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71.
Ohne Zusammenfassung 相似文献
72.
Tadahiro Yamamoto Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1279-1286
In order to study the effects of the substituents in both substrate and attacking radical on the chain-transfer reactivities of nuclear-substituted cumenes toward substituted polystyryl radicals, the polymerizations of p-substituted styrenes in the presence of p-substituted cumenes were carried out with α,α′-azobisisobutyronitrile as an initiator at 60°C, and their chain-transfer constants were determined. The relative chain transfer reactivities of p-substituted cumenes toward given p-substituted polystyryl radicals did not follow the Hammett equation, but were correlated with the modified Hammett equation, log(k/k0) = pρ + γER, which was proposed by the present authors for evaluating the substituent effects in radical reactions. On the other hand, the relative reactivities of poly-(p-substituted styrene) radicals toward given p-substituted cumenes were correlated by the Hammett equation. Thus, it was concluded that the effects of the substituents in substrate cumene depended upon the contributions of both polar and resonance factors, while those in attacking polystyryl radical depended upon only a polar factor. 相似文献
73.
Tsuneyuki Sato Takahiko Iwaki Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1983,21(4):943-952
N-methylacrylamide (NMAAm) and N-methylmethacrylamide (NMMAm) were polymerized to give polymer microspheres containing living propagating radicals. The microsphere polymer radicals were allowed to react with some binary mixtures of vinyl monomers including alternating copolymerization combinations. The reaction processes were investigated by ESR spectroscopy. In the poly(NMMAm) radical/methyl methacrylate (MMA)/styrene (St) system, the propagating radical from MMA was mainly observed at the higher MMA concentration, while polySt radical prevailed at the lower MMA concentration. In the poly(NMMAm) radical/α-methylstyrene (α-MeSt)/diethyl fumarate system, the α-MeSt radical was exclusively observed, while the maleic anhydride (MAn) radical was predominantly observed in the α-MeSt/MAn system. In the MAn/diphenylethylene system, the propagating radicals from both monomers were observed at comparable concentrations. The poly(NMAAm) microsphere radical behaved differently in the reaction with the MMA/St mixture. The poly(NMAAm) microsphere was found to incorporate preferentially St, leading to formation of the St radical. The St preference was enhanced in the St/cyclohexyl methacrylate (CHMA) system. These results were in agreement with those of block copolymerization via the reaction of poly(NMAAm) radical with the MMA/St or CHMA/St mixture, where the compositions of the resulting polymers were analyzed by pyrolysis gas chromatography. 相似文献
74.
Takayuki Otsu Kiyoshi Endo A. H. K. Yousufzai 《Journal of polymer science. Part A, Polymer chemistry》1979,17(5):1431-1440
2-Butene(2B) copolymerizes with 3-heptene(3H) and 4-methyl-2-pentene(4M2P) by a monomer-isomerization copolymerization mechanism in the presence of TiCl3–(C2H5)3Al catalyst at 80°C to yield the copolymers of 1-olefin units. By comparison, the copolymerization of 1-butene(1B) with 4-methyl-1-pentene(4M1P) was also carried out under similar conditions. The composition of the copolymers obtained from these copolymerizations was determined from the ratios of optical densities D723/D1380 and D1170/D1380 in their infrared (IR) spectra. The apparent monomer reactivity ratios for the monomer-isomerization copolymerization of 2B with 3H and 4M2P, in which the concentration of olefin monomer in the feed was used as 2-olefin, were determined as follows: cis-2B(M1)/3H(M2); r1 = 4.00, r2 = 0.20: trans-2B(M1)/3H; r1 = 3.50, r2 = 0.20; 4M2P(M1)-trans-2B(M2): r1 = 0.05, r2 = 9.0. These results indicate that the isomerization of 2-olefins to 1-olefins was important to monomer-isomerization copolymerization. 相似文献
75.
Akikazu Matsumoto Keiichiro Mizuta Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1993,31(10):2531-2539
Radical polymerizations of some cycloalkyl methacrylates bearing bridged- and fused-ring structures, i.e., bornyl methacrylate (BoMA), isobornyl methacrylate (IBoMA), 2-decahydronaphthyl methacrylate (DNMA), and 3-tetracyclo [4.4.02,5.17,10] dodecyl methacrylate (TCDMA), were carried out. The radical polymerization reactivities of these monomers depended on the structure of the cycloalkyl ester groups in the following order: TCDMA > BoMA > DNMA > CHMA > IBoMA > MMA, where CHMA and MMA are cyclohexyl and methyl methacrylates, respectively. The propagation and termination rate constants of these monomers were evaluated from the polymer radical concentration determined by electron spin resonance spectroscopy. The solubilities and microstructures of the resulting polymers were examined. Thermal properties, i.e., glass transition temperatures and decomposition behaviors, of the polymers were also investigated and related to the structures of the polymer side chain. © 1993 John Wiley & Sons, Inc. 相似文献
76.
Bunchiro Yamada Hiroaki Kamei Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1980,18(6):1917-1922
Thermal decomposition of α,α′-azobisisobutyronitrile (AIBN) and dimethyl α,α′-azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first-order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl4]/[AIBN] = 21.65 and [SnCl4]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition. 相似文献
77.
Takayuki Otsu Akihiko Shimizu Keisuke Itakura Kiyoshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1975,13(7):1589-1599
2-Pentene and 2-hexene were found to undergo monomer-isomerization copolymerizations with 2-butene by Al(C2H5)3–VCl3 and Al(C2H5)3–TiCl3 catalysts in the presence of nickel dimethylglyoxime or transition metal acetylacetonates to yield copolymers consisting of the respective 1-olefin units. For comparison, the copolymerizations of 1-pentene with 1-butene and 1-hexene with 1-butene by Al(C2H5)3–VCl3 catalyst were also attempted. The compositions of the copolymers obtained from these copolymerizations were determined by using the calibration curves between the compositions of the respective homopolymer mixtures and the values of D766/D1380 in the infrared spectra. The monomer reactivity ratios for the monomer-isomerization copolymerizations of 2-butene (M1) with 2-pentene and 2-hexene, in which the concentrations of both 1-olefins calculated from the observed isomer distribution were used as those in the monomer feed mixture, and for the ordinary copolymerizations of 1-butene (M1) with 1-pentene and 1-hexene by Al(C2H5)3-VCl3 catalyst were determined as follows: 2-butene (M1)/2-pentene (M2): r1 = 0.14, r2 = 0.99; 1-butene (M1)/1-pentene (M2): r1 = 0.30, r2 = 0.74; 2-butene (M1)/2-hexene (M2): r1 = 0.11, r2 = 0.62; 1-butene (M1)/1-hexene (M2): r1 = 0.13, r2 = 0.90. 相似文献
78.
Takayuki Otsu Akihiko Shimizu Minoru Imoto 《Journal of polymer science. Part A, Polymer chemistry》1969,7(11):3111-3117
In order to clarify the correlation between polymerization and monomer isomerization in the monomer-isomerization polymerization of β-olefins, the effects of some transition metal compounds which have been known to catalyze olefin isomerizations on the polymerizations of butene-2 and pentene-2 with Al(C2H5)3–TiCl3 or Al(C2H5)3–VCl3 catalyst have been investigated. It was found that some transition metal compounds such as acetylacetonates of Fe(III), Co(II), and Cr(III) or nickel dimethylglyoxime remarkably accelerate these polymerizations with Al(C2H5)3–TiCl3 catalyst at 80°C. All the polymers from butene-2 were high molecular weight polybutene-1. With Al(C2H5)3–VCl3 catalyst, which polymerizes α-olefins but does not catalyze polymerization of β-olefins, no monomer-isomerization polymerizations of butene-2 and pentene-2 were observed. When Fe(III) acetylacetonate was added to this catalyst system, however, polymerization occurred. These results strongly indicate that two independent active centers for the olefin isomerization and the polymerizations of α-olefins were necessary for the monomer-isomerization polymerizations of β-olefins. 相似文献
79.
Takayuki Otsu Loc Quach 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2377-2389
Head-to-head (h-h) poly(acrylic acid) (PAA) and some h-h poly(alkyl acrylates) (PRA) with methyl, ethyl, n-propyl, n-butyl, isobutyl and 2-ethylhexyl substituents were prepared by hydrolysis or esterifications of the alternating copolymer of ethylene with maleic anhydride. In general, these esterification reactions became increasingly difficult as the carbon chain in the alcohols lengthened or branched. The softening, glass transition, and degradation temperatures of the h-h polymers obtained were somewhat higher than those of the corresponding head-to-tail (h-t) polymers. The main degradation products of both h-h and h-t PRA were identified by pyrolytic gas chromatography as the alcohol and monomer. In addition, the relative ratios of the amounts of alcohol to monomer were larger for h-h than for the corresponding h-t polymers. 相似文献
80.
Loc Quach Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2391-2403
The alternating copolymer of ethylene with maleic anhydride was esterified with a number of aliphatic alcohols to yield its monoesters, which correspond structurally to equimolar (1:1) head-to-head (h-h) copolymers of acrylic acid with alkyl acrylates. In addition, they were methylated with diazomethane to 1:1 h-h copolymers of methyl acrylate with alkyl acrylates. For comparison the 1:1 head-to-tail (h-t) copolymers of methyl acrylate with alkyl acrylates were prepared by radical copolymerizations. Some chemical, physical, and thermal properties of these 1:1 h-h and h-t copolymers were evaluated and compared. The softening and glass transition temperatures of the 1:1 h-h copolymers were somewhat higher than those of the corresponding 1:1 h-t copolymers, which indicated that the h-h replacements made the polymer chain stiffer and less flexible. The 1:1 h-h copolymers were also observed to degrade thermally at somewhat higher temperatures and with higher rates than the 1:1 h-t copolymers. The ratio of alcohol to monomer found in the pyrolysis products was higher for the 1:1 h-h than for its respective 1:1 h-t copolymer. 相似文献