搅拌速率及其改变点对高抗冲聚苯乙烯相转变的影响

以四官能度过氧化物JWEB50为引发剂，本体接枝共聚法制备高抗冲聚苯乙烯（HIPS）。分别采用透射电镜以及相对扭矩变化对聚合体系的粒子结构、黏度变化进行研究，来分析恒定搅拌以及分段搅拌条件下聚合过程的相转变。研究发现，两种分析方法所得结果相近，相转变时的转化率随恒定搅拌速率的增大而降低。采用分段搅拌方式时，相转变前降低搅拌速率可使相转变时的转化率增大，相转变后降低搅拌速率对相转变时的转化率无影响；相转变过程对应的搅拌速率才是影响相转变的“有效搅拌速率”。上述结果对HIPS的产品性能控制具有极其重要的参考价值。

Effect of stirring speed and its change time on phase inversion of high impact polystyrene

High impact polystyrene (HIPS) was prepared by bulk graft copolymerization with four tetrafunctional peroxide JWEB50 as initiator. Phase inversion at constant and staged stirring conditions was analyzed through study of particle structure and viscosity of the polymerization system by transmission electron microscope and change in relative torque. Similar results were obtained from both analyses. For constant stirring, conversion at phase inversion decreased with the increase of stirring speed. For staged stirring, conversion at phase inversion increased when stirring speed was reduced before phase inversion and no effect on conversion at phase inversion was observed if stirring speed was reduced after phase inversion. Therefore, only “effective stirring speed” corresponding to the stirring speed at phase inversion process actually influenced phase inversion. These results could be very important for performance control of HIPS.