星形苯乙烯-异戊二烯-丁二烯嵌段共聚物结构与性能的关系

以环己烷为溶剂,苯乙烯(St)、丁二烯(Bd)、异戊二烯(Ip)为单体,正丁基锂为引发剂,采用负离子聚合法合成了集成橡胶———星形苯乙烯-异戊二烯-丁二烯嵌段共聚物(SIBR),考察了星形SIBR的相对分子质量、侧基含量、嵌段比(即Ip的均聚物链段与St-Bd的无规共聚物链段的质量比)与其性能的关系。结果表明,在考察范围内,星形SIBR的拉伸强度和撕裂强度随着其相对分子质量的增加而增大。随着1,2-和3,4-结构含量之和的增加,0℃和60℃时的损耗因子均有所增大。固定St/Bd(质量比)为1/3,随着嵌段比的逐渐降低,所得星形SIBR的门尼黏度逐渐增大;嵌段比为20/80时所得星形SIBR具有较好的力学性能与动态力学性能,且与溶聚丁苯橡胶2300、2305以及天然橡胶相比,具有更好的抗湿滑性和滚动阻力的平衡。

Relationship between structure and properties of star-shaped styrene-isoprene-butadiene block copolymer

The integrated rubber star-shaped styrene-isoprene-butadiene block copolymer(SIBR) was synthesized with styrene(St),isoprene(Ip) and butadiene(Bd) as monomers,n-BuLi as initiator,cyclohexane as solvent by anionic polymerization.The effects of relative molecular mass,side group content and block ratio(the mass ratio of homopolymer of Ip to copolymer of St-Bd) on the properties of SIBR were investigated.The results showed that the tensile strength and tear strength of star-shaped SIBR increased with increasing relative molecular mass within the range of the experiment.Both the loss factors at 0 ℃ and 60 ℃ increased with increasing the content of 1,2-unit and 3,4-unit.Mooney viscosity of star-shaped SIBR increased gradually with decreasing block ratio at St/Bd(mass ratio) 1/3.When the block ratio was 20/80,the star-shaped SIBR had better mechanical and dynamical mechanical properties and a better balance between wet skid resistance and rolling resistance than those of solution polymerized styrene-butadiene rubber(SSBR) 2300,SSBR 2305 and natural rubber.