Equation of state and optical luminosity of benzene, polybutene, and polyethylene shocked to 210 GPa (2.1 Mbar)

Dynamic equation-of-state data for benzene, polybutene, and polyethylene were measured in the shock pressure range 19–210 GPa using a two-stage light-gas gun. Shock-front spectral luminosities were measured for benzene and polybutene using a fast five-channel optical pyrometer. The pressure–volume Hugoniot data above 20 GPa for benzene and polybutene are in agreement with both a statistical mechanics model and a Grüneisen model for shocked hydrocarbons decomposed into a two-phase mixture of carbon in a dense diamond-like phase and hydrogen in the condensed molecular phase. Published Hugoniot data of benzene up to 13 GPa are in good agreement with a model in which benzene retains its C6H6 molecular structure. The measured, effective, radiating temperatures of shock fronts in benzene are substantially lower than the temperatures calculated theoretically assuming thermal equilibrium. This substantial difference suggests that the measured, effective, radiating temperatures are not the chemical equilibrium temperatures behind the shock front for benzene and possibly for polybutene. Chemical equilibrium calculations which include up to 12 species suggest the presence of small concentrations of a few high-molecular-weight species in strongly shocked benzene and polybutene.