乙丙嵌段共聚物相对分子质量及链结构对PP/EPR共混体系结构与性能的影响

Effects of Molecular Weight and Chain Structure of Ethylene-propylene Block Copolymers on Structure and Performance of PP/EPR Blends

设计合成了一系列不同相对分子质量和乙烯平均序列长度的乙丙嵌段共聚物(EP),并将其作为聚丙烯(PP)/二元乙丙橡胶(EPR)共混体系的增容剂,考察了EP用量、相对分子质量及乙烯平均序列长度对共混体系性能及分散相形态演变的影响。结果表明,EP增容PP/EPR体系时存在最佳添加量,少量EP的加入可有效提高PP/EPR共混体系的抗冲击性能,并对分散相尺寸及形态起到良好的调控作用;同时,EP的相对分子质量越大对共混体系的冲击性能提高越明显,EP的组成与EPR越接近,对共混体系的增容效果越明显。

A series of ethylene‑propylene block copolymers(EP)with different molecular weights and average sequence length of ethylene monomer units were designed and synthesized by using slurry polymerization process and then used as a compatibilizer for polypropylene(PP)/ethylene‑propylene rubber(EPR)blends.The effects of the content and molecular weight of block copolymer on the performance and the evolution of dispersed phase of the blends were investigated.The results indicated that there was an optimum content of EP for compatibilization in the PP/EPR blending system.The addition of EP in a small amount could efficiently control the size and morphology of dispersed phase and therefore enhanced the impact strength of the blends significantly.Meanwhile,the higher molecular weight for EP was beneficial to the impact performance of the blends.The similarity in the composition of EP and EPR was crucial to the compatibilization effect for PP/EPR blends.