Thermophysical Behavior of Methylbenzoate + n-Alkanes Mixed Solvents. Application of Cubic Equations of State and Viscosity Models

Abstract

As part of a study on the interactions between aromatic esters and n-alkanes, density, viscosity, and refractive index data were measured for methylbenzoate−n-alkane mixed solvents. From these data, excess molar volumes ( ), mixing viscosities (Δmixη), excess Gibbs energies of activation of viscous flow (Δ ), and mixing refractive indices (ΔmixnD) were deduced. From the excess volumes, the partial molar volumes of the two components were deduced using the intercept method. The cubic equations of state (EOS) proposed by Soave−Redlich−Kwong and Peng−Robinson combined with two simple mixing rules were used to process the excess molar volumes. The change with temperature of the density and viscosity measurements enabled the activation enthalpy (Δ ), activation entropy (Δ ), Gibbs free energy (Δ ), and thermal expansion coefficients (α) to be determined. These results were interpreted in terms of intermolecular interactions and structural effects. The ability of different one-parameter and two-parameter empirical models to predict mixing viscosities was also tested.