Dielectric measurements were carried out for polystyrene (PS)/polypyrrole (PPy) composite membranes immersed in dilute aqueous electrolyte solution over a frequency range from 40 Hz to 11 MHz, some differential dielectric relaxation phenomena were observed: pure PS membrane and the PS membrane interfused with PPy showed different modes of dielectric spectra, one relaxation for pure PS membrane and two relaxations for the PS membrane interfused with PPy, respectively. The dielectric relaxation mechanism was explained by the dielectric theories on Maxwell-Wagner polarization relaxation: the high frequency dielectric relaxation was due to the effects of the interfacial polarization and the lower one was due to the heterogeneous property of the composite membrane. The system was modelled and the phase parameters were calculated using Hanai’s method. The dielectric measurements for the system with the PS membrane interfused with different contents of PPy in electrolyte solutions and the analysis result indicate that the dielectric response of the membrane was influenced by the variety and concentration of the electrolyte, and the quantity of PPy contained in the composite membrane. These results give a new way of increasing the dielectric constant compared to that of pristine polymer by interfusion with electric particles and offer an important clue to the preparation of macromolecule composite compound with high conductivity and good mechanical capability.

Key words: dielectric relaxation spectroscopy, polystyrene membrane, polypyrrole particle, composite membrane, electrolyte solution, Hanai’s method