等温结晶聚对苯二甲酸丙二酯的晶体形态和熔融行为

Crystal Morphology and Melting Behavior of the Isothermally Crystallized Poly(Trimethylene Terephthalate)

采用偏光显微镜和原子力显微镜研究了在特定温度下聚对苯二甲酸丙二酯的晶体形态和熔融行为。结果表明,聚对苯二甲酸丙二酯(PTT)的结晶形态依赖于结晶温度,在不同等温结晶温度下球晶依照无环带→规则环带→锯齿形环带→无环带的规律逐渐改变;环带宽度也随结晶温度的升高而增加。环带球晶在加热过程中熔融并伴随着环带的变化,由于晶片的熔融再结晶,环带形态经历了清晰→模糊→清晰→融化的渐变过程。

The crystal morphology and melting behavior of the poly （trimethylene terephthalate）（PTT） formed in limited space at specific temperatures were studied by the polarized optical microscopy,optical microscopy,atomic force microscopy （AFM）,respectively. The results show that crystal morphology of PTT depends strongly on the temperature. When the isothermal crystallization temperature increases from 190 ℃ to 225 ℃,the spherulites continuously change in the following order：non-banded → regular banded → zigzag banded → non-banded spherulites. Furthermore,the band spacing increases with crystallization temperature. The forming of banded spherulites is due to the fold surface stress. When heating the samples,the initial banded spherulite will melt and the bandings will change its morphology in a certain range of temperatures：clear→faint→clear→melt,which is proposed to result from the melting→recrystallization→remelting of the lamellaes.