非晶聚对苯二甲酸乙二醇酯薄片在低温退火过程中的声发射现象

ACOUSTIC EMISSION DURING SUB-Tg ANNEALING FOR AMORPHOUS POLY (ETHYLENE TEREPHTHALATE) SHEET

从熔体淬火得到的聚对苯二甲酸乙二醇酯(PET)薄片在室温下呈非晶玻璃态,已经证明这是一种非平衡态。很多文献曾报道,在T_g以下对它进行退火处理后虽然观察不到明显的结晶,但是它的延伸性能及抗冲性能会迅速变坏。

Acoustic emission during sub-Tg annealing fort amorphous polyethylene terephthalate (PET) sheet quenched from melt has been observed. The mechanical properties, texture and glass transition of annealed specimens have been studied. It is shown that some of PET chains change from non-equilibrium state to equilibrium state during sub-Tg annealing, which leads to stress concentration in specimen. When the level of internal stress approaches to the limit, the acoustic waves are emitted due to sudden releasing of stress and the micro-defects are formed. This is one of the important reasons, that causes the loss of mechanical properties to annealed specimens.