流场作用对聚丙烯结晶成核过程和晶体生长过程动力学的影响  

Influence of Shear Flow on the Crystallization Kinetics of Isotactic Polypropylene in Nucleation and Crystal Growth Processes

作　　者：张子男[1] 于逢源[1] 张洪斌[1] 俞炜[1] 

机构地区：[1]上海交通大学化学化工学院高分子科学与工程系流变学研究所,上海200240

出　　处：《高分子学报》2015年第4期396-402,共7页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号10590355);国家重点基础研究发展计划(973项目;项目号2011CB606005;2012CB025901);上海市重点学科项目(项目号B202)资助

摘　　要：通过改进基于构象张量构建的流动诱导结晶理论模型,考虑了流场对结晶生长的影响,对比研究了流场作用对聚丙烯(PP)结晶过程中成核与晶体生长两阶段速率的不同影响程度.理论研究表明,虽然相比成核过程,流场诱导作用对PP晶体生长速率的加速程度有限,但要更为精确地描述流动引起的整个结晶动力学过程,特别是在剪切速率较高且熔体结晶温度较低的情况下,考虑流场对结晶生长速率的影响是十分必要的.研究结果还显示,由于分子链的松弛作用,PP在较低温度下的晶体生长速率受剪切流场的影响要大于较高温度下的影响.本文理论预测结果与实验现象和实验数据的很好吻合亦说明模型改进的合理性和可行性.Based on the modified flow induced crystallization model taking into account the effect of shear flow on the crystal growth,a compared study was made on the influence of shear flow on the crystallization kinetics of isotactic polypropylene in nucleation and crystal growth processes. It was theoretically confirmed that shear flow could also accelerate the spherulite growth rate of polypropylene though this effect was small and limited compared with that on the nucleation rate. However, in order to understand and predict the whole crystallization kinetics more accurately and practically, it is essentially necessary to consider the effect of shear flow on the spherulite growth rate especially at high shear rates and low crystallization temperatures. Our theoretic results showed that the shearing effect on the crystal growth rate was relatively large at a high supercooling degree in comparison with that at a low supercooling degree. This could be attributed to the relaxation behavior of macromolecule chains, which vanishes shear history quickly at high crystallization temperatures. The theoretically predicted curves are in good agreement with the experimental data indicating the validity of the modified model.

关 键 词：聚丙烯 构象张量 半结晶时间 结晶动力学 流场 理论模型 

分 类 号：O632.12[理学—高分子化学]