IMPACT PROPERTIES OF METALLOCENE - CATALYZED ETHYLENE-α-OLEFIN COPOLYMERS  

作　　者：Xu-rong Xu Jun-ting Xu Lin-xian Feng Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027,China Department of Polymer Science and Engineering College of Chemistry & Molecular Engineering Peking University Beijing 100871, China 

出　　处：《Chinese Journal of Polymer Science》2002年第5期473-480,共8页高分子科学（英文版）

基　　金：This work was supported by National Natural Science Foundation of China (No. 59703002).

摘　　要：The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwisecrystallization improves the impact properties, especially in the crack propagation process, to a large extent. This is due to thedecrease of entanglements by stepwise crystallization, which is advantageous for the chain slip and shear. The polymer withheterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties understepwise crystallization.The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwisecrystallization improves the impact properties, especially in the crack propagation process, to a large extent. This is due to thedecrease of entanglements by stepwise crystallization, which is advantageous for the chain slip and shear. The polymer withheterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties understepwise crystallization.

关 键 词：Metallocene-catalyzed ethylene-butene copolymer Impact properties Molecular heterogeneities Thermal treatment 

分 类 号：TQ317[化学工程—高聚物工业]