Devulcanization of Automobile Scrap Tyres by a Mechanochemical Process

Abstract

The de-vulcanization of rubber waste poses a challenging economical, environmental and social problem. We propose a new de-vulcanization process to re-use the rubber waste. It is a mechano-chemical process (MCP), where the waste is de-vulcanized by a combination of mechanical shearing, heat (110 °C) and the use of a de-vulcanizing agent (diallyl disulfide). A new look at the de-vulcanization mechanism and the influence of the de-vulcanizing agent on the mechanical properties of the ultimate re-vulcanized rubber is also presented. One of the most interesting observations is that the retention of tensile strength of the re-vulcanized rubber with respect to the original tyre was 34.9% when de-vulcanized in the absence of diallyl disulfide and 72.4% in its presence. The formation of extra crosslinks in those re-vulcanized rubbers containing disulfide was confirmed from crosslink density data and from TGA results. DMA analysis revealed that the storage modulus also increased for re-vulcanized rubber containing the disulfide.