Characterization of Polyene Sequences in Poly(vinyl Chloride)

Some aspects of the formation and propagation of polyene sequences during the thermal degradation of PVC have been discussed. The average polyene sequence length occurring in a suspension polymerized PVC, degraded in nitrogen at 190°C, was determined to ca. 10 units. The results were somewhat dependent on the type of analysis employed. The formation of internal polyene sequences was characterized by three stages. After an initial period, where the number of internal sites remained constant, new sites were rapidly formed. The high rate of formation then gradually decreased with increasing conversion. Degradation mechanisms explaining this behavior were suggested.