Phase behavior of poly(d -lactic acid), dichloromethane, and carbon dioxide ternary mixture systems at high pressure

The phase behavior of a poly(d-lactic acid) (M_w = 359 000 g/mol, polydispersity 1.7), carbon dioxide, and dichloromethane ternary system was measured by a variable-volume view cell. The experimental temperatures and pressures ranged from 313.15 to 363.15 K, up to 300 bar as various experimental conditions of the CO₂/dichloromethane mass ratio and temperature, at poly(d-lactic acid) mass fractions of 1.0, 2.0, and 3.0%. The correlation results were obtained from the hybrid equation of state (Peng-Robinson equation of state + SAFT equation of state) using the van der Waals one-fluid mixing rule for the polymer-CO₂-solvent system. The binary interaction parameters were optimized by the simplex method algorithm.