Structural modification of polydioxolane and polyoxymethylene

Structural modification of polydioxolane

803

REFERENCES 1. I. B. RABINOVICH, A. N. MOCHALOV, L. I. PAVLINOV, V. V. KORSHAK, A. L. RUSANOV and R. D. KATSARAVA, Dokl. Akad. N a u k SSSR 198: 597, 1971 2. D. S. TUGUSHI, V. V. KORSHAK, A. L. RUSANOV, V. G. DANILOV, G. M. CHERKASOVA and G. M. TSEITLIN, Vysokomol. soyed. A15: 909, 1973 (Translated in Polymer Sei. U.S.S,R. 15: 5, 1087, 1973) 3. M. M. POPOV and V. N. KOLESOV, Zh. obshch, khim. 26: 2385, 1956 4. M. M. POPOV and G. L. GAL'CHENKO, Zh. obshch, khim., 2220, 1951 5. B. W. F. GIAGNE a n d J. W. STOUT, J. Amer. Chem. Soe. 58: 1144, 1930

STRUCTURAL MODIFICATION OF POLYDIOXOLANE AND POLYOXYMETHYLENE* B. V. Oz~Rovsmu Institute of Chemical Physics, U.S.S.R. Academy of Sciences

(Received 20 February '1972) New structural modifications of polydioxolane (PDO) and polyoxymethylene (POM) have been obtained b y polymerization of dioxolane and trioxan in partially polymerized methyl methaerylate, with SnC14 as catalyst. I t is shown b y means of infrared spectra and X-radiograms t h a t PDO can exist in three structural modifications. The new form of POM gives the following absorption bands in the infrared region: 938, a shoulder at 970, 980, 1028, 1125 and 2920em -1.

T ~ molecular structure of polydioxolane (PDO), obtained by cationic polymerization of 1,3-dioxolane in the liquid phase, with BFa-ethcrate as catalyst, was examined in references [1] and [2]. The authors conclude that in the crystalline state the PDO molecule is in the form of a helix with an identity period of 36.6A (PDOx) [2]. It is known that polyoxymethylene(POM) exists in two crystalline modifications, namely hexagonal and orthorhombic. In the hexagonal form the POM moleculesform 95heliceswith G...G conformationof the units [3-5]. The polymer chain of orthorhombie POM is in the form of a 21 helix [6]. X-radiograms and infrared spectra of these modifications are available in the literature. The present paper deals with an investigation of new structural modifications of PDO and POM. Preparation of the new forms of these polymersis based on the fact that parameters of the helix should be dependent on the conditions of treatment of the polymer (temperature,solvent, conditionsof crystallization, etc.) [7, 8]. In addition the conformationof macromoleculesis altered most substantially by change in the conditions of polymerization [9]. * Vysokomol. soyed. AI6: No. 4, 698-704, 1974.

804

B.V.

OZ~ROVSKII

EXPERIMENTAL The modification PDOI was prepared by the polymerization of 1,3-dioxolane in bulk, with BF3-etherate as catalyst, and in benzene with SnCI4 as catalyst, M ~ 2 X l04. F o r preparation of PDOH 1,3-dioxolane (2.7 mole/L) was polymerized at room temperature in m e t h y l methaerylate (MMA) containing SnCI4 ( 2 x I0 -* mole/].) as catalyst. The PDO~x separated on the walls of the reaction vessel in the form of transparent droplets. I t was dried in air at room temperature, M ~ l - 5 x l04. Trioxan was polymerized in partially polymerized MMA at 20°C. The concentrations of trioxan were 1-1 and 2.5 mole/]. The partially polymerized MMA syrup at the desired degree of conversion was prepared in the light in the presence of SnCI 4 (2 X l 0 -* and 4 X 10 -8 mole/].). POI~ appeared in the solution in the form of "filaments". The isolated polymer was dried in air. F r o m the intrinsic viscosity measured in DMF at 150 ° M _~ 105. Infrared absorption spectra were recorded in a UR-20 spectrophotometer, with speei. mens in the form of films (PDO) or pellets with K B r (POM and some modifications of PDO). X-radiograms were obtained with a LTRS-60 instrument in an RK U - 1 1 4 camera and in an R K O P " A " camera, using filtered CuK, radiation. Starting materials, l)ioxolane was treated with granular K O I I , dried over metallic sodium, refluxed over sodium and redistflled through a fraetionating column, b.p. 75"6 °. Trioxan was recrystallized from water and then dissolved in ether. The solution was treated with K O I I and metallic sodium. The ether was distilled off then the trioxan was redistilled through a fractionating column from metallic sodium, b.p. 114.5 °. Stannie chloride, anhydrous, pure grade, was used without preliminary purification.

RESULTS AND DISCUSSION

Polydioxolane. As a result of these investigations it was discovered tha~ in addition to the structure proposed in reference [2], PDO can exist in two other modifications, PDOII and PDOm. The structure of the molecules and the crystal structure of P D 0 change when the conditions of polymerization are altered. The

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FIe. I. Infrared spectra of PDOI (I), P D O n

(2) and P D O m

(3).

Structural modification of polydioxolane modification PD0~ polymerized ~

is f o r m e d w h e n

805

1 , 3 - d i o x o l a n e is p o l y m e r i z e d i n p a r t i a l l y

c o n t a i n i n g SnC14 as c a t a l y s t . A t 3 6 - 4 0 ° P D O ~ is c o n v e r t e d

t o P D O m . N o t e t h a t w h e n 1 , 3 - d i o x o l a n e is p o l y m e r i z e d i n b e n z e n e w i t h SnC14 as c a t a l y s t o r d i n a r y P D O I is o b t a i n e d . T h i s s h o w s t h a t t h e v i s c o u s m e d i u m o f p a r t i a l l y p o l y m e r i z e d M M A is e s s e n t i a l f o r p r o d u c t i o n of P D 0 ~ . TABLE 1. IN]rRAREDSP~.CTRAOF eRYST.~T.IN]~MODIFICATIONSOF PDO PDOI V, Crtl-i 2962 2943 2931

PDOII I

v, cm_ 1 2962

I

'1 I

m

PDOIII v, cin_ i

I

2966

m

2933 2918

w w

2891

w

PDOI

laDOii

v, cm- i

I

v, om_ 1

I

1195 1173

m v. s

1195 1169

v. w v. s

1120

v.s

1124

v.s

1091 1074

v. s v. s

,

v, / ortl_ 1 [

2912 2905 2886 2828 2808 2786 2756 2722 1476

! 2886 2781

1353 1327 1322 1297 1279 1251

v. w v. w I 1

1050

v. s

1035

v. s

995 1463

1459 1451 1425 1414 1402

m

1419 1401 1369

1315 1295

1453 1424

m w

930

m

~ 1398 1371

w w

1330 v.w t m ! 1292 ! 1275 m 1238 i 1225

w

847 838 640 620

s s v. w w

531 509 470

w w v. w

P

]

1253

w v. w m w

v.s v. s

980

v.s

v.s

m

w w w

1027 1008

915 880 855 828 640 614 554 527 487

PD0m

1168 1138

w v.s

1105

w

1055 1045 1037

v. s v. s v. s

1003

m

965 918 900 w 882 m i 855 w i 818 v. w I 645 v. w v.w I w 527 w 457 v.w

I

v. s m w m w w m

]

w v. w

T h e s p e c t r a o f t h e s e m o d i f i c a t i o n s o f P D O are p r e s e n t e d i n T a b l e 1 a n d F i g . 1. T h e region of the s p e c t r u m m o s t sensitive to c o n f o r m a t i o n a l changes in the P D O c h a i n is t h e 8 0 0 - 1 5 0 0 c m -1 r e g i o n , i n w h i c h , i t is well k n o w n , lie t h e f r e q u e n c i e s o f t h e v c - o a n d v c - c s k e l e t a l v i b r a t i o n s ( 9 0 0 - 1 1 4 0 cm-1), t h e scissors v i b r a t i o n o f t h e CH2 g r o u p s ( 1 4 4 0 - 1 5 0 0 c m -1) a n d all t y p e s o f e x t e r n a l d e f o r m a t i o n v i b r a t i o n s o f t h e CH~ g r o u p ( ~ 1 2 0 0 - 1 4 3 0 a n d N 8 0 0 - 9 2 0 cm-~). I n o u r case o n p a s s i n g from PDOI to PDO~ and PDOnI the following changes occur in the spectrum i n t h e 8 0 0 - 1 5 0 0 c m -1 r e g i o n . I n t h e s p e c t r u m o f P D O u s t r o n g b a n d s a p p e a r t a 980, 1008, 1027, 1074 a n d 1091 c m -1 a n d t h e 995, 1035, 1050, 1140 a n d 1 3 5 8 c m -1

806

B.V.

Oz~itovsx.ii

b a n d s a r e a b s e n t . I n t h e i n f r a r e d s p e c t r u m o f P D 0 m b a n d s a p p e a r a t 965, 1045, 1238 a n d 1371 c m - * a n d t h e r e is n o a b s o r p t i o n i n t h e 930, 1120, 1251 a n d 1358 c m -* regions.

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cf

I0

12

14 ~ , lO-~ ¢ m -I

FIG. 2. Infrared spectra of a 1 % solution of PDOI in CCl, (I) and of P D O m

(9).

Comparative study of the spectra of the polymers in the crystalline and molten states provides the possibility of distinguishing bands that are split as a r e s u l t o f i n t e r m o l e c u l a r i n t e r a c t i o n [10]. TABLE 2. P~ESULTS OF MEASUREMENT OF T~L~ P]DO DIFFRACTOGRAMS PDOt

PDOu

20

(0uK=) 22.3 26 30"4 34.1 35.7 38-3 41 43.3 46"2 50.7 55.4 57.6 62.5

PDOI

20

I

PDOn

20

(CuK=)

X

(CuK=)

20

1

(CuK~)

I

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v. s

11.4

s

65"8

v. w

39.6

m

s m s m m m w m s w w v. w

13.2 14'2 15.7 16.9 20.8 21.6 28.9 30"3 32.4 34.1 35-8 38.9

m m s s m v. m v. w m v. s w

68"5 73"3

v. w v. w

41.1 41.8 43.7 46 46.5 47"3 50.9 52.2 53.3 54 54.2 58"4

w m w m w m v. w v. w w w v. w

Analysis of the spectra gives grounds for thinking that such marked changes in the spectra on passing from PDOz to PDOn and PDOm are brought about by difference in the conformation of the chains in the crystalline regions of the

Structural modificationof polydioxolane

807

polymers. It is seen from a comparison of the spectra (Fig. 1) that the infrared spectrum of PDOI in the main contains all the bands characteristic of PDO~ and PDOm. It may therefore be supposed that the polymer chain of PDOI contains segments with the characteristic conformations of both PDOII and PDOm.

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FIO. 3. Infrared spoctra of samples of P O M obtained by polymerization of trioxan with SnCI~ in partiallypolymerized M M A at 15% (1) and 5 % (2) conversion,and in pure ~ A (3) (pelletswith KBr). It is easily seen from Fig. 2 that the vibration frequencies for P D O I in solution are the same as for a crystalline sample of PDOnl. The slight splitting of

the PDOIH bands is obviously caused by intermolecular interaction in the crystalline regions of the polymer. Thus these results ~ndicate that in solution the polymer chains of PD01 take up the conformation of the PDO~r chains. The values of the angles 20 and the intensities I of the corresponding reflections were found from the X-radiograms of PDOI and PDO~ (Table 2). It has not yet been possible however to obtain a satisfactory X-radiogram of PDOm and therefore in this paper this new form of PDO is characterized only spectroscopically. The substantial differences in the X-ray diffraction patterns of PDOI and PDOH suggest that the lattice parameters of these two modifications are different. Polyoxymethylene. It is well known that when trioxan is polymerized with cationic catalysts in ordinary solvents (benzene, cyclohexane, nitrobenzene, etc.) highly crystalline POM is formed, the molecules of which are in the form of 95 helices. Whcn trioxan is polymerized in MMA orthorhombic POM is not formed and therefore w(~ present below a comparative study of the new structural modification of PO1V[ and its hexagonal form. It is seen from the spectra presented in Fig. 3 that when trioxan is polymerized with SnC14 in pure 1VI1VIAthe P O ~ formed gives a spectrum identical with the spectrum of hexagonal POM. The infrared spectrum of the POM prepared in a 5% partially polymerized MMA syrup shows considerable differences in the region

808

B.V.

OZERO~'SKII

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FIG. 4. Infrared spectra of samples of POM prepared in partially polymerized MMA at the following concentrations: trioxan 2.5 mole/1, and SnC144 × 10-* mole/1. (•); trioxan 1.1 mole/ /1. and SnC1, 2 × 10-* mole/1. (2); hexagonal PONI (3). sensitive to c o n f o r m a t i o n a l changes o f t h e p o l y m e r chain. T h e i n t e n s i t y of the 457, 903 a n d 1238 cm -1 bands falls and additional a b s o r p t i o n occurs in t h e 980 a n d 1125 em -1 regions. T h e greatest changes in the P O M s p e c t r u m occur w h e n f00 8O

I

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It

g5 8

I

I

I

l

I

12

r

I

tl

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I

30

v. lO-Zcm-1

~ G . 5. Infrared speotra of a 1% solution of POM in D M F (1) and of POM fl'om p ~ i a l i y

polymerized MMA. t r i o x a n is polymerized in a 15% syrup. T h e bands a t 457, 631 a n d 903 cm -1 disappear, t h e 1238 c m -1 b a n d becomes v e r y w e a k a n d the 980 a n d 1125 cm -I bands become strong. I t was f o u n d t h a t the infrared s p e c t r u m of P O M is d e p e n d e n t on t h e conc e n t r a t i o n of SnC14 in the MMA s y r u p a n d on t h e initial c o n c e n t r a t i o n of t r i o x a n (Fig. 4). F r o m t h e spectra p r e s e n t e d it is seen t h a t t h e bands a t 457, 631, 903, a n d 1238 cm -1 are stronger in t h e first instance t h a n in t h e second.

809

Structural modification of polydioxolane

The very unusual spectrum of POM prepared in a 15% MMA syrup assisted in the search for the conditions for the existence of POM with the same chain conformation. A 1 °/o solution of POM with the trade name Delrin was prepared in DM:F at 150 °. Subsequent slow cooling of this caused the polymer to crystallize.

iiiiii FIG. 6. X-radiograms of hexagonal POM (a) and of POM prepared in 15% partially polymerized MMA (b). The infrared spectrum of POM in solution in DMF or tetrachloroethane at 20 ° has additional bands at 1015 and 1150 cm -1 and the 903 cm -1 band is absent (Fig. 5). The general form of the spectrum of POM prepared in partially polymerized MMA is very similar to the spectrum of a 1% solution of POM in DMle (allowing for some shift of some bands, namely 1015-~980 cm -1 and 1150-* 1125 cm-1). These experimental results give grounds for the following conclusions. Firstly the viscous polymeric matrix of PMMA affects the conformation of the POM chain and this in turn is reflected in the infrared spectrum. Secondly all the changes occur in the 400-1500 cm -~ region and the infrared spectrum of the polymer occupies an intermediate position between the spectra of hexagonal POM and POM prepared b y polymerization of trioxan in 15% partially polymerized MMA. It is now necessary to find what vibrations of the polymer chain of hexagonal POM correspond to the absorption in the 400-1500 cm -1 region. The calculated normal vibrations of the 95 helical chain of POM with G...G conformation of the units are in good agreement with experiment [7, 11]. In the region of the skeletal vibrations there are bands at 457, 631, 903, 938, 1097 and 1238 cm -1. Figure 6 shows the spectrum of ordinary POM, which is in agreement with spectra published in the literature.

810

B. V° OZEROVSKII

The bands at 457 and 631 cm -1 are produced b y deformation vibrations of the polymer chain backbone in the helical form. In the main the valence angles and angles of internal rotation are involved in these vibrations. In theoretical analysis the skeletal deformation vibrations are included among the normal vibrations of an infinite polymer chain. Consequently for these bands to appear in the spectrum the segments of the P 0 M macromolecules having a helical conformation must be fairly long. The bands at 938 and 1097 cm -1 correspond to the symmetrical and asymmetrical vibrations of the C--O group. It is shown in references [3] and [9] that the band at 903 cm -~ is produced b y interaction of the rocking vibrations of the CH~ group with the skeletal vibrations of the P01~I chain. The high intensity of this band is explained b y the helical conformation of the chain. The band at 1238 cm -~ is produced b y interaction between the rocking vibrations of the CH s group and deformation vibrations in the helical POM chain. It is considered that the intensity of this band can be used as a measure of the proportion of helical segments in the chain. Thus the theoretical data and experimental evidence indicate that the bands in the 400-1500 cm -~ region are associated with the chain transformation of hexagonal PON[. As was mentioned above, it is in that region that we find the greatest difference in the spectrum of the polymer prepared in partially polymerized (Fig. 3). The evidence in the literature and our results suggest that under these polymerization conditions the conformation of the POYI chain is altered. In the region of the valency vibrations of the CH group hexagonal P0!~I gives bands at 2790, 2920, and 2978 cm -1 while the spectrum of POM prepared in the MMA syrup contains a single band with a maximum at about 2920 cm -1. It is seen from the X-radiograms, that the POM molecules produced b y polymerization of trioxan in partially polymerized MMA with SnCla as catalyst, form a highly crystalline product (Fig. 6). The reflections in this X-radiogram are somewhat different from those in the X-radiograms of hexagonal and orthorhombie P O ~ published in the literature. The infrared spectrum and X-radiograms indicate a new structural modification of POM. Change in the structure of the polymer chains exerts an effect on the morphology of POM. Polymerization of trioxan in partially polymerized MMA, eatalysed b y SnC14, produces a fibrillar supermolecular structure and a helical form of the POM. Translated by E. O. PHrLL~PS REFERENCES 1. V. P. ROSHCI~JPKI~, B. V. 0 Z ~ 0 V S K H

L. M. VOLKOVA and G. V. KOROLEV,

Vysokomol. soyed. Bg: 723, 1967 (Not translated in Polymer Sci. U.S.S.R.) 2. E. F. OLEINIK and N. S. YENIKOLOPYAN, Vysokomol. soyed. Ag: 2609, 1967 (Translated in Polymer Sci. U.S.S.R. 9" 12, 2951, 1967)

Deformational properties of crystalline polypropylcne

811

3. M. TADOKORO, T. YASUMOTO, S. MURAHASKI and I. NITTA, J. Polymer Sci. 44: 266, 1960 4. G. A. CARAZZOLO, J. Polymer Sei. A I : 1573, 1963 5. H. TADOKORO, M. KABAYASHI, Y. KAVAGUCHI and S. MURAHASHI, J. Chem. Phys. 38: 703, 1963 6. G. A. CARAZZOLO and M. MAMMI, J. Polymer Sol. AI: 965, 1963 7. V. ZAMBONI and G. ZERBI, J. Polymer Sei. A2: 153, 1964 8. E. F. OLEINIK and N. S. YENIKOLOPYAN, Vysokomol. soyed. 8: 583, 1966 (Translated in Polymer Sci. U.S.S.R. 8: 4, 638, 1966) 9. A. NOVAK and E. WHALLEY, Trans. F a r a d a y Soc. 55: 1485, 1959 10. A. S. DAVIDOV, Teorya pogloshcheniya sveta molekulyarnymi kristallami (Theory of Light Absorption by Molecular Crystals). Izd. Akad. Nauk SSSR, 1951 11. L. MORTH.L~tRO, G. GALIAZZO and S. BEZZI, Chimica e industria 46: 139, 1964

EFFECT OF PLASTICIZATION ON THI~ DEFORMATIONAL PROPERTIES OF CRYSTALLINE POLYPROPYLENE* G. P. A3DRIANOVA, A. V. YEFIMOV, N. IV[. STYRI:KOVICH a n d P. V. KOZLOV M. V. Lomonosov State University, Moscow A. V. Topehicv Institute of Petrochemical Synthesis, U.S.S.R. Academy of Sciences

(Received 10 March 1972) I t is shown that addition of polyethylsfloxane fluid to polypropylono brings about change in both the mechanical properties and the mechanism of deformation of spherulitic films of the polymer. Elongations of the order of 300°/o can be attained at room temperature without substantial molecular orientation. A method is proposed for generalizing the data on the temperature dependence of the conditions for transition to a neck on the concentration of the silicone fluid.

O~E of the most widely used methods in the technology of plastics for modifying their physicomeehanical properties, is that of blending them with low molecular components, called, in the very widest sense, plasticization. The usuM approach to an explanation of the effects so produced involves the idea of increase in the free volume of the system on molecular blending of the polymer with the plasticizer. This mechanism can obviously play a large part when the plasticizer content of the system is fairly high. Meanwhile the existence of stable supermoleeular structures within the boundaries of both the amorphous and crystalline regions of polymers, which remain complete under mechanical action and are capable of moving along the surfaces of separation between them, gives these boundaries a specific role in the mechanical behaviour of the polymer. This * Vysokomol. soyed. A16: No. 4, 705--712, 1974.