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Relaxation transitions and the structure of polyethylene
RELAXATION TRANSITIONS AND THE STRUCTURE OF POLYETHYLENE* L
A. 0SINTSEVA, L. Y u . ZLATKEVICH, M. ]3. KONSTANTINOPOL'SKAYA, V. G. I~IKOL'SKII, V. A. SOKOL'SKII a n d A. V. KRYUKOV Chemical Physms Institute, U.S.S.R. Academy of Sciences L Ya. Karpov Physmal Chemistry Research Institute (Revewed 5 June 1972)
The structure and the properties of the "Rlgldex" ethylene product, produced by crystalhzatlon from the melt under normal conditions, or under high pressure, and from the solution, were investigated. The y- and ~-relaxatlon transitions of these samples, and the activation energies of relaxation were studmd m the range 100-270 °K by rachothermolummescence (RTL). The low temperature tranmtlons took place m the various samples m the range 200-225°K. At still lower temperatures there were transitions at 190, 170 and 150°K, and also around 125°K. The positions and intensities of these tranmtlons greatly depended on the fine structure of the samples. Increasing the pressure during erystalhzatlon resulted m a gradual weakening of the p-tranmtlon. The same samples yielded records with intense peaks at 150 and 190°K. The results were examined from the aspect of the collective features of the relaxation processes. Various types of local relaxatmn processes in the ~gmns of defective crystal structures were also examined.
THE r e l a x a t i o n s p e c t r u m of a p o l y m e r , especially o f p o l y e t h y l e n e (PE), will in m o s t eases c o n t a i n a-, fl-, y- a n d ~-relaxation processes [1-6]. T h e a- a n d y-processes h a d b e e n f o u n d to h a v e a c o m p l i c a t e d structure, i.e consist of several processes h a v i n g similar a c t i v a t i o n energies. A n indication of this is t h e presence in t h e ga n d ~-peaks of t h e m e c h a n i c a l loss curves of a fine s t r u c t u r e [3, 4], a n d on t h e r a d i o t h e r m o l u m i n e s c e n e e ( R T L ) curves [7, 8]. T h e m e c h a n i s m o f m o l e c u l a r r e l a x a t i o n a n d t h e e s t a b l i s h m e n t o f t h e connection b e t w e e n t h e characteristics o f t h e r e l a x a t i o n processes a n d t h e superm o l e c u l a r o r g a n i z a t i o n in P E are of considerable interest. Studies of t h i s n a t u r e are b e s t carried o u t on s a m p l e s p r o d u c e d f r o m t h e s a m e original P E b a t c h , as t h e m o l e c u l a r r e l a x a t i o n d e p e n d s on t h e c r y s t a l l i z a t i o n conditions as well as on t h e m o l e c u l a r w e i g h t d i s t r i b u t i o n (MWD), t h e c o n c e n t r a t i o n s of s u b s t i t u e n t s or b r a n c h e s a n d a whole series of o t h e r factors. I n this w o r k we i n v e s t i g a t e d t h e s t r u c t u r e a n d t h e r e l a x a t i o n t r a n s i t i o n s on P E s a m p l e s p r o d u c e d b y crystall i z a t i o n fr~)m t h e m e l t a t n o r m a l a n d a t high pressures, a n d also f r o m solution. * Vysokomol. soyed. A16: No. 2, 340°348, 1974. 394
Relaxatmn transttmns a n d the structure of polyethylene
395
EXPERIMENTAL The maternal studmd was a "Rlgidex" P E with a mol.wt, of 80,000. The P E granules (samples A or original) had almost the same structure as those produced b y cooling the melt at a rate of 30-50°C/see. The P E single crystals (samples B) were produced from a 0.1~/o solution of polymer m trmhloroethaue (TCE) cooled at a rate of l°C/mm. The crystal suspension was filtered at 77°C through a glass filter and vacuum suctmn was then applied until the weight was constant. The solvent concentratmn in this material did not exceed 0 02 ~/o w/w aceordmg to infrared spectroscopy. THE STRUCTURAL PARAMETERS OF THE STUDIED SA~P:LES
Arbitrary sample symbol A B B-1 B-2 C D E-1 E-2 E-3
TO~ ~
77-78 77-78 77-78 132 128 210 240 270
Density, g/cm a
%
0 9565 0 9840
70'5 90
0 9682 0.9686 0 974O 0 9873 0 9940
74.5 74-6 82 5 92 95
mp, °C 132 136
134 134 137 139 144
Larger permd, /k 120 110 189 600 240 240 220 :Not fixed
fl-Peak intensity in RTL, rel. u m t s 1
> 0 002 ~ 0-005
~ 0-01 0-1-0 05 0.1-0.05 0.6 0-3 0-2-0 1
The single crystals produced m thin way wore tempered at 120°C m hermetmally sealed cells (sample B-I), or a t 132°C (sample B-2), after winch they were slowly cooled to 20°C. Films with anjaular spheruhtes (samples C) were produced from 0"2~o P E solutions in xyleno on hot glycerol at 132°C, after whmh the glycerol was washed off with dmtflled water and the sample subjected to vacuum. The xylene content of the sample after such t r e a t m e n t was less t h a n 0 . 1 7 ~ w/w. The samples with large ra&al spheruhtes (samples D) were produced b y crystalhzah e n from the melt at 128°C for 1 5 hr. P E crystals wath a predominantly straight chum conformahon (samples E) were produced b y isothermal crystalhzahon at 210-270°C at 300-7000 a t m pressure from the melt. The apparatus used for this purpose was desembed m an earher report [9]. All the samples were subjected to small a n d wide angle structural X-ray analysm using instruments URS-50I and KRM-1 [10]. The structure was also studied under the optical microscope MI:N-8 and b y electron-nneroscope JEM-5. The molt.rag temperatures of the samples were deternnned b y DTA nsmg the apparatus of [11] The crystallmity x was determined from the density p measured b y the gradmnt tube method, 1.e. x~(p--pa)/ /(pk--pa). I t was assumed for calculation purposes t h a t the density of amorphous P E is pa=0.853 g[cm 3 wlnle that of the crystalline P E is pk----0-936 g/cm 3 [12]. The relaxatmn transition temperature ranges were determined b y the R T L method from the peak positions on the luminescence curves [13, 14]. The samples were freed under v a c u u m from a n y gas absorbed m them at 77°K, lrra&ated m glass ampoules with a ?-ray dose of 1 Mrad maximum, and were then heated m a cryostat. I t was noticed t h a t the pomt m n of the ~-peak m tiae R T L of a n y polymer corresponded with t h a t of the dmlectrm or mechanical losses to within 0 1-1 Hz, a n d agreed fairly well with the glass temperature Tg determined b y the dllatemetrm method [15, 16]. A similar comparison can also be made for the low temperature peaks To determine the a c h v a t m n energy of relaxatmn Ea we made
L. A. OSn~TSEVAe$ aL
396
use of the initial rate method [17] and stepwlse heating of the ]rradaated sample to consecutlvely higher temperatures. Earlier we had shown that the values of Ea produced by this method corresponded with those determined from the temperature dependence of relaxation frequency [17]. RESULTS
The f a c t t h a t several platelets were observed to p r o t r u d e in the shape of a " s h e a f " f r o m t h e surface of the cut, and t h a t t h e y were s y m m e t r i c a l l y a r r a n g e d relative to the centre, led to the conclusion t h a t the original P E h a d a spherulitic
la
FIa. 1. Electron-mmroscope photographs of the following specimens: a--A; b--B; e--C; f D; g--E; c--smglo crystal; d--specunen B, annealed at 142°C. Fro. 4 Mmrophotographs off a--specimen C; b--specimen D.
Relaxation tranmtlons and the structure of polyethylene
397
structure (Fig l a) The dimensions of the structural parameters are listed m the Table The luminescence curves of sample A (Fig 2) show an intense fl-peak m the range 200-240°K (the fl-peak temperature equals 223°K) and also three low temperature peaks, 1 e one at about 125°K. (It must be pointed out that this peak on the R T L curve could be false as it is close to the irradiation temperature .of the sample, i e. about 20-40°K irom it, so that it could represent only a part of a larger peak situated at a still lower temperature. To make sure that this peak is real it will be necessary, if possible, to reduce the irradiation temperature of the sample), and two less pronounced ones at 151 and 171°K. ~felant/s 78
!
f50
250 ~ °K
FIo. 2. 1--Th~ RTL curve, 2--the actlvahon energy of relaxation, of a sample of A. The activation energy m the range 100-135°K for sample A equals 6-5 kcal/mole, b u t 11 kcal/mole in the range 145-170°K. This difference in the values of Ea measured at different sections of the curve of the fl-peak is typical; it increases from 16 to 25 keal]mole as a function of temperature The structural non-uniformity of the polymer is known to result in a broadening of the relaxation transition range and the corresponding broadening of the peaks on the mechanical loss curves, but also on those of R T L As in the case of the earlier studies on low density P E samples [17], the low temperature peaks were found to be several times "wider" than the "elementary" peaks. (The latter are those of a uniform relaxation process, i e one having a single relaxation period This question is dealt with m greater detail elsewhere [17]) In contrast to other types of PE, the original "Rigidex" sample also has a very broad fl-peak. Its half-width is 2-2.5 times greater than that of an "elementary" peak; this appears to be due to the presence of a broad distribution of fl-relaxation periods The P E samples cooled at a rate of 30-50°C/see from the melt had the same luminescence curve as the samples of type A. Reduction of the cooling rate during preparation of the sample produced a lower fl-peak intensity and the peak itself was displaced towards lower temperatures.
L. A OSI~TSEVAe$ al.
398
Figure lb shows that the single crystal of sample B was 15-20/~m in dimension; the platelet was 90 A thick The unit cell calculation based on the electron photograph showed it to be orthorhombic; a----7.35 and b=5.05/~. This agrees well with the published data [18].
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~oK 250
Fro. 3. The RTL curves of: /--samples B; 2--B-l; 3--B-2; 4--after heating a sample of B at 142°K and coohng at l°K/mm; 5--Ea of sample B. Vacuum tempering at 120 and 132°K did not alter the external appearance of sample B. The X-ray studies showed a gradual enlargement of the larger period of the crystal L002. Heating to above the melting temperature (Tm=142°C), followed by slow cooling from the melt produced considerable morphological change, i.e. a spherulitic structure formed in the sample (Fig. ld). The most intense peak on the RTL curve of samples B (Fig. 3) was situated around 125°K. The high temperature descending part from this peak showed other less distinct peaks, i.e. at about 150 and 170°K The determination of Ea in the range 100-140°K on the B samples did not exceed 7.5 kcal/mole. Begining from 140°K, Ea raises and at 170-200°K gave values between 13 and 17 kcal/mole. The very weak fl-peak can be found in the range 200-230°K. Ea for the ]?-relaxations was 25 kcal/mole. A typical feature of the B samples is the low RTL intensity throughout the temperature range studied Heating of the B sample at 120 and 132°K was accompanied by a 5 to 10-fold increasing in RTL intensity, but the positions of the individual peaks and their relative intensities remained almost the same (Fig. 3). Note that all the RTL curves in Fig. 3, and those in Figs. 2, 5 and 7, were standardized to the unit height of the most mtense peak. To compare the sample intensities with each other it was necessary to make use of a Table in wh,ich the fl-peak intensity of sample A was taken as the standard unit. The result of heating sample B at 142°K and of slow cooling from the melt a l°K/min caused a further multiple RTL intensity increase so that the curve showed an intense fl-peak around 200°K (Fig. 3, curve 4). A similar curve was got also when A ~amples were heated under the same conditions.
Relaxatmn transttmns and the structure of polyethylene
399
The annular spherulites (samples C) had uniform dimensions and the width of thc rings remained constant (0.5/~m) (Fig. 4a). The study of carbon-palladium replicas of the C sample (Fig. le) showed the spherulites to consist of regularly alternating zones which had approximately the same dimensions of 150 A. The RTL curves of the C samples showed several peaks of approximately the same intensity (Fig 5, curve 1), i.e. about 125, 148 and 167°K; some of the samples also showed a peak at 185°K The fl-peak in the range 210-215°K is less distinct t h a n for the A samples. The use of a polarization microscope with the D samples showed radial spherulites to be present (Fig. 4b). The replica of the D sample under the electron microscope (Fig. l f) gives the picture of twisted platelets without sharp boundaries between them Typical is that the C- and D samples had approximately the same crystalhnity (75%), larger period and Tm
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1
I
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I00
I
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FIG 5
750 ~°K
"~1 b
150
15~
250 T,°K
Fm 6
FIG 5. The RTL curves of. l--C; 2--D samples FIG. 6. 1--RTL curves, 2--Es for samples a--E-l; b--E-2; c--E-3, d--E-3 tempered at 160°C under normal pressure The RTL curve of the samples of D {Fig. 5, curve 2) is identical with that of C. One can also see here again the 3 low temperature peaks in the range 125,.,148 and 168°K, and also the fl-peak at about 205°K; the position is several degrees lower than t h a t for the C sample. I t must be pointed out that the shape of the RTL curve of the samples is
400
L. A. OSII~TSEVAe$ al.
sensitive to the slightest change of the heat treatment conditmns and particularly to those of cooling rates used after crystallization. The electron photommrographs of the samples of E crystallized under 7000atm pressure make it clear (Fig. lg) that the samples consist of individual 1-3/~m dimension blocks. Increase of pressure from 3000 to 7000 arm was accompanied b y increases in density and Tm.
t: ~a
\
q
FIG. 7. a--Platelet defects; b--defects of a PE crystal with straight chain conformatmns. /--complete vaca~acy; 2--relaxing end m a double vacancy zone; 3--mar~nal dislocation; 4--Renecker defects; 5--1rink block structure. The crystallization of P E under high pressure was accompanied b y a substantial change m the shape of the R T L curve (Fig. 6). In addition to this the sample became opaque. Comparisons made amongst them and also with other samples are difficult where R T L intensity is concerned. It was noticed however that luminescence for a samples of E was weaker than that of the original polymer. The reduction in intensity of luminescence was especially large in the fl-transition range. The crystallization under 7000 arm pressure almost completely suppressed the fl-peak. The intense R T L peaks of the samples of E are situated at 150 and 190°K. Good reproducibility of the temperatures of these peaks applied to the whole series of samples. However, those crystallized under practically identical conditions showed quite large differences in peak height at 150°K. The peak was very intense in individual samples of E and exceeded that situated at higher
Relaxation transitions and the structure of polyethylene
401
temperature b y a factor of 1.5-2.5 One can presume this to be due to considerable differences in the cooling conditions after crystallization One further, less intense R T L peak of E is present in the range 120°K. The Ea for relaxations of E smoothly increases as a function of temperature, as Fig. 6 shows This seems to be connected with the large non-uniformity of the samples, i.e the broadening of the whole spectrum of relaxation transitions The heating of samples of E at 160°K under normal pressure results in the change m shape of the R T L curve; a fl-peak appears and increases in size with the temperature, its position is at 223°K like for the original P E (Fig. 6d) There is a noticeable decrease in the peak before tempering at 150°K, after which the sample will show two peaks in the region, i e at about 148 and 162°K. A typical feature is that heating at 160°K had almost no effect on the position or intensity of the peak situated in the 190°K region. We were thus able to show for the first time m this Work that changes of the crystallization conditions and of tempering are accompanied b y changes of intensities and individual relaxation transition temperatures in the case of PE, as recorded b y R T L Such a difference will primarily appear in the position and intensity of the fl-peak of some samples. One notices at the same time that the relaxation processes of all the samples studied have much in common, such as the number of structural transitions and their individual positions, and approximately the same values of Ea Especially noticeable is the coincidence of the R T L curves for the samples of C and D. This appears to be connected with the fact that local as well as collective molecular relaxation processes mainly depend on the structure of the individual laminae rather than the dimension or t y p e of spherulites, on the defect concentrations present in them, the relative contribution made b y the disorder in the near-surface layer, i e on the 2A1/lo ratio (Fig 7), on the mutual positions of the laminae, the number of chains interlinking them, etc. Bearing all this in mind one can conclude that the spherulites of the samples of C and E are made up of the same structural units and differ only as regards their remote order. We shall now examine some of the relaxation transitions characteristics of P E In the 100-250°K range there are several transitions in the studmd polymer samples, i.e. the fl-transition of the A-samples around 223°K which varies between 200 and 240°K for the other samples, those around 150 and 170°K, 180-190°K which are most distinct in the case of samples of E, and the transition in the l10-140°K range. The fl-transitions of P E are normally associated with the start of collective relaxation in the parts with a chaotic arrangement of structures [1, 3, 19-21] Outstanding in this connection is the reduction of the fl-peak R T L intensities in the case of samples of E at increased pressures during the crystallization of P E From thls follows that the fl-process of P E depends to a large extent on the presence of folded surface layers. A typical feature of the fl-transitions of P E is that changes of crystallization
402
L. A OSlI~TSEVAet al.
or tempering conditions produce a distinct shift of the transition temperature [1, 22, 23]. The thickness of the layer with random order of structures between adjacent laminae of PE, 2Al (Fig 7), is not particularly large in most cases. The fl-relaxation process is therefore affected by the orderly distribution of the segments. This is also the reason for the appearance of different types of effects
]m
i I I
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I
I
i
I
I
t
t
Fzo 8. The loosening m layers near the surface of a lamella and thread formation during mmro-fissurmg. associated with the compression of the less orderly layer or with its stretching the resulting microfissures inside it, etc. The most probable reason for the reduction of fl-peak temperature which can be detected when melts are slowly cooled seems to be the microfissures which form between spherulites and the platelets present in them Such fissures will be produced by heat treatment, since any increase in density of the sample, gradual orientation of a steadily increasing number of macromolecules, the tightening of the network, the decrease of the number of chains passing from one lamella to another, etc., will not be accompanied by a radmal shrinkage of the spherulite [24]. The fissuring will result in stress reduction in the non-oriented laminae present between adjacent platelets and facilitate easier segmental movement. An important factor is t h a t fissuring will not result in the formation of a smooth surface layer. The presence of the interlinking chains, of "whips" or entanglements, the network interlinking adjacent platelets, will cause numerous thin threads consisting of several macromolecules to be present in the zone of the growing fissure, structures with a "window"-typelinkage [25], very small loop-shaped fold, i.e. "ciliate" shapes. The surface of such a fissure, as Fig. 8 shows, will greatly differ from the surface of a fissure forming in glass of low molecular weight, for example. As the smallest cooperating sub-system i n , h e fl-relaxation process is considerably larger t h a n one causing local relaxation, a considerable number of the segments present at the surface of the micro-fissure during its formation will participate in the local relaxation processes. This seems also to be the reason for the reduction of the fl-relaxation intensities when large enough spherulites form much more quickly in P E (see Table) when compared with the rate at which the total number of disarranged segments decreases.
Relaxatmn transltmns and the structure of polyethylene
403
The samples of B which had not been tempered had a very weak fl-peak, although their crystallinities did not exceed 90%. Such a result means that isolated platelets without intimate contact with others, have a very loose structure near the surface layer, so that no collective g-relaxation process is possible. In order to get a a-relaxation to appear it is necessary to have very close contact between platelets, and this can be attained b y heating the sample or b y applying pressure to it so that an "adhesive", fairly dense layer is produced A non-radiative inactivation of the states of excitation in a loose layer near the surface is highly probable as they form b y charge recombination. This is apparently the reason for the low R T L intensity of the samples of B throughout the 100-250°K range observed in our study The transitions in the 140-170°K range were earlier detected on the single crystals [2, 3] and on P E samples crystallized from the melt [1]. These were frequently thought to be associated with the movements of small segments (several methylene groups long) in the amorphous zones (?a-relaxation) [5, 26], the movements of individual segments at the surface of polymer crystals [5, 6, 26, 27], the reorientations of molecular chain ends ,nside the platelets (?c-relaxation) [19], or the reorientations in the region of defect vacancies which form as a result of a zig-zag chain contraction at right angles to its axis [28] It is difficult to give preference at present to any of the suggested mechamsms of ?-relaxations. The transitions detected b y us in the 150 and 170°K range and the Ea -----9-12 kcal/mole for all the samples in the 140-180°K range agree with those of y-transitions recorded in earlier studies [1, 3, 28] It is worth noting that the ?-transition (or transitions) ,s relatively weak in samples of A and B, but distinct in samples of C, D and E The decrease in Intensity of the fl-transit, on in the three samples mentioned last (compared with A-samples) is not accompanied b y a ?-peak weakening, and its intensity increased in some cases. This indicates that the ?a-relaxation makes only a small contribution to the ?-transition intensity. The local relaxation of the chain segments m the regions of the microfissures and vacancies seems to play the main part The transition in the 150°K range for samples of E is particularly intense. This is assocmted with the fact that the concentration of the defects (single and multiple vacancms, Renecker defects, etc ) must be exceptionally large in such samples because practically all the chain ends and branching points are here situated inside the parts having a straight chain conformation. The samples m addition contain a substantial number of microfissures. The whole ensures intense relaxation processes The tempering of these samples must result in the repair of the torero-fissures and of the larger defects, so that the ?-relaxations will become less intense as a result. The peak reduction in the 150°K range as a result of tempering of sample E can be seen in Fig. 6 The transition in the 180-190°K range is quite distinct only with the samples of E and some of samples of C. Samples with a larger values of lo and straight chain conformations will be more affected b y the presence of dislocation t y p e
404
L . A . OSINTSEVA et al
defects at the edges which form as a result of the vacancies migrating from the chain ends to the platelet surfaces, and due to the "sticking together" of chain ends (Fig. 7). Such dislocations ought to be very heat resistant and are not likely to disappear unless the samples are recrystallized The concentration of the dislocations at the edges of samples of E must be approximately the same as that at the chain ends and branches. On the basis of these features we believe that the 190°K transition having Ea----14-19 kcal/mole is determined by the presence of extremal dislocations or larger structural defects w]thm the limits of a part with a straightened chain conformation (e.g the presence of kink block structures examined by Pechhold [4]), and to be linked with a re-orientation of the Renecker defects near these dislocations. This points to high stab]lity of the peak to sample heating. The lowest of the recorded temperature peaks is situated in the l10-140°K range; it is evident in all the samples studied, but most intense in those of A and B, less so in samples of E. It is important that Ea is the same for all the samples in the l10-140°K range i e. 6-7.5 keal/mole This is probably the ya-peak (Tmax----llS-150°K. Ea~-5 kcal/mole) and the ?X-peak (Tmax=l18-127°K, Ea =7-7"5 keal/mole) detepted by Illers [20] and Buben and co-workers [14] respectively during the studies of the mechanical relaxations of PE We should also like to point out that low der~sity PE, amorphous-crystalline paraffin and polybutadiene elastomers have values of Ea which are also in the 5-5.5 kcal/mole range in the examined temperature range [17, 25]. Local relaxations of very small segments or terminal groups, relatively independent of the supermoleeular structural features, are likely to be responsible in all these cases. The authors express their thanks to N. F Bakeyev for his valuable criticisms of the results. Translated by K
A..Ar.T,~N
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Kmetms of polymerization and eopolymermatlon of MAS
12. 13. 14
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20. 21. 22. 23. 24 25. 26. 27. 28
405
KARCIN, Vysokomol. soyed. Ag: 1816, 1967 (Translated in Polymer Sei. U.S.S.R. 9: 6, 1473, 1967) E. I~.LLMUTH and R. WUNDERLIgH, J. Appl. Phys. 86: 3039, 1965 V. G. NIKOL'S~I~ and N. Ya. BUBEN, Dotd. Akad. Nauk SSSR 134: 134, 1960; Vysokomol. soyed. 4: 922, 1962 (Not translated in Polymer Sei. U.S.S.R ) N. Ya. BUBEN,'V. I. GOL'DANSIKII, L. Yu. ZLATKEVICH, V. G. NIKOL'SKII and V. G. RAYEVSKII, Vysokomol soyed. A9: 2275, 1967 (Translated in Polymer Sei. U.S.S.R. 9: 10, 2575, 1967) V. G. NIKOL'SKII, Ideen des exakten Wlssens, 555, 1971 V. G. NIKOL'SKII, Dmsertatmn, 1966 V. G. NIKOL'SKII and G. M. BURKOV, Khlm. vys. energn 5. 416, 1971 C. W. RUNN, Trans. F a r a d a y Soc. 35: 482, 1939 J. D. GORMAN, G. WILLIAMS and E. PASSAGLIA, Perekhody i relaksatmonnye yavleniya v pohmerakh (The Transitions and Relaxation Phenomena in Polymers). p. 193, Izd. "Mlr", 1968 K. H. Hff.ERS, Rheol Acta 3" 202, 1964 A. PETERLIN, Croatlca chemlea Acta 42: 335, 1970 E. PASSAGLIA, M. GORDON and G. M. MARTIN, ff Res. Nat. Bur. Standards A68: 519, 1964 A. CRISMANN and E. PASSAGLIA, ft. Res. Nat Bur Standards A7O. 225, 1966 I. MASAKAZU, J. Polymer Scl. 55: 443, 1961 Mc A. I. HUGH and I. M. SCHULZ, Phil. Mag. 24: 155, 1971 R. F. BOYER, Rubber Chem. and Technol. 36: 1308, 1963 J. WADA, R. NAYAKAWA and T. NISHI, ft. Polymer Sci C15: 101, 1961 I. M. SINNOTT, J. Polymer Scl. B3 945, 1965, Polymer Preprmts 6: 652, 1965
STUDY OF THE KINETICS OF POLYMERIZATION AND COPOLYMERIZATION OF METHACRYLIC ACID SUI~HOLANATE* A. I. VOROB'EVA,E I. ABLYAKIMOV, G. V. LEPLYANIN,S. 1:{,.RAJ~'LKOVand G. P. GLADYSHEV Chemistry Institute, Bashklr Branch U.S S.R. Academy of Sciences
(Recesved 7 July 1972) The kinetics of polymerization of methaeryhc acid sulpholanate (MAS) of its copolymemzatlon with methyl methacrylate, styrene and methacryhc acid were investigated. An increased activity of M_AS was notmed, when compared with the majority of known methacrylates, in the radical polymerazatlon reactions.
SULPHUR contaming polymers have a number of valuable properties, especially heat, temperature, light and chemical stability [1-4], large dielectric and physite-chemical characteristics [1, 5], good adhesion to various materials [6]. This * Vysokomol soyed. AI6: No. 2, 349-353, 1974.
A. 0SINTSEVA, L. Y u . ZLATKEVICH, M. ]3. KONSTANTINOPOL'SKAYA, V. G. I~IKOL'SKII, V. A. SOKOL'SKII a n d A. V. KRYUKOV Chemical Physms Institute, U.S.S.R. Academy of Sciences L Ya. Karpov Physmal Chemistry Research Institute (Revewed 5 June 1972)
The structure and the properties of the "Rlgldex" ethylene product, produced by crystalhzatlon from the melt under normal conditions, or under high pressure, and from the solution, were investigated. The y- and ~-relaxatlon transitions of these samples, and the activation energies of relaxation were studmd m the range 100-270 °K by rachothermolummescence (RTL). The low temperature tranmtlons took place m the various samples m the range 200-225°K. At still lower temperatures there were transitions at 190, 170 and 150°K, and also around 125°K. The positions and intensities of these tranmtlons greatly depended on the fine structure of the samples. Increasing the pressure during erystalhzatlon resulted m a gradual weakening of the p-tranmtlon. The same samples yielded records with intense peaks at 150 and 190°K. The results were examined from the aspect of the collective features of the relaxation processes. Various types of local relaxatmn processes in the ~gmns of defective crystal structures were also examined.
THE r e l a x a t i o n s p e c t r u m of a p o l y m e r , especially o f p o l y e t h y l e n e (PE), will in m o s t eases c o n t a i n a-, fl-, y- a n d ~-relaxation processes [1-6]. T h e a- a n d y-processes h a d b e e n f o u n d to h a v e a c o m p l i c a t e d structure, i.e consist of several processes h a v i n g similar a c t i v a t i o n energies. A n indication of this is t h e presence in t h e ga n d ~-peaks of t h e m e c h a n i c a l loss curves of a fine s t r u c t u r e [3, 4], a n d on t h e r a d i o t h e r m o l u m i n e s c e n e e ( R T L ) curves [7, 8]. T h e m e c h a n i s m o f m o l e c u l a r r e l a x a t i o n a n d t h e e s t a b l i s h m e n t o f t h e connection b e t w e e n t h e characteristics o f t h e r e l a x a t i o n processes a n d t h e superm o l e c u l a r o r g a n i z a t i o n in P E are of considerable interest. Studies of t h i s n a t u r e are b e s t carried o u t on s a m p l e s p r o d u c e d f r o m t h e s a m e original P E b a t c h , as t h e m o l e c u l a r r e l a x a t i o n d e p e n d s on t h e c r y s t a l l i z a t i o n conditions as well as on t h e m o l e c u l a r w e i g h t d i s t r i b u t i o n (MWD), t h e c o n c e n t r a t i o n s of s u b s t i t u e n t s or b r a n c h e s a n d a whole series of o t h e r factors. I n this w o r k we i n v e s t i g a t e d t h e s t r u c t u r e a n d t h e r e l a x a t i o n t r a n s i t i o n s on P E s a m p l e s p r o d u c e d b y crystall i z a t i o n fr~)m t h e m e l t a t n o r m a l a n d a t high pressures, a n d also f r o m solution. * Vysokomol. soyed. A16: No. 2, 340°348, 1974. 394
Relaxatmn transttmns a n d the structure of polyethylene
395
EXPERIMENTAL The maternal studmd was a "Rlgidex" P E with a mol.wt, of 80,000. The P E granules (samples A or original) had almost the same structure as those produced b y cooling the melt at a rate of 30-50°C/see. The P E single crystals (samples B) were produced from a 0.1~/o solution of polymer m trmhloroethaue (TCE) cooled at a rate of l°C/mm. The crystal suspension was filtered at 77°C through a glass filter and vacuum suctmn was then applied until the weight was constant. The solvent concentratmn in this material did not exceed 0 02 ~/o w/w aceordmg to infrared spectroscopy. THE STRUCTURAL PARAMETERS OF THE STUDIED SA~P:LES
Arbitrary sample symbol A B B-1 B-2 C D E-1 E-2 E-3
TO~ ~
77-78 77-78 77-78 132 128 210 240 270
Density, g/cm a
%
0 9565 0 9840
70'5 90
0 9682 0.9686 0 974O 0 9873 0 9940
74.5 74-6 82 5 92 95
mp, °C 132 136
134 134 137 139 144
Larger permd, /k 120 110 189 600 240 240 220 :Not fixed
fl-Peak intensity in RTL, rel. u m t s 1
> 0 002 ~ 0-005
~ 0-01 0-1-0 05 0.1-0.05 0.6 0-3 0-2-0 1
The single crystals produced m thin way wore tempered at 120°C m hermetmally sealed cells (sample B-I), or a t 132°C (sample B-2), after winch they were slowly cooled to 20°C. Films with anjaular spheruhtes (samples C) were produced from 0"2~o P E solutions in xyleno on hot glycerol at 132°C, after whmh the glycerol was washed off with dmtflled water and the sample subjected to vacuum. The xylene content of the sample after such t r e a t m e n t was less t h a n 0 . 1 7 ~ w/w. The samples with large ra&al spheruhtes (samples D) were produced b y crystalhzah e n from the melt at 128°C for 1 5 hr. P E crystals wath a predominantly straight chum conformahon (samples E) were produced b y isothermal crystalhzahon at 210-270°C at 300-7000 a t m pressure from the melt. The apparatus used for this purpose was desembed m an earher report [9]. All the samples were subjected to small a n d wide angle structural X-ray analysm using instruments URS-50I and KRM-1 [10]. The structure was also studied under the optical microscope MI:N-8 and b y electron-nneroscope JEM-5. The molt.rag temperatures of the samples were deternnned b y DTA nsmg the apparatus of [11] The crystallmity x was determined from the density p measured b y the gradmnt tube method, 1.e. x~(p--pa)/ /(pk--pa). I t was assumed for calculation purposes t h a t the density of amorphous P E is pa=0.853 g[cm 3 wlnle that of the crystalline P E is pk----0-936 g/cm 3 [12]. The relaxatmn transition temperature ranges were determined b y the R T L method from the peak positions on the luminescence curves [13, 14]. The samples were freed under v a c u u m from a n y gas absorbed m them at 77°K, lrra&ated m glass ampoules with a ?-ray dose of 1 Mrad maximum, and were then heated m a cryostat. I t was noticed t h a t the pomt m n of the ~-peak m tiae R T L of a n y polymer corresponded with t h a t of the dmlectrm or mechanical losses to within 0 1-1 Hz, a n d agreed fairly well with the glass temperature Tg determined b y the dllatemetrm method [15, 16]. A similar comparison can also be made for the low temperature peaks To determine the a c h v a t m n energy of relaxatmn Ea we made
L. A. OSn~TSEVAe$ aL
396
use of the initial rate method [17] and stepwlse heating of the ]rradaated sample to consecutlvely higher temperatures. Earlier we had shown that the values of Ea produced by this method corresponded with those determined from the temperature dependence of relaxation frequency [17]. RESULTS
The f a c t t h a t several platelets were observed to p r o t r u d e in the shape of a " s h e a f " f r o m t h e surface of the cut, and t h a t t h e y were s y m m e t r i c a l l y a r r a n g e d relative to the centre, led to the conclusion t h a t the original P E h a d a spherulitic
la
FIa. 1. Electron-mmroscope photographs of the following specimens: a--A; b--B; e--C; f D; g--E; c--smglo crystal; d--specunen B, annealed at 142°C. Fro. 4 Mmrophotographs off a--specimen C; b--specimen D.
Relaxation tranmtlons and the structure of polyethylene
397
structure (Fig l a) The dimensions of the structural parameters are listed m the Table The luminescence curves of sample A (Fig 2) show an intense fl-peak m the range 200-240°K (the fl-peak temperature equals 223°K) and also three low temperature peaks, 1 e one at about 125°K. (It must be pointed out that this peak on the R T L curve could be false as it is close to the irradiation temperature .of the sample, i e. about 20-40°K irom it, so that it could represent only a part of a larger peak situated at a still lower temperature. To make sure that this peak is real it will be necessary, if possible, to reduce the irradiation temperature of the sample), and two less pronounced ones at 151 and 171°K. ~felant/s 78
!
f50
250 ~ °K
FIo. 2. 1--Th~ RTL curve, 2--the actlvahon energy of relaxation, of a sample of A. The activation energy m the range 100-135°K for sample A equals 6-5 kcal/mole, b u t 11 kcal/mole in the range 145-170°K. This difference in the values of Ea measured at different sections of the curve of the fl-peak is typical; it increases from 16 to 25 keal]mole as a function of temperature The structural non-uniformity of the polymer is known to result in a broadening of the relaxation transition range and the corresponding broadening of the peaks on the mechanical loss curves, but also on those of R T L As in the case of the earlier studies on low density P E samples [17], the low temperature peaks were found to be several times "wider" than the "elementary" peaks. (The latter are those of a uniform relaxation process, i e one having a single relaxation period This question is dealt with m greater detail elsewhere [17]) In contrast to other types of PE, the original "Rigidex" sample also has a very broad fl-peak. Its half-width is 2-2.5 times greater than that of an "elementary" peak; this appears to be due to the presence of a broad distribution of fl-relaxation periods The P E samples cooled at a rate of 30-50°C/see from the melt had the same luminescence curve as the samples of type A. Reduction of the cooling rate during preparation of the sample produced a lower fl-peak intensity and the peak itself was displaced towards lower temperatures.
L. A OSI~TSEVAe$ al.
398
Figure lb shows that the single crystal of sample B was 15-20/~m in dimension; the platelet was 90 A thick The unit cell calculation based on the electron photograph showed it to be orthorhombic; a----7.35 and b=5.05/~. This agrees well with the published data [18].
I, re/unifs
/
~
//~(X-
lilr. ~, I~/X~X~-
~l I
I ~,'~ I ~
-
$ N::f-d ', /50
~oK 250
Fro. 3. The RTL curves of: /--samples B; 2--B-l; 3--B-2; 4--after heating a sample of B at 142°K and coohng at l°K/mm; 5--Ea of sample B. Vacuum tempering at 120 and 132°K did not alter the external appearance of sample B. The X-ray studies showed a gradual enlargement of the larger period of the crystal L002. Heating to above the melting temperature (Tm=142°C), followed by slow cooling from the melt produced considerable morphological change, i.e. a spherulitic structure formed in the sample (Fig. ld). The most intense peak on the RTL curve of samples B (Fig. 3) was situated around 125°K. The high temperature descending part from this peak showed other less distinct peaks, i.e. at about 150 and 170°K The determination of Ea in the range 100-140°K on the B samples did not exceed 7.5 kcal/mole. Begining from 140°K, Ea raises and at 170-200°K gave values between 13 and 17 kcal/mole. The very weak fl-peak can be found in the range 200-230°K. Ea for the ]?-relaxations was 25 kcal/mole. A typical feature of the B samples is the low RTL intensity throughout the temperature range studied Heating of the B sample at 120 and 132°K was accompanied by a 5 to 10-fold increasing in RTL intensity, but the positions of the individual peaks and their relative intensities remained almost the same (Fig. 3). Note that all the RTL curves in Fig. 3, and those in Figs. 2, 5 and 7, were standardized to the unit height of the most mtense peak. To compare the sample intensities with each other it was necessary to make use of a Table in wh,ich the fl-peak intensity of sample A was taken as the standard unit. The result of heating sample B at 142°K and of slow cooling from the melt a l°K/min caused a further multiple RTL intensity increase so that the curve showed an intense fl-peak around 200°K (Fig. 3, curve 4). A similar curve was got also when A ~amples were heated under the same conditions.
Relaxatmn transttmns and the structure of polyethylene
399
The annular spherulites (samples C) had uniform dimensions and the width of thc rings remained constant (0.5/~m) (Fig. 4a). The study of carbon-palladium replicas of the C sample (Fig. le) showed the spherulites to consist of regularly alternating zones which had approximately the same dimensions of 150 A. The RTL curves of the C samples showed several peaks of approximately the same intensity (Fig 5, curve 1), i.e. about 125, 148 and 167°K; some of the samples also showed a peak at 185°K The fl-peak in the range 210-215°K is less distinct t h a n for the A samples. The use of a polarization microscope with the D samples showed radial spherulites to be present (Fig. 4b). The replica of the D sample under the electron microscope (Fig. l f) gives the picture of twisted platelets without sharp boundaries between them Typical is that the C- and D samples had approximately the same crystalhnity (75%), larger period and Tm
Jr,eeLun/~ ./,,"elc~nds I I
1
I
o.o--o
I00
I
I
/50
ZOO
FIG 5
750 ~°K
"~1 b
150
15~
250 T,°K
Fm 6
FIG 5. The RTL curves of. l--C; 2--D samples FIG. 6. 1--RTL curves, 2--Es for samples a--E-l; b--E-2; c--E-3, d--E-3 tempered at 160°C under normal pressure The RTL curve of the samples of D {Fig. 5, curve 2) is identical with that of C. One can also see here again the 3 low temperature peaks in the range 125,.,148 and 168°K, and also the fl-peak at about 205°K; the position is several degrees lower than t h a t for the C sample. I t must be pointed out that the shape of the RTL curve of the samples is
400
L. A. OSII~TSEVAe$ al.
sensitive to the slightest change of the heat treatment conditmns and particularly to those of cooling rates used after crystallization. The electron photommrographs of the samples of E crystallized under 7000atm pressure make it clear (Fig. lg) that the samples consist of individual 1-3/~m dimension blocks. Increase of pressure from 3000 to 7000 arm was accompanied b y increases in density and Tm.
t: ~a
\
q
FIG. 7. a--Platelet defects; b--defects of a PE crystal with straight chain conformatmns. /--complete vaca~acy; 2--relaxing end m a double vacancy zone; 3--mar~nal dislocation; 4--Renecker defects; 5--1rink block structure. The crystallization of P E under high pressure was accompanied b y a substantial change m the shape of the R T L curve (Fig. 6). In addition to this the sample became opaque. Comparisons made amongst them and also with other samples are difficult where R T L intensity is concerned. It was noticed however that luminescence for a samples of E was weaker than that of the original polymer. The reduction in intensity of luminescence was especially large in the fl-transition range. The crystallization under 7000 arm pressure almost completely suppressed the fl-peak. The intense R T L peaks of the samples of E are situated at 150 and 190°K. Good reproducibility of the temperatures of these peaks applied to the whole series of samples. However, those crystallized under practically identical conditions showed quite large differences in peak height at 150°K. The peak was very intense in individual samples of E and exceeded that situated at higher
Relaxation transitions and the structure of polyethylene
401
temperature b y a factor of 1.5-2.5 One can presume this to be due to considerable differences in the cooling conditions after crystallization One further, less intense R T L peak of E is present in the range 120°K. The Ea for relaxations of E smoothly increases as a function of temperature, as Fig. 6 shows This seems to be connected with the large non-uniformity of the samples, i.e the broadening of the whole spectrum of relaxation transitions The heating of samples of E at 160°K under normal pressure results in the change m shape of the R T L curve; a fl-peak appears and increases in size with the temperature, its position is at 223°K like for the original P E (Fig. 6d) There is a noticeable decrease in the peak before tempering at 150°K, after which the sample will show two peaks in the region, i e at about 148 and 162°K. A typical feature is that heating at 160°K had almost no effect on the position or intensity of the peak situated in the 190°K region. We were thus able to show for the first time m this Work that changes of the crystallization conditions and of tempering are accompanied b y changes of intensities and individual relaxation transition temperatures in the case of PE, as recorded b y R T L Such a difference will primarily appear in the position and intensity of the fl-peak of some samples. One notices at the same time that the relaxation processes of all the samples studied have much in common, such as the number of structural transitions and their individual positions, and approximately the same values of Ea Especially noticeable is the coincidence of the R T L curves for the samples of C and D. This appears to be connected with the fact that local as well as collective molecular relaxation processes mainly depend on the structure of the individual laminae rather than the dimension or t y p e of spherulites, on the defect concentrations present in them, the relative contribution made b y the disorder in the near-surface layer, i e on the 2A1/lo ratio (Fig 7), on the mutual positions of the laminae, the number of chains interlinking them, etc. Bearing all this in mind one can conclude that the spherulites of the samples of C and E are made up of the same structural units and differ only as regards their remote order. We shall now examine some of the relaxation transitions characteristics of P E In the 100-250°K range there are several transitions in the studmd polymer samples, i.e. the fl-transition of the A-samples around 223°K which varies between 200 and 240°K for the other samples, those around 150 and 170°K, 180-190°K which are most distinct in the case of samples of E, and the transition in the l10-140°K range. The fl-transitions of P E are normally associated with the start of collective relaxation in the parts with a chaotic arrangement of structures [1, 3, 19-21] Outstanding in this connection is the reduction of the fl-peak R T L intensities in the case of samples of E at increased pressures during the crystallization of P E From thls follows that the fl-process of P E depends to a large extent on the presence of folded surface layers. A typical feature of the fl-transitions of P E is that changes of crystallization
402
L. A OSlI~TSEVAet al.
or tempering conditions produce a distinct shift of the transition temperature [1, 22, 23]. The thickness of the layer with random order of structures between adjacent laminae of PE, 2Al (Fig 7), is not particularly large in most cases. The fl-relaxation process is therefore affected by the orderly distribution of the segments. This is also the reason for the appearance of different types of effects
]m
i I I
I I j
I
I
i
I
I
t
t
Fzo 8. The loosening m layers near the surface of a lamella and thread formation during mmro-fissurmg. associated with the compression of the less orderly layer or with its stretching the resulting microfissures inside it, etc. The most probable reason for the reduction of fl-peak temperature which can be detected when melts are slowly cooled seems to be the microfissures which form between spherulites and the platelets present in them Such fissures will be produced by heat treatment, since any increase in density of the sample, gradual orientation of a steadily increasing number of macromolecules, the tightening of the network, the decrease of the number of chains passing from one lamella to another, etc., will not be accompanied by a radmal shrinkage of the spherulite [24]. The fissuring will result in stress reduction in the non-oriented laminae present between adjacent platelets and facilitate easier segmental movement. An important factor is t h a t fissuring will not result in the formation of a smooth surface layer. The presence of the interlinking chains, of "whips" or entanglements, the network interlinking adjacent platelets, will cause numerous thin threads consisting of several macromolecules to be present in the zone of the growing fissure, structures with a "window"-typelinkage [25], very small loop-shaped fold, i.e. "ciliate" shapes. The surface of such a fissure, as Fig. 8 shows, will greatly differ from the surface of a fissure forming in glass of low molecular weight, for example. As the smallest cooperating sub-system i n , h e fl-relaxation process is considerably larger t h a n one causing local relaxation, a considerable number of the segments present at the surface of the micro-fissure during its formation will participate in the local relaxation processes. This seems also to be the reason for the reduction of the fl-relaxation intensities when large enough spherulites form much more quickly in P E (see Table) when compared with the rate at which the total number of disarranged segments decreases.
Relaxatmn transltmns and the structure of polyethylene
403
The samples of B which had not been tempered had a very weak fl-peak, although their crystallinities did not exceed 90%. Such a result means that isolated platelets without intimate contact with others, have a very loose structure near the surface layer, so that no collective g-relaxation process is possible. In order to get a a-relaxation to appear it is necessary to have very close contact between platelets, and this can be attained b y heating the sample or b y applying pressure to it so that an "adhesive", fairly dense layer is produced A non-radiative inactivation of the states of excitation in a loose layer near the surface is highly probable as they form b y charge recombination. This is apparently the reason for the low R T L intensity of the samples of B throughout the 100-250°K range observed in our study The transitions in the 140-170°K range were earlier detected on the single crystals [2, 3] and on P E samples crystallized from the melt [1]. These were frequently thought to be associated with the movements of small segments (several methylene groups long) in the amorphous zones (?a-relaxation) [5, 26], the movements of individual segments at the surface of polymer crystals [5, 6, 26, 27], the reorientations of molecular chain ends ,nside the platelets (?c-relaxation) [19], or the reorientations in the region of defect vacancies which form as a result of a zig-zag chain contraction at right angles to its axis [28] It is difficult to give preference at present to any of the suggested mechamsms of ?-relaxations. The transitions detected b y us in the 150 and 170°K range and the Ea -----9-12 kcal/mole for all the samples in the 140-180°K range agree with those of y-transitions recorded in earlier studies [1, 3, 28] It is worth noting that the ?-transition (or transitions) ,s relatively weak in samples of A and B, but distinct in samples of C, D and E The decrease in Intensity of the fl-transit, on in the three samples mentioned last (compared with A-samples) is not accompanied b y a ?-peak weakening, and its intensity increased in some cases. This indicates that the ?a-relaxation makes only a small contribution to the ?-transition intensity. The local relaxation of the chain segments m the regions of the microfissures and vacancies seems to play the main part The transition in the 150°K range for samples of E is particularly intense. This is assocmted with the fact that the concentration of the defects (single and multiple vacancms, Renecker defects, etc ) must be exceptionally large in such samples because practically all the chain ends and branching points are here situated inside the parts having a straight chain conformation. The samples m addition contain a substantial number of microfissures. The whole ensures intense relaxation processes The tempering of these samples must result in the repair of the torero-fissures and of the larger defects, so that the ?-relaxations will become less intense as a result. The peak reduction in the 150°K range as a result of tempering of sample E can be seen in Fig. 6 The transition in the 180-190°K range is quite distinct only with the samples of E and some of samples of C. Samples with a larger values of lo and straight chain conformations will be more affected b y the presence of dislocation t y p e
404
L . A . OSINTSEVA et al
defects at the edges which form as a result of the vacancies migrating from the chain ends to the platelet surfaces, and due to the "sticking together" of chain ends (Fig. 7). Such dislocations ought to be very heat resistant and are not likely to disappear unless the samples are recrystallized The concentration of the dislocations at the edges of samples of E must be approximately the same as that at the chain ends and branches. On the basis of these features we believe that the 190°K transition having Ea----14-19 kcal/mole is determined by the presence of extremal dislocations or larger structural defects w]thm the limits of a part with a straightened chain conformation (e.g the presence of kink block structures examined by Pechhold [4]), and to be linked with a re-orientation of the Renecker defects near these dislocations. This points to high stab]lity of the peak to sample heating. The lowest of the recorded temperature peaks is situated in the l10-140°K range; it is evident in all the samples studied, but most intense in those of A and B, less so in samples of E. It is important that Ea is the same for all the samples in the l10-140°K range i e. 6-7.5 keal/mole This is probably the ya-peak (Tmax----llS-150°K. Ea~-5 kcal/mole) and the ?X-peak (Tmax=l18-127°K, Ea =7-7"5 keal/mole) detepted by Illers [20] and Buben and co-workers [14] respectively during the studies of the mechanical relaxations of PE We should also like to point out that low der~sity PE, amorphous-crystalline paraffin and polybutadiene elastomers have values of Ea which are also in the 5-5.5 kcal/mole range in the examined temperature range [17, 25]. Local relaxations of very small segments or terminal groups, relatively independent of the supermoleeular structural features, are likely to be responsible in all these cases. The authors express their thanks to N. F Bakeyev for his valuable criticisms of the results. Translated by K
A..Ar.T,~N
REFERENCES
1 A. WOODWARD and J. SAWYER, Sb : P r o b l e m y fiz~ki 1 khnnh tverdogo sostoyamya orgamchesklkh soyedmemi (In: Problems of the Sohd-state Physms and Chemistry of Organic Compounds). p. 329, Izd. "Mir", 1968 2. I. M. SINNOTT, J. Appl. Phys. 37" 3385, 1966 3. K. H. H.I.ERS, Kolloid-Z. und Z. Polymere 281. 662, 1969 4. W. PECITHOLD, Kolloid-Z und Z Polymere 228: 1, 1968 5. T. F. SCHATZKI, P o l y m e r P r e p n n t s 6: 646, 1964 6. F. W. FISCH~,,R and A. PETERLIN, Makromol. Chemie 74" 1, 1964 7. V. A. AULOV, Dissertation, 1971 8. I. BOUSTEAD, J. Polymer Sci. 8 A2: 143, 1970 9. Yu. A. ZUBOV, M. B. KONSTANTINOPOL'SKAYA, V. I. SFLIKHOVA, A. P. KOROBKO, V. A. SOKOL'SKII, A. S. TRIFONOV, A. V. KRYUKOV and V. A. KARGIN, Vysokomol. soyed. A13: 1078, 1971 (Translated in Polymer Sci. U.S.S.R. 13: 5, 1212, 1971) 10. K. Kh. RAZIKOV, Yu. A. ZUBOV, G. S. MARKOV and V. A. KARGIN, Vysokomol. soyed. 5: 760, 1963 (Translated in Polymer Sci. U.S.S.R. 4: 6, 1471, 1963) 11. S. M. SAMOILOV, M. B. KONSTANTINOPOL'SKAYA, Z. Ya. BERESTNEVA and ¥. A.
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STUDY OF THE KINETICS OF POLYMERIZATION AND COPOLYMERIZATION OF METHACRYLIC ACID SUI~HOLANATE* A. I. VOROB'EVA,E I. ABLYAKIMOV, G. V. LEPLYANIN,S. 1:{,.RAJ~'LKOVand G. P. GLADYSHEV Chemistry Institute, Bashklr Branch U.S S.R. Academy of Sciences
(Recesved 7 July 1972) The kinetics of polymerization of methaeryhc acid sulpholanate (MAS) of its copolymemzatlon with methyl methacrylate, styrene and methacryhc acid were investigated. An increased activity of M_AS was notmed, when compared with the majority of known methacrylates, in the radical polymerazatlon reactions.
SULPHUR contaming polymers have a number of valuable properties, especially heat, temperature, light and chemical stability [1-4], large dielectric and physite-chemical characteristics [1, 5], good adhesion to various materials [6]. This * Vysokomol soyed. AI6: No. 2, 349-353, 1974.