TIME-DOMAIN DIELECTRIC STUDY OF NONIONIC MICROEMULSIONS

The dielectric behavior of a microemulsion prepared from dodecane, but anol, water and polyoxyethylene (10) oleylalcohol (Brij 97) has been s tudied by time domain dielectric spectroscopy over the frequency range of 10(5)-10(10) HZ for temperatures between 10 and 40 degrees C with varying water content. Several dielectric dispersion regions with the typical characteristic relaxation times of the order of nanoseconds an d tens of picoseconds are observed. They are analyzed in time domain i n terms of macroscopic dipole correlation functions and are attributed to the relaxation mechanisms of the different chemical compounds with in the microemulsion. The appearance and intensity of the peaks for th e relaxation processes depend on the water content. The types of motio n of different kinetic units that can be manifested as local relaxatio n processes are proposed. The dielectric properties of microemulsions depend on the underlying phase behavior and on the consequent morpholo gy in these systems. The results suggest that changes in the microstru cture of polarization and relaxation mechanisms occur in the water fra ction content intervals of 5-10, 10-35 and 35%.