Abstract

The results of kinetic studies of the recombination of radicals in the cage and in bulk of polymers obtained by nanosecond laser photolysis are summarized. The films of rubbers (poly(ethylene-co-butylene)), biaxially oriented polypropylene depending on the preliminary heat treatment, polystyrene, craton (polystyrene-block-poly(ethylene-butylene)-block-polystyrene), silicones, and acrylates are studied. By direct observation, the significant effect of the magnetic field on the kinetics of the recombination of radicals both in the cage and in the bulk of rubber films is recorded. Stretching the rubber film significantly delays the escape of radicals from the matrix cage and, accordingly, bimolecular recombination in the bulk (when stretched 3 times, both processes slow down by a factor of 2). The effect is significantly higher that that expected based on the change in the free volume of the polymer. The increased content of polypropylene in the rubber leads to a stronger cage effect due to the slower escape of radicals into the bulk; at the same time, the recombination rate in the bulk increases and the reaction takes place in the restricted areas of the polymer matrix. The comparative analysis of the kinetic characteristics in polymer of different classes is carried out.

中文翻译：

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聚合物中自由基的重组动力学：磁场效应

摘要

总结了通过纳秒激光光解获得的笼中和本体中的自由基重组的动力学研究结果。橡胶（聚（乙烯-共-丁烯）），双轴取向聚丙烯（取决于初步热处理），聚苯乙烯，克拉通（聚苯乙烯-嵌段-聚（乙烯-丁烯）-嵌段-聚苯乙烯），有机硅和丙烯酸酯的薄膜为研究。通过直接观察，记录了磁场对笼子和大部分橡胶膜中自由基重组动力学的显着影响。拉伸橡胶膜会显着延迟自由基从基质笼中逸出的速度，因此，会导致本体中的双分子重组（拉伸3次时，两个过程的速度都会降低2倍）。该效果明显高于基于聚合物自由体积变化所预期的效果。橡胶中聚丙烯含量的增加由于自由基向本体中的逃逸较慢而导致更强的笼罩效果。同时，本体中的复合率增加，并且反应在聚合物基体的受限区域中发生。对不同种类的聚合物的动力学特性进行了比较分析。