Radial elasticity of multi-walled carbon nanotubes

TL;DR

This study combines experimental and theoretical approaches to investigate how the radial elasticity of multi-walled carbon nanotubes varies with their external radius, revealing a decreasing Young's modulus that approaches 30 GPa.

Contribution

It provides new experimental measurements and theoretical analysis of radial elasticity in multi-walled carbon nanotubes as a function of radius.

Findings

Radial Young's modulus decreases with increasing radius

Young's modulus approaches approximately 30 GPa for larger radii

Molecular dynamics and Hertz theory are used to interpret results

Abstract

We report an experimental and a theoretical study of the radial elasticity of multi-walled carbon nanotubes as a function of external radius. We use atomic force microscopy and apply small indentation amplitudes in order to stay in the linear elasticity regime. The number of layers for a given tube radius is inferred from transmission electron microscopy, revealing constant ratios of external to internal radii. This enables a comparison with molecular dynamics results, which also shed some light onto the applicability of Hertz theory in this context. Using this theory, we find a radial Young modulus strongly decreasing with increasing radius and reaching an asymptotic value of 30 +/- 10 GPa.