COMPUTER-SIMULATIONS OF CRYSTALLINITY GRADIENTS DEVELOPED IN INJECTION-MOLDING OF SLOWLY CRYSTALLIZING POLYMERS

A model is developed to simulate the crystallinity gradients developed in injection molding of slowly crystallizing polymers. In this model, effects of nonisothermal and stress-induced crystallization kinetics are taken into account through phenomenological relationships. Computer simulations included calculations of the temperature, velocity, and pressure distributions as well as two dimensional crystallinity distributions in the final products. In addition, effects of various processing conditions: mold temperature, injection flow rate, and holding time are also included in the calculations. The crystallinity gradients obtained through computer simulations agree with the experimental results obtained with poly (p-phenylene sulfide) under a variety of processing conditions.