|
|
||
|
|
|
|
Figure 7. Shell buckling of (10,10) SWCNTs. (a) Finite element method analysis of the axial compressive load versus compressive strain up to the onset of shell buckling; inset shows the MD atomic configuration of the nanotube during symmetric shell buckling. (b) Critical dynamic shell-buckling loads fav of the SWCNT in water for different adatom-vacancy defect densities dav. (c) Critical dynamic shell-buckling loads f SW of the SWCNT in water for different Stone-Wales defect densities dSW. Dashed lines in (b) and (c) denote the maximum axial forces caused by flow drag on nanotubes of different lengths L as functions of the defect density, where both surface and end drags of the nanotube are considered.
This and the next image are from:
H.B. Chew (1), M.-W. Moon (2), K.R. Lee (2) and K.-S. Kim (1)
(1) School of Engineering, Brown University, Providence, RI 02912, USA
(2) Computational Science Center, Interdisciplinary Fusion Technology Division, Korea Institute of Science and Technology, Seoul 136-791, Korea
“Compressive dynamic scission of carbon nanotubes under sonication: fracture by atomic ejection”, Proceedings of The Royal Society A, Vol. 467, No. 2129, pp 1270-1289, 2011, https://doi.org/10.1098/rspa.2010.0495
ABSTRACT: We report that a graphene sheet has an unusual mode of atomic-scale fracture owing to its structural peculiarity, i.e. single sheet of atoms. Unlike conventional bond-breaking tensile fracture, a graphene sheet can be cut by in-plane compression, which is able to eject a row of atoms out-of-plane. Our scale-bridging molecular dynamics simulations and experiments reveal that this compressive atomic-sheet fracture is the critical precursor mechanism of cutting single-walled carbon nanotubes (SWCNTs) by sonication. The atomic-sheet fracture typically occurs within 200fs during the dynamic axial buckling of a SWCNT; the nanotube is loaded by local nanoscale flow drag of water molecules caused by the collapse of a microbubble during sonication. This is on the contrary to common speculations that the nanotubes would be cut in tension, or by high-temperature chemical reactions in ultrasonication processes. The compressive fracture mechanism clarifies previously unexplainable diameter-dependent cutting of the SWCNTs under sonication.
Page 71 / 76