嵌段共聚物苯乙烯-异戊二烯-苯乙烯结构与性能的关系

Relationship between structure and property of SIS block copolymer

采用阴离子聚合的方法合成了嵌段共聚物苯乙烯-异戊二烯-苯乙烯(SIS),研究了SIS的分子质量、嵌段比与其机械性能之间的关系,并探究了其影响机理。结果表明,在SIS分子质量一定时,随着苯乙烯链长的增加,300%定伸强度、永久变形、硬度增大,扯断伸长率和熔融指数减小;SIS嵌段比一定时,熔融指数会随PS段分子质量的增大而减小,而硬度受分子质量的影响较小。PS段(聚苯乙烯)分子质量是影响拉伸性能的重要参数,随着PS段分子质量的增加,拉伸强度先增大后减小。并通过透射电子显微镜(TEM)和差示扫描量热法(DSC)对其影响机制进行了验证。

Styrene-isoprene-styrene(SIS)block copolymer is synthesized via anionic polymerization method.The relationship between the molecular weight and block ratio of SIS and its mechanical properties is studied,and the affecting mechanism is explored.The results show that SIS’s stress at 300%elongation,permanent deformation and hardness increase but its elongation at break and melting index decrease as SIS molecular weight remains constant and the increase of styrene chain length increases.As the SIS block ratio is constant,the melting index decreases with the increase of molecular weight of PS(polystyrene)segment,while the hardness is less affected by PS molecular weight.The molecular weight of PS segment is an important parameter affecting the tensile properties.With the increase of the molecular weight of the PS segment,the tensile strength of SIS increases firstly and decreases then.The affecting mechanism is verified by transmission electron microscope(TEM)and differential scanning calorimetry(DSC).