A review of electrically conductive poly(ether ether ketone) materials

Poly(ether ether ketone) (PEEK) is a high-performance thermoplastic with a distinctive combination of corrosion resistance, thermo-oxidative stability and outstanding physical and mechanical properties at high temperatures. A pertinent step forward in the development of this thermoplastic has been the inclusion of electrically conductive fillers to expand its functionality. In this review an overview of the research on electrically conductive PEEK composites is provided. Conductive filler type, fabrication methods, characterization details and different properties are described. Carbon nanotubes, graphene nanoplatelets and other organic and inorganic conductive fillers such as expanded graphite and nickel have been incorporated into PEEK by techniques such as extrusion, injection moulding and cold and hot compression moulding and in some cases with pre-processing steps including mechanochemical modifications in organic solvents. The influences of type, loading and compatibilization of fillers and processing conditions on the mechanical and electrical conductivity properties of the composites are analysed and compared. The incorporated fillers have been able to enhance the electrical conductivity of the PEEK composites to either the semiconducting or conductive regions. PEEK composites containing carbon nanotubes compatibilized by polysulfones and poly(ether imide) achieved electrical conductivity values in the semiconducting region at the lowest electrical percolation threshold of 0.1 wt%. Additionally, the inclusion of 10 wt% expanded graphite and 10 vol% inorganic macroparticles of nickel noticeably improved the electrical conductivity of PEEK into the conductive region. (c) 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.