Viscosity and local liquid structure in dimethyl sulfoxide-water mixtures

Abstract

The shear viscosity and density of ten dimethyl sulfoxide (DMSO)-water mixtures have been measured over the concentration range 0.1 to 0.8 mole fraction (mf) DMSO and over the temperature range 213 ≤ T ≤ 293° K. Density data are reported and have been fitted to a quadratic equation of the form ρ = a + bT + cT2. The maximum in the viscosity-concentration curve observed by others at elevated temperatures is found to sharpen considerably at low temperatures. The very large positive ΔSη* calculated for viscous flow in the region of 0.33 mole fraction DMSO at low temperatures is indicative of an extensive disordering process. Analysis in terms of WLF theory yields To = 120° in the region of 0.3 mf DMSO.