Effect of environmental conditions on the electrical conductivity of epoxy/carbon fiber composites

The effect of environmental conditions on the electrical conductivity of epoxy/carbon fiber composites has been investigated. It was shown that mass uptake due to the water diffusion to epoxy/carbon composites increased as a function of water diffusion time. As a result, the electrical conductivity of epoxy/carbon fiber composite decreased due to the debonding between epoxy matrix and carbon fiber. It was found that epoxy/carbon fiber composite with multi-directional carbon fiber lay up has higher conductivity drop due to the increase of capillary diffusion between epoxy and carbon fiber. Epoxy/carbon fiber composites used at high temperature showed low electrical conductivity due to the thermal expansion of matrix materials. This phenomena is more pronounced in composites used in repeated heating and cooling conditions. In addition, it was found that this phenomena could be minimized by adding conductive additives to composites.