成型方法对PE-UHMW/PE-HD共混物流变行为和力学性能影响

Influence of Forming Methods on Rheological behavior and Mechanical Property of PE-UHMW/PE-HD Blends

通过熔融共混法制备超高分子量聚乙烯(PE-UHMW)/高密度聚乙烯(PE-HD)共混物,经注塑和模压制备晶/晶两相同构聚乙烯合金,应用差示扫描量热(DSC)分析、旋转流变仪、扫描电子显微镜(SEM)和电子万能试验机等剖析了成型方法对合金的熔融结晶、流变、力学性能与微观结构之间的影响。流变分析表明,成型方法对共混物的相容性和流变行为有明显的影响,随着共混物中PE-UHMW含量的增加,模压成型合金出现微相分离且流变行为处于PE-UHMW相的高弹橡胶态;力学分析发现,模压合金的力学性能远优于注塑合金,模压合金的拉伸强度可达46.9 MPa;采用SEM进一步剖析成型方法对合金的微观结构的影响,发现PE-UHMW相以微米级粒子形态分布,PE-HD相有利于PE-UHMW分子链扩散使得两相混溶,模压合金的力学增强是由于良好的界面结合和微米级高弹性“PE-UHMW粒子”的应力传递作用。

PE-UHMW/PE-HD blends were prepared by melt blending method,after the injection and molding the preparation of crystal/crystal two-phases homogeneous polyethylene blend.The influences of the forming methods on the melting and crystallization process,rheological behavior,macroscopic properties and microstructure of the blend were analyzed by d differential scanning calorimetry(DSC),rotating rheometer,scanning electron microscope(SEM)and electronic universal testing machine.The rheological analysis shows that the forming method has obvious influence on the compatibility and rheological behavior of the blends.With the increase of PE-UHMW content in the blend,the injection molding alloy phase separation behavior is not obvious.The microphase separation occurs in the compression molded blends and the rheological behavior presents the“solid-like”high elastic rubber state of PE-UHMW phase.The mechanical analysis shows that the mechanical properties of the compress molding blends are much better than that of the injection molding blends,and the tensile strength is up to 46.9 MPa.SEM was used to further analyze the influence of the forming method on the microstructure of the blends.It is found that the PE-UHMW phase is distributed in the form of micron particles,and the PE-HD phase is conductive to the diffusion of PE-UHMW molecular chain to make the twophase compatible.The mechanical enhancement of the compress molding blends is due to the good interface bonding and the stress transfer of micron high elastic“PE-UHMW particles”.