中文摘要：

从基于聚合机理的基元反应和物料衡算出发，考虑聚合过程中的体积收缩和热引发，详细推导了直链型双官能度引发剂引发苯乙烯聚合的动力学模型，考虑凝胶、玻璃化和笼蔽效应等对各速率常数和物性参数的影响，利用基于自由体积理论的扩散控制速率参数和矩方法求解各物种浓度、聚合速率、分子量及多分散度的表达式．利用模型计算了不同温度和引发剂[2，5-二甲基-2，5-（2-乙基己酰基过氧）己烷（DMDEHPH）]浓度下的转化率、分子量和多分散度，均与实验结果相符．模型还可计算各自由基、含过氧键和双端终止聚合物浓度，结果表明浓度对转化率曲线中均有一峰值，双自由基浓度比单自由基浓度低几个数量级，不同聚合物浓度则仅差几倍．不同引发剂浓度下同物种浓度曲线无交点，且引发剂浓度越大物种浓度越高；不同温度下的曲线有交点，凝胶效应阶段温度越低浓度越大，凝胶效应之前和之后则温度越低浓度越小．

英文摘要：

A mathematical model for free radical polymerizations initiated by a linear bifunctional initiator was described in detail from the fundamental reactions based on the polymerization mechanism and species balance, considering the volume contraction and thermal initiation. The model presented herein utilized diffusion-controlled rate constants based on free volume theory and employed the method of moments to solve the various species concentrations, polymerization rate, molecular weight and polydispersity, considering gel effect, glass effect and cage effect. Conversion, average molecular weight and polydispersity at various initiator [2,5-dimethyl-2,5-di（2-ethylhexoylperoxy）hexane] （DMDEHPH） concentrations and temperatures were calculated with the mathematical model of styrene free radical bulk polymerizations with the linear hifunctional initiator. Model predictions agreed well with experimental data. The various species concentrations were also calculated. The model demonstrated that plot of every species concentration vs. conversion had a maximum value for either various polymer or radical concentrations. Based on model predictions, the biradical concentration was several orders of magnitude smaller than monoradical concentration while polymer concentrations were only different in several times. The plots at various initiator concentrations had no cross-points. And the higher the initiator concentration was, the higher both the radical and polymer concentrations were. The plots had cross-points at various temperatures. And the lower the temperature, the higher the radical and polymer concentrations at geleffect phase, while the lower the temperature, the smaller the radical and polymer concentrations before and after gel-effect phase.