Conformational equation of state for fluids of chain molecules

Abstract

This paper discusses the mathematical formulation of the modelling of fluids of chain molecules as fluid mixtures of molecular conformations with the concentration of these conformations obtained through a constrained freeenergy minimization. Thermodynamic relationships can then be applied to obtain other properties, and an approximation is derived for the virial coefficients of chain molecules. Problems regarding the implementation of this approach through the virial equation at low densities and the generalized van der Waals equation of state at higher densities, and possible solutions to these, are also discussed. Feasibility studies for the case of n-octane show agreement with the experimental observations regarding the molecular shape in gas and liquid phases.