悬浮接枝共聚法合成EPM-g-MAN及其对SAN树脂的增韧作用

Suspension grafting copolymerization of EPM-g-MAN and its toughening effect on SAN resin

以悬浮接枝共聚法合成了二元乙丙橡胶(EPM)接枝甲基丙烯酸甲酯-丙烯腈(MMA-AN)的共聚物(EPM-g-MAN),用其与SAN树脂共混制备了耐老化黄变性能优异的高抗冲塑料AEMS。研究了EPM/MMA-AN的接枝反应条件对单体转化率(CR)、接枝率(GR)、接枝效率(GE)以及AEMS抗冲性能的影响。结果表明,当AN在MMA-AN中的质量百分率(fAN)为15%,EPM在反应物EPM与MMA-AN中的质量百分率(fEPM)为60%,BPO用量为0.6%,接枝体系的CR、GR和GE分别为89.1%、32.9%和55.4%,在此条件下EPM-g-MAN对SAN树脂有较高的增韧效率,其AEMS在EPM含量为25%时缺口冲击强度达到了55.9kJ/m2。TEM分析表明,在AEMS中EPM相以平均径向尺寸约0.15μm的串珠形态构成的近连续相结构均匀分布于SAN基体中,SEM分析表明其AEMS的冲击断面呈"须根"结构,其增韧机理为剪切屈服机理,从而赋予AEMS以高抗冲韧性。DMA分析表明,以fAN为15%合成的EPM-g-MAN与SAN树脂有良好的相容性。

EPM-g-MAN was prepared by graft copolymerization of methyl methacrylate（MMA） and acrylonitrile（AN） onto ethylene-propylene bipolymer（EPM） with suspension polymerization.The high impact plastics（AEMS）,which had excellent resistance to weatherability and yellow discoloration and ageing property,were prepared by blending EPM-g-MAN with SAN resin.The effects of the condition of suspension grafting copolymerization on monomer conversion ratio（CR）,grafting ratio（GR）,grafting efficiency（GE） and the impact strength of AEM were investigated.The result showed that when fAN was 15%,fEPM was 60% and the mass ratio of BPO/（EPM＋MMA-AN） was 0.6%,CR,GR and GE were 89.05%,32.86% and 55.35% respectively.The grafting copolymer had a remarkable toughening effect on SAN.When the EPDM/AEMS mass ratio was 25%,the notched Izod impact strength of AEMS reached 55.9kJ/m2.TEM analysis indicated that EPM phase was near continuous phase which liked a string of beads with its diameter of 0.15μm,and had good compatibility with SAN resin.SEM analysis indicated that the AEMS fracture surface appeared ＂root beard＂ morphology.The toughening mechanism of AEMS was shear yielding of matrix,which endowed AEMS with remarkable toughness.DMA analysis showed that the compatibility of EPM-g-MAN and SAN resin improved when the grafting chain polarity was appropriate.