Adiabatic compression and expansion of polystyrene

Abstract Equations relating temperature and pressure for adiabatic compression and expansion of polystyrene are derived from Spencer & Gilmore's equation of state for equilibrium conditions. The temperature changes determined experimentally are larger than expected and the results are correlated if a constant in the equation of state is altered. Compressions and expansions are found to be essentially reversible and adiabatic for the time scale of the experiments and for the time scale occurring in injection moulding.