Volumetric, viscometric, spectral studies and viscosity modelling of binary mixtures of esters and alcohols (diethyl succinate, or ethyl octanoate plus isobutanol, or isopentanol) at varying temperatures

Abstract

Density, viscosity and refractive index of four binary mixtures consisting of diethyl succinate or ethyl octanoate + 2-methyl-1-propanol or 3-methyl-1-butanol have been measured at atmospheric pressure and over the temperature range from 288.15 K to 323.15 K. Excess and deviation functions have been calculated from these data and fitted to the Redlich-Kister equation. The values of excess molar volume and deviation functions, with FT-IR study, were further used in the analysis of molecular interactions present in the mixture as well as the temperature influence on them. Molar excess Gibbs free energies of activation of viscous flow were additionally calculated from measured density and viscosity data for better understanding of present molecular interactions. Viscosity modelling was done with two approaches, predictive by group contribution models (UNIFAC-VISCO and ASOG-VISCO), and correlative by one to three-parameter models (Teja-Rice, Grunberg-Nissan, McAlister, Eyring-UNIQUAC and Eyring-NRTL). The obtained results were compared with experimental data and conclusions about applied approaches and models were made.