Vapor−liquid equilibria P, T, x for the methanol + poly(ethylene glycol) 250 dimethyl ether (PEGDME 250) binary system were obtained by the static method in the range of temperatures from 293.15 K to 423.15 K at 10 K intervals. A modified Barker's method was used to accurately calculate the liquid and vapor composition from the overall composition of the sample, the measured pressure and temperature, and the Redlich−Kister expression for the excess Gibbs free energy of the liquid phase at each temperature. The obtained P, T, x data were correlated by the NRTL and UNIQUAC temperature-dependent activity coefficient models using the maximum likelihood method. This system shows nearly ideal behavior at lower temperatures but negative deviation at higher temperatures. Also with the increase in temperature and composition of poly(ethylene glycol) 250 dimethyl ether, the logarithm of activity coefficients of methanol becomes more negative. The excess molar enthalpy was calculated using the Gibbs−Helmholtz equation and the NRTL and UNIQUAC parameters at 303.15 K and compared with experimental data existing in the literature.

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Kinematic viscosities were measured over the entire range of composition and at atmospheric pressure for the binary systems trifluoroethanol (TFE)-H,O, TFE-tetraethylene glycol dimethyl ether (TEGDME), and TEGDME-H20 from 293.15 to 333.15 K. The data were fitted by the Stephan and Heckenbergber (1989) correlation, which accounts for the dependence on temperature and mixture composition.Methods for predicting ternary excess viscosities from excess viscosity data for the three binary mixtures involved are examined and tested for the system TFE-H,O-TEGDME at 303.15 K by comparing predicted and experimental data. The empirical correlation of Colinet (1967) is shown to be the best for this system. On a mesurk les viscositks cinkmatiques h la pression atmosphCrique dam une vaste gamme de composition pour les systkmes binaires trifluordthanol (TFE)-H,O, TFE-tktraCthylbne glycol dimkthyle &her (TEGDME) et TEGDME-H,O, entre 293,15 et 333,15 K. Les donnks ont kt6 calks par la corrClation de Stephan et Heckenberger (1989), qui tient compte de la dkpendance en temphature et par rapport h la composition des mClanges. Les mkthodes de prckliction des viscositks d'exds temaires h partir des domks de viscositk d'exds des trois mklanges binaires sont examinks et testks pour le systbme TFE-H,O-TEGDME h 303,15 K par comparaison des donnks praites et exphimentales. On montre que la corrklation empirique de Colinet (1967) est la meilleure pour ce syst&me.