Self-induced field model for crystal twisting in spherulites
Self-induced field model for crystal twisting in spherulites
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DOI：
10.1016/s0032-3861(02)00724-3
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发表时间：
2003-01-01
期刊：
影响因子：
4.6
通讯作者：
Schultz, JM
中科院分区：
文献类型：
--
作者：
Schultz, JM
观察到的球晶中晶体围绕生长方向的扭曲被模拟为对晶体生长过程中产生的场的响应。这些字段可以是组合的，也可以是机械的。在任何一种情况下，界面附近熔体中的高局部场值都会减慢生长速度。晶体围绕生长方向的扭曲使生长表面的所有部分与场值较低的熔体接触，从而提高了生长速度。本文分析了组分场的影响，使用移动点源的延伸来计算扭曲晶体之前熔体中的组份。分析中考虑了晶体弹性扭转的滞后效应。利用可结晶/不可结晶聚乙烯共混物的参数，对矩形截面的晶体进行了数值模拟。结果与观测结果在定量和定性上是一致的。对模型中的简化和模型的影响进行了评论。(C)2002年由爱思唯尔科学有限公司出版。
The observed twisting of crystals about the growth direction in spherulites is modeled as a response to fields generated during the crystal growth process. These fields can be compositional or mechanical. In either case, the high local field value in the melt near the interface acts to reduce the growth velocity. Twisting of the crystal about the growth direction places all portions of the growth surface in contact with melt of lower field value than would be the case for untwisted growth, thereby increasing the growth velocity. The effect of a compositional field is analyzed here, using an extension of the moving point source to compute the composition in the melt ahead of a twisting crystal. The retarding effect of the elastic twisting of the crystal is included in the analysis. Simulations using parameters for a crystallizable/uncrystallizable polyethylene blend are carried out for a crystal with thin, rectangular cross-section. The results are quantitatively and qualitatively consistent with observation. Comments on simplifications within and implications of the model are given. (C) 2002 Published by Elsevier Science Ltd.