物理老化对非晶态PET结构、性能以及结晶的影响

采用密度、DSC、应力—应变测量、溶剂诱导结晶和声速测定等方法研究了物理老化对非晶态PET膜和纤维结构与性能的影响.研究结果表明,非晶态PET经物理老化后DSC曲线上的Tg增加,并出现吸热峰,热结晶变慢,溶剂诱导结晶和溶剂扩散速率变慢,初始模量和屈服应力增加,从物理老化引起PET中凝聚缠结增加这一结构变化的角度对上述实验现象进行了解释.

EFFECTS OF PHYSICAL AGING ON THE STRUCTURE,PROPERTIES AND CRYSTALLIZATION OF AMORPHOUS PET

Effects of physical aging on the structure, mechanical properties and crystallization behavior of amorphous PET film and fiber are studied by density,DSC,stress-strain curve ,solvent-induced crystallization and sonic velocity measurements. It is shown that both the temperature and the solvent-induced crystallization as well as the diffusion velocity of toluol into PET are slow down after being annealed below Tg,an endothermic peak is appeared on the DSC curve with the increase of Tg,its initial modulus and yield stress increase while the sonic modulus keeps unchanged. All experimental results are explained by the assumption that the number of cohesional entanglements increases during physical aging.