Reduced ethanol emissions by a combination of epoxidized natural rubber and silane coupling agent for silica-reinforced natural rubber-based tire treads

In an attempt to reduce the high volatile organic compound (ethanol) emissions from silica-reinforced NR compounds, this work aimed to, at least partially, replace the use of large quantities of silane coupling agent bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT). The use of 7.5 phr of epoxidized natural rubber (ENR-51) as compatibilizer between NR and silica enhances the properties, which can be further improved by half or even lower amounts than required with TESPT alone. The properties obtained with TESPT are nearly matched, except for steric limitations imposed upon the ENR molecules to cap the silanol groups on the silica surface to the same extent as TESPT can do. Furthermore, TESPT donates reactive elemental sulfur to the compound during vulcanization, which needs to be compensated for in use with ENR.