Thermodynamic law of corresponding shock states in flexible polymeric foams

Based on thermodynamic considerations and experimental data on isothermal compression of elastomeric foams, a simple equation of state of flexible polymeric foams was developed. The developed equation of state is, in fact, a simple universal function relating the thermodynamic properties of the material of which the skeleton of the foam is made and the foam porosity. It was shown that the Hugoniot adiabat of foams, whose porosity is less than 0.3 and which are exposed to moderate shocks, could be expressed in a form similar to that of bulk solids, i.e., D — C_o + Su, where D is the shock front velocity, C_o is the speed of sound, u is the particle velocity and S is the maximum material compressibility.