Mechanical characteristics of swollen elastomers under cyclic loading

The environmental and economic concerns have raised the popularity of biodiesel as a potential replacement for conventional fuel. However, the incompatibility of engineering rubber components with biodiesel affects significantly the performance of the components. Majority of the compatibility studies focus on evaluating the degradation of mechanical properties of the rubbers due to contamination of different types of biodiesel. Nevertheless, the resulting mechanical responses of swollen rubbers, in particularly under cyclic and fatigue loading conditions, are rarely investigated. In engineering applications where elastomeric components are concurrently subjected to fluctuating mechanical loading and contamination of hostile liquids such as biodiesel, it is crucial to investigate the mechanical responses of these components for durability analysis. In this view, the present study aims to investigate the effect of swelling, due to biodiesel diffusion in the elastomers, on the macroscopic mechanical responses under cyclic loading conditions. Simple stress-free immersion tests are conducted on elastomers and the resulting mechanical responses are evaluated. The focus of the present work is on the effect of biodiesel diffusion on the inelastic responses classically observed in elastomers under cyclic loading conditions, i.e. stress-softening, hysteresis and stress relaxation. The results show that the above inelastic responses decrease significantly when the swelling level increases.