Phase diagram and physical properties of a waterless sodium bis(2-ethylhexylsulfosuccinate)- ethylbenzene-ethyleneglycol microemulsion: An insight into percolation

Volumetric and transport studies have been carried out for the nonaqueous ternary microemulsion system containing sodium bis(2-ethylhexylsulfosuccinate) aerosol-OT (AOT), ethylbenzene (EB), and ethyleneglycol (EG). The results obtained for the conductivity sigma are presented over a wide range of volume fraction of dispersed phase phi and different molar concentration ratio omega=[EG]/[AOT]=2-10 at 30 degrees C and discussed in context of percolation theory. The variation of sigma with respect to temperature (T=10-60 degrees C) shows an increase in the conductance values but no percolation-type phenomenon is observed. The measurements of viscosity, density, and ultrasonic velocity have also been carried out to understand the behavior of this nonaqueous microemulsion system. The phase behavior of the microemulsion is sensitively dependent on the EG to AOT molar ratio. A simple structural model has been applied for the calculation of the various parameters, i.e., aggregation number (n), core radius (r(n)), and surface number density of the surfactant molecule at interface (alpha(s)).