- Email: [email protected]
Estimation of the Packing density of solid polymers—III. Crystalline polymers
1139
P a c k i n g d e n s i t y o f solid p o l y m e r s - - I I I
REFERENCES 1. J. N. M E S H K O V A , G. M. B A K O V A , B. J. T S V E T K O V A a n d N. M. C H I R K O V , V y s o k o m o l . soedin. 3: 1516, 1961 2. H. ROHA, L. KREIDER, M. FREDERICK and W. BREARS, J. P o l y m e r Sei. 38: 51, 1959 3. J. M. K O L ' T G O F a n d E. B. SENDEL, K o l i c h e s t v e n n y i analiz. ( Q u a n t i t a t i v e Analysis.) (loskhimizdat, 1948 4. P o l i e t i l e n n i s k o v o d a v l e n i y a . ( L o w - p r e s s u r e P o l y e t h y l e n e . ) ( l o s k h i m i z d a t , 1958
ESTIMATION OF THE PACKING DENSITY OF SOLID POLYMERS--III. CRYSTALLINE POLYMERS* A. A. TAGER,
M. V. TSILIPOTKINA
and
D.
M. ROMANOVA
Ural State University
(Receiced 19 Ja~tary
1961)
Till*; degree o f t h e p a e k i n g o f p o l y m e r c h a i n s c a n n o t a l w a y s b e e s t i m a t e d f r o m a s t u d y o f the d e n s i t y o f t h e p o l y m e r since t h e d e n s i t y o f t h e s u b s t a n c e d e p e n d s , n o t o n l y o n t h e a v e r a g e d i s t a n c e b e t w e e n its molecules, b u t also o n t h e n a t u r e o f t h e a t o m s e n t e r i n g t h e molecule. B e c a u s e o f this, e v e n w i t h i d e n t i c a l d e n s i t i e s o f t h e c h a i n p a c k i n g , p o l y m e r s w h i c h differ i n t h e i r c h e m i c a l n a t u r e , h a v e different densities, w h i c h is p e r f e c t l y n a t u r a l . Therefore the development of a method of estimation of the density of polymer chains a n d t h e d i s t a n c e b e t w e e n t h e c h a i n s is v e r y i m p o r t a n t b o t h t h e o r e t i c a l l y a n d p r a c t i e a l l y . I n a series o f p a p e r s it w a s i n d i c a t e d q u a n t i t a t i v e l y t h a t h i g h l y - e l a s t i c p o l y m e r s were p a e k e d j u s t as d e n s e l y as l o w - m o l e e u l a r w e i g h t liquMs, w h e r e a s t h e degree o f p a c k i n g o f " g l a s s y " p o l y m e r s c a n v a r y in v e r y wide l i m i t s f r o m v e r y d e n s e ( p o l y - v i n y l - a l e o h o l ) to v e r y l i g h t ( p o l y s t y r e n e ) . H o w e v e r , t h e m e t h o d s u s e d in t h e s e p a p e r s d i d n o t p e r m i t a q u a n t i t a t i v e e s t i m a t i o n o f t h e d e n s i t y o f 1,he p a c k i n g o f t h e p o l y m e r chains. A n a t t . e m p t w a s m a d e in [1] to a p p l y m e t h o d s , d e v e l o p e d for t h e d e t e r m i n a t i o n o f t h e specific surface a r e a a n d p o r e d e n s i t y o f solid s o r b e n t s , t o solid p o l y m e r s for t h e e s t i m a t i o n o f t h e p a c k i n g d e n s i t y o f t h e i r chains. I n this, we b e g a n w i t h a c o n s i d e r a t i o n o f t h e rigid s t r u c t u r e o f t h e solid " g l a s s y " p o l y m e r . If' its ehain.~ are p a c k e d loosely, t h e d i s t a n c e b e t w e e n t h e c h a i n s c h a n g e s a n d h a s t h e s a m e o r d e r as t h e d i s t a n c e in solid, u l t r a - m i c r o p o r o u s s o r b e n t s o f t h e t y p e s , a c t i v a t e d c a r b o n a n d silica gel, i.e. o f t h e o r d e r o f a n _~ngstr6m. W e o b t a i n e d v a l u e s o f t h e specific surface a r e a a n d p o r e v o l u m e for a r a n g e of glassy p o l y m e r s b y a n i n v e s t i g a t i o n o f t h e s o r p t i o n o f t h e v a p o u r of liquids, i n e r t w i t h r e s p e c t to t h e p o l y m e r s . ( I t was n e c e s s a r y that, t h e liquids s h o u M be i n e r t t o p r e s e r v e t h e solid s t r u c t u r e o f t h e s o r b e n t p o l y m e r i n t h e process o f s o r p t i o n . ) W e c a r r i e d o u t t b e d e t e r m i n a t i o n o f t h e I)Or(' v o l u m e o f t h e glassy p o l y m e r s b y t h e m e t h o d o f D u b i n i n R a d u s h k e v i c h [2]. L a t e r t h i s m e t h o d w a s u s e d in t h e e s t i m a t i o n of t h e c h a n g e o f p a c k i n g d e n s i t y o f fibres, e x p o s e d to v a r i o u s k i n d s o f influences [3]. * V y s o k o m o ] . s o e d i n . 3: No. 12, 1857--1859, 196I.
1140
A . A . TAGER et al.
EXPERIMENTAL :For t h e i n v e s t i g a t i o n , t w o t y p i c a l crystallic p o l y m e r s - - p o l y e t h y l e n e (PE) a n d polyt e t r a - f i n e r - e t h y l e n e ( P T F E ) a n d t h e c o - p o l y m e r s v i n y l c h l o r i d e (15~o) a n d v i n y l i d i n e c h l o r i d e ( S a r a n ) were t a k e n . T y p i c a l c r y s t a l l i n e i n t e r f e r e n c e s were d i s p l a y e d b y e l e c t r o n m i c r o s c o p y o f t h e l a t t e r [4]. A s t u d y was m a d e o f t h e s o r p t i o n o f v a p o u r s o f liquids w h i c h were i n e r t w i t h respec£ t o t h e s e p o l y m e r s . F o r P E a n d P T F E - - m e t h y l a l c o h o l v a p o u r , for S a r a n -- r e d i s t i l l e d w a t e r a n d b e n z e n e . T h e m e t h y l a l c o h o l was a b s o l u t e ( d e h y d r a t e d ) , t h e b e n z e n e t a k e n w a s cryoscopically p u r e . T h e p h y s i c a l c o n s t a n t s o f all t h e liquids, w h i c h were d e t e r m i n e d b y us, a g r e e d well w i t h t h e d a t a i n t h e l i t e r a t u r e . F o r t h e i n v e s t i g a t i o n , a m o d i f i c a t i o n o f t h e a p p a r a t u s , d e s c r i b e d earlier [5] was used. T h e m o d i f i c a t i o n was, t h a t t o m e a s u r e s m a l l e q u i l i b r i u m pressures, a M a c L e o d m a n o m e t e r w a s s o l d e r e d i n t o t h e w o r k i n g p a r t o f t h e a p p a r a t u s . All t h e m e a s u r e m e n t s were c a r r i e d o u t a t a r e s i d u a l p r e s s u r e o f 10 6 m m H g a t 25 °.
The sorption-isotherms in P E and P T F E are presented in Figure 1. From the Figure 1, it follo~,s that the characteristics of the sorption isotherms of methyl alcohol in both the crystalline polymers are identical, namely: practically no sorption takes place in both polymers in the region of small, relative, pressures of vapour, when p l / p ° = 0.55 the branch of the isotherm rises sharply and reaches u small constant value. Such a form of sorption-isotherm does not resemble either the isotherm characteristic of ultra-microporous sorbent (such an isotherm is presented in the Fig. 1 for comparison), or the sorption-isotherm of non-porous sorbents, or y e t the S-shaped sorption-isotherm of sorbents with transitive pores. It seems to us that such a type of sorption-isotherm is explained b y the two-phase structure of such crystalline polymers as polyethylene and P T F E . The absence of sorptive ability of the polymers in the region of small relative vapour pressures is indicative of the very, dense, packing of the chain. At p~/po =0.55 the less densely packed amorphous areas sor]) insignificantly.
7.z!
0. jill lll]g
O-6 O'q
a,,,.,qg
!
p/p,
FI(~. 1. T h e s o r p t i o n - i s o t h e r m s o f m e t h y l alcohol in PE and PTFE and polystyrene. (1) P E ; (2) P T F E ; (3) p o l y s t y r e n e .
!
1.zF 08
"
1
~ . ~
~ . ~ N ~ x w
0
0'2
O q.
I
0"8
I
I
0"8__ 1
FIG. 2. T h e s o r p t i o n - i s o t h e r m s o f w a t e r v a p o u r a n d b e n z e n e i n S a r a n : (1) w a t e r ; (2) b e n z e n e .
Packing density o f solid polymers -- ]I[
1141
The sorption-isotherms of water and benzene vapours in Saran are presented in Figure 2. These isotherms resemble the sorption-isotherms in non-i)orous hard sorbents [6] and closely-packed, "glassy", polymers of the polyvinyl-aleohol type. From the Figure 2 it can be seen the sorption-isotherm of water-vapour runs above t h a t of benzene vapour and is clearly accounted for by the size of the molecule. The picture observed here is characteristic of the sorption of vapours on zeolites--of crystalline sorbents with a very small pore-size. Such sorbents will sorb only the small water-molecules and under the same conditions will not sorb the larger benzene-molecules. In this way, the data obtained by us, indicates the very small micro-porosity of the crystalline polymers or the very close packing of their chains. Since all the sorption isotherms, obtained by us, did not have the characteristics of the isotherm for finely-porous sorbents (curves with saturation) we did not consider it feasible to use the method of Dubinin-Radushkevieh for the calculation of the pores. The BET method was nominally used by us to calculate the specific surface area of Saran. I t can be seen in Figure 3, that the region of
arl-p/po) o
l
I
1
Z70"l 0"2 0"3 O# 0.5
Fic. 3. The sorption-isotherms of water-vapour in Saran in the linear fomn according to the BET equation.
relative pressures, in which BET is observed to be applicable (linearly dependent), is the same as t h a t for activated carbon [2], cellulose [7] and polymer fibres [8]. By calculation the value is given of the specific surface area of Saran S~p=23.4 m~/g. Since the characteristics of the isotherm is indicative of the absence of ultra-micropores in Saran, then it is evident t h a t the calculated value of S~p must refer to an external surface of small grains.
CONCLUSIONS
(1) The sorption of the vapours of inert liquids on 3 crystalline polymers polyethylene, polytetrafluorethylene and Saran was studied.
1142
A. A. TAGER and M. V. TSIL[POTKINA
(2) The characteristics of the sorption-isotherms bear evidence of a very dense packing of the chains of all the 3 polymers and completely agrees with contemporary views of the two-phase structure of crystalline polyethylene and polytetrafluorethylene. Translated by J. C. LOMAX REFERENCES 1. A. A. TAGER, M. B. TSILIPOTKINA and A. I. SUVOROVA, Dokl. Akad. Nauk SSSR, 120: 570, 1958 2. M. M. DUBININ, E. D. ZAVERINA and L. B. RADUSHKEVICH, Zh. fiz. khimii 21 : 1351, 1947 3. V. A. BERESTNEV, T. V. GATOVSKAYA and V. A. KARGIN, Vysokomol. soedin. 2: 916, 1960 4. V. A. KARGIN and G. S. MARKOVA, Zh. fiz. khimii 27: 1525, 1953 5. A. A. TAGER and B. A. KARGIN, Kolloidn. zh. 10: 455, 1948 6. A. V. KISELEV, Zh. fiz. khimii, 23: 452, 1949 7. K. P. MISHCHENKO, S. L. TALMUD and V. I. YAKIMOVA, Kolloidn. zh. 21: 330, 1959 8. I. W. ROWEN and R. L. BLAIN, Industr. and Engng. Chem. 39: 1659, 1947
ESTIMATION OF THE PACKING DENSITY OF SOLID P O L Y M E R S - - I V . ISOTACTIC P O L Y S T Y R E N E * A. A. TAGER and M. V. TSILIPOTKINA Ural State University
(Received 19 January 1961) FI~O3I paper [1] it follows t h a t atactic, amorphous, "glassy" polystyrene during sorption acts as an ultra-microporous sorbent, the summary pore-volume of which is 0"03 cma/g. Such behaviour of atactic polystyrene is tied to loosely-packed, irregular, chain construction, randomly disposed in space, as with the larger phenyl substituted compounds. From this point of view, the study of the sorptive ability of isotactic polystyrene presented great interest. The present work was devoted to an investigation of the sorption of methyl alcohol v a p o u r on amorphous and crystalline samples of isotactic polystyrene. F r o m the Department of High Molecular Compounds in the Moscow State University we obtained samples of isotactic polystyrene which were freed from catalyst by boiling with toluene, followed by precipitation of pure, amorphous polystyrene with methyl alcohol. Crystallization of the polystyrene was carried out by heating for 5 hours at 116 ° in n-octane. The molecularweights of" the samples under investigation were determined by viscometry in benzene solutions. The dissolution of crystalline polystyrene was carried out at a temperature of 60 °. I n the calculation of the molecular weights the equation (g)= 1.13 × 10 4 ~V/0-:a was used [2]. * Vysokomol. soedin. 3: No. 12, 1860-1862, 1961.
P a c k i n g d e n s i t y o f solid p o l y m e r s - - I I I
REFERENCES 1. J. N. M E S H K O V A , G. M. B A K O V A , B. J. T S V E T K O V A a n d N. M. C H I R K O V , V y s o k o m o l . soedin. 3: 1516, 1961 2. H. ROHA, L. KREIDER, M. FREDERICK and W. BREARS, J. P o l y m e r Sei. 38: 51, 1959 3. J. M. K O L ' T G O F a n d E. B. SENDEL, K o l i c h e s t v e n n y i analiz. ( Q u a n t i t a t i v e Analysis.) (loskhimizdat, 1948 4. P o l i e t i l e n n i s k o v o d a v l e n i y a . ( L o w - p r e s s u r e P o l y e t h y l e n e . ) ( l o s k h i m i z d a t , 1958
ESTIMATION OF THE PACKING DENSITY OF SOLID POLYMERS--III. CRYSTALLINE POLYMERS* A. A. TAGER,
M. V. TSILIPOTKINA
and
D.
M. ROMANOVA
Ural State University
(Receiced 19 Ja~tary
1961)
Till*; degree o f t h e p a e k i n g o f p o l y m e r c h a i n s c a n n o t a l w a y s b e e s t i m a t e d f r o m a s t u d y o f the d e n s i t y o f t h e p o l y m e r since t h e d e n s i t y o f t h e s u b s t a n c e d e p e n d s , n o t o n l y o n t h e a v e r a g e d i s t a n c e b e t w e e n its molecules, b u t also o n t h e n a t u r e o f t h e a t o m s e n t e r i n g t h e molecule. B e c a u s e o f this, e v e n w i t h i d e n t i c a l d e n s i t i e s o f t h e c h a i n p a c k i n g , p o l y m e r s w h i c h differ i n t h e i r c h e m i c a l n a t u r e , h a v e different densities, w h i c h is p e r f e c t l y n a t u r a l . Therefore the development of a method of estimation of the density of polymer chains a n d t h e d i s t a n c e b e t w e e n t h e c h a i n s is v e r y i m p o r t a n t b o t h t h e o r e t i c a l l y a n d p r a c t i e a l l y . I n a series o f p a p e r s it w a s i n d i c a t e d q u a n t i t a t i v e l y t h a t h i g h l y - e l a s t i c p o l y m e r s were p a e k e d j u s t as d e n s e l y as l o w - m o l e e u l a r w e i g h t liquMs, w h e r e a s t h e degree o f p a c k i n g o f " g l a s s y " p o l y m e r s c a n v a r y in v e r y wide l i m i t s f r o m v e r y d e n s e ( p o l y - v i n y l - a l e o h o l ) to v e r y l i g h t ( p o l y s t y r e n e ) . H o w e v e r , t h e m e t h o d s u s e d in t h e s e p a p e r s d i d n o t p e r m i t a q u a n t i t a t i v e e s t i m a t i o n o f t h e d e n s i t y o f 1,he p a c k i n g o f t h e p o l y m e r chains. A n a t t . e m p t w a s m a d e in [1] to a p p l y m e t h o d s , d e v e l o p e d for t h e d e t e r m i n a t i o n o f t h e specific surface a r e a a n d p o r e d e n s i t y o f solid s o r b e n t s , t o solid p o l y m e r s for t h e e s t i m a t i o n o f t h e p a c k i n g d e n s i t y o f t h e i r chains. I n this, we b e g a n w i t h a c o n s i d e r a t i o n o f t h e rigid s t r u c t u r e o f t h e solid " g l a s s y " p o l y m e r . If' its ehain.~ are p a c k e d loosely, t h e d i s t a n c e b e t w e e n t h e c h a i n s c h a n g e s a n d h a s t h e s a m e o r d e r as t h e d i s t a n c e in solid, u l t r a - m i c r o p o r o u s s o r b e n t s o f t h e t y p e s , a c t i v a t e d c a r b o n a n d silica gel, i.e. o f t h e o r d e r o f a n _~ngstr6m. W e o b t a i n e d v a l u e s o f t h e specific surface a r e a a n d p o r e v o l u m e for a r a n g e of glassy p o l y m e r s b y a n i n v e s t i g a t i o n o f t h e s o r p t i o n o f t h e v a p o u r of liquids, i n e r t w i t h r e s p e c t to t h e p o l y m e r s . ( I t was n e c e s s a r y that, t h e liquids s h o u M be i n e r t t o p r e s e r v e t h e solid s t r u c t u r e o f t h e s o r b e n t p o l y m e r i n t h e process o f s o r p t i o n . ) W e c a r r i e d o u t t b e d e t e r m i n a t i o n o f t h e I)Or(' v o l u m e o f t h e glassy p o l y m e r s b y t h e m e t h o d o f D u b i n i n R a d u s h k e v i c h [2]. L a t e r t h i s m e t h o d w a s u s e d in t h e e s t i m a t i o n of t h e c h a n g e o f p a c k i n g d e n s i t y o f fibres, e x p o s e d to v a r i o u s k i n d s o f influences [3]. * V y s o k o m o ] . s o e d i n . 3: No. 12, 1857--1859, 196I.
1140
A . A . TAGER et al.
EXPERIMENTAL :For t h e i n v e s t i g a t i o n , t w o t y p i c a l crystallic p o l y m e r s - - p o l y e t h y l e n e (PE) a n d polyt e t r a - f i n e r - e t h y l e n e ( P T F E ) a n d t h e c o - p o l y m e r s v i n y l c h l o r i d e (15~o) a n d v i n y l i d i n e c h l o r i d e ( S a r a n ) were t a k e n . T y p i c a l c r y s t a l l i n e i n t e r f e r e n c e s were d i s p l a y e d b y e l e c t r o n m i c r o s c o p y o f t h e l a t t e r [4]. A s t u d y was m a d e o f t h e s o r p t i o n o f v a p o u r s o f liquids w h i c h were i n e r t w i t h respec£ t o t h e s e p o l y m e r s . F o r P E a n d P T F E - - m e t h y l a l c o h o l v a p o u r , for S a r a n -- r e d i s t i l l e d w a t e r a n d b e n z e n e . T h e m e t h y l a l c o h o l was a b s o l u t e ( d e h y d r a t e d ) , t h e b e n z e n e t a k e n w a s cryoscopically p u r e . T h e p h y s i c a l c o n s t a n t s o f all t h e liquids, w h i c h were d e t e r m i n e d b y us, a g r e e d well w i t h t h e d a t a i n t h e l i t e r a t u r e . F o r t h e i n v e s t i g a t i o n , a m o d i f i c a t i o n o f t h e a p p a r a t u s , d e s c r i b e d earlier [5] was used. T h e m o d i f i c a t i o n was, t h a t t o m e a s u r e s m a l l e q u i l i b r i u m pressures, a M a c L e o d m a n o m e t e r w a s s o l d e r e d i n t o t h e w o r k i n g p a r t o f t h e a p p a r a t u s . All t h e m e a s u r e m e n t s were c a r r i e d o u t a t a r e s i d u a l p r e s s u r e o f 10 6 m m H g a t 25 °.
The sorption-isotherms in P E and P T F E are presented in Figure 1. From the Figure 1, it follo~,s that the characteristics of the sorption isotherms of methyl alcohol in both the crystalline polymers are identical, namely: practically no sorption takes place in both polymers in the region of small, relative, pressures of vapour, when p l / p ° = 0.55 the branch of the isotherm rises sharply and reaches u small constant value. Such a form of sorption-isotherm does not resemble either the isotherm characteristic of ultra-microporous sorbent (such an isotherm is presented in the Fig. 1 for comparison), or the sorption-isotherm of non-porous sorbents, or y e t the S-shaped sorption-isotherm of sorbents with transitive pores. It seems to us that such a type of sorption-isotherm is explained b y the two-phase structure of such crystalline polymers as polyethylene and P T F E . The absence of sorptive ability of the polymers in the region of small relative vapour pressures is indicative of the very, dense, packing of the chain. At p~/po =0.55 the less densely packed amorphous areas sor]) insignificantly.
7.z!
0. jill lll]g
O-6 O'q
a,,,.,qg
!
p/p,
FI(~. 1. T h e s o r p t i o n - i s o t h e r m s o f m e t h y l alcohol in PE and PTFE and polystyrene. (1) P E ; (2) P T F E ; (3) p o l y s t y r e n e .
!
1.zF 08
"
1
~ . ~
~ . ~ N ~ x w
0
0'2
O q.
I
0"8
I
I
0"8__ 1
FIG. 2. T h e s o r p t i o n - i s o t h e r m s o f w a t e r v a p o u r a n d b e n z e n e i n S a r a n : (1) w a t e r ; (2) b e n z e n e .
Packing density o f solid polymers -- ]I[
1141
The sorption-isotherms of water and benzene vapours in Saran are presented in Figure 2. These isotherms resemble the sorption-isotherms in non-i)orous hard sorbents [6] and closely-packed, "glassy", polymers of the polyvinyl-aleohol type. From the Figure 2 it can be seen the sorption-isotherm of water-vapour runs above t h a t of benzene vapour and is clearly accounted for by the size of the molecule. The picture observed here is characteristic of the sorption of vapours on zeolites--of crystalline sorbents with a very small pore-size. Such sorbents will sorb only the small water-molecules and under the same conditions will not sorb the larger benzene-molecules. In this way, the data obtained by us, indicates the very small micro-porosity of the crystalline polymers or the very close packing of their chains. Since all the sorption isotherms, obtained by us, did not have the characteristics of the isotherm for finely-porous sorbents (curves with saturation) we did not consider it feasible to use the method of Dubinin-Radushkevieh for the calculation of the pores. The BET method was nominally used by us to calculate the specific surface area of Saran. I t can be seen in Figure 3, that the region of
arl-p/po) o
l
I
1
Z70"l 0"2 0"3 O# 0.5
Fic. 3. The sorption-isotherms of water-vapour in Saran in the linear fomn according to the BET equation.
relative pressures, in which BET is observed to be applicable (linearly dependent), is the same as t h a t for activated carbon [2], cellulose [7] and polymer fibres [8]. By calculation the value is given of the specific surface area of Saran S~p=23.4 m~/g. Since the characteristics of the isotherm is indicative of the absence of ultra-micropores in Saran, then it is evident t h a t the calculated value of S~p must refer to an external surface of small grains.
CONCLUSIONS
(1) The sorption of the vapours of inert liquids on 3 crystalline polymers polyethylene, polytetrafluorethylene and Saran was studied.
1142
A. A. TAGER and M. V. TSIL[POTKINA
(2) The characteristics of the sorption-isotherms bear evidence of a very dense packing of the chains of all the 3 polymers and completely agrees with contemporary views of the two-phase structure of crystalline polyethylene and polytetrafluorethylene. Translated by J. C. LOMAX REFERENCES 1. A. A. TAGER, M. B. TSILIPOTKINA and A. I. SUVOROVA, Dokl. Akad. Nauk SSSR, 120: 570, 1958 2. M. M. DUBININ, E. D. ZAVERINA and L. B. RADUSHKEVICH, Zh. fiz. khimii 21 : 1351, 1947 3. V. A. BERESTNEV, T. V. GATOVSKAYA and V. A. KARGIN, Vysokomol. soedin. 2: 916, 1960 4. V. A. KARGIN and G. S. MARKOVA, Zh. fiz. khimii 27: 1525, 1953 5. A. A. TAGER and B. A. KARGIN, Kolloidn. zh. 10: 455, 1948 6. A. V. KISELEV, Zh. fiz. khimii, 23: 452, 1949 7. K. P. MISHCHENKO, S. L. TALMUD and V. I. YAKIMOVA, Kolloidn. zh. 21: 330, 1959 8. I. W. ROWEN and R. L. BLAIN, Industr. and Engng. Chem. 39: 1659, 1947
ESTIMATION OF THE PACKING DENSITY OF SOLID P O L Y M E R S - - I V . ISOTACTIC P O L Y S T Y R E N E * A. A. TAGER and M. V. TSILIPOTKINA Ural State University
(Received 19 January 1961) FI~O3I paper [1] it follows t h a t atactic, amorphous, "glassy" polystyrene during sorption acts as an ultra-microporous sorbent, the summary pore-volume of which is 0"03 cma/g. Such behaviour of atactic polystyrene is tied to loosely-packed, irregular, chain construction, randomly disposed in space, as with the larger phenyl substituted compounds. From this point of view, the study of the sorptive ability of isotactic polystyrene presented great interest. The present work was devoted to an investigation of the sorption of methyl alcohol v a p o u r on amorphous and crystalline samples of isotactic polystyrene. F r o m the Department of High Molecular Compounds in the Moscow State University we obtained samples of isotactic polystyrene which were freed from catalyst by boiling with toluene, followed by precipitation of pure, amorphous polystyrene with methyl alcohol. Crystallization of the polystyrene was carried out by heating for 5 hours at 116 ° in n-octane. The molecularweights of" the samples under investigation were determined by viscometry in benzene solutions. The dissolution of crystalline polystyrene was carried out at a temperature of 60 °. I n the calculation of the molecular weights the equation (g)= 1.13 × 10 4 ~V/0-:a was used [2]. * Vysokomol. soedin. 3: No. 12, 1860-1862, 1961.