EQUATION OF STATE BEHAVIOR AND INTERFACIAL PROPERTIES OF LATTICE CHAIN FLUIDS - A COMPARISON OF LATTICE FLUID THEORY AND MONTE-CARLO SIMULATION

Monte Carlo simulation results for interacting chains at zero and elev ated pressures ace presented using a new simulation method. Both bulb and interfacial properties are investigated over a broad range of pres sures and temperatures, thus covering high and low lattice fluid densi ties. The bulk simulation data are used to investigate the predictive capabilities of the Sanchez-Lacombe lattice fluid theory and an equati on of state theory including nonrandom effects which are assessed usin g Guggenheim's quasichemical approximation. The nonrandom mixing theor y accurately predicts all available data even up to the lowest densiti es whereas the Sanchez-Lacombe theory overestimates moderate densities and completely fails at low densities. Interface profiles exhibit gen erally larger density variations for the systems including interaction s in comparison to athermals, and the effect of pressure is concentrat ed in the system on the interface.