悬浮法EPDM-g-MS/PS的冲击和耐候性能的研究

Study on Impact Property and Weather Resistance of EPDM-g-MS/PS by Suspension Copolymerization

以三元乙丙橡胶(EPDM)、甲基丙烯酸甲酯(MMA)和苯乙烯(St)为原料,采用悬浮接枝共聚法合成了EPDM接枝MMA-St共聚物(EPDM-g-MS),再与聚苯乙烯(PS)树脂共混制备了EPDM-g-MS/PS(MES)高抗冲塑料。研究了接枝体系的单体配比(fMMA)和接枝产物所含MMA-St共聚物的共组成质量比(FMMA)对MES的缺口冲击强度的影响,以及MES的相结构与增韧机理、热稳定性和耐候性,并与苯乙烯-丁二烯-苯乙烯共聚物(SBS)/PS的性能进行了比较。结果表明:当fMMA为15%、FMMA为29.1%时,EPDM-g-MS对PS的增韧效果最好;当MES所含EPDM质量分数为30%时,其缺口冲击强度高达45.1 kJ/m2;在MES的微观结构中,橡胶相EPDM以具有包藏结构的分散相存在,MES的增韧机理为裂纹分支终止兼有轻度基体剪切屈服;而在SBS/PS中,橡胶相(聚1,4-丁二烯嵌段)以网络状连续相存在,其增韧机理为基体剪切屈服。MES的热稳定性和耐气候老化黄变性能显著高于SBS/PS。

With ethylene-propylene-diene mischpolymere （EPDM）, methyl methacrylate （MMA）, and styrene （St） as raw materials, EPDM graft MMA-St copolymers （EPDM-g-MS） synthesized by suspension grafting copolymerization was blended with polystyrene （PS） resin to prepare a EPDM-g-MS/PS （MES） high impact resisitance plastic. The effects offMnA,weight fraction of MMA in the charge monomers MMA-St, and FMMA, weight fraction of MMA unit in the copolymer formed by MMA-St, on notched impact strength of MES were investigated. The phase structure, toughening mechanism, thermal stability and weathering resist- ance of MES were studied, and compared with the properties of SBS/PS blends. The results showed that EPDM-g-MS had the best toughening effects on PS resin whenfMMA and FMMA was 15% and 29. 1% respectively, the notched impact strength of MES containing 30% of EPDM, reached 45.1 kJ/m^2. EPDM phase exhibited dispersed phase with concealed structure in microstructure of MES, whose toughening mechanism was branch and termination of crack, accompanying slight shear yielding of matrix. In comparison, 1,4-polybutadiene block of SBS exhibited continuous phase in microstructure of SBS/PS blends, and the toughening mechanism of which was shear yielding of matrix. Thermal stability and properties of resistance to yellow discoloration by weathering aging of MES were significantly higher than those of SBS/PS blends.