Characterization of Interlayer Sliding Deformation for Individual Multiwalled Carbon Nanotubes Using Electrostatically Actuated Nanotensile Testing Device

We have developed an in situ scanning electron microscopy (SEM) nanomaterial manipulation system, including a newly designed electrostatically actuated nanotensile testing device (EANAT), in order to investigate the mechanical characteristics of multiwalled carbon nanotubes (MWCNTs) synthesized by atmospheric pressure-chemical vapor deposition. The new EANAT can measure uniaxial tensile displacement of nanomaterials using a capacitive displacement sensor incorporated into a cantilever motion amplification system. The resolution of the measurement displacement was 0.28 nm at the minimum. The nanomaterial manipulation system allows for an individual MWCNT to be picked up from a substrate and to be attached to an EANAT. The stress-strain relationships for the individual MWCNTs were successfully obtained from the nanotensile tests, and Young´s moduli were estimated to be in the range from 338 to 623 GPa. The deformation of individual MWCNTs under uniaxial loading was accompanied by repeated stick-slip and hard sticking events like telescopic motion. The shear strength at a stick-slip event during interlayer sliding of MWCNTs under tensile loading was directly derived from the shear interaction force in the tensile load-displacement curves and SEM observations. On the basis of the single-shot extraction model, the shear strength was estimated to be an average of 78 MPa greater than that for high-quality crystalline graphite, which might be caused by the hard sticking between layers.