本体法合成反式-1,4-结构丁二烯-异戊二烯共聚物中单体定向聚合的竞聚率(英文)

Reactivity ratio of monomers in synthesis of trans-1,4-butadiene-isoprene copolymer by stereospesific polymerization

采用负载型Ziegler-Natta催化剂催化丁二烯、异戊二烯进行本体聚合,合成了高反式-1,4-结构的丁二烯-异戊二烯共聚物(丁二烯和异戊二烯的反式-1,4-结构摩尔分数均高于85%)。采用傅里叶变换红外光谱及核磁共振氢谱对聚合物的微观结构及组成进行表征,计算得到了反式-1,4-丁二烯-异戊二烯共聚物的组成,研究了聚合温度及起始投料比对共聚物组成的影响,采用Kelen-Tudos’法计算了共聚单体的竞聚率。结果表明,丁二烯单体的反应活性要大于异戊二烯单体,丁二烯单体的竞聚率随温度的升高从20℃时的1.8增大到40℃时的7.1;异戊二烯单体的竞聚率对温度的变化不太敏感,在温度为20～40℃时,竞聚率为0.10～0.20。

Polymerizations of dienes are interesting topics in synthetic rubber fields. Stereospecific copolymerization of butadiene（Bd） and isoprene （Ip） has attracted lots of attentions due to the desirable dynamic prop- erties of trans-1,4--Bd-Ip copolymers（TBIR） , including excellent fatigue properties and low heat ＂build-up. Many investigations for the Bd and Ip copolymerization focus on the solution copolymerization, and most references focus on the synthesis of cis-1,4-Bd-Ip copoly- mer. In this study, the copolymerization of Bd and Ip at different feeding ratios and different reaction temperatures with supported Ziegler-Natta catalyst were investigated. According to the results of Fourier transform infrared spectroscopy and 1 H-nuclear magnetic reso- nance spectroscopy, it was found that TBIR with high trans-1,4-unit content（the mole fraction of trans-1,4-unit of both of Bd and Ip was larger than 85% ） were synthesized with the supported Ziegler-Natta catalyst. The TBIR compositions （F1 represents the mole fraction of Bd unit in TBIR） at different feeding ratios （f1 0 represents the mole fraction of Bd in the feed stock） were calculated, the results were shown in Table 1.was much more sensitive to the temperature and changed from 1.8 at 20 ℃ to 7.1 at 40 ℃, while the reactivity ratio of Ip （ rz ） changed little with increasing temperature.