Rheological Behavior of Mixtures of Ionic Liquids with Water

Abstract

The changes in viscosity exhibited upon mixing remain one of the major challenges for substance property prediction. Viscosity often drastically changes after even small changes in concentration of one of the compounds in the mixture. The viscosity behavior of mixtures of ionic liquids with water has been studied. First, a generalized evaluation of the shape of the viscosity‐concentration curves has been done. About one‐tenth of the investigated systems exhibited maxima or inflection points of the curve. The simple logarithmic mixing rule turns out to be applicable as a first approximation for many systems. However, it tends to underestimate mixture viscosity. Following these results, parameters for a group contribution method were fitted and evaluated. This method is based on the Grunberg and Nissan extension of the logarithmic mixing rule.

Thermo‐Rheology of a Proline‐Based Surface‐Active Ionic Liquid: Mixtures with Water and n‐Octane

“…This behavior was found for other SAIL mixtures at low concentrations in the presence of water and similar hydrocarbons [29]. In both processes, a progressive drop (about ten times) of the viscous and elastic moduli with increasing temperature (from 25 to 55°C) was observed, corroborating that flow was favored at the highest temperatures [12]. In this case, G dominates and holds a fixed value over a large frequency spectrum, and G increases smoothly until crossing over with G .…”

“…8 b) profiles exhibited similar patterns. In both processes, a progressive drop (about ten times) of the viscous and elastic moduli with increasing temperature (from 25 to 55°C) was observed, corroborating that flow was favored at the highest temperatures [12]. The rate of decrease of both moduli was slower at the lowest temperatures (< 37.5 ± 2.5°C) and increased notably above that temperature.…”

“…1). The apparent viscosity values agree with those evaluated for other non-Newtonian SAIL like 1-butyl-3-methyl-imidazolium DS ([C 4 mim]DS) [10], and shear-thinning IL [11,12]. The return flow curve did not match with the outgoing curve.…”