摘要
本文采用DSC方法研究了PET和添加型PET(添加CaCO_3)的结晶动力学。结果表明,PET是以异相杂质为中心沿径向生长的,在不同温度,不同的异相杂质被活化成为晶核,导致PET有不同的结晶机制。反映在结晶动力学参数之一——Avrami指数不是整数,且随结晶温度发生变化。CaCO_3活化了PET中原有的异相杂质,使成核活化能降低,CaCO_3也使晶片折叠面自由能σ_e减小,导致结晶速率对结晶温度的依赖性减小。结果还表明,添加型PET容易在生长面的表面发生二次成核,二次成核与晶体生长过程重叠,致使n值升高。
The isothermal crystallization kinetics of pure PET and filled PET have been studied by DSC. The results indicate that PET nucleates heterogeneously. These heterogeneities may be the remainders of catalytic system, occasional impurities, or various ingredients. Different types of heterogeneities become active at different temperature, so PET have different crystallization mechanism at different temperature. Specially, one of the crystallization parameters-Avrami exponent n is fractional, and the fractional value of n is not constant in the temperature range studied. Additive CaCO3 may active the originally present heterogeneities, cause the nucleation activation energy to decrease; The result that filled PET has lower fold-surface free energy σe indicate that the chain diffusion activation energy decrease after CaCO3 is added to PET. Lower values of nucleation activation energy and chain diffusion activation energy means the dependence of the rate of crystallization on temperature decreased. The secondary nucleation is presented during crystallization of filled PET.
出处
《高分子材料科学与工程》
EI
CAS
CSCD
北大核心
1989年第6期36-42,共7页
Polymer Materials Science & Engineering
