期刊
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
卷 40, 期 6, 页码 593-601出版社
JOHN WILEY & SONS INC
DOI: 10.1002/polb.10118
关键词
plasticity; dislocation; twist defect; mechanical relaxation; polyethylene (PE); poly(propylene) (PP)
The plasticity of semicrystalline polymers is analyzed in the framework of Young's dislocation model under the assumption of nucleation of screw dislocations from the lateral surface of the crystalline lamellae. It is proposed that the driving force for the nucleation and propagation across the crystal width of these screw dislocations relies on chain twist defects that migrate along the chains stems and allow a step-by-step translation of the stems through the crystal thickness. Such defects are identified as thermally activated conformational defects responsible for the so-called crystalline relaxation. Dislocation kinetic equations are derived. Plastic flow rates attainable by dislocation motion in polyethylene and polypropylene are assessed with frequency-temperature data of the crystalline relaxation. Comparisons are made with experimental strain rates that enable homogeneous plastic deformation. In addition to temperature, the crystal lamellar thickness, which is a basic factor of the plastic flow stress in Young's dislocation model, is a major factor in dislocation kinetics through its influence on chain twist activation. (C) 2002 Wiley Periodicals, Inc.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据