Abstract
Microemulsions have been prepared from either benzene, toluene, ethylbenzene, or o-xylene and water using a mixture of surfactants of Span 80 and Tween 20 in the volume ratio of 1:4. These formulated microemulsions having propanol as the cosurfactant have been characterized by measuring their dynamic properties, i.e., conductance σ, density ρ, viscosity η, and ultrasonic velocity u, as a function of the volume fraction of water φ at 30 °C. The conductance values change exponentially as the volume fraction of water is increased. The use of a percolation model gives reasonable agreement between the experimental and calculated values. The viscosities vary in a nonmonotonic way, giving two peaked plots when the water content increases, indicating a lack of correlation with conductivity. The ultrasonic velocity and isentropic compressibility data throw some light on structural changes that occur in the microemulsion. An attempt has also been made to calculate the density and isentropic compressibility m of the micellar phase from the experimental data. The results indicate a trend toward an enhanced waterlike character of the dispersed phase at a high volume fraction of water φ.
- Received 23 September 1994
DOI:https://doi.org/10.1103/PhysRevE.51.5732
©1995 American Physical Society