Carbon nanotube triaxial woven films with high mechanical properties for impacting protection

Fiber-based fabrics have great potential in impacting protection as composite materials. Herein, we proposed a novel nanostructure in which the (5,5) single-walled CNTs (SWCNTs) with a diameter d of ∼6.67 Å were employed to weave triaxial 2D films with an angle of adjacent CNTs as 60°. The bending angle of a single CNT in the structure unit length was set at 90°, while the bent length was 196.87 Å. The in-plane mechanical properties and impacting properties of triaxial woven films (TWFs) were investigated through a fully atomic molecular dynamics (MD) simulation. Experiments verified that the tensile mechanical properties of TWFs were related to the loading directions. The impacting test of single-layer films showed that the TWF possessed impacting protection and reached its force peak at the center of the sphere passing through the film. In addition, for bilayer composite films of TWFs and plain woven films, this combination developed a high strain with high stress. The impacting properties of the composite film in both directions (plain/triaxial and triaxial/plain) were investigated, and the percentages of absorbed energy were calculated to be 87.8% and 86.9% for the Plain/Triaxial and Triaxial/Plain films, respectively, indicating an outstanding impacting protection for the composite films. This work provides an in-depth understanding of the mechanical properties of TWFs and broadens the applications of CNT-based nanomaterials.