聚2-吡咯烷酮的非等温结晶动力学

Nonisothermal Crystallization Kinetics of Poly(2-pyrrolidone)

用差示量热扫描热分析仪(DSC)测试了不同降温速率下聚2-吡咯烷酮(PPD)样品的温度-热焓曲线,样品黏均分子量为2.2×10~4,熔点为272℃。采用Jeziorny法、Ozawa法和莫志深法分析了PPD的非等温结晶动力学。结果表明,在给定降温速率范围内,Ozawa法不适用于描述PPD的非等温结晶动力学过程,Jeziorny法只适用于描述PPD的主结晶阶段,而莫志深法能很好地描述整个结晶过程。Jeziorny法处理结果表明,PPD主结晶阶段的Avrami指数(n)为1.68~1.78,晶体生长为准二维生长。莫志深法处理结果表明,在单位结晶时间里达到某一相对结晶度所需的降温速率随相对结晶度的增加而增大。用Kissinger方程求得PPD的非等温结晶活化能为-31.9kJ/mol。

Temperature-enthalpy curves of poly（2-pyrrolidone）（PPD） were investigated using Differential Scanning Calorimeter （DSC）.The viscosity-average molecular weight of PPD sample is 2.2×10~4 and the melting temperature is 272℃.The nonisothermal crystallization kinetics of PPD were analyzed by Jeziorny model,Ozawa model and Mo model,respectively.Ozawa model is inappropriate for analysing nonisothermal crystallization kinetics of PPD,and Jeziorny model is only suitable for primary crystallization stage.However,it can be described perfectly by Mo model.The Avrami constant n calculated by Jeziorny model ranges from 1.68 to 1.78,indicating that PPD crystals grow in quasi-twodimensional direction in primary crystallization stage.Mo model gives the information that faster cooling rate is required to achieve a certain degree of crystallinity in the unit crystallization time.Activation energy for nonisothermal crystallization of PPD is-31.9kJ/mol by Kissinger equation.