Theoretical and experimental study of molecular interaction between Propylene glycol and Ether alcohols

Abstract

This study investigates the thermophysical properties of binary liquid mixtures of propylene glycol (PG) with ether alcohols-propylene glycol monopropyl ether (2-PE) and ethylene glycol monobutyl ether (2-BE)-across the entire composition range at temperatures T= (298.15 - 323.15) K. Viscosity measurements were performed at T= (298.15 - 308.15) K. From the experimental data, excess properties such as molar volume, isentropic compressibility, speed of sound, isobaric thermal expansion coefficient, and deviation in viscosity were calculated. Partial molar properties and their excess values, including those at infinite dilution, were also derived. The excess properties were correlated using the Redlich-Kister polynomial, and the results were analysed using the Prigogine-Flory-Patterson theory to explore intermolecular interactions. Viscosity correlations were carried out using empirical and semi-empirical models, while density was modelled using the perturbed chain statistical associating fluid theory (PC-SAFT), accounting for hydrogen bonding effects. The speed of sound was predicted using Schaaff's collision factor theory (SCFT) and Nomoto's relation (NR), with density data from PC-SAFT as input. Viscosity modelling employed free volume theory (FVT) as a fitted approach. The findings provide insights into the thermophysical behaviour of these mixtures and the role of intermolecular interactions. © 2025