The Molecular Structure of SBR and Filler Type Effects on Thermal Diffusivity of SBR/BR Compounds Used in Tire Tread

This research work is devoted to the study of the thermal diffusivity of SBR/BR compounds used as the tread of radial tires. Three series of rubber compounds were prepared, in which two solution SBR grades (with and without extra oil) as well as an emulsion SBR were selected. Five compounds with different CB/silica ratios were designed for each of the three series. Moreover, three compounds without fillers were prepared as reference samples. Thermal diffusivities of the compounds were determined by a novel technique to solve an inverse heat transfer problem. Abaqus and Isight codes were used to carry out the finite element solution and optimization. It is shown that, in all the compounds the thermal diffusivities were reduced with increasing the temperature. In addition, the macro- and micro- structures of SBR as well as the CB/silica ratios greatly affected the variations in thermal diffusivities with temperature. The thermal diffusivity and its variabilities were studied and discussed by different structural and functional parameters such as intermolecular distance, molecular vibrational energy, difference between the thermal diffusivities of the polymer and filler, and the chemical bonds between the polymer and silica.