Percolation in Multi-Wall Carbon Nanotube-Epoxy Composites Influence of processing parameters, nanotube aspect ratio and electric fields on the bulk conductivity

• DOI: 10.1557/proc-788-l2.10
• Publication Date: 2011-04-06T12:43:10Z
• Authors: Jan K.W. Sandler; Alan H. Windle; Christian A. Martin; Matthias-Klaus Sc...; Wolfgang Bauhofer; Karl Schulte; Milo S.P. Shaffer
• Keywords: Percolation (cognitive psychology); Carbon nanotube actuators; Aspect ratio (aeronautics)

ABSTRACTA simple mechanical stirring process leads to charge-stabilised dispersions of aligned, substrate-grown, CVD-grown multi-wall carbon nanotubes in an epoxy resin. Subsequent sample processing, after the addition of the hardener, can be used to induce the nanotube agglomeration necessary to achieve electrically conductive bulk composites at low loading fractions. Both the nanotube percolation threshold and the resulting bulk conductivity can be adjusted by selection of suitable processing parameters and nanotube aspect ratio. This behaviour of aligned CVD-grown multi-wall carbon nanotubes allows lower electrical percolation thresholds than are possible with entangled multi-wall carbon nanotubes, single-wall carbon nanotube bundles, or carbon black in an epoxy matrix. Furthermore, the application of electric fields during composite processing induces the formation of aligned multi-wall carbon nanotube networks between electrodes dipped into the dispersion. Such composites show an electrical conductivity above the anti-static level and retain a degree of optical transmissivity.