Phase equilibria of fluid mixtures using a modified perturbed hard-sphere-chain equation of state

We propose a new model for the calculation of phase equilibria for the flui d mixtures based on the perturbed hard-sphere-chain (PHSC) equation of stat e. We modified the bonding term of the PHSC equation by introducing the for m proposed by Chapman et al. The model predicts Monte Carlo simulation data for the compressibility factor better than those predicted by the PHSC equ ation in the entire density region. We can describe vapor/liquid equilibria of pure volatile saturated fluids with three characteristic parameters. By introducing two additional binary adjustable parameters, the liquid/liquid coexistence curve of a binary fluid mixture can be calculated. In the pred ictions of the specific volume of polymers, our model shows better agreemen t with the experimental data than predictions by the PHSC equation. (C) 200 0 Elsevier Science B.V. All rights reserved.