High-pressure phase equilibrium data for the (carbon dioxide + l-lactide + ethanol) system

• Equilibrium data are important for polymerization of l-lactide at high pressure.
• Addition of ethanol causes a reduction in pressure to obtain a homogeneous region.
• Experimental results were modeled using the Peng–Robinson (PR) equation of state.

Experimental phase equilibrium values (cloud points) for the ternary system involving carbon dioxide, l-lactide and ethanol have been measured in order to provide fundamental values to conduct the polymerization reaction in supercritical carbon dioxide medium. The experiments were performed using a variable-volume view cell over the temperature range from 323 K to 353 K, system pressure between 9 MPa and 25.0 MPa and different mole ratios of ethanol to l-lactide (0.5:1, 1:1 and 1.5:1). Phase transitions of vapour-liquid types were observed. The experimental results were modelled using the Peng–Robinson (PR) equation of state with the Wong–Sandler (PR–WS) mixing rule, providing a good representation of the experimental phase equilibrium values.