| Abstract
| - Cloud-point phase behavior curves to 190 °C and 2570 bar are measured for binary and ternary mixtures ofpoly(isobutyl acrylate)−CO2−isobutyl acrylate, poly(tert-butyl acrylate)−CO2−tert-butyl acrylate, poly(isobutylmethacrylate)−CO2−isobutyl methacrylate, and poly(tert-butyl methacrylate)−CO2−tert-butyl methacrylatesystems. The phase behavior for the poly(isobutyl acrylate)−CO2−isobutyl acrylate system with cosolventconcentrations of 0, 3.2, 8.8, 18.1, 31.9, and 40.7 wt % are measured in the changes of the pressure−temperatureslope. With 58.7 wt % isobutyl acrylate to the poly(isobutyl acrylate)−CO2 solution significantly changing,the phase behavior curves takes on the appearance of a typical LCST boundary. The cloud-point curves forthe poly(tert-butyl acrylate)−CO2−0, 8.5, 14.9, 34.7, 56.0, and 57.7 wt % tert-butyl acrylate system changesthe P−T curve from the UCST region to the LCST region as the tert-butyl acrylate concentration increases.The cloud-point curves for the poly(isobutyl methacrylate)−CO2−isobutyl methacrylate system show theslope changes of the pressure−temperature diagram and cosolvent concentrations of 0, 6.5, 12.6, 21.7, and32.3 wt %. With 49.8 wt % isobutyl methacrylate added to the poly(isobutyl methacrylate)−CO2 solution,the phase behavior curves show a typical LCST boundary. And also, the cloud-point curves for the poly(tert-butyl methacrylate)−CO2−0, 10.2, 20.5, 31.3, and 46.4 wt % tert-butyl methacrylate system change theP−T curve from the UCST region to the LCST region as the tert-butyl acrylate concentration increases.High-pressure vapor−liquid equilibria are obtained for the CO2−isobutyl acrylate, CO2−tert-butyl acrylate,CO2−isobutyl methacrylate, and CO2−tert-butyl methacrylate systems at the range of temperature of 40−120 °C and pressure up to 160 bar. The CO2−isobutyl acrylate, CO2−tert-butyl acrylate, CO2−isobutylmethacrylate, and CO2−tert-butyl methacrylate systems exhibit type-I phase behavior with a continuousmixture-critical curve. Three-phase, liquid−liquid−vapor equilibrium was not observed at these conditions.The experimental results for CO2−isobutyl acrylate, CO2−tert-butyl acrylate, CO2−isobutyl methacrylate,and CO2−tert-butyl methacrylate mixtures are modeled using the Peng−Robinson equation of state.
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