PEB/MMA-AN悬浮接枝共聚反应机理

研究了乙烯-1-丁烯共聚物(PEB)弹性体与甲基丙烯酸甲酯(MMA)-丙烯腈(AN)悬浮接枝共聚反应行为及接枝共聚产物对SAN树脂增韧作用随反应时间的变化规律, 用凝胶渗透色谱法和傅里叶变换红外光谱法对接枝共聚产物进行了表征, 分析了接枝共聚反应机理, 推算了接枝链分子量. 结果表明, 体系首先发生链增长自由基向PEB转移终止形成非接枝共聚物(MAN_L)和PEB大分子自由基引发单体共聚形成接枝链(g-MAN)的反应, 接枝反应结束后体系发生明显的非接枝共聚形成非接枝共聚物(MAN_H)的反应; MAN_L的分子量低于g-MAN的分子量, 而g-MAN的分子量明显低于MAN_H的分子量; 在接枝共聚过程中发生已接枝和未接枝PEB断链并随机再接生成多嵌段共聚物的副反应; 在反应初期, 接枝链的AN单元含量接近于非接枝共聚物的AN单元含量, 在反应中后期前者远低于后者.

Mechanism of Graft Polymerization of Methyl Methacrylate-Acrylonitrile onto Poly (ethene-co-1-butene)

The effects of reaction time on reaction behavior of suspension grafting copolymerization of methyl methacrylate(MMA)-acrylonitrile(AN) onto poly(ethene-co-1-butene)(PEB) and toughening effect of PEB-g-MAN on SAN resin were investigated.The grafting polymerization product was characterized by GPC and FTIR analysis,the grafting copolymerization mechanism was investigated and the formula of calculating molecular weight of grafted chain was established.The results show that firstly the polymerization is mainly forming non-grafted copolymer with low molecular weight(MANL) of the transferring terminating polymerization of chain propagating free radicals and forming the grafted chains(g-MAN) of the transferring graft polymerization,and then the polymerization is mainly forming non-grafted copolymer with high molecular weight(MANH) of bimolecular terminating polymerization of chain propagating free radicals;molecular weight of MANL is less than that of g-MAN and molecular weight of g-MAN is less than that of MANH;there exist chain scission and random regrafting of the backbone of PEB-g-MAN and ungrafted PEB which result in the production of multi-block polymer of PEB and PEB-g-MAN during the grafting copolymerization;mass fraction of AN unit in grafted chain is close to mass fraction of AN unit in non-grafted copolymer in the initial stage and the former is much less than the later in the later stage.