SYSTEMATICS OF HIGH-PRESSURE AND HIGH-TEMPERATURE BEHAVIOR OF HYDROCARBONS

Hugoniot data of eight different hydrocarbon compounds comprising four different proportions of hydrogen to carbon content have been analyzed using a model. The model assumes that hydrocarbons at high pressure (≳ 10 GPa) and high temperature (≳ 1000 K) dissociate into carbons in the diamond phase and hydrogen in a condensed molecular phase. The theoretical Hugoniots of hydrocarbons are evaluated under the assumption that the volume and its ratio to the Grüneisen gamma of the hydrocarbons at any given pressure and 0 K are the weighted sums of the hydrogen and carbon contents. The model gives hydrocarbon Hugoniots that agree remarkably well with the experimental data. Evidence supporting the model and several implications of the model are given. © 1979 American Institute of Physics.