PAPER WITHDRAWN-The Effects of Surface Free Energy and Surface Area of Silica On the Particle Dispersion Efficiency and Dynamic Mechanical Properties in Silica Filled Ssbr/BR

Improvements in silica particle dispersion efficiency in elastomers remains a challenge for the tyre manufacturers and researchers. At present, the relationship between filler particle surface properties, filler-elastomer interfacial mechanics, filler particle-humidity interaction and filler particle  dispersibility are not fully understood for these complex silica reinforced elastomers. In this study, the surface free energy of silica particles was determined by inverse gas chromatography (IGC), moisture sorption isotherms by Dynamic Vapour Sorption (DVS) and N₂ Brunauer-Emmett-Teller adsorption (BET) analysis were carried out on four silicas with surface areas ranging from 106 m²/g to 212 m²/g. A comparison of these silicas compounded with sSBR/BR rubbers at 80 phr (per hundred rubber) loading using passenger tyre tread formulation is discussed. The effect of the silica on micro-dispersion is investigated by Transmission Electron Microscopy (TEM), whilst dynamic mechanical analysis also provided a good indication about the silica particle interaction in the rubber phase. This study demonstrated that the silica surface area and their surface activity have a direct influence on the dynamic mechanical properties of the filled elastomers, but have only a marginal effect in tensile properties.

Key Words: tyre, silica-filled sSBR/BR, dispersive surface energy, filler dispersion, dynamic mechanical analysis.