Analysis of nonvolatile oxidation products of polypropylene. III. Photodegradation

Abstract

Abstract The nonvolatile oxidation products of photodegraded polypropylene have been analyzed by infrared spectroscopy and chemical reactions. The major functional group is ester followed by vinyl alkene, then acid. In comparison, thermally oxidized polypropylene contains relatively more aldehyde, ketone, and γ‐lactone and much less ester and vinyl alkene. Photodegraded polyethylene contains mostly vinyl alkene followed by carboxylic acid. Gel‐permeation chromatography (GPC) determined the decrease in polypropylene molecular weights with exposure time. A calculation determined that there is one functional group formed per chain scission; in thermal oxidation there are two groups formed per scission.