Co-solvent concentration influence of two- and three-component systems on the high pressure cloud-point behavior for the poly(vinyl stearate) under supercritical CO2

Abstract

In this research, the experiment in high pressure cloud-point behavior at T (temperature) ≤484.7 K and at p (pressure) ≤207.70 MPa is carried out for the poly(vinyl stearate) [P(VS)] + vinyl stearate (VS) [or C3H8(propane), C4H10(butane), C3H6O(acetone) and C2H5OH(ethanol)] containing supercritical CO2(carbon dioxide). The phase equilibria data for the P(VS) + (10.6 to 54.6) wt% VS mixtures in CO2 are reported for a variety of curves from [UCST(upper critical solution temperature) to LCST(lower critical solution temperature)] in the pressure-temperature space in accordance with the increase of the VS weight fraction. Curves for P(VS) + CO2 + 63.0 wt% VS phase behavior intersect a phase (fluid) → LV (liquid + vapor) curve at ∼383 K (at ∼19.00 MPa). The position of the cloud-point for P(VS) + CO2 curve shifts to lower pressures and temperatures as soon as VS is added. The solubility curves for the P(VS) + (21.9 to 47.9) wt% propane and P(VS) + (27.7 to 46.0) wt% butane mixture under supercritical CO2 vary from UCST to LCST with a decrease in pressure and a co-solvent increase. And also, co-solvent effect of (25.8–95.0) wt% acetone and (13.9–95.0) wt% ethanol in P(VS) + CO2 mixture is shown in the UCST region at temperature range of (428.3 ≤ T ≤ 484.7) K.Phase equilibria data at high pressures was presented for the VS + CO2 system at p ≤ 27.40 MPa and at (313.2 ≤ T ≤ 393.2) K. The VS + CO2 system shows type-I phase curve with a consecutive mixture critical line and was properly correlated with the Peng-Robinson equation.