Devulcanization of Styrenebutadiene (SBR) waste tire by controlled oxidation

Abstract

This work describes the devulcanization of vulcanized SBR (Styrene Butadiene Rubber) based on controlled oxidation with nitric acid. IR, 1H and 13C-NMR, CHN elemental analyses, TG, GPC and TPD-MS (Temperature Programmed Decomposition-Mass Spectrometry) experiments suggest that nitric acid promotes two processes: (i) devulcanization by oxidation of the sulfide crosslinks and (ii) oxidation of the carbon framework leading to the formation of -COOH and -NO2 groups. Under aggressive conditions (HNO3, reflux) the polymer chain is strongly oxidized and fragmented to a highly oxygenated low molecular weight fraction, which is soluble in water. ©2006 Sociedade Brasileira de Química.