Enhancement of the surface electrical conductivity of thermoplastic composite matrices

Abstract

Enhancement of the surface electrical conductivity is desirable in a number of applications where composite structures are exposed to environments with high electrical activity. A high surface conductivity is desirable on aircraft that can be subject to lightning strikes or in manufacturing environments where static build up can produce safety issues. This article considers the addition of various conducting fillers to a thermoplastic to enhance the conductivity of the polymer matrix. The thermoplastic is one which is conventionally used to toughen epoxy resin composites. It was found that enhancement of the resin matrix depends on the filler, method of processing and subsequent thermal treatment. Conducting data are presented on the blends containing carbon nanotubes, nanographite and carbon black in various proportions and doped and undoped with additional conducting salts. The latter have been added to the resin so as to enhance conduction between the filler particles. While the levels of conductivity are significantly lower than those observed with a pure metal skin, values are achieved, which would allow discharge of electricity within relatively short periods of time.