Role of polymer morphology in the oxidation of polypropylene

The γ‐initiated oxidation and presensitized photooxidation of polypropylene films and fibers are shown to be insensitive to sample thickness (if <150 μm) and a range of morphological parameters such as molecular orientation (in drawn samples) and fibrillar and void content. The relevance of these observations is discussed in the light of the many previous assertions as to the influence of morphological effects on oxidation rates. The γ‐initiated oxidation was studied in preference to conventional thermal or photoinitiated oxidation because of the greater control over the rate of radical production available by this method.