悬浮法EPDM-g-MAN对SAN的增韧及其共混物的热稳定性分析

用悬浮法在乙烯-丙烯-乙叉降冰片烯三元乙丙橡胶(EPDM)上接枝甲基丙烯酸甲酯-丙烯腈(MMA-AN),将接枝共聚物EPDM-g-MAN与苯乙烯-丙烯腈共聚物(SAN)树脂共混,得到高抗冲、耐老化性能优异的工程塑料。FTIR分析表明,EPDM确已接枝上了MMA-AN支链。研究了AN含量和EPDM含量对EPDM-g-MAN/SAN共混物力学性能的影响。随着EPDM含量的增加,共混物缺口冲击强度先升后降,在AN质量分数为5%,EPDM质量分数为25%时达到最大值76.8kJ/m2,拉伸和弯曲强度逐步下降。扫描电镜(SEM)和差示扫描热(DSC)分析表明,在EPDM质量分数为15%时,共混物室温条件下受外界冲击发生脆韧转变,EPDM-g-MAN与SAN具有较好的相容性。TG分析表明,随着EPDM含量增加,EPDM-g-MAN/SAN共混物的热失重起始温度有所上升,热稳定性得到提高。

Toughening effect on SAN of EPDM-g-MAN synthesized by suspension copolymerization and thermal stability of their blends

The graft copolymer EPDM-g-MAN,synthesized by methyl methacrylate and acrylonitrile（MMA-AN）grafted onto ethylene-propylene-diene（EPDM）with suspension technique,was blended with styrene-acrylonitrile copolymer（SAN）resin to prepare engineering plastic with high-impact strength and excellent resistance to weatherability.FTIR showed that MMA-AN brand chain had grafted onto EPDM evidently.The effect of various AN and EPDM content on the mechanical properties of EPDM-g-MAN/SAN blends was investigated.The results showed that the notched Izod impact strength of EPDM-g-MAN/SAN blend reaches its maximum value,76.8 kJ/m2,with AN content at 5% and EPDM content,25%,respectively.The tensile strength and flexural strength of EPDM-g-MAN/SAN blends decrease gradually.SEM and DSC showed that,with EPDM content of 15%,brittle and ductile transition（BDT）of EPDM-g-MAN/SAN blends was induced in impact tests at ambient temperature,EPDM-g-MAN had a good compatibility with SAN resin.TG analysis indicated that the onset temperature of thermal degradation of EPDM-g-MAN/SAN blends increased gradually and thermal stability was improved with an increase of EPDM content.