二乙二醇单乙醚基钡/三异丁基铝/正丁基锂引发体系合成高反式苯乙烯-异戊二烯-丁二二烯三元共聚物

摘要

High trans styrene-isoprene-butadiene rubber(SIBR) was synthesized by anionic polymerization with barium salt of di( ethylene glycol) monoethyl ether ( simplified as Ba)/triisobutyl aluminum (simplified as Al)-butyl lithium (simplified as Li) as initiation system, the effects of components of initiation system, ratio of monomers and polymerization temperature on microstructure of SIBR were investigated, and effects of Al/Li( mole ratio) and butadiene (Bd)/isoprene (Ip) ( mass ratio) on glass transition temperature (Tg) and melting point were also studied. The results showed that the SIBR with number-average molecular weight of 1.60 × 105 and polydispersity index of 1.5 could be obtained. When Ba/Al/Li was 1/4/4, the mole fraction of trans1,4-unit was up to 85.6％, but the polymerization temperature and ratio of monomers had little effect.The Tg of SIBR decreased gradually with the increase of Al/Li. When Bd was larger in the ratio of monomers, SIBR had cool crystallization and melting phenomena, but the phenomena disappeared and Tg increased with decreasing Bd.%以二乙二醇单乙醚基钡(简称Ba)/三异丁基铝(简称Al)/正丁基锂(简称Li)为三元引发体系,采用负离子聚合法合成了高反式苯乙烯-异戊二烯(Ip)-丁二烯(Bd)三元共聚物(SIBR),考察了引发剂组分、单体配比和聚合温度对SIBR微观结构的影响,并研究了Al/Li(摩尔比)和Bd/Ip(质量比)对SIBR结晶行为的影响.结果表明,所制得SIBR的数均分子量为1.60×105,分子量分布指数约为1.5;当Ba/Al/Li为1/4/4时,SIBR中反式结构摩尔分数达到最高,为85.6%;聚合温度和Bd/Ip对反式结构含量的影响不明显;随着Al/Li的增大,SIBR的玻璃化转变温度(Tg)略有降低;当单体配比中Bd 含量较高时,SIBR出现冷结晶和熔融现象,随着Bd含量的减少,该现象消失且Tg升高.