Effects of ultrasonication on the microstructures and mechanical properties of carbon nanotube films and their based composites

Carbon nanotube (CNT) film has been considered as a promising preform of CNTs for developing high performance composites that possess high content of CNTs. However, due to the intertube van der Waals interactions, CNTs in the films are often tightly bundled together, making the impregnation of resin materials to CNTs very challenging. In this work, an eco-friendly ultrasonic-assisted resin infiltration process has been developed, and its effects on CNT bundles diameter, CNT crystallinity, CNT film stretchability, and the mechanical properties of CNT films and their based composites have been systematically investigated. It has been found that CNT bundles became thinner and the film stretchability became higher upon the ultrasonication, and thus the performance of CNT film-based composites were improved. However, extensive sonication would severely destroy the crystal structures of CNTs and thus degrade the mechanical properties of CNT films and their based composites. The underlying mechanisms for the evolution of CNT networks during the ultrasonic treatment were also discussed.