Coarse-grained Molecular Dynamics Simulation of the Effects of Strain Rate on Tensile Stress of Cross-Linked Rubber

Abstract

A cross-linked rubber model with different cross-linking densities was created using the bead-spring model, and a uniaxial elongation simulation was conducted to evaluate the strain rate dependence of tensile stress. To evaluate the effect, the relaxation rate, which is calculated from Rouse relaxation time using the uncross-linked linear polymer model with different numbers of beads, was compared with the strain rate of a rubbery state, indicated by the flat region in the stress–strain rate curve. Moreover, by comparing the stress–strain curve of the models and that of cross-linked chloroprene rubber in an experiment, the reduced unit of the model was converted to realistic units. Thus, it was confirmed that the model can be used to simulate elongation behavior using standard elongation speed. From the uniaxial elongation simulation results of the cross-linked rubber model, it was found that the variation of stress at a small strain rate affected the number of cross-links, which contributed to the relaxation rate of the molecules between cross-links.