REVIEW OF THE RECLAIMING OF RUBBER WASTE AND RECENT WORK ON THE RECYCLING OF ETHYLENE–PROPYLENE–DIENE RUBBER WASTE

ABSTRACT Rubbers do not decompose easily, and therefore, disposal of rubber waste is a serious environmental concern. Raw material costs, diminishing natural resources, and the growing awareness of environmental issues and sustainability have made rubber recycling a major area of concern. Reclaiming and recycling rubber waste is a major scientific and technological challenge facing rubber scientists today. This article reviews a number of important areas related to the reclaiming, characterizing, testing, and recycling of rubber waste. These include chemical and microbial devulcanization with particular emphasis on main chain scission and kinetics of chemical devulcanization reactions; the cutting-edge techniques for reclaiming devulcanized rubber waste by the action of large shearing forces, heat, and chemical agents: and analytical techniques and methods for characterizing composition and testing of devulcanized rubber waste, respectively. In addition, some aspects of the recycling of devulcanized ethylene–propylene–diene rubber (EPDM) waste will be reported. EPDM is used extensively in automotive components worldwide, and recycling the rubber at the end of its useful service life is of major importance to manufacturers of automotive components.