Excess molar volumes, refractive indices and transport properties of aqueous solutions of poly(ethylene glycol)s at (303.15–323.15) K

Abstract

Densities, ρ, refractive indices, nD, and viscosities, η, for aqueous solutions of poly(ethylene glycol)s with an average molecular weight of 300 (PEG 300) and 400 (PEG 400) were measured. Densities were measured by an Anton Paar vibrating tube digital densimeter and viscosities by Anton Paar Stabinger viscometer. Experiments were carried out for solutions of each PEG at twenty different compositions covering the whole concentration range at five different temperatures ranging from 303.15 to 323.15K at atmospheric pressure. Excess (deviation from additivity) molar volume, VmE, excess molar refraction, RmE, deviation in viscosity, Δη, and the thermodynamics of viscous flow-enthalpy of activation, ∆H⁎, entropy of activation, ∆S⁎, free energy of activation, ∆G⁎, and their excess values — ∆H⁎E, ∆S⁎E, and ∆G⁎E have been derived from the measured properties. Measured properties ρ, nD, and η, were fitted to polynomial equation and derived properties VmE, RmE, ∆η, ∆H⁎E, ∆S⁎E, and ∆G⁎E were fitted to Redlich–Kister equation. The properties of aqueous solutions of the two glycols have been discussed in terms of interactions between the components in the binary solutions. In addition, the properties of the studied systems have been compared with available literature values of di(ethylene glycol) (DEG), tri(ethylene glycol) (TrEG) and tetra(ethylene glycol) (TeEG) for a general understanding on glycol–water interactions.