Give detailed note on strength of carbon nanotubes.

I. The tensile strength of carbon nanotube is very large as compared to many bulky materials.

II. The tensile strength is the result of the covalent sp² bonds between carbon-carbon atoms. But, under excessive tensile strain nanotubes display permanent deformations.

III. When compared to their tensile strength compressive strength is low.

IV. Nanotubes are much softer along radial directions permitting bending like rubber tube.