Analyzing the Role of Interface in Creep Resistance of Natural Rubber-Silica Composites

Long term durability of rubber components under heavy loads is greatly dependent on the creep resistance and it must be guaranteed for a number of applications such as seismic isolators, rubber bridge bearings, suspension of rolling stock, etc. In this research, controlling filler-polymer interaction by restricting slippage at the interface is considered as a means to increase the creep resistance of natural rubber-silica composites. Bifunctional silane, Bis(triethoxysilylpropyl) disulfide that is widely used in rubber industry is employed to induce various degrees of covalent bonds at the rubber-silica interface. The change of deformation upon an imposed tensile force was monitored using the DMTA instrument. Results indicated that both the initial creep deformation as well as the rate of creep is deeply affected by the degree of bonding at the interface. It seems that the lower amount of bonding at the interface is advantageous for imparting creep resistance as it reduces both the initial creep deformation and also the rate of creep when compared to the untreated silica reinforced rubbers. However, silica with full bonding at the interface was found to be inappropriate for creep resistance probably because of the elimination of filler network, and the absence of rubber layers with restricted mobility.