Nonisothermal Crystallization Kinetics of Poly(2-pyrrolidone)

Temperature-enthalpy curves of poly(2-pyrrolidone) (PPD) were investigated using Differential Scanning Calorimeter (DSC). The viscosity-average molecular weight of PPD sample is 2.2×10⁴ 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-two-dimensional 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 -31.9 kJ/mol by Kissinger equation.