Temperature and Concentration Induced Complex Behavior in Ternary Microemulsion

Abstract

Viscosity measurements were performed in water/AOT (sodium bis(2-ethylhexyl) sulfoccinate)/isooctane microemulsions as a function of temperature between 25 and 55°C, molar ratio W0 = water/AOT ranging from 3 to 45 and three values of AOT/isooctane volume fractions (Φm= 0.1, 0.15, and 0.2). It was shown that microemulsions behaved as Newtonian fluids in the studied range of shear rate. For a critical molar ratio, W0c, the corresponding viscosity, η0c, was shown to be constant with temperature but dependent on the micellar concentration. For W0 W0c, where the viscosity increased with temperature. For some values of W0, the viscosity reached a maximum, which could be explained by attractive interdroplet interactions and formation of droplet clusters.

Keywords

• microemulsion
• micellar concentration
• viscosity
• temperature
• percolation
• aggregation