Ultrasonic assisted stretching approach toward aligned CNT for high strength and conductive nanocomposite

Carbon nanotubes (CNTs) reinforced polymeric nanocomposite is one of the most promising candidates for the future lightweight and multifunctional material. Two prerequisites for the development of high-performance nanocomposites are the strong interfacial interaction and high orientation of CNTs in the matrix, which are extremely challenging due to the fact that CNTs tend to mostly agglomerate into bundles. Herein, we demonstrated an ultrasonic assisted stretching strategy to enhance interfacial interaction and the orientation of CNTs in composites, which was attributed to the de-bundling effect of CNTs generated by ultrasonic cavitation and the inter-tube sliding effect assisted by resin lubrication during stretching processing. Under the optimal ultrasonic processing conditions, the strength, modulus, toughness and electrical conductivity of aligned nanocomposites can be improved by up to 43.5%, 68.8%, 42.5% and 144.1%, respectively, compared with those without ultrasonic treatment. This ultrasonic assisted stretching strategy could be easily extended to develop composites reinforced by other discontinuous fillers, such as boron nitride nanotubes, carbon nanofibers, and many whiskers.