Thermo-viscous investigations of molecular interactions for the binary mixtures of polyethylene glycol-400 and polyethylene glycol-600 with dimethyl sulfoxide and water at different temperatures

•Solute-solvent interactions effects the thermodynamic/transport behaviour of binary mixtures.•Studied excess parameters shows presence of intermolecular interactions in binary mixtures.•Intermolecular interactions in PEG-400 + DMSO are stronger than those in PEG-600 + Water.•Validity of five mixing rules of viscosities for binary liquid mixtures has been checked.•Existence of clathrate formation in the PEG-600 + Water is predicted. Thermo-viscous investigations of molecular interactions for the binary mixtures of polyethylene glycol-400 + dimethyl sulfoxide and polyethylene glycol-600 + water has been done within the temperature range 298.15 K to 308.15 K. Several thermo-dynamical parameters such as Moelwyn-Hughes parameter, Beyer's non-linear parameter, Lattice Gruneisen parameter, Sharma's constant, Excess Gibbs free energy of activation, and Gruenberg-Nissan interaction parameter have been determined. The validity of five mixing rules for viscosities viz; Bingham's relation, Arrhenius relation, Kendall Munroe relation, Hind-Ubbelohde relation, and Frankel relation is checked for the systems under study. The obtained results are compared with pertinent experimental values. The variations of thermo-dynamical parameters and the deviations in excess viscosity values are explained in terms of the polymer–solvent interactions. Excess Gibbs free energy of activation values are fitted with the Redlich-Kister polynomial equation. A quantitative analysis of the molecular interactions prevalent in these binary systems is described in terms of nature, type and strength of interactions, anharmonicity and structural changes.