悬浮法EPDM-g-MAN的合成及其对PVC树脂的增韧作用

Synthesis of EPDM-g-MAN by Suspension Polymerization and Toughening Effect on PVC Resin

以三元乙丙橡胶(EPDM)、甲基丙烯酸甲酯(MMA)和丙烯腈(AN)为原料,以悬浮接枝共聚合法合成了接枝共聚物EPDM-g-MAN,用其与PVC树脂熔融共混制备了抗冲性能优异的增韧塑料。研究了反应条件对单体转化率(CR)、接枝率(GR)、接枝效率(GE)及PVC/EPDM-g-MAN共混物冲击性能的影响。结果表明:在适宜的聚合条件下,EPDM/MMA-AN悬浮接枝体系具有较高的CR、GR和GE,分别可达92.5%、64.0%和69.2%。EPDM质量分数为15%的PVC/EPDM-g-MAN共混物的缺口冲击强度高达89.5 kJ/m2。SEM分析表明:随着在合成EPDM-g-MAN时MMA/AN质量比的增加,共混物的增韧机理由裂纹支化终止兼有剪切屈服向剪切屈服为主转变。TEM分析表明:在EPDM/MMA-AN质量比为50/50,MMA/AN质量比为80/20时,共混物的EPDM相以近连续相结构存在,PVC树脂与EPDM-g-MAN具有良好的相容性。

Ethylene propylene diene monomer grafted methyl methacrylate and acrylonitrile （EPDM-g- MAN） was prepared by graft eopolymerization of methyl methacrylate （MMA） and acrylonitrile （AN） onto ethylene-propylene-diene monomer （EPDM） with suspension polymerization. The high impact plastics were prepared by blending EPDM-g-MAN with polyvinyl chloride （PVC） 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 PVC/EPDM-g-MAN resin blends were investigated. The results showed that CR, GR and GE were high while befittingly, CR, GR and GE were 92.5%, 64. 0% and 69. 2%, respectively and the notched Izod impact strength of PVC/EPDM-g-MAN resin blends reached 89. 5kJ/m^2 when EPDM content was 15%. Scanning electron microscopy （SEM） analysis indicated that the toughening mecha- nism was that branch and termination of crack accompanied by shear yielding changed into shear yielding of matrix with increasing MMA/AN ratio. Transmission electron microscopy （TEM） analysis showed that EPDM of the blends exhibited pseudo continuous phase in EPDM/MMA-AN ratio of 50/50 and MMA/AN ratio of 80/ 20. Under this condition, PVC resin had a good compatibility with EPDM-g-MAN.