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PVC degradation during injection molding: Experimental evaluation

This paper focuses on experimental observations of poly(vinyl chloride) (PVC) degradation during injection molding. Degradation of poly(vinyl chloride) has been extensively studied. These studies have been performed in quiescent systems with very little or no strain applied to the sample. However, during processing, the polymer experiences very large deformations, in particular in the case of injection molding. This work demonstrates that the large shear during injection molding causes a significant increase of degradation as compared to studies in quiescent systems. It was also observed that degradation occurs in less than 1/10 the time required for quiescent systems. Finally, the flow geometry also affects the degradation behavior during processing. Understanding the parameters leading to degradation could lead to schemes to avoid it. J. Vinyl Addit. Technol. 10:17–40, 2004. © 2004 Society of Plastics Engineers.