Viscosity, Gibbs Free Energy, and Refractive Indices for Binary Mixtures of o-Cresol + Poly(ethylene glycols) at T = 288.15–308.15 K and 96.5 kPa

Abstract

The viscosities (η) and refractive indices (n D) were measured for the binary mixtures of o-cresol + PEG 200/PEG 300/PEG 400 over the whole composition range at five different temperatures (288.15, 293.15, 298.15, 303.15, and 308.15 K). From the experimental results, the viscosity deviation (Δη), the excess Gibbs free energy of activation of viscous flow (ΔG *E), the deviation in refractive index (Δϕ n D), and the molar refraction (R m) have been calculated. The excess or deviation properties were fitted with Redlich–Kister polynomial equation and their coefficients and standard deviations were calculated. The positive and negative excess or deviation properties were discussed in terms of specific molecular interactions between mixture components. The excess or deviation property values (Δη, ΔG *E, and Δϕ n D) follow the order PEG400 > PEG300 > PEG200. On the basis of the viscosity data, Gibbs energies of viscous flow (ΔG*), enthalpy of activation of viscous flow (ΔH*), and entropy of activation of viscous flow (ΔS*) were also calculated.

Densities, Viscosities, and Self-Diffusion Coefficients of Ethylene Glycol Oligomers

“…Pd-catalyzed reactions (the importance of these can be seen in the 2010 Nobel prize award for their discovery) have also been carried out in PEG under both homocatalytic and heterocatalytic conditions where Pd is immobilized onto a porous silica material. − PEGs have also been successfully used as components in deep eutectic solvents. − Despite all of these successes, there are only limited experimental and theoretical studies on the dynamics of neat PEG. − Experimental physicochemical properties of PEGs are needed to further this effort. In this respect, densities and viscosities have been repeatedly reported for several polydisperse PEGs usually as part of studies on binary mixtures involving polydisperse PEGs. − The polydisperse PEGs are composed of mixtures of PEG oligomers with approximately a Gaussian mole fraction distribution around the mean chain length. ,, It is likely that the exact mole fraction distribution may vary from vendor to vendor and possibly even from batch to batch. Unfortunately, a composition analysis of polydisperse PEGs is typically not included in the above cited studies.…”