Simulations of shock compression of fully neutralized poly(ethylene-co-acrylic acid) ionomers

Using coarse-grained molecular dynamics simulations, we analyze the shock compression response of fully neutralized poly(ethylene-co-acrylic acid) ionomers. We investigate systems with uniform chain lengths that are sufficiently short to avoid entanglements, while varying the number of charged particles per chain and temperature. In the preshocked state, charged particles group into clusters, with packing features controlled by charge density and temperature. During shock compression we find that the speed of sound in the system is controlled by density, that here depends on charge number and temperature. The increase in shock widths as the density of charged particles increases indicates that shock attenuation is influenced by the presence of charged particles. Strong shocks can break the charged particle clusters, similarly to the homogenization effect achieved by increasing temperature, thereby contributing to the redistribution of energy introduced by the shock.