Polymer recycling: potential application of radiation technology

Management of solid waste is an important problem, which is becoming progressively worse as a byproduct of continuing economic growth and development. Polymeric materials (plastics and rubbers) comprise a steadily increasing proportion of the municipal and industrial waste going into landfill. Development of technologies for reducing polymeric waste. which are acceptable from the environmental standpoint, and which are cost-effective, has proven to be a difficult challenge due to complexities inherent in the reuse of polymers. Establishing optimal processes for the reuse/recycling of polymeric materials thus remains a worldwide challenge as we enter the new century. Due to the ability of ionizing radiation to alter the structure and properties of bulk polymeric materials, and the fact that it is applicable to essentially all polymer types, irradiation holds promise for impacting the polymer waste problem. The three main possibilities for use of radiation in this application are: (1) enhancing the mechanical properties and performance of recovered materials or material blends, principally through crosslinking, or through surface modification of different phases being combined; (2) treatment causing or enhancing the decomposition of polymers, particularly through chain scission, leading to recovery of either low molecular weight mixtures. or powders, for use as chemical feedstocks or additives; (3) production of advanced polymeric materials designed for environmental compatibility. This paper provides an overview of the polymer recycling problem. describes the major technological obstacles to the implementation of recycling technologies, and outlines some of the approaches being taken. A review of radiation-based recycling research is then provided. followed by a discussion of future directions where irradiation may be relevant to the problems currently inhibiting the widespread recycling of polymeric materials. Published by Elsevier Science Ltd.