Synthesis and utilization of epoxidized polybutadiene rubber as an alternate compatibilizer in green-tire composites

In the present study, epoxidized polybutadiene rubber (EBR) was synthesized from commercial-grade cispolybutadiene rubber (BR) and was characterized by NMR, FTIR, differential scanning calorimetry, thermogravimetric analysis and surface energy by contact angle measurement. To circumvent the drawback of the existing compatibilizers, the EBR was successfully used as an alternate compatibilizer for a silica-based ‘green-tire’ composite. The significant rise of surface energy was observed after epoxidation of BR, which represents the enhancement of the polar character of the rubber chains and eventually leads to improved compatibility between silica fillers and rubber chains. Out of various epoxidation levels, EBR with 30 mol% epoxidation showed the best compatibilizing effect. The optimum loading of EBR was found to be 12% with respect to total silica content. Apart from using EBR alone as a compatibilizer, combination of EBR with commercial silane-coupling agents, namely, bis(triethoxy-silylpropyl) tetrasulphide (TESPT) and 3-aminopropyltrimethoxy silane, was also investigated. The physico-mechanical and dynamic properties of the compounds with a combination of TESPT:EBR (40:60–60:40) were comparable with those of the compound prepared using TESPT compatibilizer. The results observed with EBR-compatibilized samples revealed that EBR has a potential to be an effective compatibilizer which eventually could minimize the drawbacks associated while using commercial silane as a compatibilizer at the industrial scale.