Heat and ultraviolet aging of poly(vinyl chloride)

Abstract

Polyvinyl chloride polymers were exposed to ultraviolet radiant energy and to heat, in a vacuum and in air. Benzene was among the products evolved in most cases and acetone was produced during exposure to heat in air. Catalyst fragments or other incorporated impurities affected initiation at very mild conditions. Susceptibility to degradation increased with increasing oxygen content and unsaturation of the untreated polymer. Pyrolysis indicated a two-stage degradation: (1) loss of hydrogen chloride, and (2) decomposition of the resultant polyene chain. Color formation was attributed to both oxidation and conjugated un-saturation because exposure in air following exposure in a vacuum, and vice versa, caused bleaching of the degraded polymer. Edward V. Sayre LB - B4 LB - General causes and processes of deterioration