Epoxy/CNT@X nanocomposite: Improved quasi-static, dynamic fracture toughness, and conductive functionalities by non-ionic surfactant treatment.

The present work investigated the effects of non-ionic surfactant treatment on the dispersibility, surface chemistry and structure of carbon nanotube (CNT) particles. Subsequently, the fracture experiments of as-prepared epoxy/CNT@X nanocomposites were carried out under quasi-static and dynamic loading conditions. By simply introducing the steric repulsive force between CNT@X filler and epoxy matrix, improved mode-I critical-stress-intensity factor (K Ic) and dynamic crack initiation toughness (K I i d) of the epoxy/CNT@X nanocomposite were simultaneously obtained without compromising other desired physical properties, such as electrical properties and electro-thermal behavior. In the case of SHPB impact loading, high-speed imaging along with digital-image-correlation (DIC) technology was utilized to determine dynamic fracture parameters. The results showed a notable reinforcement for the epoxy/CNT@X nanocomposite category, producing maximum increase of ~79% and ~153% in K Ic and K I i d values relative to epoxy/CNT nanocomposite at such maximum content of 1.0 wt%, respectively. The most delayed crack initiation time (59.9–68.4 μs) and slowest crack-tip velocity (229 ± 28 m/s) were also observed in the epoxy/CNT@X_1.0 case. These results may be explained by improved dispersibility and interfacial adhesion after surfactant treatment. • Improved fracture behaviors of nanocomposite with surfactant treatment were obtained. • An optical DIC method along with high-speed imaging was used to extract dynamic SIFs histories. • Introduced steric repulsive force improved the dispersibility of CNTs throughout the matrix domain. • Improved dispersibility and interfacial adhesion could provide stronger interfacial interactions. • Physical adsorption of the surfactant molecule did not compromise the conductive functionalities of CNT networks. [ABSTRACT FROM AUTHOR]