Heat and ultraviolet aging of poly(vinyl chloride)

F?ur poly~vinyl chloride) polymers l?repared with different initiators were exposed to ultravIOlet radIant energy and to heat, III a vacuum and in air.The gaseous products evo!ved were analyzed by mass spectrometry.Changes in chemical structure were followed by Illfrared spectrophotometry.Benzene was among the products evolved in most cases and acetone was produced during exposure to heat in air.Catalyst fragments or othe; incorpor~ted.impurities .aff ~cted i,nitiation at very mild conditions.Susceptibility to degradatIon Illcreased with Illcreasmg oxygen content and unsaturation of the un treated polymer.Pyrolysis studies indicated a two tage degradation: (1) dehydrochlorination, and (2) d ecomposition 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 t h e degraded polymer.