Measurement and modeling of poly(vinyl stearate) in supercritical fluids

초록

The cloud-points (CPs) of poly(vinyl stearate) (PVS) in several fluids, such as carbon dioxide (CO 2 ), propane, butane, propylene, 1-butene, and dimethyl ether (DME), and in their mixtures are reported herein. A high-pressure apparatus with a variable-volume view cell was used to measure the CPs of the PVS mixtures. The measured CP pressures for all the systems exhibited a lower critical solution temperature (LCST) phase behavior. The CPs for ternary systems consisting of CO2, DME, propylene, 1-butene, and PVS were distributed over the temperature range of 333-453K and the pressure range of 35 - 203 MPa. To understand the effect of interactions between the solvents, co-solvents, and PVS at a molecular level, the perturbed-chain statistical associating fluids theory (PC-SAFT) model was applied to the modeling of these systems, and the predicted results were observed to be consistent with the tendency of experimental data. A theoretical investigation using the PC-SAFT model revealed some important information. The strong interactions between PVS and CO2 resulted in the high solubility of PVS in the CO2/DME mixture, while the weak interactions between CO2 and the co-solvent (i.e., propylene, 1-butene) increased the solubility of PVS in their mixtures.

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