Ternary Phase Diagram for Polymer/ Solvent/ Supercritical-CO2 by Sanchez-Lacombe Model

Ternary phase diagrams for [polyethylene (Mw—420,000, Mw/Mn—2.6) / n-butane/carbon dioxide], [polypropylene (Mw—290,000, Mw/Mn—1.32)/ n-pentane/carbondioxide] and [polystyrene (Mw—187,000)/ cyclohexane/ carbon dioxide] have been generated using the Sanchez-Lacombe (SL) lattice-fluid model. The results show that atrelatively low pressure, the ternary phase diagram has a L-L-V three-phase region bounded by two two-phase regions (L-V and L-L). At high pressure, L-L-V and L-V regions disappear and only the L-L region remains. With an increase of pressure this two-phase L-L region becomes smaller. This model can also predict transition LCST to UCST by increasing pressure. For polystyrene/ cyclohexane/ carbon dioxide mixture, the calculated results obtained using the SL-model are compared with the reported calculated results created by the perturbed hard-sphere chain model (PHSC) and the reported experimental data which indicate good agreement with both the calculated results by PHSC-model and experimental data.