Journal of Supercritical Fluids, Vol.79, 27-31, 2013
High-pressure phase equilibrium data for the L-lactic acid plus (propane plus ethanol) and the L-lactic acid plus (carbon dioxide plus ethanol) systems
Biodegradable polymers have received increased attention due to their potential applications in the medicine and food industries; in particular, poly(L-lactic acid) (PLA) is of primary importance because of its biocompatibility and resorbable features. Recently, the synthesis of this biopolymer through the enzyme-catalyzed ring-opening polymerization of L-lactic acid in a compressed fluid has been considered promising. The aim of this work was to report the phase equilibrium data (cloud points) of the L-lactic acid + (propane + ethanol) and the L-lactic acid +(carbon dioxide + ethanol) systems. The phase equilibrium experiments were conducted in a variable-volume view cell employing the static synthetic method. These experiments were conducted in the temperature range of 323.15-353.15K and at pressures up to 25 MPa; the mass ratio of ethanol to either CO2 or propane was maintained at 1:9. The L-lactic acid + (propane + ethanol) system exhibited vapor-liquid, liquid-liquid and vapor-liquid-liquid transitions, whereas the L-lactic acid + (carbon dioxide + ethanol) system only exhibited liquid-liquid type transitions. (C) 2013 Elsevier B.V. All rights reserved.