Processing-induced properties in glassy polymers - Development of the yield stress in PC

A new method is employed to directly predict the development of yield stress distributions in injection molded products of glassy polymers. The approach is based on the results of a study on the temperature dependence of the evolution of yield stress during annealing of polycarbonate below T-g. In combination with the process-related thermal history, derived from numerical simulations of the injection molding process, an estimate of the yield stress distribution throughout a product can be obtained. Computed yield stresses of injection molded plates prove to be in excellent agreement with the experimental values, including their dependence on mold temperature and plate thickness.