A Critical Assessment of Electrical Conductivity and Multifunctionality of MWCNT/Epoxy Nanocomposites

Using available data from the literature and our own results, we critically examine the multifunctionality of epoxy-multiwalled carbon nanotube (MWCNT) composites. A major advantage of adding MWCNTs is that the key properties of the pristine epoxy are largely retained or even bettered. How the synthesis process affects the dispersion of the nanofillers and their properties is studied. Ideas from percolation theory are used to study and understand the nature of the variation of dc electrical conductivity with filler content and that of ac conductivity with both filler content and frequency. The electromagnetic shielding effectiveness over a broad microwave frequency range is investigated. Tensile strength, fracture properties, and thermal conductivity of the nanocomposites are also investigated. Thus, the multifunctionality of MWCNT-epoxy composites is critically assessed. Overall, we demonstrate that a deep understanding of the conduction mechanisms has been achieved. Also, the limitations of these materials have been identified and potential applications are mapped out. Their use as tough and durable electrically conductive adhesives (ECAs) is indicated. It is also shown that the major impediments to more versatile applications of these materials are their poor thermal conductivity and loss of flowability with increasing MWCNT content.