聚酯固相缩聚等温结晶特性的研究

Study on isothermal crystallization of poly(ethylene terephthalate) with solid state polycondensation (SSP)

聚酯(PET)固相缩聚(SSP)中切片的结晶性能及其演变影响固相缩聚反应,采用差示扫描量热仪(DSC)和热台偏光显微镜研究了固相缩聚反应前后PET切片的等温结晶特性。结果表明:PET切片在DSC中的等温结晶符合Avrami 方程,等温结晶温度升高,结晶速率常数K值减小,即结晶速率降低;热台偏光显微镜中不同等温结晶温度下形成了不同的球晶形态:黑十字消光图以及环形消光图;随着PET特性粘数(平均分子质量)增大,结晶速率常数K值减小,球晶生长速率减小,Avrami指数n值增大,形成更加复杂的消光图。对于固相缩聚前PET基础切片,球晶最大结晶速率在190℃左右。

Crystallization behavior of PET changes with SSP. The isothermal crystallization of PET with SSP was investigated using differential scanning calorimetry （DSC） and polarizing microscope （with heating and freezing stage）. The isothermal crystallizati constant K decreases, on of PET suit Avrami equation, and as the crystallization temperature rises, crystallization rate that is to say, crystallization rate decreases. There are different morphologies with different isothermal crystallization temperature. As intrinsic viscosity （average molecular weight） of PET increases, crystallization rate constant K decreases, spherulite growing rate decreases, Avrami constant n increases, and forms more complex morphology.