DEGRADATION MECHANISMS OF POLY(VINYL FLUORIDE) FILMS

The mechanism of degradation of poly(vinyl fluoride) films in both oxidative and nonoxidative environments has been examined. In nonoxidative environments, the homogeneous pyrolysis of related small molecules like 2-fluoropropane or 2-fluoropentane constitutes a useful model for both the product distributions and the rates. The oxidative chemistry, however, occurs at much lower temperatures and will dominate the degradation mechanism at even small partial pressures of oxygen. It is a radical chain process leading to oxygen incorporation in the polymer, main chain cleavage, and formation of new acyl fluoride chain ends. HF is formed in both mechanisms. In the oxidative chemistry, a plausible route to HF is the hydrolysis of acyl fluorides by water vapor generated in situ.