The Photooxidative Degradation of Polypropylene. Part II. Photostabilization Mechanisms

All polymeric materials photodegrade to a greater or lesser extent on exposure to terrestrial sunlight in the presence of oxygen. For most commercially important polymers, some form of photo-stabilization is essential if adequate outdoor lifetimes are to be achieved. This has led to the development of many UV stabilizers for general use in films, fibers, and moldings. Comprehensive lists of UV-stabilizers and stabilizer structures have appeared in the recent literature [1–4].