提高高抗冲聚苯乙烯抗冲击性能的工艺优化

Process optimization in improving the impact property of polystyrene with high impact property

采用透射电子显微镜观察高抗冲聚苯乙烯GH660,1300,466F的粒径,根据其粒径分布发现,橡胶的接枝率和橡胶粒子粒径及其分布是造成GH660力学性能偏低的主要原因。结合提高接枝率的方法和大小粒子协同增韧理论,通过增加一台预聚合反应器,采用双预聚合反应器的方法,对预聚合系统进行优化,调整两台预聚合反应器中的温度和搅拌速率控制苯乙烯转化率和橡胶粒子粒径及其分布,使GH660的表观接枝率由93%增至100%,真实接枝率由81%增至94%;橡胶粒子粒径由3.0μm降至约2.0μm,且小粒径橡胶粒子明显增多。优化后GH660的重均分子量达3.00×105,且相对分子质量分布变窄,力学性能明显改善,拉伸屈服应力比参考指标高10%以上。

The particle sizes of high impact polystyrene（HIPS） GH660,1330,466F were observed by transmission electron microscopy（TEM）, and according to their particle distribution, the main factors that resulted in low mechanical properties of GH660 were grafting ratio, particle size and its distribution. The pre-polymerization system was optimized by adding another pre-polymerization reactor in combination with the method of improving grafting ratio and the theory of synergistic toughening with large and small particles. The conversion rate of styrene and the particle size and its distribution of the rubber particle were controlled by using double pre-polymerization reactor technology via adjusting the operating temperature and stirring rate of each pre-polymerization reactor. The apparent grafting ratio of GH600 was increased from 93% to 100% and the actual grafting ratio from 81% to 94%. The particle size of the rubber particle was decreased from 3.0 μm to about 2.0 μm, and the proportion of the particles with small size was increased significantly. The weight average molecular mass of GH600 reached 3.00×10 5 after optimization and the relative molecular mass distribution got narrower, and the mechanical properties of GH660 were improved remarkably. The tensile stress at yield of GH660 was 10% higher than that of the reference value.