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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-2,5-二(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。
Starting from the fundamental reaction and material balance calculation based on the polymerization mechanism, the kinetic model of styrene polymerization initiated by the linear bifunctional initiator is deduced in detail considering the volume shrinkage and thermal priming in the polymerization process. Considering the influence of gelling, glass And cage effect on the rate constants and physical parameters. The expressions of concentration, polymerization rate, molecular weight and polydispersity of each species were solved by diffusion-controlled rate parameter and moment method based on free-volume theory. The conversion, molecular weight and polydispersity at different temperatures and initiator concentrations of [2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexanes (DMDEHPH) The results also show that the model can also calculate the concentration of each free radical, peroxygen bond-containing and double-ended polymer. The results show that the concentration has a peak in the conversion curve, the concentration of diradical is several orders of magnitude lower than that of the single radical The concentration of polymer is only a few times.Under the different initiator concentration, there is no intersection with the species concentration curve, and the higher the concentration of initiator, the higher the species concentration; the curves of different temperature have the intersection point, the gel effect phase temperature is lower concentration Large, the lower the temperature the smaller the concentration before and after the gel effect.