RECYCLING OF SCRAP TIRES USING NOVEL ENVIRONMENTAL SAFE D-LINKING MIXTURES

Abstract

Disposal of used and discarded tires has posed a problem. Its recycling is environmentally attractive, but it is not proved to be economically feasible. Recyclining of used tires is done via pyrolysis. Grinding of used rubber and mixing the rubber grains is newly used.

Devulcanization10f used rubber is considered a new trend. The process starts by shredding the used rubber to one inch, then the one inch pieces are converted to brittle material via liquid nitrogen at- 190 °C.

Material size reduction is done via a hammer mill. Fiber is removed by passing air stream, while iron is removed by a magnet. The obtained material is called crumb rubber. The crumb rubber is mixed with D-linking mixtures containing essentially mercaptothiozaole .

The C-S and S-S links will be cleaved and proton also transfers. To follow up

D-linking process, solubility test and charts on N.M.R and GC-FTIR. are done.

The m ercaptothiozaole i s considered the main accelerator in D -linking process. This material is expensive and unsafe. Therefore it is replaced by methyl iodide and dibenzylcyanoguanidin. The best progress in D-linking process is obtained. Moreover the cost reduced by 25 % and the material is relatively safe.

It is worth notion that recycling of used rubber after devulcanization produced a material suitable to be mixed with rubber in grindings to manufacture new rubber.

Laboratory set up is used to produce crumb rubber and to perform D-linking process. Also an industrial unit to proceed D-linking is proposed.