Mechanical Properties of Carbon Nanotubes Inferred from TEM

Abstract The discovery of carbon nanotubes by Iijima has stimulated considerable research into their structural, chemical, electrical and mechanical properties. Apart from their intrinsic beauty as macromolecules, and their possibilities as one-dimensional conductors, researchers are stimulated by the notion that a structurally perfect nanotube may be one of the strongest known materials. It is known that when nanotubes are bent through large angles, regions of high curvature buckle to develop crimps, similar to those observed when metal pipes are bent too much. Figure la shows a multi-walled nanotube that has one end embedded in a ceramic matrix. The other end is snagged so that the tube is bent. Several crimps are visible on the nanotube. Figure lb shows the same nanotube imaged a few moments later. Remarkably, the nanotube has sprung straight and the crimps have disappeared. This demonstrates that buckling in nanotubes does not involve plastic deformation, and that nanotubes can maintain their structural integrity even after severe deformation.