Load transfer between cross-linked walls of a carbon nanotube

Cross links between inner and outer walls of multiwalled carbon nanotubes are believed to increase nanotube modulus and therefore nanotube effectiveness for reinforcing composites. In order to investigate changes in the Young's modulus of individual double-walled nanotubes (DWNTs) as a function of cross-link density and type, molecular-dynamics simulations are employed to evaluate strain coupling and corresponding load transfer from outer to inner walls. Results show that interwall $s{p}^{3}$ bonds and interstitial carbon atoms can increase load transfer between DWNT walls and that interwall $s{p}^{3}$ bonds are most effective. However, the maximum size of the modulus increase is limited to about 25% for the investigated small-diameter, short DWNTs because the defects decrease the stiffnesses of the nanotube walls.