NEW DEVELOPMENTS IN THE DEGRADATION,STABILIZATION, AND SENSITIZATION OF POLY(METHYL METHACRYLATE)

Abstract

Physical and chemical processes, combined under the general term aging, begin immediately after formation of a polymer. Oxygen and other components of the environment -ozone, water, etc.-are involved. Aging is accelerated by a rise in temperature, light, strong ionizing radiations, and mechanical stresses, which are especially rapid under processing conditions for thermoplastic polymers. Poly(methy1 methacrylate) (PMMA) is of particular interest, since at least at temperatures where thermal degradation is important, photolysis occurs by end-group initiation and is accompanied by extensive depolymerization. This polymer has also been photodegraded in air at room temperature by radiation from a low-pressure mercury lamp, and a quantum yield for random chain scission has been determined. Owing to the importance of these points, it is believed that a review of studies of degradation, stabilization, and sensitization of PMMA up to the present date will supply information on the most general problems of behavior of polymeric items during their service lives.