Eliminating PVC degradation during injection molding using computational techniques

New vinyl compounds with lower viscosity and increased thermal stability have been developed for injection molding. Furthermore, more advanced and robust computational techniques allow for proper design of molds and determination of process conditions. Yet, even with all the recent advancements, there still exists a need for either expertise or a "trial-and-error" approach to optimize injection molding of vinyl compounds. This is due to the limited amount of detail that can be included when designing complex parts in order to reduce computational time. Research was performed in order to gain better understanding of important parameters for injection molding of vinyl compounds. The goal of the research was to increase the level of detail in the thickness direction and include a model of the degradation kinetics by reducing the complexity of the geometry being studied. The parallel plate flow geometry was evaluated in this study using a finite difference scheme to provide detailed information about viscous heating during injection. A "stop-and-go" technique was used to simulate the filling process; the degree of degradation was evaluated by implementing a computational tracer method. The simulation results were compared to experiments performed using a spiral mold.