Miscibility and phase separation behavior, and the volumetric properties of poly(epsilon-caprolactone) (PCL) solutions in acetone + CO2 binary fluid mixtures were investigated for PCL concentrations of 2.0, 5.0, 9.0, 12.0, 15.0, 25.0 and 34.9 wt% at temperatures up to 410 K and pressures up to 28 MPa. Experiments were carried out by using a unique high pressure variable-volume view-cell equipped with a dual set of pistons and dual set of sapphire windows which permit measurements of both the transmitted light intensities for determination of phase boundaries, and the scattered light intensities for assessment of the mechanism and the kinetics of phase separation. The system allows the continuous recording of the piston positions and thus the solution densities as a function of pressure at a given temperature from which liquid-vapor or liquid-liquid-vapor phase boundaries are easily assessed and the isothermal compressibilities and isobaric expansivities are readily evaluated. It is shown that these solutions display lower critical solution temperature (LCST) type behavior with respect to their liquid-liquid (LL) phase boundaries and the LL phase separation proceeds via nucleation and growth for 2.0, 5.0, 25.0 and 34.9 wt% solutions and via spinodal decomposition for 9.0, 12.0, and 15.0 wt% solutions. It is shown that the LL phase separation pressure which is a function of temperature scales with the solution density and shifts to higher densities with increasing polymer concentration, with the rate of change of LL phase separation pressure with density becoming higher at concentrations above the critical polymer concentration. The compressibilities in the homogeneous mixtures are found to decrease with increasing PCL concentration. At pressures below the LL phase separation pressures, the rate of decrease in compressibility with pressure is higher which is interpreted as being a consequence of the difference in the phase compositions of the polymer-lean and polymer-rich phases that develop at pressures below LL phase separation. Isobaric expansivities increase with temperature at a given pressure. They become more sensitive to temperature at lower pressures. The excess volumes for all PCL solutions display large negative values, indicative of close-packing of the polymer plus solvent molecules. (C) 2013 Elsevier B.V. All rights reserved.