Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load

The tensile strengths of individual multiwalled carbon nanotubes (MWCNTs) w ere measured with a "nanostressing stage" located within a scanning electro n microscope. The tensile-loading experiment was prepared and observed enti rely within the microscope and was recorded on video. The MWCNTs broke in t he outermost Layer ("sword-in-sheath" failure), and the tensile strength of this Layer ranged from 11 to 63 gigapascals for the set of 19 MWCNTs that were Loaded. Analysis of the stress-strain curves for individual MWCNTs ind icated that the Young's modulus E of the outermost Layer varied from 270 to 950 gigapascals, Transmission electron microscopic examination of the brok en nanotube fragments revealed a variety of structures, such as a nanotube ribbon, a wave pattern, and partial radial collapse.