Modified quadrupole Cubic Plus Association Equation of State (mqCPA EoS) for thermodynamic modeling of polymer-supercritical CO2 systems

In this work, a modified quadrupole Cubic Plus Association Equation of State (mqCPA EoS) is used to model the cloud point pressure of polymers-supercritical carbon dioxide (scCO2) systems. The residual Helmholtz free energy is expressed as sum of SRK and Quadrupole terms. We used the experimental data of the cloud point pressure for the different copolymer-scCO2 systems to investigate the capability of the present model through liquid-liquid equilibrium calculations. Using mqCPA EoS, the cloud point pressures of the polymer-scCO2 systems for the three types of poly(lactic acid) (PLA), the three types of poly(1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside) (P(AcGlcVE) and seven types of poly(vinyl acetate-alt-dibutyl maleate) (PVAc-alt-PDBM) were calculated. These copolymers have different molecular structures, end groups and molar masses. Moreover, we applied both PC-SAFT and PCP-SAFT equations of state for the same polymer-scCO2 systems and their results were compared to those obtained by mqCPA EoS that showed in overall the both PCP-SAFT and mqCPA EoSs give better results with very good accuracy.