Gradient composites of nickel coated carbon fibre filled epoxy resin moulded under centrifugal force

Abstract

Epoxy resin filled with nickel coated carbon fibres was prepared under centrifugal force in order to obtain functionally gradient materials. The gradient in fibre content was evaluated from the density distribution of a sample in the direction of centrifugal force. The electrical conductivity of a sample was measured by either the parallel plate electrode method or the four-probe method in parallel or perpendicular to the centrifugal force direction. The conductivity of the sample measured by parallel plate electrodes showed almost constant values regardless of the magnitude of centrifugal force and the distance from the bottom of the sample to the centre of a sliced specimen. In contrast, the conductivity measured by the four-probe method was affected by the magnitude of centrifugal force and the position of the specimen. The conductivities by both methods showed less than 10−3 S/cm for all samples. It was confirmed by optical microscopic observation that most of fibres aligned perpendicular to the direction of centrifugal force. The gradient polymer composites with the electrical conductivity were derived by centrifugal force application.