Viscosity and Speed of Sound of Potassium Nitrate and Lithium Nitrate in Poly(ethylene glycol)

Abstract

Densities, viscosities, and speeds of sound of 0.15[xKNO3 + (1 − x)LiNO3] + 0.85[poly(ethylene glycol)] and 0.20[xKNO3 + (1 − x)LiNO3] + 0.80[poly(ethylene glycol)] systems (molecular weight of poly(ethylene glycol) = 300) were measured as functions of composition (x = 0.0 to 1.0 mole fraction) and temperature (273.15 ≤ T/K ≤ 343.15). The viscosity and the structural relaxation time were found to be non-Arrhenius temperature dependent and were analyzed by using the Vogel−Tamman−Fulcher equation. The normalized viscosity isotherm exhibits a significant mixed alkali effect for the 0.20[xKNO3 + (1 − x)LiNO3] + 0.80[poly(ethylene glycol)] system at 273.15 K. The onset of the mixed alkali effect in this system has been explained by the competitive polarization model. The absence of the mixed alkali effect in the 0.15[xKNO3 + (1 − x)LiNO3] + 0.85[poly(ethylene glycol)] system is attributed to the lesser amount of total alkali ion content in the system.