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研究了苯乙烯在不同浓度溴乙烷溶液中，－７８℃γ－射线辐射聚合。聚合 速度随苯乙烯浓度减小而上升，在低浓度区通过最大值然后迅速下降。所得聚 合物分子量在单体浓度１５％（克分子）以上变化不大，而低浓度范围内，随单 体浓度降低迅速下降。按溶剂及单体获得的总能量计算引发Ｇ值随浓度变化不 大。根据实验结果及动力学初步演算可认为，聚合反应是按离子历程进行的。 溴乙烷辐照生成Ｃ离子直接参与引发。当溴乙烷存在下，热电子主要被其 俘获形成负离子，而苯乙烯正离子不稳定，不直接引发聚合反应。在单体浓度 较高时终止反应通过单体转移，在低浓度时，为单分子终止。所获结果与实验 事实较好地符合。 添加物对转化率的影响进一步证明了聚合按离子历程进行．自由基聚合部 分极少（小于１％），可忽略不计。
The polymerization of styrene in γ-ray at -78 ℃ in different concentrations of bromoethane was studied. The rate of polymerization increases as the styrene concentration decreases, passes the maximum at low concentrations and then decreases rapidly. The molecular weight of the obtained polymer did not change much above the monomer concentration of 15% (mol), but decreased rapidly with the decrease of the monomer concentration in the low concentration range. Solvent and monomer obtained by the total energy calculated by the trigger value of G with little change. According to the experimental results and preliminary calculations of kinetics can be considered, the polymerization reaction is carried out according to ion history. Bromoethane irradiation generates C ions directly involved in initiation. When bromoethane is present, the hot electrons are mainly trapped to form negative ions, whereas the styrene positive ions are unstable and do not directly initiate the polymerization reaction. The termination of the reaction at the higher monomer concentration is by monomeric transfer and, at low concentrations, single-molecule termination. The results obtained are in good agreement with the experimental facts. The influence of the additives on the conversion rate further proves that the polymerization proceeds according to the ion history. Radical polymerization part of the few (less than 1%), negligible.