Multi-walled carbon nanotube and carbon nanofiber/polyacrylonitrile aerogel scaffolds for enhanced epoxy resins

Despite the unique characteristics of carbon nanostructures such as carbon nanotube (CNTs) and carbon nanofibers (CNFs), their practical applications are limited because of their extremely low solubility and poor dispersion characteristics. To obtain composites with favorable electrical, thermal and mechanical properties, a network of nanofiller/polyacrylonitrile (PAN) aerogel was prepared by non-solvent and thermally induced phase separation (NIPS/TIPS) method and used as a scaffold to create epoxy nanocomposite. Compared with the conventional mixing, this method brought about a considerable increase of compressive strength (about 500%). Furthermore, an electrical percolation threshold as low as 0.0028 and 0.019 vol % was observed for CNT/polyacrylonitrile/epoxy nanocomposites (CNT/PA/E) and CNF/polyacrylonitrile/epoxy nanocomposites (CNF/PA/E), respectively. To the best of our knowledge, this small amount of percolation threshold has not yet been reported for CNT and CNF based nanocomposites. Such intriguing performance can mainly be related to a three-dimensional nanotube and nanofiber network structure in the resin matrix.