Langmuir, Vol.15, No.21, 7176-7179, 1999
Phase behavior and water/oil microemulsion formation of alpha-sulfonate methyl ester derived from palm stearin/l-hexanol/hydrocarbon/water systems
The formation of a water/oil (w/o) microemulsion in the isotropic region of sodium salt a-sulfonate methyl ester derived from palm stearin (alpha-SMEPS)/1-hexanol/alkane/water systems was investigated at 30.0 +/- 0.1 degrees C. The formation of clear isotropic microemulsion phases in quaternary mixtures of surfactant, cosurfactant, oil, and water was mapped in phase composition diagrams. This region is associated with electrical conductivity due to the water connectivity in the system. The effect on the percolation threshold in the isotropic region by linear hydrocarbons of different chain lengths was also observed by electric conductivity measurements. The percolation threshold of the w/o microemulsion was found to decrease with an increase in the hydrocarbon chain length. A similar trend also occurred as the weight ratio of (alpha-SMEPS + 1-hexanol):alkane increased.
Keywords:IN-OIL MICROEMULSIONS;LIGHT-SCATTERING;PERFLUOROPOLYETHERMICROEMULSIONS;DIELECTRIC-RELAXATION;CONDUCTIVITY BEHAVIOR;QUATERNARY SYSTEM;MICRO-EMULSIONS;PERCOLATION;SURFACTANT;DROPLETS