Electrical relaxations in polymeric particulate composites of epoxy resin and metal particles

Composites of epoxy resins and nickel particles in various amounts were prepared and their dielectric spectra were measured in the frequency range 5 Hz-13 MHz and temperature interval from ambient to 140degreesC. The formalism of electric modulus proved to be efficient in analysing and interpreting obtained data. For these composites two relaxation processes are revealed in the frequency range and temperature interval of the measurements. One is an interfacial dielectric relaxation (Maxwell-Wagner-Sillars), MWS and the other is a conductivity relaxation. They both follow the Cole-Davidson approach with the exponent gamma reflecting a distribution of relaxation times with the characteristics of each process. AC conductivity of these composites is frequency and temperature dependant, it generally follows the exponential law sigma(ac) similar to omega(s) and reveals a conductivity relaxation process, in the low frequencies. (C) 2002 Elsevier Science Ltd. All rights reserved.