高温熔融对PP/EPR/PE-UHMW分子链扩散作用以及流变和结晶性能的影响

Diffusion Effect of Melting at High Temperature on PP/EPR/PE-UHMW and Its Influence on Rheological and Crystallization Behavior

采用一种简便易行的方法使高度缠结的超高相对分子质量聚乙烯(PE-UHMW)与乙丙橡胶(EPR)的分子链得到有效的扩散,并最终将EPR/PE-UHMW预混物与聚丙烯(PP)共混形成PP/EPR/PE-UHMW三元共混物。并研究了该三元共混物的流变性能和结晶性能。结果表明,在预混物体系中,经历高温熔融处理后,流变曲线出现不同于一般EPR材料的难松弛结构的低频平台区,说明PE-UHMW与EPR分子链相互扩散形成长分子链缠结结构;其缠结结构在PP/EPR/PE-UHMW共混物中减慢了PP基体流变曲线低频平台区出现的趋势,限制了EPR向PP基体的扩散;EPR与PE-UHMW分子链之间的相互扩散,对高度缠结的PE-UHMW具有增塑作用,导致PE-UHMW结晶温度下降和结晶度上升;二元预混物添加进入PP基体中,促使PP多重熔融现象的发生。

A simple method was used to promote the diffusion of highly-entangled molecular chains of ultra high molecular weight polyethylene （PE-UHMW） and ethylene propylene rubber （EPR） leading to blends of EPR/PE-UHMW, which was further mixed with polypropylene （PP） forming PP/EPR/PE-UHMW ternary blends. The blends were characterized by rheological measurement and differential scanning calorimeter （DSC）. The theological tests displayed a long relaxation mechanism occurring in the low-frequencies region. The inter-entanglement structure restricted the diffusion of EPR into PP matrix. DSC showed that the plasticization of PE-UHMW resulted in decreasing in crystallization temperature and increasing indegree of crystallinity. The addition of EPR/PE-UHMW blend to PP matrix caused a multiple melting behavior of PP.