Thermophysical properties of low-density polystyrene under extreme conditions using ReaxFF molecular dynamics

Abstract

ABSTRACT The low-density polystyrene is often chosen as the converter material in high energy density physics experiments. The accurate thermodynamic and transport properties of polystyrene under extreme conditions are necessary for reliable magneto-hydrodynamic simulations. Based on the ReaxFF molecular dynamics (RMD) simulation, the equation of state, thermal conductivity, atomic structure, and self-diffusion coefficient of low-density polystyrene have been investigated across a wide range of temperatures (1000–10,000 K) and densities (0.01–3.4 g/cm3). The results using RMD calculations considering the bond dissociation of polystyrene along with the principal Hugoniot curve show good agreement with experimental and the SESAME model. The transport properties (self-diffusion coefficient) from the corresponding microscopic time autocorrelation functions are obtained using RMD simulation, and the thermal conductivities are calculated using non-equilibrium molecular dynamic simulation. By investigating the bond dissociation of polystyrene, the stable H–H bond is found to be affected greatly by high temperatures and pressures. The calculation results can be helpful for future theoretical and experimental studies in high energy density research.