固相缩聚反应温度与时间对PET结晶的影响

Effects of solid-state polycondensation temperature and time on PET crystallinity

研究了聚对苯二甲酸乙二醇酯(PET)切片在固相缩聚反应中特性粘数和结晶度随反应条件的变化及其热行为。结果表明:固相缩聚PET特性粘数随反应温度和反应时间不断增大,反应温度为215～ 225℃时较佳,随反应的进行新结晶产生,一定时间后结晶度增加缓慢并趋于平衡;DSC分析表明固相缩聚反应后的PET存在一个特征熔融峰(253℃左右)和固相缩聚峰,随着反应温度和反应时间的增加,固相缩聚峰不断向特征熔融峰靠拢,一定反应温度和反应时间后融合为单峰,之后低温峰跨过特征熔融峰向高温移动。

The changes of intrinsic viscosity and crystallinity with reaction conditions were studied for polyethylene terephthalate （PET） chips during solid-state polycondensation. The thermal behavior of PET chips was also analyzed. The results showed that the intrinsic viscosity of PET chips was increased with the reaction temperature and time and was optimized in the range of 215 - 225 ℃. The crystallization occurred while the reaction proceeding and slowed down to equilibrium after a fixed period of time. The DSC curves showed that a characteristic meh peak at about 253℃ and a solid-state polycondensation peak were observed for PET after solid-state polycondensation. The solid-state polycondensation peak shifted towards the characteristic melt peak while increasing reaction temperature and time, then became a single peak at a specific reaction temperature and time, and finally moved to high temperature range from low temperature range, separating from the characteristic melt peak.