Phase equilibria of binary, ternary and quaternary systems for polymerization/depolymerization of polycarbonate

Vapor-liquid phase equilibrium is studied for the systems composed of phenol, diphenyl carbonate (DPC), bisphenol A (BPA) and CO2. Bubble point pressures and vapor-phase compositions are measured at various temperatures (343.15-473.15 K) for several compositions of the following systems: two binary systems DPC-CO2 and BPA-CO2, three ternary systems phenol-DPC-CO2, phenol-BPA-CO2 and DPC-BPA-CO2, and one quaternary system phenol-DPC-BPA-CO2. The Peng-Robinson equation of state (PR EOS) binary interaction parameters for the systems DPC-CO2 and BPA-CO2 are optimized by directly fitting to the corresponding experimental data. The PR EOS binary interaction parameters for phenol-DPC, phenol-BPA and DPC-BPA are obtained by fitting to experimental data of the ternary systems involving these constituents and CO2. The binary interaction parameters are then used to predict the phase equilibrium behavior of the quaternary system. A reasonable agreement with the experimental observations of this quaternary system indicates the predictive ability of the model in the range of our experimental measurements.