Strain Rate Effects on the Mechanical Properties of Styrene-Butadiene Rubber (SBR) under Dynamic Loading

Strain rate effect has been regarded as an important factor affecting the mechanical properties of rubbery polymers, while there are fewer reports on the mechanical properties of styrene-butadiene rubber (SBR) under dynamic loadings, especially at the range of medium strain rate. In this study, the uniaxial compression tests of SBR over a range of strain rates from 0.001 to 220 s-1 were investigated experimentally. The stress-strain characteristics as well as the relationship between strain rate and mechanical properties were discussed first, and then the strain rate sensitivity was analyzed. Experimental results show that the compressive mechanical responses of SBR display nonlinear characteristics and strain rate dependent, in which yield stress and flow stress increase approximately exponentially with the increase of logarithmic strain rates. Subsequently, absorbed energy per unit volume and specific absorption energy of SBR was selected to study the influence of strain rate on energy absorption capability. Finally, a visco-hyperelastic constitutive model consisting of a nonlinear spring and a Maxwell element was proposed to describe the mechanical behavior of SBR, and a good agreement between experimental data and model predictions was found. These research results can provide a guide for the design and optimization of SBR structures against impact loading.