Interfacial charges manifestations: Kerr and dielectric relaxation studies in a microemulsion system

Abstract

Dielectric relaxation (10²–10⁹ Hz), transient- and phase (1–10⁷ Hz) electric birefringences were carried out cojointly on a W/O ternary microemulsion system from water, benzene, and BHDC as surfactant, for different ratios w _o : (water)/(BHDC) and volume fractions φ values. From the Kerr-effect approaches it is possible to distinguish the existence of dimers, trimers, and an unexpected sign-reversal of the Kerr constant as w _o decreases, whatever the φ values. Preliminary analysis of the dielectric measurements evidences a freqeuncy power law of the conductivity below 10³ Hz. The hypothesis of a quasi dc (i.e., dispersive) transport charge process is proposed and credits the possible presence of temporal self-similar clusters. Four marked dielectric relaxations have been found. The contributions of the Maxwell-Wagner interfacial polarization, the space charge manifestations via a surface resistivity and a double-layer polarization, as well as a possible molecular relaxation process are proposed.