Vapor-Liquid Equilibrium, Volumetric, and Compressibility Properties of 1-Propanol + Poly(ethylene glycol) Dimethyl Ether 250 and 500 Binary Mixtures

In this work, some of the thermodynamic properties of binary {1-propanol + poly(ethylene glycol) dimethyl ether (PEGDME)} mixtures were studied. The activity of 1-propanol was determined in (1-propanol + PEGDME) systems with polymer molar masses of 250 and 500 g.mol(-1) by the use of isopiestic method at 298.15 K. The effect of the polymer molar mass on the solvent activity and also vapor pressure depression was discussed. More vapor pressure lowering is obtained when we use PEGDME with a molar mass of 500 g.mol(-1). The obtained solvent activity data were correlated with the Flory-Huggins, modified Flory-Huggins, nonrandom two liquid (NRTL), nonrandom factor (NRF)-NRTL, Wilson and NRF-Wilson models. The interaction parameter obtained from the Flory-Huggins model for PEGDME500 is less than that for the PEGDME250, indicating that the solvent activity has been reduced by increasing the molar mass of polymer. This result leads to an increase in the interaction between the solvent and the polymer by increasing the polymer molar mass. Measurements of the density and speed of sound were also performed at T = (298.15 to 318.15) K for the mentioned systems. From these data, the excess molar volumes, isentropic compressibility deviations, and deviation in speed of sound were calculated; and it was found that excess molar volumes and isentropic compressibility deviations are decreased with increasing temperature. The obtained values of excess molar volumes for PEGDME500 are more negative. These results supply stronger packing effects in the 1-propanol with the PEGDME500 system rather than in the system with PEGDME250. The obtained excess and deviation values were also satisfactorily fitted to the Redlich-Kister and Ott et al. equations