Characterization and supercritical CO2 devulcanization of cryo-ground tire rubber: Influence of devulcanization process on reclaimed material

Ground truck-tire rubber (GTR) was characterized and subsequently devulcanized in supercritical CO2 (scCO2) in the presence of Diphenyl Disulfide (DD) as devulcanizing agent.Temperature and pressure were kept respectively at 180 °C and 15 MPa and the ratio between rubber and DD was 10 wt %.The treatment effect on the properties of GTR was widely studied. The reached degree of devulcanization was about 50% with a low amount of sol fraction.The results display that the treatment with the DD in presence of scCO2 reduces the crosslink density of the GTR, increasing the property of the gel fraction and the compatibility of this material with the raw rubber.The suitability of the devulcanized GTR to be reemployed in new tire blends was investigated through the final mechanical properties.The unreacted DD can strongly affect the revulcanization process and the mechanical properties of the blends containing devulcanized rubber, resulting the only limiting factor for the application of this devulcanization process.