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Free radical copolymerization of 2,3-diphenyl-1,3-butadiene
Eur. P&m. J. Vol. 33, No. 10-12, pp. 1819-1822, 1997 0 1997 EisevierScienceLtd. All rights resewed Printed in Great Britain
PII: SOOM-3057@7)00029-3
0014-3057/97 517.00+ 0.00
SHORT COMMUNICATION
FREE RADICAL COPOLYMERIZATION 2,3-DIPHENYL-1,3-BUTADIENE
OF
DIETRICH BRAUN, HARTMUT ELSASSER and KRISTINA HAIMER Deutsches Kunststoff-Institut, SchloBgartenstraBe 6, D-64289 Darmstadt, Germany (Received 8 May 1996; accepted in final form 24 October 1996)
Absttact-The copolymerization behaviour of 2,3-diphenyl-I ,3-butadiene was studied at WC in bulk with azoisobutyronitrile as initiator, and cc-methylstyrene, p-chlorostyrene, acrylonitrile, methyl methacrylate and styrene as comonomers. The reactivity ratios were determined according to the extended Kelen-TtiddSs method. Based on the reactivity ratios of these five systems the average Q and e values of 2,3-diphenyl-1,3-butadiene were determined to be Q = 2.51 and e = -0.74. 2,3-diphenyl-1,3-butadiene can be classified to the same quadrant of the Q-e scheme as styrene. 0 1997 Elsevier Science Ltd
Perkin-Elmer 554 spectrophotometer in tetrahydrofuran at 25°C.
INTRODUCTION The cationic and the free radical polymerization of 2,3-diphenyl-1,3-butadiene (2,3-DPB) were studied by several authors [l-4]. The homopolymeric 2,3-DPB has already been the object of some physical analyses [S-8]. But knowledge of the copolymerization behaviour of this monomer is still insufficient [9]. In particular, no Q and e values [lo] are known. Knowing Q and e values, the general characterization of the copolymerization behaviour is possible. In order to determine reliable Q and e values of 2,3-DPB the reactivity ratios of five copolymerization systems were calculated. A classification of 2,3-DPB in the Q-e scheme can be made with these reactivity ratios.
EXPERIMENTAL Tetrahydrofuran (THF) was dried over potassium hydroxide and distilled over potassium. Azoisobutyronitrile (AIBN) was recrystallized from dry ethanol and dried under vacuum. p-Chlorostyrene (PCS), styrene, a-methylstyrene (aMS), acrylonitrile (AN) and methyl methacrylate (MMA) were freed from inhibitor by washing with dilute aqueous sodium hydroxide followed by distilled water. The monomers were dried over calcium hydride and distilled over calcium chloride. 2,3-DPB was prepared according to a method described by Inoue et al. 111: (lit. -_ mo49”C . . 111 .~ mp 4%50°C). _ Copolymer samples for determining reactivity ratios were prepared in ampules under nitrogen. After the polymerization in a thermostat at 6O”C, the contents of the ampules were dissolved in THF and dropped into methanol. The precipitated copolymers were dried, dissolved in THF and precipitated again. The copolymers were isolated and dried under vacuum at 40°C. ‘H NMR spectroscopic analysis of the copolymers was carried out with a Bruker WM-300 spectrometer in deuterochloroform at 25°C with tetramethylsilane as standard. The microanalyses of the copolymers were carried out with a Perkin-Elmer 240 B microanalyzer. The UV absorptions of the copolymers were. measured with a
RESULTSAND DISCUSSION Determination
of the reactivity ratios
For determination of reactivity ratios, several monomer mixtures were polymerized at 60°C (system 2,3-DPB/ctMS at 55°C) with AIBN as initiator and the obtained copolymers were analyzed. Due to the large difference in carbon content of the comonomers (67.9l%C in AN, 69.33%C in PCS and 93.16%C in 2,3-DPB), the composition of the systems 2,3-DPB/ AN and 2,3-DPB/PCS could be determined accurately by means of microanalyses. The copolymer composition in the system 2,3-DPB/aMS and 2,3-DPB/styrene could be determined by means of UV spectroscopy. The absorptions of the copolymers were measured in THF at 270 nm and the copolymer compositions could be determined on the basis of a calibration curve. In the system 2,3-DPB/MMA the analyses of the obtained copolymers were carried out using ‘H NMR spectroscopy. The signals at 6 6.3-7.3 (aromatic protons of 2,3-DPB) and 6 0.5-l (a-methyl protons of MMA) were used to determine the copolymer composition according to: Area GHJ peak/ 10 X2.3.DPB Area CH, peak/3 = 1 - XZ,WWJ’
(1)
where x2,3_DPs is the mole fraction of 2,3-DPB in the copolymer. According to the terminal model of copolymerization [l 11, the reactivity ratios may be calculated with the following equation: 2
_
l$.rl.MI
+ M2
m2 - M2 r2.M~ + MI
(2)
where M, and mi are the mole fraction of monomer respectively, and
i in the feed and in the copolymer,
1819
1820
Short Communication
r, and r2 are the reactivity ratios. According to the extended Kelen-TiidBs (KT) linearization method [12] the copolymerization equation (1) is transformed into (3) q and 5 are functions of the copolymer and feed composition, the gravimetric conversion and of a. c( is an auxiliary parameter whose value has to be chosen in a way that all experimental points get the same statistical weight in the following determination of the reactivity ratios (least-squares method). In this method an average feed composition is related to an average copolymer composition. The average feed composition depends on the gravimetric conversion and the average copolymer composition can be equated with the experimentally measured copolymer composition. Considering these facts, the extended KT method yields highly reliable results for experimental data obtained at high conversion levels. Plotting 9 and 5 a straight line is obtained which extrapolated to 5 = 0 and < = 1 gives --Y~!a, respectively, r, (both as intercepts). Also the 95% confidence intervals and the quantity So [ 131,suitable for classification of the systems, were determined for the calculated reactivity ratios. 2,3-DPB was copolymerized with a-methylstyrene (aMS) at 55°C because of the low ceiling temperature [14] of EMS. The copolymerizations were carried to a conversion level about 30 wt%. The KT plot shows
good agreement with the experimental data, therefore the value for the correlation coefficient amounts to r = 0.99. The obtained values of the reactivity ratios are r, = 2.45 + 0.40 (2,3-DPB = MI) and r2 = 0.35 + 0.12 (aMS = M2). The copolymerization curve of the system is illustrated in Fig. 1. The solid line is obtained according to equation (1) using the calculated reactivity ratios. The experimental points deviate only slightly from the copolymerization curve and the low value of the quantity ho = 0.05 confirms this result. In the second system, p-chlorostyrene (PCS) was copolymerized with 2,3-DPB at 60°C. The reactivity ratios calculated according to Kelen-Tiidiis are r, = 1.63 + 0.64 (2,3-DPB = MI) and r2 = 0.54 + 0.26 (PCS = M,); the value of the quantity 60 = 0.14. As can be seen, 2,3-DPB is inserted preferably into the polymer chain (Fig. 1) and the agreement between experimental points and the calculated curve is satisfactory. The copolymerizations of 2,3-DPB with acrylonitrile (AN) were carried to a maximum conversion of 39 wt%. The reactivity ratios evaluated according to the extended KT method are r, = 1.48 + 0.30 (2,3-DPB = MI) and r2 = 0.04 f 0.04 (AN = M2); the value of the quantity do = 0.22. The copolymerization curve is illustrated in Fig. 2. Also 2,3-DPB is inserted preferably into the polymer chain. Another monomer with positive Q and e value is methyl methacrylate (MMA). It was copolymerized with 2,3-DPB under the same conditions as PCS and
1
045 x2,3-DPB
094
0
092
034
W
W3
1
X23-DPB
Fig. 1. 2,3-DPB-aMS copolymerization curve, 55 C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1). 2,3-DPB-PCS copolymerization curve, 60°C in bulk with AIBN: (A) experimental values; (- - -) calculated according to equation (1).
1821
098
0 0
092
094
096
1
098
x2.3.DI’B Fig. 2. 2,3-DPB-AN copolymerization curve, 60°C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1). 2,3-DPB-MMA copolymerization curve, 60°C in bulk with AIBN: (A) experimental values; (- - -) calculated according to equation (1).
.
1
0.8
0.6
X230,4
‘)
0
0.1
02
0.3
0.4
0,5
0.6
0,7
0.8
0.9
1
X 25-Dm Fig. 3. 2,3-DPB-styrene copolymerization curve, 60°C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1).
1822 Table
Short Communication I. Reactivity
ratios and calculated from copolymerization Comonomers
System 2,3-DPB/aMS’ 2,3-DPB/PCS 2,3-DPB/AN 2,3-DPB/MMA 2,3-DPB/styrene
Q and e values of 2,3-DPB at 60°C Reactivity ratios
2,3-DPB
Q
e
Q
r
II
I?
0.97 I .33 0.48 0.78 1.00
-0.81 -0.64 1.23 0.40 -0.80
3.81 3.11 1.52 1.23 2.89
- 1.20 - 1.00 -0.45 -0.2 -0.85
2.45 1.63 1.48 1.40 2.77
0.35 0.54 0.04 0.50 0.36
of 2,3-DPB can be determined from the systems 2,3_DPB/aMS/AIBN/55”C, 2,3-DPR/PCS/AIBN/ 6O”C, 2,3-DPB/AN/AIBN/6O”C, 2.3-DPB/MMA/ AIBN/60”C and 2,3-DPB/styrene/AIBN/60”C. The Q and e values of the comonomers, the reactivity ratios and the Q and e values calculated from each system are included in Table 1. The average Q and e values of 2,3-DPB are Q = 2.51 and e = -0.74. Therefore 2,3-DPB has to be classified in the same quadrant of the Q-e scheme as styrene.
“T= 55 C.
AN. A small content of 1,2 links of monomer units was observed in the copolymerization of 2,3-DPB with MMA by ‘H NMR spectroscopy. The mole fraction of 1,2 linked monomer units was found between 0.05 and 0.25. Therefore, the KT plot and the copolymerization curve show evident deviations from experimental data. The value of a0 = 0.31 is relatively high. The influence of the penultimate effect on the system was also studied, but the copolymerization curve calculated according to the penultimate equation [ 151is not significantly different to the curve shown (Fig. 2). The reactivity ratios are rl = 1.40 f 0.63 (2,3-DPB = M,) and rz = 0.50 i 0.35 (MMA = M2). Styrene was copolymerized with 2,3-DPB under the same conditions as PCS and AN. The copolymerization curve shows only slight deviations from experimental points and confirms the preferable insertion of 2,3-DPB (Fig. 3). The reactivity ratios calculated according to Kelen-TiidBs are r, = 2.77 + 1.10 (2.3-DPB = MI) and r2 = 0.36 f 0.18 (PCS = Ml); the value of the quantity ho = 0.21. Determination
qf Q and
e values
Knowing the reactivity ratios of a copolymerization system and the Q and e values of one monomer, the Q and e values of the other monomer can be calculated according to the following equations [lo]: cl
=
e2 _t
Q, = $.exp[
v/ -
In(r,.r2)
-ez(ez - e,)].
(4)
(5)
Since the Q and c values of the comonomers of 2,3-DPB are well known [14] and the Q and c values
Acknowledgemenr-Financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged.
REFERENCES
I.
Inoue, H., Helbig, M. and Vogl, O., Macromolecules,
1977, 10, 1331. 2. FBldes, E., Deak, G., Tiidiis, F. and Vogl, O., Eur. Polym. J., 1993, 29, 321. 3. Asami, R., Hasegawa, K. and Onoe, T., Polym. J., 1976, 8, 43. 4. Asami, R. and Hasegawa, K., Polym. J., 1976, 8, 53. 5. Berlin, A. A., Drabkin, I. A., kosenstein, L. D.,
Cherkaskin. M. I.. Chauser. M. F. and Kisilitsa. P. P.. Izc. Akad. hauk.‘SSSR, Ser. Khim., 1967, 1334. 6. Livshits, V. A., Lyubchenko, L. S. and Blumenfeld, L. A., Zh. Strukt. Khim., 1969, 10, 1019. 7. Meshkov, A. M., Akimov, I. A., Cligin, A. N., Chauser,
N. N., Chauser, M. G., Charkashin, M. I. and Berlin, A. A., Dokl. Akad. Nauk. SSSR, 1970, 192, 1307. 8. Sharin, V. A., Beshenko, S. I., Berlin, Y. A. and Enikolopyan, N. S., Vysokmol. Soedin., 1982, A24(1 I), 2304. 9. Iino, M., Matsuda, M. and Asami, R., Polymer Letters, 1971, 9, 473. 10. Alfrey, F. and Price, C. C., J. Polym. Sci., 1947, 2, 101. Il. Mayo, F. R. and Lewis, F. M., J. Am. Chem. Sot., 1944, 66, 1594. 12.
Tiidiis, F., Kelen, T., FBldes-Berezsnich, T. and Turcsanyi, B., J. Macromol. Sci.-Chem., 1976, A10(8),
1513. 13. Braun, D., Czerwinski, W., Disselhoff, G., TiidBs, F., Kelen, T. and Turcsanyi, B., Angew. Makrom. Chem.,
1984, 125, 161. Brandrup, J. and Immergut, E. H., Polymer Handbook. John Wiley and Sons, New York, 1989. 15. Merz, E., Alfrey, T. and Goldfinger, G., J. Poiym. Sci., 1946, 1, 75. 14.
PII: SOOM-3057@7)00029-3
0014-3057/97 517.00+ 0.00
SHORT COMMUNICATION
FREE RADICAL COPOLYMERIZATION 2,3-DIPHENYL-1,3-BUTADIENE
OF
DIETRICH BRAUN, HARTMUT ELSASSER and KRISTINA HAIMER Deutsches Kunststoff-Institut, SchloBgartenstraBe 6, D-64289 Darmstadt, Germany (Received 8 May 1996; accepted in final form 24 October 1996)
Absttact-The copolymerization behaviour of 2,3-diphenyl-I ,3-butadiene was studied at WC in bulk with azoisobutyronitrile as initiator, and cc-methylstyrene, p-chlorostyrene, acrylonitrile, methyl methacrylate and styrene as comonomers. The reactivity ratios were determined according to the extended Kelen-TtiddSs method. Based on the reactivity ratios of these five systems the average Q and e values of 2,3-diphenyl-1,3-butadiene were determined to be Q = 2.51 and e = -0.74. 2,3-diphenyl-1,3-butadiene can be classified to the same quadrant of the Q-e scheme as styrene. 0 1997 Elsevier Science Ltd
Perkin-Elmer 554 spectrophotometer in tetrahydrofuran at 25°C.
INTRODUCTION The cationic and the free radical polymerization of 2,3-diphenyl-1,3-butadiene (2,3-DPB) were studied by several authors [l-4]. The homopolymeric 2,3-DPB has already been the object of some physical analyses [S-8]. But knowledge of the copolymerization behaviour of this monomer is still insufficient [9]. In particular, no Q and e values [lo] are known. Knowing Q and e values, the general characterization of the copolymerization behaviour is possible. In order to determine reliable Q and e values of 2,3-DPB the reactivity ratios of five copolymerization systems were calculated. A classification of 2,3-DPB in the Q-e scheme can be made with these reactivity ratios.
EXPERIMENTAL Tetrahydrofuran (THF) was dried over potassium hydroxide and distilled over potassium. Azoisobutyronitrile (AIBN) was recrystallized from dry ethanol and dried under vacuum. p-Chlorostyrene (PCS), styrene, a-methylstyrene (aMS), acrylonitrile (AN) and methyl methacrylate (MMA) were freed from inhibitor by washing with dilute aqueous sodium hydroxide followed by distilled water. The monomers were dried over calcium hydride and distilled over calcium chloride. 2,3-DPB was prepared according to a method described by Inoue et al. 111: (lit. -_ mo49”C . . 111 .~ mp 4%50°C). _ Copolymer samples for determining reactivity ratios were prepared in ampules under nitrogen. After the polymerization in a thermostat at 6O”C, the contents of the ampules were dissolved in THF and dropped into methanol. The precipitated copolymers were dried, dissolved in THF and precipitated again. The copolymers were isolated and dried under vacuum at 40°C. ‘H NMR spectroscopic analysis of the copolymers was carried out with a Bruker WM-300 spectrometer in deuterochloroform at 25°C with tetramethylsilane as standard. The microanalyses of the copolymers were carried out with a Perkin-Elmer 240 B microanalyzer. The UV absorptions of the copolymers were. measured with a
RESULTSAND DISCUSSION Determination
of the reactivity ratios
For determination of reactivity ratios, several monomer mixtures were polymerized at 60°C (system 2,3-DPB/ctMS at 55°C) with AIBN as initiator and the obtained copolymers were analyzed. Due to the large difference in carbon content of the comonomers (67.9l%C in AN, 69.33%C in PCS and 93.16%C in 2,3-DPB), the composition of the systems 2,3-DPB/ AN and 2,3-DPB/PCS could be determined accurately by means of microanalyses. The copolymer composition in the system 2,3-DPB/aMS and 2,3-DPB/styrene could be determined by means of UV spectroscopy. The absorptions of the copolymers were measured in THF at 270 nm and the copolymer compositions could be determined on the basis of a calibration curve. In the system 2,3-DPB/MMA the analyses of the obtained copolymers were carried out using ‘H NMR spectroscopy. The signals at 6 6.3-7.3 (aromatic protons of 2,3-DPB) and 6 0.5-l (a-methyl protons of MMA) were used to determine the copolymer composition according to: Area GHJ peak/ 10 X2.3.DPB Area CH, peak/3 = 1 - XZ,WWJ’
(1)
where x2,3_DPs is the mole fraction of 2,3-DPB in the copolymer. According to the terminal model of copolymerization [l 11, the reactivity ratios may be calculated with the following equation: 2
_
l$.rl.MI
+ M2
m2 - M2 r2.M~ + MI
(2)
where M, and mi are the mole fraction of monomer respectively, and
i in the feed and in the copolymer,
1819
1820
Short Communication
r, and r2 are the reactivity ratios. According to the extended Kelen-TiidBs (KT) linearization method [12] the copolymerization equation (1) is transformed into (3) q and 5 are functions of the copolymer and feed composition, the gravimetric conversion and of a. c( is an auxiliary parameter whose value has to be chosen in a way that all experimental points get the same statistical weight in the following determination of the reactivity ratios (least-squares method). In this method an average feed composition is related to an average copolymer composition. The average feed composition depends on the gravimetric conversion and the average copolymer composition can be equated with the experimentally measured copolymer composition. Considering these facts, the extended KT method yields highly reliable results for experimental data obtained at high conversion levels. Plotting 9 and 5 a straight line is obtained which extrapolated to 5 = 0 and < = 1 gives --Y~!a, respectively, r, (both as intercepts). Also the 95% confidence intervals and the quantity So [ 131,suitable for classification of the systems, were determined for the calculated reactivity ratios. 2,3-DPB was copolymerized with a-methylstyrene (aMS) at 55°C because of the low ceiling temperature [14] of EMS. The copolymerizations were carried to a conversion level about 30 wt%. The KT plot shows
good agreement with the experimental data, therefore the value for the correlation coefficient amounts to r = 0.99. The obtained values of the reactivity ratios are r, = 2.45 + 0.40 (2,3-DPB = MI) and r2 = 0.35 + 0.12 (aMS = M2). The copolymerization curve of the system is illustrated in Fig. 1. The solid line is obtained according to equation (1) using the calculated reactivity ratios. The experimental points deviate only slightly from the copolymerization curve and the low value of the quantity ho = 0.05 confirms this result. In the second system, p-chlorostyrene (PCS) was copolymerized with 2,3-DPB at 60°C. The reactivity ratios calculated according to Kelen-Tiidiis are r, = 1.63 + 0.64 (2,3-DPB = MI) and r2 = 0.54 + 0.26 (PCS = M,); the value of the quantity 60 = 0.14. As can be seen, 2,3-DPB is inserted preferably into the polymer chain (Fig. 1) and the agreement between experimental points and the calculated curve is satisfactory. The copolymerizations of 2,3-DPB with acrylonitrile (AN) were carried to a maximum conversion of 39 wt%. The reactivity ratios evaluated according to the extended KT method are r, = 1.48 + 0.30 (2,3-DPB = MI) and r2 = 0.04 f 0.04 (AN = M2); the value of the quantity do = 0.22. The copolymerization curve is illustrated in Fig. 2. Also 2,3-DPB is inserted preferably into the polymer chain. Another monomer with positive Q and e value is methyl methacrylate (MMA). It was copolymerized with 2,3-DPB under the same conditions as PCS and
1
045 x2,3-DPB
094
0
092
034
W
W3
1
X23-DPB
Fig. 1. 2,3-DPB-aMS copolymerization curve, 55 C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1). 2,3-DPB-PCS copolymerization curve, 60°C in bulk with AIBN: (A) experimental values; (- - -) calculated according to equation (1).
1821
098
0 0
092
094
096
1
098
x2.3.DI’B Fig. 2. 2,3-DPB-AN copolymerization curve, 60°C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1). 2,3-DPB-MMA copolymerization curve, 60°C in bulk with AIBN: (A) experimental values; (- - -) calculated according to equation (1).
.
1
0.8
0.6
X230,4
‘)
0
0.1
02
0.3
0.4
0,5
0.6
0,7
0.8
0.9
1
X 25-Dm Fig. 3. 2,3-DPB-styrene copolymerization curve, 60°C in bulk with AIBN: (m) experimental values; (-) calculated according to equation (1).
1822 Table
Short Communication I. Reactivity
ratios and calculated from copolymerization Comonomers
System 2,3-DPB/aMS’ 2,3-DPB/PCS 2,3-DPB/AN 2,3-DPB/MMA 2,3-DPB/styrene
Q and e values of 2,3-DPB at 60°C Reactivity ratios
2,3-DPB
Q
e
Q
r
II
I?
0.97 I .33 0.48 0.78 1.00
-0.81 -0.64 1.23 0.40 -0.80
3.81 3.11 1.52 1.23 2.89
- 1.20 - 1.00 -0.45 -0.2 -0.85
2.45 1.63 1.48 1.40 2.77
0.35 0.54 0.04 0.50 0.36
of 2,3-DPB can be determined from the systems 2,3_DPB/aMS/AIBN/55”C, 2,3-DPR/PCS/AIBN/ 6O”C, 2,3-DPB/AN/AIBN/6O”C, 2.3-DPB/MMA/ AIBN/60”C and 2,3-DPB/styrene/AIBN/60”C. The Q and e values of the comonomers, the reactivity ratios and the Q and e values calculated from each system are included in Table 1. The average Q and e values of 2,3-DPB are Q = 2.51 and e = -0.74. Therefore 2,3-DPB has to be classified in the same quadrant of the Q-e scheme as styrene.
“T= 55 C.
AN. A small content of 1,2 links of monomer units was observed in the copolymerization of 2,3-DPB with MMA by ‘H NMR spectroscopy. The mole fraction of 1,2 linked monomer units was found between 0.05 and 0.25. Therefore, the KT plot and the copolymerization curve show evident deviations from experimental data. The value of a0 = 0.31 is relatively high. The influence of the penultimate effect on the system was also studied, but the copolymerization curve calculated according to the penultimate equation [ 151is not significantly different to the curve shown (Fig. 2). The reactivity ratios are rl = 1.40 f 0.63 (2,3-DPB = M,) and rz = 0.50 i 0.35 (MMA = M2). Styrene was copolymerized with 2,3-DPB under the same conditions as PCS and AN. The copolymerization curve shows only slight deviations from experimental points and confirms the preferable insertion of 2,3-DPB (Fig. 3). The reactivity ratios calculated according to Kelen-TiidBs are r, = 2.77 + 1.10 (2.3-DPB = MI) and r2 = 0.36 f 0.18 (PCS = Ml); the value of the quantity ho = 0.21. Determination
qf Q and
e values
Knowing the reactivity ratios of a copolymerization system and the Q and e values of one monomer, the Q and e values of the other monomer can be calculated according to the following equations [lo]: cl
=
e2 _t
Q, = $.exp[
v/ -
In(r,.r2)
-ez(ez - e,)].
(4)
(5)
Since the Q and c values of the comonomers of 2,3-DPB are well known [14] and the Q and c values
Acknowledgemenr-Financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged.
REFERENCES
I.
Inoue, H., Helbig, M. and Vogl, O., Macromolecules,
1977, 10, 1331. 2. FBldes, E., Deak, G., Tiidiis, F. and Vogl, O., Eur. Polym. J., 1993, 29, 321. 3. Asami, R., Hasegawa, K. and Onoe, T., Polym. J., 1976, 8, 43. 4. Asami, R. and Hasegawa, K., Polym. J., 1976, 8, 53. 5. Berlin, A. A., Drabkin, I. A., kosenstein, L. D.,
Cherkaskin. M. I.. Chauser. M. F. and Kisilitsa. P. P.. Izc. Akad. hauk.‘SSSR, Ser. Khim., 1967, 1334. 6. Livshits, V. A., Lyubchenko, L. S. and Blumenfeld, L. A., Zh. Strukt. Khim., 1969, 10, 1019. 7. Meshkov, A. M., Akimov, I. A., Cligin, A. N., Chauser,
N. N., Chauser, M. G., Charkashin, M. I. and Berlin, A. A., Dokl. Akad. Nauk. SSSR, 1970, 192, 1307. 8. Sharin, V. A., Beshenko, S. I., Berlin, Y. A. and Enikolopyan, N. S., Vysokmol. Soedin., 1982, A24(1 I), 2304. 9. Iino, M., Matsuda, M. and Asami, R., Polymer Letters, 1971, 9, 473. 10. Alfrey, F. and Price, C. C., J. Polym. Sci., 1947, 2, 101. Il. Mayo, F. R. and Lewis, F. M., J. Am. Chem. Sot., 1944, 66, 1594. 12.
Tiidiis, F., Kelen, T., FBldes-Berezsnich, T. and Turcsanyi, B., J. Macromol. Sci.-Chem., 1976, A10(8),
1513. 13. Braun, D., Czerwinski, W., Disselhoff, G., TiidBs, F., Kelen, T. and Turcsanyi, B., Angew. Makrom. Chem.,
1984, 125, 161. Brandrup, J. and Immergut, E. H., Polymer Handbook. John Wiley and Sons, New York, 1989. 15. Merz, E., Alfrey, T. and Goldfinger, G., J. Poiym. Sci., 1946, 1, 75. 14.