Group Contribution Lattice Fluid Equation of State: Application to Polymer+solvent Systems

Abstract

- A group contribution equation of state recently proposed by the authors is used to calculate the activity of solvents in polymer+solvent solutions. The model is based on the generalized van der Waals theory and combines the Staverman-Guggenheim combinatorial term with an attractive lattice gas expression. The results show that the equation correlates the properties of pure solvents and polymers accurately. Furthermore, the equation satisfactorily represents the vapor-liquid equilibrium of solutions containing polymer and solvents of different polarities

Vapor–liquid equilibrium of copolymer+solvent mixtures: Thermodynamic modeling by two theoretical equations of state

“…For the calculation of copolymer parameters, the strategy adopted in previous works [21,22] for homopolymers, based on density calculations, could not be used since density data, as well as parameters for experimental correlations of density (such as the correlation of Tait [27]) are not available for copolymers. In this work, the pseudo-monomer concept proposed by Silva et al [6] was used, the copolymer is considered formed by repeating units of pseudo-monomers, in which each co-monomer is represented weighted by its mole fraction in the copolymer.…”

“…The PC-SAFT EoS is based on a reference hard-sphere chain term and a perturbation contribution term, a res =ã hc +ã pert (21) whereã = A/NkT and k is the Boltzmann constant. The hardchain contribution [28] was based on the first-order thermodynamic perturbation theory [29][30][31]:…”

“…When associating compounds are used, it is necessary to add a term to Eq. (21) in order to take in account the contribution due to association (ã assoc ), which is given by:…”

“…One of the models is a LGTbased EoS, developed by Silva [19] and Mattedi et al [20] and successfully applied to VLE calculations of polymer + solvent systems [21,22]. The other one is the PC-SAFT EoS, developed by Gross and Sadowski [23] and successfully extended to copolymers by Gross et al [24] and Arce and Aznar [25].…”