New technique to measure high-pressure and high-temperature polymer-solvent vapor-liquid equilibrium

A new technique, based on absolute vapor pressure measurement, has been used to measure high-pressure polymer-solvent vapor-liquid equilibria (VLE). VLE data are presented for binary mixtures of low density polyethylene (LDce:simple-paraE) with n-pentane, 1-pentene, cyclopentane, 3-pentanol, 3-pentanone, propyl acetate, and isopropyl amine at temperatures of 150°C and 200°C, and solvent concentrations up to 50% by weight. The experimental data obtained are compared with the predictions from the UNIFAC-FV model and the modified GCLF-EOS model. Modifications are also considered to extend the applicability of UNIFAC-FV model to temperatures above the critical point of the solvent. The model predictions are in good agreement with the experimental data at high pressures and temperatures, even above the critical temperature of the solvents.