Influence of Silane-Modified Soybean Oil as an Environmentally Friendly Processing Oil on the Properties of Silica-Reinforced Rubber Compounds

Abstract

This study focuses on the influence of soybean oil (SO) modified by TESPT silane coupling agent as an environmentally friendly processing oil on the properties of the silica-reinforced rubber compounds. A proton nuclear magnetic resonance (1H-NMR) spectroscopy confirmed that a novel processing oil based on silane-modified SO was successfully prepared in the laboratory. It was found that the unsaturated structures in SO reduced after modification. The properties of the rubber compounds with different types of processing oils were investigated by comparison to the rubber compound without processing oils. The addition of processing oils into the rubber compounds reduced filler-filler interactions within the rubber matrix due to a shielding effect of silica surfaces by processing oils. The silane-modified SO could react with the silanol group on the silica surfaces, leading to a hydrophobicity of silica surfaces. So, the use of silane-modified SO showed lowest filler-filler interactions. In addition to the filler-filler interactions, the presence of processing oils in the rubber compounds reduced the viscosity of the materials as indicated by minimum torque received from a cure curve. The levels of filler-filler interactions in the rubber compounds correlated well with the viscosity. The crosslinking points within the rubber matrix of the oil-added compounds were lower than the one without processing oil. Furthermore, the mechanical properties of the rubber compounds with and without processing oils were considered. The processing oils did not affect the tensile strength, but strongly improved elongation at break.