亚微米核壳橡胶粒子改性聚苯乙烯 ——接枝度对形态结构及力学性能的影响

通过乳液接枝聚合技术合成不同聚丁二烯(PB)含量的聚丁二烯接枝聚苯乙烯(PB-g-PS)共聚物, 共混改性聚苯乙烯(PS), 使PB含量控制在20wt％。通过对接枝共聚物PB-g-PS接枝度的测定, 分析了不同接枝度对橡胶粒子分散状态以及橡胶粒子内部结构的影响, 考察了不同接枝度对改性聚苯乙烯力学性能的影响。通常认为橡胶粒子只有在1~3μm时才能对聚苯乙烯进行有效增韧, 然而实验结果表明, 使用粒径约为300nm的核壳橡胶粒子改性聚苯乙烯冲击韧性提高很大。此时, 接枝共聚物具有最佳核壳比PB/PS为70/30, 橡胶粒子呈均匀分散状态, 且最大冲击强度为124.9J/m, 相当于纯聚苯乙烯冲击强度的10倍。

Sub-micron core-shell rubber particles modified polystyrene——Effects of grafting degree on morphology and mechanical property

Core-shell PB-g-PS impact modifiers with different mass ratios of polybutadiene (PB) to polystyrene (PS) were prepared with emulsion polymerization by grafting styrene onto polybutadiene latex. The mass ratio of polybutadiene to polystyrene was in a range from 30/70 to 90/10. Then these core-shell impact modifiers were blended with polystyrene to prepare the PB-g-PS/PS blends with a constant PB content of 20wt%. The grafting degrees of PB-g-PS copolymers were measured and the effects of different grafting degrees on the dispersion state and morphologies of rubber particles are discussed. It was generally accepted that polystyrene could only be toughened effectively by 1~3μm rubber particles. However, the experimental results of this paper show that PS can be actually toughened by sub-micron core-shell rubber particles. The optimal degree of grafting is 28.3% and the ratio of PB/PS in PB-g-PS copolymer is 70/30. The TEM photograph of PB-g-PS/PS (70/30) shows that the rubber particles disperse homogeneously in the PS matrix, and the izod notched impact strength attains 124.9J/m.