Mechanical relaxation and "intramolecular plasticity" in carbon nanotubes

The question of how carbon nanotubes (CNT)-believed to be the strongest filaments-relax under tension has been addressed. A dislocation theory applied to a two-dimensional nanocrystal such as the CNT describes the main routes of mechanical relaxation in this molecular structure: a brittle cleavage or, at high temperatures, a plastic flow. Both start with diatomic rotation, which "unlocks" the pristine wall of CNT by creating a dislocation dipole with the pentagon-heptagon cores. Under high stress, the dislocations depart from each other along helical paths, leaving behind a nanotube of smaller diameter, well-defined new symmetry, and changed electrical properties. (C) 1998 American Institute of Physics.