Computational prediction of PVC degradation during injection molding in a rectangular channel

A computational model has been developed to calculate the degradation of PVC during injection molding. The results in this work are for the flow in a rectangular geometry. The effects of the injection speed, melt temperature, and material properties were examined. It was determined that the principal factor influencing PVC degradation is the injection speed. Very good agreement between computational and experimental results was obtained. Furthermore, it was calculated that the materials are more thermally sensitive during processing, with activation energy of 65 kcal/mol. Finally, it was calculated that the degradation becomes significant when the melt temperature is above 250degreesC, independent of the material studied. The model could be used to design the process to avoid degradation. (C) 2004 Society of Plastics Engineers.