Extraordinary impact resistance of carbon nanotube film with crosslinks under micro-ballistic impact

Abstract

The crosslinks of carbon nanotubes (CNT) film has been demonstrated to owing the ability to reinforce the quasi-static mechanical properties. But it is unclear whether crosslinks improve the ballistic impact resistance of CNT film. Here, we investigated the impact resistance of CNT film with crosslinks by combining micro-ballistic impact experiments with coarse-grained molecular dynamics (CGMD) simulations. The impact resistance is quantitatively characterized in terms of the specific penetration energy. Meanwhile, the effective enhancement of impact resistance contributed to the crosslinks is directly observed in the experiment. CGMD simulations are employed to unveil the corresponding mechanisms in terms of deformation behavior, energy dissipation mode, and failure behavior. Our results indicate that with the increase of crosslink density, the energy dissipation mode of the CNT film transforms from bending-dominated to stretching-bending-dominated due to enhanced interaction between the adjacent CNTs. This leads to a transformation of perforated morphology from cascaded interfaces sliding to crosslink-restricted deformation with crosslinks. Our simulations also indicate that the length, bending stiffness of CNTs, and film’s thickness play essential roles in the impact resistance of CNT film at various crosslink densities. These results provide a feasible strategy to improve the protective performance of CNT film.