A Generalized Avrami Equation for Crystallization Kinetics of Polymers with Concomitant Double Crystallization Processes

Concomitant double crystallization processes widely occur in semicrystalline polymers and their blends because of structural and morphological heterogeneity. In this work, a generalized kinetics model was established for the isothermal crystallization in the presence of concomitant double crystallization processes, based on the Avrami theory for single crystallization process. The different situations of the double crystallization processes, including independent, competitive, and composite types, are considered in the model by introducing the concept of “domains”. This model was applied to crystallization of triblock terpolymer with morphological defects, polymorphic poly­(vinylidene fluoride)/nanoclay nanocomposite, isotactic polypropylene with a broad isotacticity distribution, and poly­(ethylene terephthalate) ultrathin film. It is found that, besides the information on crystallization kinetics, other information such as morphological defect, nucleation density, cocrystallization, and structure of ultrathin film can also be provided by this model.