Dielectric measurements were made on middle phase microemulsions (MPEM) composed of sodium dodecylsulfate (SDS), cetyltrimethylammonium bromide (CTAB), n-butanol, n-heptane and brime. Distinct dielectric phenomena, with characteristic frequency depending regularly on the salinity of the microemulsions, were observed in the low-frequency range. Useful information such as structural feature and electrical properties of the system was obtained by means of analyzing the dielectric spectroscopies. The data were interpreted using some current models and theoretical formulas. From the theoretical values of relaxation time based on the models, it was found that the multifarious polarization mechanisms contributed mainly to the present dielectric relaxations. Among all the mechanisms for the dynamic processes the interfacial polarization is dominant. The results of analysis and theoretical calculations are consistent with each other, revealing the influence of salinity scanning on the structure of middle phase microemulsion and giving possible mechanisms.

Key words: MICROEMUSION, RELAXATION TIME, POLARIZATION, ALKYLSULFONATE, HEPTANE, BUTANOL