聚乙烯相结构与性能的关系

Relationship between morphological structure of polyethylene and its properties

将均聚低分子量高密度聚乙烯(HDPE)组分和共聚高分子量线型低密度聚乙烯(LLDPE)组分按不同比例熔融共混,制备了双峰聚乙烯,对其进行了力学性能、流变、DSC测试,以表征共混物中的均聚HDPE组分与共聚LLDPE组分的溶混性。采用SEM观察了不同比例的熔融共混物试样的冲击断面,当高分子量组分LLDPE在共混物中的含量小于50%(w)时,共混试样中会观察到椭圆状的分散相,从而直观地看到共混物中存在较大尺度的相分离结构。这种由于两种组分黏度差异大造成的相分离对HDPE/LLDPE共混物的力学性能有一定的影响。

Bimodal polyethylene was prepared by melt blending the homopolymer component of low molecular weight high-density polyethylene(HDPE)and copolymer component of high molecular weight linear low-density polyethylene(LLDPE)in different proportions.The tests of mechanical properties,rheological properties and DSC were carried out to characterize the miscibility of homopolymer HDPE and copolymer LLDPE.SEM was used to observe the impact sections of the blend samples with different proportions.When the content of the high molecular weight component LLDPE in the blend is less than 50%(w),the elliptic dispersed phase can be observed in the blend sample,so as to intuitively see the existence of large scale phase separation structure in the blend.The phase separation caused by the great viscosity difference between the two components has a certain effect on the mechanical properties of HDPE/LLDPE blend.