Influence of different cosurfactants on conductance, viscosity and ultrasonic velocity in water in oil microemulsion

Conductance, viscosity and ultrasonic velocity measurements have been carried out on microemulsions containing water, STS as surfactant and different alkanols (C-4-C-10) as cosurfactant and hexane as oil. A drastic decrease in conductance is observed when hexanolloctanol/decanol are substituted for butanol/pentanol as cosurfactant. Similarly in case of viscosity, no sharp break is observed when higher alkanols (C-4-C-10) are employed as cosurfactant. However in case of ultrasonic velocity, when hexanol is used as cosurfactant, a minima is observed instead of maxima as in case of butanol and pentanol. With heptanol, there is no maxima or minima and with octanol and decanol first there is an increase in velocity, which then levels to a constant value.