Dielectric Characterization of Composites Based on Coated Conducting Fibres Embedded in Epoxy Matrix

The dielectric properties of composites consisting of an epoxy matrix loaded with coated copper fibres or coated carbon fibres have been studied over the frequency range 100 Hz to 1 MHz. The fibres are coated with an insula-ting material in order to prevent continuous conducting paths from being formed in the composite. The dielectric behaviour of.these composites is quite similar to that of heterogeneous dielectrics where interfacial polarization is important. High values of the real part of the dielectric permittivity (one hundred to five hundred relative to co) are obtained throughout the frequen-cy range. The imaginary parts of the permittivity are very high at low fre-quencies (of the order of 106 at 100 Hz) for carbon fibre loaded epoxy, but decrease by three orders of magnitude at 1 MHz. Key Words: epoxy, coated carbon fibre, coated copper fibre, composite, dielectric permittivit