Recycling

Biography

Biography: Saeed Ostad Movahed

Abstract

Rubber recycling or reclaiming is growing worldwide because of increasing raw material costs. In addition, extensive use of rubber articles and their eventual disposal is a major concern for the environment Rubber recycling is the process of recycling rubbers that are no longer suitable for use due to wear or irreparable damages. The product of rubber reclaiming in most cases is a partially devulcanized rubber which can replace partially virgin rubber and can be revulcanized for manufacturing new rubbery articles. In rubber devulcanization, three dimensional rubber networks which is the outcome of vulcanization reactions, are broken. In sulphur vulcanization, the formation of both C–S and S–S bonds takes place, and it is therefore expected that during devulcanization, only C–S and S–S bond cleavage should occur. Several techniques were used for rubber devulcanization. They are, chemical, thermo chemical, mechanical, irradiation and biological processes. Irradiation process may include microwave irradiation. The three dimensional rubber network can be broken down by microwave. The energies required to break monosulfidic C-S, polysulfidic S-S and peroxide C-C bonds are 270, 240 and 345 kJ/mol, respectively. Hence, enough caution should be considered during microwave irradiation to break, only C_S and S-S bonds during devulcanization. In this study the microwave devulcanization of three famous waste rubbers, namely, butyl rubber (IIR), tire rubbers and ethylene-propylene-diene rubber (EPDM) were studied. The effect of various parameters, i.e., microwave temperature, several devulcanization agents and corresponding values, were estimated on devulcanization efficiency. The potential use of devulcanized waste rubber as a substitution for new virgin rubber, also were evaluated.