DEPENDENCE OF SLOW CRACK-GROWTH IN POLYETHYLENE ON BUTYL BRANCH DENSITY - MORPHOLOGY AND THEORY

被引:251
作者
HUANG, YL
BROWN, N
机构
[1] Department of Materials Science & Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
关键词
D O I
10.1002/polb.1991.090290116
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
A theoretical equation has been developed to describe the rate of slow crack growth in an ethylene-hexene copolymer in terms of the basic morphological parameters. These parameters are spacing of the butyl branches, number of tie molecules, and the thickness of the lamellar crystal. Experimentally, the thickness of the lamellae and the long period were determined as functions of the branch density. The calculation of the number of tie molecules is based on the values of the molecular weight an the long period. The model of slow crack growth is based on the rate of disentanglement of the tie molecules. The rate of disentanglement varies inversely with the number of tie molecules and directly with the number of tie molecules that are not pinned by the branches.
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页码:129 / 137
页数:9
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