Equations of state for polyethylene and its shock-driven decomposition products

We construct new equations of state (EOS) for high density and ultrahigh molecular weight polyethylene and their chemical decomposition products under shock loading. The former were built using the SESAME framework, based in part on new specific heat and thermal expansion data reported here. The products EOS was based on thermochemical modeling under the assumption of full thermodynamic and chemical equilibrium. The products are represented as the ideal mixture of bulk carbon in the form of diamond, H2, H, and CH4. In the process of building a new EOS for the products, we recalibrated our exponential-6 pair potential for methane in order to better agree with data that have appeared since its original parameterization. The polyethylene EOS were calibrated to thermal, thermomechanical, and shock data, and their performance was evaluated in hydrodynamic modeling of deep release experiments reported previously.