The role of disorder on the AC and DC electrical conductivity of vapour grown carbon nanofibre/epoxy composites

Four dispersion methods were used for the preparation of vapour grown carbon nanofibre (VGCNF)/epoxy composites. It is shown that each method induces certain levels of VGCNF dispersion and distribution within the matrix, and that these have a strong influence on the composite electrical properties. A homogenous VGCNF dispersion does not necessarily imply higher electrical conductivity. In fact, it is concluded that the presence of well distributed clusters, rather than a fine dispersion, is more important for achieving larger conductivities for a given VGCNF concentration. It is also found that the conductivity can be described by a weak disorder regime.Foundation for Science and Technology, Lisbon, for financial support through the 3 Quadro Comunitário de Apoio, the POCTI and FEDER programmes, Projects PTDC/CTM/69316/2006 and NANO/NMed-SD/0156/2007, and Grants SFRH/BD/60623/2009 (J.S.) and SFRH/BD/41191/2007 (P.C.). Joint Luso-American Foundation (FLAD) – NSF US Research Networks Program research grant (F.H. and D.K.). We also thank Albermarle for the hardener, Hexion Specialty Chemicals for the epoxy resin, and Applied Sciences for providing their facilities