Overview of ultrasonic assisted manufacturing multifunctional carbon nanotube nanopaper based polymer nanocomposites

Carbon nanotube (CNT) nanopaper (NP) has become a promising platform to fabricate light weight multifunctional polymer nanocompos- ites, because of superior properties of CNTs including low density, high strength and modulus, high electrical and thermal conductivities, etc. However, the low permeability of CNT NP (10^-17to 10-¹⁹m²) makes it difficult to be impregnated by resin to fabricate nanocomposites via conventional approaches, such as resin transfer molding and hot melt compression molding. The resin infiltration time is usually more than one hour, and uniform resin impregnation is difficult to be achieved. Additionally, solvent is required to decrease the resin viscosity to facilitate the resin infiltration. All these make the process environmentally unfriendly and significantly limit the industrial applications of NP/polymer nanocomposites. Therefore, a novel ultrasonic assisted infiltration technology is developed to fabricate the NP/polymer nanocomposites with a uniform nanoparticle dispersion and high loadings (>20 wt%). The high frequency (20 kHz) ultrasonic vibration al- lows to effectively infiltrate various types of resins, including thermoplastic polyurethane (TPU), thermoset epoxy (EP), and elastomer polydimethylsiloxane (PDMS) into CNT NP within a few seconds, followed by polymerization. A systematic review was conducted to re- port on the NP/polymer nanocomposite fabrication process and the properties of the nanocomposites together with their detailed exempla- ry applications.