Vapor−Liquid Equilibria, Density, and Speed of Sound for the System Poly(ethylene glycol) 400 + Methanol at Different Temperatures

Abstract

Solvent activity measurements have been performed on the system poly(ethylene glycol) 400 (PEG 400) + methanol at T ) (298.15 to 328.15) K using the improved isopiestic method. The obtained solvent activity data were correlated with the original and modified Flory-Huggins models. It was found that for the studied system at any mass fraction, as the temperature is increased the solvent activity and Flory parameter are both decreased, indicating an increase of interaction between polymer and methanol as the temperature is increased. The density and speed of sound data were also measured at T ) (288.15 to 328.15) K for the PEG 400 + methanol system. From the obtained density values, the excess molar volume data were calculated and fitted to the Redlich-Kister equation. The excess molar isentropic compression values calculated from the measured speed of sound and density data were also fitted to the Redlich-Kister equation.

Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

“…Table 1 also shows that both of density and speed of sound of (ILs + methanol) solutions increase very slightly with increasing alkyl chain length of ILs. The similar behavior (temperature and concentration effect) has also been observed in the case of methanolic solutions of other ILs [12,[50][51][52], sodium bromide [53], tetraphenylphosphonium bromide [53], and polyethylene glycol (PEG) [54].…”

“…However, the infinite dilution apparent molar volume of the hydrocarbon portion of the ILs in methanol increases by increasing temperature. As mentioned above, the infinite dilution apparent molar volumes of simple electrolyte such as NaBr in methanol decrease by increasing temperature [53] but for non-ionic polymers such as PEG [54] the / 0 V values increase by increasing temperature. The contribution of Br À ion to volume at different temperature is known [53].…”

“…Volumetric studies of methanolic solutions of sodium bromide [53], tetraphenylphosphonium bromide [53], and tetraalkylammonium bromides [55] show that these systems have a similar behavior with ILs. However, it was found that [54,56,57] the apparent molar volumes of polymers (such as PEG400 [54], PEGMA360 [56], and PEGDME250 [57]) in methanol increase by increasing both polymer concentration and temperature. Similar to the aqueous solutions, the reliability of the Redlich-Mayer and Pitzer equations in the correlation of the obtained apparent molar volume data for the investigated ILs in methanol has also been tested.…”

Measurement and correlation of density and viscosity of polyvinylpyrrolidone solutions in alcohols at different temperatures

“…Knowledge of volumetric properties of polymer solutions has been proven to be a very useful tool in evaluating the structural interactions occurring in these solutions [1][2][3][4]. Knowledge of the viscosity of polymer solutions is important for practical and theoretical purposes.…”

“…Many research groups have focused their attention on obtaining information on the thermodynamics of aqueous polyethylene glycol (PEG), which is often used in biotechnology. In this respect, thermodynamic properties such as (vapour + liquid) equilibrium, density, and viscosity have been obtained [1][2][3][4]. However, similar information on the thermodynamics of aqueous solutions of polyvinylpyrrolidone (PVP), which is also a very important system with respect to its use in biotechnology, is scarce.…”