Oxidation is one of the most important of all degradation processes. Oxidation can occur in every stage of the life cycle of a polymer: during manufacture and storage of the polymer resin, as well as during processing and end use of the plastic article produced. Numerous oxidation products are formed as the result of the degradation of polymers, such as peroxides, alcohols, ketones, aldehydes, acids, peracids, peresters and γ-lactones. Elevated temperatures, irradiation (e.g. UV) and catalysts such as metal ions increase oxidation rates. Also, most polymers have structural elements that are particularly prone to oxidative degradation reactions