Application of the Avrami, Tobin, Malkin, and simultaneous Avrami macrokinetic models to isothermal crystallization of syndiotactic polypropylenes

Various macrokinetic models (the Avrami, Tobin, Malkin, and simultaneous Avrami models) were applied to describe the primary crystallization of syndiotactic polypropylene (sPP) under isothermal conditions. Analysis of the experimental data was carried out using a direct-fitting method such that the experimental data were fitted directly to each macrokinetic model using a nonlinear multivariable regression program. Comparison of the kinetics parameters obtained from the program to those obtained from the traditional analytical procedure suggested that applicability and reliability of the direct-fitting method are satisfactory. Prediction of the time-dependent relative evolution of crystallinity at other crystallization temperatures was demonstrated based on the bulk kinetics parameters obtained from the analysis.