Entanglement and the nonlinear elastic behavior of forests of coiled carbon nanotubes

TL;DR

This paper investigates the nonlinear elastic response of coiled carbon nanotube forests under impact, revealing that entanglement among coils is key to understanding their unique mechanical behavior.

Contribution

It introduces an analytical model highlighting the importance of entanglement in explaining the nonlinear impact response of coiled carbon nanotube forests.

Findings

Entanglement significantly influences the nonlinear elastic behavior.

The model explains the non-Hertzian impact response.

No plastic deformation observed in experiments.

Abstract

Helical or coiled nanostructures have been object of intense experimental and theoretical studies due to their special electronic and mechanical properties. Recently, it was experimentally reported that the dynamical response of foamlike forest of coiled carbon nanotubes under mechanical impact exhibits a nonlinear, non-Hertzian behavior, with no trace of plastic deformation. The physical origin of this unusual behavior is not yet fully understood. In this work, based on analytical models, we show that the entanglement among neighboring coils in the superior part of the forest surface must be taken into account for a full description of the strongly nonlinear behavior of the impact response of a drop-ball onto a forest of coiled carbon nanotubes.