Factors that Influence the Kinetics of the Degradation of Poly(vinyl Chloride)

Abstract

Abstract The degradation of five samples of PVC having different degrees of polymerization has been studied by a technique that permits a precise measurement of the rate of hydrogen chloride elimination as % HCl/min. All samples followed acceleratory kinetics at both low and high conversions. The conversion rate, which changed from the beginning to the end of a degradation, depended primarily upon the fraction of chains producing hydrogen chloride. The fraction of producing chains and the kinetic pattern were influenced by the presence of hydrogen chloride, the physical state of the sample, the previous degradation history, and the presence of intentionally added substances. Zipper kinetics permit the reproduction of kinetic data in terms of three parameters: k1, the fraction of chains initiating per second, k2, the fraction of a zip chain that zips per second, and k3, an arbitrary parameter that accounts for residual hydrogen chloride after degradation has ceased.