ELECTRIC PERCOLATION OF WATER-IN-OIL MICROEMULSIONS - THE APPLICATIONOF EFFECTIVE-MEDIUM THEORY TO SYSTEM SODIUM DODECYL BENZENESULFONATE (DDBS) N-PENTANOL/N-HEPTANE/WATER/

The electric conductive behavior of the system water/sodium dodecylben zenesulfonate (DDBS)/n-pentanol/n-heptane has been studied. The result s showed that the system has an intrinsic electric percolation phenome non. The water induced percolation threshold, phi(d)(p), varies over a wide range and is higher than the theoretically predicted value of be low 1/3. To use the changed form of the effective medium theory, a sec ond-order polynomial relationship between sigma phi(d) and the conduct ivity sigma of system, is much better than to use the plot of sigma ve rsus phi(d) in fitting the conductivity data of W/O microemulsion, whe re phi(d) is the volume fraction of the disperse phase. A linear equat ion exists when the volume fraction phi d of the disperse phase does n ot exceed percolation threshold phi(d)(p) much more. The content P of n-pentanol and DDBS affects the properties of the system significantly , but the influences on the limit conductivity of the disperse phase a nd that of the continuous phase are in the same tendency; also the dis tribution of alcohol among inner water core, surfactant shell, and con tinuous phase are changed. (C) 1996 Academic Press, Inc.