s p r a c t i c a l l y t h e s a m e i n t h e p r e s e n c e o f fi ll e rs , w h e t h e r t h e y a r e u n m o d i f i e do r m o d i f i e d : a f t e r 0 .5 h r , t h e c o n v e r s i o n o f a f il le d a n d o f a n u n f i l le d m o n o m e r m i x t u r ei s ap p ro x im ate ly 5 ~o ( ex p e r ime n t s 1 , 4 , 9, 1 1, 1 2 ) . A t t en t io n s h o u ld , h o w ev er , b e g iv ent o t h e c o n s i d e r a b l e i n c r e a s e i n t h e c o p o l y m e r s ' m o l e c u l a r m a s s ( b y a f a c t o r o f 3 - 5 )i n t he c a s e o f c o p ol y m e r s f o r m e d u n d e r h e t e r o g e n e o u s c o n d i ti o n s a s c o m p a r e d w i t ht h o s e o b t a i n e d u n d e r h o m o g e n e o u s c o n d i t i o n s ( T a b l e 1 ) . I t s h o u l d b e n o t e d t h a t w ea r e r e f e r r i n g t o t h e m o l e c u l a r m a s s o f t h e u n g r a f t e d c o p o l y m e r s i n c e t h e g r a f t e d c o -p o l y m e r , s e p a r a t e d f r o m t h e f i ll e r b y d i s s o l v in g t h e l a t t e r i n h y d r o f l u o r i c a c i d , i s in -s o l u b le in k n o w n s o l v e n ts . S u c h a m a r k e d i n c r e a s e i n t h e m o l e c u l a r m a s s o f t h e p o l y m e r sf o r m e d i n t h e f i ll e d s y s t e m w h i l s t t h e o v e r a l l r a t e o f th e p r o c e s s r e m a i n s u n c h a n g e di s ev i d e n ce t h a t t h e w a y i n w h i c h t h e e l e m e n t a r y r e a c t i o n s o f p r o p a g a t i o n a n d e s p e c i a l l yt e r m i n a t i o n o c c u r is c h a n g e d ( t h e r a t e o f i n i t i a ti o n , b e c a u s e o f t h e u s e o f a n o i l - s o lu b l ei n i t i a t o r , n a m e l y b e n z o y l p e r o x i d e , s h o u l d n o t b e a l t e r e d ) . T h e e f f e c t s t h a t h a v e b e e nr e v e a l e d a re c o n n e c t e d w i t h s t r u c t u ra l f e a t u r e s o f t h e p o l y m e r i z a t i o n s y s t e m a n d w i t ht h e p o s s i b il i ty o f t h e g e l- e ff e c t a p p e a r i n g i n e a r l y s t a g e s o f p o l y m e r i z a t i o n b e c a u s e o fthe d isperse f i l ler .

M o d i f i c a t i o n o f t h e S i vo l s u r f a c e b y M E S g r o u p s l e a d s t o t h e f o r m a t i o n o f u n g r a f t e dc o p o l y m e r s w h o s e m o l e c u l a r m a s s i n t h e i n i ti a l p e r i o d o f t h e r e a c t i o n i s l o w e r t h a n t h a to f c o p o l y m e r s o b t a i n e d i n t h e p r e s e n c e o f u n m o d i f i e d S i vo l, t h is e f f e c t b e c o m i n g m o r em a r k e d a s t h e c o n c e n t r a t i o n o f s u r f a c e M E S g r o u p s i s i n c r e a s e d . I n t h e p r e s e n t c a s ei t i s c l e a r l y n e c e s s a r y t o t a k e a c c o u n t o f t h e p o s s i b i l i t y t h a t c h a i n s g r o w i n g i n t h ev o l u m e m a y t r a n s f e r t o t h e m o d i f i e d s u r fa c e , w h i c h c a n l e a d e i t h e r t o t h e i r a n n i h i l a t i o no r t o b r a n c h i n g o f th e g r a f t e d c o p o ly m e r s . C h a i n t r a n s f e r m a y b e a c c o m p l i s h e d b yc a p t u r e o f a m o b i l e h y d r o g e n a t o m f r o m t h e m e t h y l e n e g r o u p o f M E S . O f c o u r s e ,t h e p r o b a b i l i ty o f th i s p r o c e s s i n c re a s e s a s th e c o n c e n t r a t i o n o f M E S g r o u p s o n t h esu r face i s i n c reased .

L e t u s fo l lo w th ese r e l a t io n sh ip s a t h ig h er co n v er s io n s ( ~ 2 5 //o o r A ero s i l o r ,-~ 4 0f o r S i v ol ) w h e n , t o j u d g e f r o m F i g . 2, t h e s u r f a c e M E S g r o u p s h a v e p r a c t i c a l l y d i s a p p e a r -e d o r a r e b l o c k e d b y t h e g r a f t e d l a y e r t h a t h a s b e e n f o r m e d . I n t h e c a s e o f A e r o s i l ,w h e t h e r u n m o d i f i e d o r m o d i f i e d , t h e o v e r a l l r a t e o f c o p o l y m e r i z a t i o n h a r d l y d i f f e rs


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2 3 3 0 S.S. IVANCHEVet al .TABLE 1 . C O P O L Y M E R I Z A T I O N O F A $TYRENE-ACRYLONITRILE AZEOTROPIC MIXTURE IN THE PRESENCE

OF A FILLER, UNMODIFIED OR MODIFIED WITH MES

Exp.No.

[ M E S ] s n r t c oFiller (65 l./g)

Aerosil*,, 0.47,, 0.47,, 0-47,, 0.47

0.47~Sivol t

,, 0-28,, 0.98,, 0.98,, 0.98

mmolemole/kg m~ x

[ 103

o~dO

O

- 0 5- 4- 4

2 0 0 52 0 12 0 22 ' 0 42 0 8- 0 5- 4

0 ' 6 0 52 ' 6 0 ' 52 6 42 6 8

Q

= Ee~8

X ~

Concentration ofacrylonitrile in mo-

nomer mixture,mole ~o

grafted ungraftod5.0

27 827 2

5.45.5

13.825 645-5

5'445 '0

5 05 3

42 050 0

0.250-280.740.730.740-760 770 940.940 740.651.42

4446

153147152170187217217152125401

000

39'6_+38.8_+40 1_+41.4_+

00

50-4_+54 2 _+43'7_+40 4 _+

37 8_+ 1 237 8 _+ 1 237 9 _ 1 2

1 3 38 8_ 1 31 3 38 8_+1.31 . 3 40 1_+1.31 3 37 8_+1 2

40.3 _+ 1 341 4_+ 1.3

1 6 40.3_+1-31 8 42.2 -+ 1 41.4 40.7-+ 1 31.3 34.9_+1.1

* P ar t i c le d i am e te r . 15 -35 r i m . s pe c i f i c s ur fac e , s = 175 + 25 m 2/ g .t M i c r of i br ous m ate r i a l , e x te r na l d i am e te r o f f ibr es , 30 -35 r i m ; d i am e te r o f c e ntr a l c api Uary , 5 - 10 r i m : Sm . . , , , ~ = 4 70

m = / S S . , ~ , . = 1 0 0 0 r a 2 1 S .

q g/g q3

o 3

2 q 8T/me he

f0 7

0 . 5

03

07

Fie. 2. Dependence of the yield, q, of: 1 and 2- gra fte d; 3 and 4- ung raf te d copolymers, togetherwith the dependence of the efficiency of grafting J( 5 and 6) on time in the presence of the following:1, 3 and 5-Aerosil; 2, 4 and 6-Sivol. The monomer mixture had the azeotropic composition,


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Copolym erization of styrene with acrylonitrile in solution 2331a t a l l f r o m t h a t i n a h o m o g e n e o u s s y s t e m ( e x p e r i m e n t s 2 , 3 a n d 7 ) . T h e p r o d u c t sm o l e c u l a r m a s s i n c r e a s e s s li g h t ly a s t h e c o n v e r s i o n r i se s . I n t h e e a s e o f S i v o l, t h e r a t eo f th e p r o c e s s a n d t h e m o l e c u l a r m a s s o f t h e c o p o l y m e r s a r e s u b s t an t i al l y i n c r e a s e d .D e s p i t e t h e f a c t t h a t t h e r e i s n o t a l a r g e d i f f e r e n c e b e t w e e n t h e v a l u e s o f t h e c o p o l y -m e r i z a t i o n r a t e s o n t h e m o d i f i e d a n d t h e u n m o d i f i e d S i vo l ( e x p e r i m e n t s 1 0 a n d 1 3),t h e m o l e c u l a r m a s s o f t h e g r a f t e d c o p o l y m e r o b t a i n e d i n t h e p r e s e n ce o f t h e M E S -s u b s t i t u te d S i v o l i s m u c h t h e g r e a t e r ( b y a f a c t o r o f a p p r o x i m a t e l y 2 ).

L [tSW[% - ..20 qo 60 80 N ~mole

FIG. 3. Dependence of the overall rate o f copolymerization of styrene with acrylonitrile o n the c on -centration of acrylonitrile, M, in the monomer mixture in the presence of: 1-unmodified Sivoland 2-M ES -subst i tu ted Sivol ; 3 - in the absence of a fi ller .T h e s e d a t a m a y b e t a k e n a s e v id e n c e th a t , i n t h e p r e s e n c e o f t h e t w o f a c t o r s i n t r o -

d u c e d b y t h e f il le r a n d a f f e c t in g t h e k i n e t i c s o f t h e p r o c e s s , n a m e l y t h e c h e m i c a l a n d t h es t e r i c f a c t o r , t h e l a t t e r b e c o m e s d o m i n a n t a s t h e r e a c t i o n p r o c e e d s . I t f o l l o w s f r o m t h er e s u l t s t h a t t h e p r i n c i p a l f a c t o r a f f e c t in g th e o n s e t o f t h e g e l -e f fe c t i n s u c h a s y s t e mis t h e e x i s t en c e o f a h i g h ly d e v e l o p e d s u r f a c e s e p a r a t i n g t h e p h a s e s . I n t h i s r e s p e c ti t m a y b e p o s t u l a t e d t h a t , d u r i n g t h e c h e m i c a l g ra f t in g o f th e p o l y m e r a s d i s t i n c t f r o mu n g r a f t e d c o p o l y m e r i z a t i o n , t h e r e is a u n i f o r m d i s t ri b u t io n o f t h e p o l y m e r o n t h es u r f a c e s o f th e i n d i v i d u a l p a r ti c l e s a n d , a s a r e s u l t o f th i s , t h e s o l i d p h a s e r e m a i n s h i g h l yd i s p e r s e d t h r o u g h o u t t h e e n t i r e d u r a t i o n o f t h e p r o c e s s a n d i ts e ff e c t o n t h e k i n e t i c so f t h e p r o c e s s is r e ta i n e d t o h i g h d e g re e s o f c o n v e r s io n o f t h e m o n o m e r s .

I t w a s o f i n t e r e s t t o s t u d y t h e e f f e c t o f t h e s o l i d s u r fa c e o n t h e c o m p o s i t i o n o f t h ec o p o l y m e r f o rm e d . T h e i n v e s ti g a ti o n w as c a r r i e d o u t w i t h g r a f t e d a n d a ls o u n g r a f t e dc o p o l y m e r s o b ta i n e d w it h t h e c o m p o s i t io n o f th e c o m o n o m e r m i x t u r e v a r ie d f r o m1 0 : 9 0 t o 9 0 : 1 0, th e d e g r e e o f c o n v e r s i o n o f t h e m o n o m e r s b e i n g n o t g r e a t e r t h a n5 - 1 0 ~ . T h e q u a n t it a t iv e d e t e r m i n a t i o n o f th e c o p o l y m e r c o m p o s i t i o n w a s c a r r i e d o u tb y i n t e r n a l n o r m a l i z a t i o n o f t h e a r e a s o f th e a c r y l o n i t r i l e a n d s t y r e n e p e a k s o n t h ec h r o m a t o g r a m s o f t h e v o l a t i l e p r o d u c t s o f p y r o l y s i s ( F ig . 4 ), t h e r e l a t i v e c o e f f ic i e n tso f se n s i ti v i ty o f t h e c o m p o n e n t s t o b e d e t e r m i n e d b e i n g t a k e n i n t o a c c o u n t [7 ].

I t m a y b e s e e n f r o m T a b l e 1 a n d F i g . 5 t h a t t h e p r e s e n c e o f a n u n m o d i f i e d f i ll e r( e i t h e r A e r o s i l o r S i v o l) i n t h e r e a c t i o n z o n e r e s u l t s i n h a r d l y a n y c h a n g e i n t h e c o p o l y -m e r c o m p o s i t i o n a s c o m p a r e d w i t h t h e u n fi ll ed c o p o l y m e r a t a ll v a lu e s o f t h e a c r y l o -n i t r i l e - s t y r e n e r a t i o , t h a t i s , t h e a d s o r p t i o n i n t e r a c t i o n b e t w e e n t h e f il le r s u r f a c e a n d t h em o n o m e r s h a s i n s u ff ic i e n t e f f e ct t o s u b s t a n t i a ll y d i s r u p t t h e c o p o l y m e r c o m p o s i t i o n .


6/9

Fillex

1"20

~-~

0 . 0 2 3 0 . 0 1 30 . 0 2 6 0 . 0 0 50 . 0 3 0 0 - 0 0 8

rl l 2

g r a ft e d c o p o l y m e r

r2 / 1 J r l f 2

ungrafted copolymer

- 10-90Unm odified Sivol 10-90MES-substituted 10-90Sivol* 10-4040-90

* IMlSSlffi0.28mole/kg.

0.831-4- 0 . 2 60 . 6 3 6 0 . 1 20 . 6 8 2 0 . 1 2

0 019 [0 0 2 00 0 2 0

24 l

no graf ted copolymer0.085_+0.005 0.380+0.11

0_+0.004 0.119+0.030.087_+0.005 0.47 1 _+0.180.03200 . 0 4 1

2 3 3 2 S . S . I V A N C H B V et alTABLE 2. COPOLYMERIZATI ON CONSTANTS FOR STYRENE AND ACRYL ONITR ILE IN THE HOMOGLtNEOUS

AND HETEROGENEOUS PROCESS

2 0 tOTime re . inFIG. 4 . Ch rom atogram obtained from the vola t ile products of the pyrolysis of a s tyreneaerylonitr ile graf ted copolymer. 1 , 3- l ow -bo il in g poin t com ponents formed in the de-gradation o f the modified Sivol; 2-a cry loni tr i le ; 4 -s t yr en e.

T h e p r e s e n c e o f M E S - s u b s t i t u t e d S i vo l i n th e c o p o l y m e r i z a t i o n z o n e l e a d s t o t h e f o r -m a t i o n o f a g r a f t e d c o p o l y m e r c o n s i d e r a b l y e n r i c h e d i n a c ry l o n i t r il e li n k s F i g. 5 ,T a b l e 1); t h e e n r i c h m e n t g r a d u a l l y b e c o m e s l e ss a s t h e c o n v e r s i o n i n c r e a s e s. T h e d e v i a -t i o n o f t h e c o m p o s i t i o n o f th e g r a f t e d c o p o l y m e r f r o m t h a t o f t he u n g r a f t e d c o p o l y m e rw a s o b s e r v e d n o t o n l y w h e n S iv o l w i t h a h i g h c o n c e n t r a t i o n o f M E S g r o u p s o n i tss u r f a c e w a s u s e d 0 .9 8 m o l e / k g ; T a b l e 1 ) b u t a l s o w h e n t h e c o n c e n t r a t i o n o f th e s eg r o u p s w a s t h r e e t im e s l e s s 0 .2 8 m o l e / k g , F i g . 5). I t s h o u l d b e n o t e d t h a t , w h e n u n -g r a f t e d c o p o l y m e r i z a t i o n o c c u r r e d s i m u l t a n e o u s l y w i t h g r a f t e d c o p o l y m e r i z a t i o n ,t h e s e l ec t iv e ef fe c t o f t h e s u r f a c e o n t h e m o n o m e r s w a s h a r d l y o b s e r v e d a t a ll .


7/9

Copolymerizationof styr n with acrylonitrile n solution 2333The copolymerization constants for styrene, r,, and acrylonitrile, r2, were calcu-

lated from the Fineman-Ross equation using a computer method to linearize the curves.Table 2 indicates that rl and r2 during ungrafted copolymerization in the presenceof both the modified and also the unmodified Sivol surfaces hardly differ from thecorresponding values characterizing the unfilled system. During grafted copolymeri-zation, however, r2 increases by a factor of almost three whereas rl decreases slightly.To judge from the increase in the value of rl r2, the degree of disorder in the distributionof the links increases in the grafted chains. The change in the monomers' copolymerizationconstants for grafted polymerization may be evidence of a change in the monomersreactivity in the presence of MES groups, or it may be connected with an increasein the local concentration of acrylonitrile in a surface zone.

r e , m o l e1 0 0

50

II

/ e l/g

5 0 1 0 0M ~rnoleF IG . 5. D e p e n d e n c e o f th e c o m p o s i t io n o f 1 - t h e gr a ft e d a n d 2 - t h e u n g r a f te d c o p o l y m e r o n t h ec o m p o s i t i o n o f th e m o n o m e r m i x t u re in th e p re s en c e o f I a n d 2 - u n m o d i f i e d S iv o l a n d 3 - M E S -

s u b s t i t u t e d S i v o l ; 4 - i n t h e a b s e n c e o f S i v o l .

In considering the results, it is, however, necessary to note two factors. Firstly,an assessment of the adsorption potential of the fillers showed that MES-substitutedSivol has a potential that is lower than that of the unmodified Sivol (Fig. 6), that is,in this case it is impossible to relate the selective effect of the filler to its adsorptionactivity. Secondly, the use of Aerosil with a concentrat ion of MES groups of 0.47 mole/kgas the filler does not lead to any disruption of the composition of the grafted copolymer,that is, modification of the filler surface with MES groups is a necessary condition,


8/9

2334 S . S . IV NCHEV t a l .b u t n o t a s u f f i c i e n t c o n d i t i o n , f o r t h e s u r f a c e to e x e r t a s e l e c ti v e a c t i o n o n t h e c o m o -n o m e r s .

F r o m a ll t h e i n d ic a t io n s , t h e r e a s o n f o r t h e o b s e r v e d c h a n g e i n t he c o m p o s i t i o no f t h e g r a f t e d c o p o l y m e r is c o n c e a l e d in a n o v e r a ll f a c t o r w h i c h h a s c o n t r i b u t i o n sf r o m t h e c h em i c a l e ff e ct o f t h e M E S g r o u p s o n t h e m o n o m e r s r e a c ti v i ty as w e ll a sc o n t r i b u t i o n s f r o m s t ru c t u r a l f e a t u r e s o f S i v ol . I f w e t a k e a c c o u n t o f t h e p r i n c i p a ls t r u c t u r a l d i f f e re n c e b e t w e e n S iv o l a n d A e r o s i l , n a m e l y , t h e p r e s e n c e o f a d e v e l o p e dc a p i l l a r y s y s t e m i n t h e l a t t e r , w e c a n a s s u m e t h a t t h e e n r i c h m e n t o f t h e g r a f t e d c o -p o l y m e r in a c r y l o n i t r i l e i s a c o n s e q u e n c e o f t h e c a p i l l a r y e f fe c t, w h i c h l e a d s t o a n i n -c r e a s e in t h e l o ca l c o n c e n t r a t i o n o f a c r y l o n i tr i l e a n d t o a n e n h a n c e d p r o b a b i l i ty o fi n t e r a c t io n b e t w e e n t h e r e a c t iv e p a i r o f c o m o n o m e r s , n a m e l y a c ry l o n i t ri l e a n d M E S :i n t h e f i n a l an a l y s is , t h e c a l c u l a t e d c o p o l y m e r i z a t i o n c o n s t a n t s a r e e f f e c ti v e c o n s t a n t sa n d d e p e n d o n t h e c o n c e n t r a t i o n o f t h e c o m o n o m e r s . I n o r d e r t o c o n f i r m th i s, t h ev a l u e s o f rx a n d r 2 w e r e c a l c u la t e d f o r m o n o m e r m i x t u r e s w i t h v a r i o u s r a n g e s o f a c r y l o -n i t r il e c o n c e n t r a t i o n . I t m a y b e se e n f r o m t h e d a t a i n T a b l e 2 t h a t t h e v a l u e s o f r ta n d r2 d u r i n g g r a f te d c o p o l y m e r i z a t i o n d e p e n d o n t h e d e g r e e o f s a t u r a ti o n o f th e m o n o -m e r m i x t u r e w i th a c r y l o n i tr i le ; i n t h e c as e o f p o l y m e r i z a t i o n o f a m o n o m e r m i x t u r ee n r i c h e d i n a c r y lo n i t ri l e t h e p r o b a b i l it y o f f o r m i n g a c o p o l y m e r w i t h a m o r e r e g u l a rs t ruc tu re~ i s inc reased ( r l r2 - -~O) .

/ 6

/ 2 [ - . ,~I I/

/2

I I I .2 3 Q . l O a q

FIG. 6. Dependence of the failer s absorp tion potential , A/t , on the degree of occupancy by iro n(HI ) hydroxo-aquo complexes : Q . lF e3 +] =4 x l0 -7 g -ion /1 , room temperature: / -u nm od i f i edSivol ; 2-M ES -subs t i tu ted Sivol.T h e r e s u l ts o b t a i n e d t h is g i v e e v i d e n c e t h a t n o t o n l y t h e n a t u r e o f t h e f u n c t i o n a l

c o v e r i n g o f t h e f il le r b u t a l s o i t s s tr u c t u r a l c h a r a c t e r i s t i c s p l a y a m a j o r p a r t i n t h e c r e -a t i o n o f th e g e l -e f fe c t i n t h e f il le d p o l y m e r i z a t i o n s y s t e m a s w e l l a s i n p r o d u c i n g t h ec h a n g e i n t h e c o m p o s i t i o n o f th e c o p o l y m e r f o r m e d d i r e c t l y i n t h e s u rf a c e zo n e a n di n a ff e c t in g t h e r e g u l a r i t y o f t h e d i s t r i b u t i o n o f m o n o m e r i c l i n k s in t h e m a c r o m o l e c u l e s .

T r a n s l a t e d b y G. F. MODLENREFEREN ES

1. S. S. IVANCH EV and A. V. DMITRENKO, Uspekhi khimii 51: 7, ] ]78, 19822. S. S. IVANCHEV, A. V. DM1TRE~O, B. V. POLOZOV, V. A. DEMH OVA, A. K. DABA-GOVA a n d N . V . S E R G I Y E N K O P l a st . m a s s y 1 0 2 0 1 9 8 2


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Polyamides with benzimMazole links included symmetrically in chain 23353. S. S. IVANCHEV, A. V. DMITRENKO, V. A. DEMIDOVA and A. K. DABAGOVA, Vysoko-reel. soyed. A27: 5, 1086, 1985 (Translated in Polymer Sci. U.S.S.R. 27: 5, 1217, 1985)4. V. P. PRYANISHNIKOV, N. F. GUSYNIN, N. F. SOROKIN and K. I. CHEPIZHNYI, U.S.S.R.Pat. 579246. Byull izobr., No. 41, 80, 19775. V. P. BUDTOV, L. F. DOKUKINA, E. F. DAVYDOVA, T. N. PAVLOVA, G. P. FRADKINAand N. G. PODOSENOVA, Manuscript deposited at the All-Union Institute of Scientific andTechnical Information (VII'4ITI) Moscow, Dep. 14o. 1242-776. Opredeleniye aktivnosti tverdykh veshchestv potentiometricheskim metodom. Metodicheskoyeukazaniye k laboratornym rabotam (Determination of the Activity of Solids by the Potentio-metric Method. Instructions Regarding the Procedures for Laboratory Work), Lensovet Technicalinstitute, Leningrad, 19807. N. CRASSIE, Developm. Polymer Degradation, 214 pp, Appl. Sci. Publ., 1979

olymerS c i e n c e U . S . S . R . V o l . 2 8 , N o . I 0 , p p . 2 3 3 5 - 2 3 4 2 , 1 9 8 6P r i n t e d i n P o l a n d 0 0 3 2 - 3 9 5 0 1 8 6 1 0 . 0 0 + . 0 0 1 9 87 P e r g a m o n J o u r n a l s L td .

H Y D R O D Y N A M I C A N D O P T IC A L P R O P E R T IE S O FP O L Y A M I D E S W I T H B E N Z I M I D A Z O L E LIN K S IN C L U D E D

S Y M M E T R I C A I J , Y IN T H E C H A I N

P. N. LAVRENKO, L N. SttTENNIKOVA,T. I. GARMONOVA,O. I. MIKRYUKOVA, M. M. GEL'MONTand L. S. EFROSInstitute for High-Molecular Compounds, U.S.S.R. Academy of Science,

Received 18 February 1985)Forward diffusion, intrinsic viscosity and flow birefringence in acetic acid solutions havebeen investigated for polyamide benzimidazoles differing in the way in which the benzimida-zole rings are incorporated in the molecular chain. It is shown that an increase in the propor-tion of benzimidazole rings orientated one to another in the head-to-head position from

2/3 to 1 does not give rise to any appreciable change in the equilibrium rigidity of the polyamide benzimidazole molecules in solution or to the optical anisotropy of unit chain length.

Trm meth ods of molecul ar hydrody namics and optics in solution have been used [1, 2]to investigate the properti es o f polyamide-benzimidazole (PABI) and it has been showmthat the in troductio n of the benzimidazole ring into the poly-p-phenyleneterephthal-amide chain leads to a reduction in the equilibrium rigidity of the macromoleculeby a facto r of approximately 1.5. The chemical structure of the PABI chain consistsof a random sequence of three types of links [3].

* Vysokomol. soyed. A28: No. 10, 2102-2107, 1986.

aspects of the copolymerization of styrene with acrylonitrii,e in solution in the presence of...

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