Phase Equilibrium Calculation of Mixtures containing Polymer, Supercritical Fluids and Cosolvent using Lattice Fluid Equation of State

摘要

Supercritical fluids are considered as an alternative media for polymer processing since they exhibit considerable solubility and gas-like viscosity. For simple polymers such as polyolefins, supercritical carbon dioxide can be a good media for separation and reaction because they show high solubility even just above the critical pressure of carbon dioxide. However, polymers with complex structures exhibit limited solubility. Cosolvents can be introduced to enhance solubility of supercritical fluids for polymer processing. The choice of the cosolvent fo specific polymer processing requires experience and a significant amount of experiments among a broad spectrum of solvent candidates. In this study, phase equilibrium calculations have been performed for polymer + supercritical fluid + cosolvent systems and accuracies of calculation and effect of cosolvents are discussed. The nonrandom lattice fluid equation of state with hydrogen bonding (NLF-HB EoS) proposed by the current authors were used because they can be extended toward group contribution model and further extended to predict the effect of the solubility enhancement of cosolvents. Also effects of hydrogen bonding on solubility of polymers are being discussed.