Improving the sustainability of 'green' tyre tread compound by using recovered silica filler

In this study, recovered silica fillers from pyrolysis and geothermal sources, referred to as 'rSilica' and 'geoSilica', respectively, have been mixed with epoxidised natural rubber (ENR) to determine whether they can be used to improve the sustainability of 'green' tyre tread compounds. The effect of using silica recovered by a geothermal and pyrolysis process as filler in an ENR compound with and without X50S silane coupling agent was investigated in this study. Both recovered silicas also have been characterised and the physical and mechanical properties of the filled ENR compounds measured. All the results obtained have been compared with the industrial silica grade of Zeosil 1165. Based on the test results obtained, rSilica did show reasonably good physical properties such as tensile strength, hardness and abrasion resistance as well as good processing characteristics compared to the commercial-grade silica (Zeosil). rSilica-filled ENR compounds with silane also showed better physical properties than the non-silane compound, which indicates that rSilica still can react with the silane, despite the fact that the amount of silanol groups on the rSilica surface were reduced by the pyrolysis process.