The structure and properties of bis(γ-triethoxysilylpropyl) tetrasulfide modified silica/epoxidized natural rubber nanocomposites as tire tread

Epoxidized natural rubber (ENR) is a modified natural rubber (NR) prepared by the epoxidation of NR. Dispersion of silica in the ENR nanocomposite is crucial for the performance, but there is not a definite relationship among ENR and silane coupling agent bis(γ-triethoxysilylpropyl) tetrasulfide (TESPT) and silica. In this work, ENR/silica with different amounts of TESPT nanocomposites (ENR/silica-xT) were prepared, and the structure and critical properties of ENR/silica-xT for tire tread applications were investigated and compared with NR/silica-TESPT nanocomposite. There is a competitive relationship between TESPT and epoxy groups on the rubber molecular chain in improving silica dispersion. Epoxy groups produce stronger filler-rubber interaction while TESPT provides more chemical crosslinking density. Accordingly, as the amount of TESPT increases, the tear strength, tensile strength, wet-skid resistance, abrasion resistance, as well as rolling resistance performance of ENR/silica-xT improves. The ENR/silica-6T demonstrates significant improvements compared to NR/silica-6T, with a 207 % enhancement in wet-skid resistance, a 29 % increase in abrasion resistance, and a 29 % reduction in rolling resistance. This work will be of significance in guiding the preparation of green tire tread.