Computational modeling and numerical simulation of flow-induced crystallization kinetics during injection molding of polyethylene terephthalate

A flow-induced crystallization kinetics model for semi-crystalline polymer polyethylene terephthalate (PET) was proposed based on the hypothesis that the energy of dissipation speeds up crystallization. By assuming that the effect of flow on crystallization only influenced the crystallization rate constant, the basic quiescent-state crystallization equation could be directly applied to the model flow-induced crystallization kinetics. The model predicts most of the features of flow-induced crystallization and can be easily used, especially when the real manufacturing process is considered because unknown parameters can be kept to a minimum. As an illustrative example, the injection molding of a PET part was simulated, during which the development of crystallization was controlled through the temperature of the mold resulting in a feasible method, through which transparent PET products were produced.