The dielectric properties of two electrorheological liquid (ERL) systems, NaA zeolite/silicone oil and NaA zeolite/coal oil, were measured by dielectric spectroscopy, and an obvious dielectric relaxation at about 10⁵ Hz can be observed in each of systems. The single relaxation Cole-Cole equation was used to fit the dielectric parameters of the systems, and the results indicated that NaA zeolite/silicone oil possessed larger dielectric increment (?ε). Furthermore, for both of the two systems, the relationship between the volume fraction (φ) and dielectric increment obeyed the linear function ?ε＝4ε_mφ (ε_m, the permittivity of oil medium). By means of calculating and analyzing the dielectric mismatch parameter between zeolite particle and oil medium, the contribution of ε_{m to the interface polarization intensity of ERL was clarified. Moreover, the effect of adsorbed water on the interface polarization of zeolite ERL was researched as well. The results indicated that the permittivity of zeolite particle was enhanced and the relaxation time was reduced in the presence of adsorbed water, however, no change was found in ?ε of zeolite ERL with adsorbed water. Based on the dielectric mismatch theory, the adsorbed water was proved to be positive to the interface polarization rate of zeolite ERL.}

Key words: zeolite, electrorheological liquid, dielectric spectroscopy, dielectric mismatch, interface polarization