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研究了苯乙炔在1.5,6和10小时的热聚合过程中温度对聚合物分子量的影响。所得结果表明,在150—500°的温度范围内,随着聚合温度的增高,聚合物的分子量都是逐渐降低,表明在高温时聚合物有裂解现象发生。红外光谱显示,400°所得聚合物的光谱吸收峯较之200°聚合物的为小,500°聚合物则出现无明显吸收峯的连续吸收,并且背景升高(“背景效应”)。聚合物的碳氢含量此同样随着聚合温度的升高而增大。这些结果,以及300°以上聚合物在溶液中显示明显的萤光等,被认为是表明聚苯乙炔在高温时发生结构改变,除裂解成小分子外,可能还有环化、脱氢、芳构化等发生,从而由链状结构变为稠环结构乃至三维共轭结构。 聚合物的电子自旋共振测试表明,聚苯乙炔的自由基浓度随下列顺序递增: 300°聚合物<400°聚合物<500°聚合物。
The effect of temperature on the molecular weight of phenylacetylene during 1.5, 6 and 10 hours of thermal polymerization was investigated. The results show that the molecular weight of the polymer gradually decreases with the increase of the polymerization temperature in the temperature range of 150-500 ° C, indicating that the polymer cracking occurs at high temperature. Infrared spectroscopy showed that the absorbance peak of the 400 ° polymer was smaller than that of the 200 ° polymer and that the 500 ° polymer showed a continuous absorption with no apparent absorption peak and increased background (“background effect”). The hydrocarbon content of the polymer also increases with increasing polymerization temperature. These results, together with the obvious fluorescence of the polymers above 300 ° in solution, are believed to indicate that structural changes occur at high temperatures of polyphenylacetylene, in addition to the cleavage into small molecules, and possibly cyclization, dehydrogenation, Structuring and the like occur, thereby becoming a condensed ring structure or even a three-dimensional conjugate structure from a chain structure. Electron spin resonance measurements of the polymers showed that the free radical concentration of the polyphenylacetylene increased in the following order: 300 ° polymer <400 ° polymer <500 ° polymer.