Evaluation of nano deformation mechanisms of MWCNT by MEMS-based tensile test and molecular dynamics simulation

This research investigated nanoscale deformation and fracture mechanisms of individually bridging multi-walled carbon nanotubes (MWCNTs) by Electrostatically Actuated NAnotensile Test devices (EANATs). The EANATs were settled into the in-situ SEM nanomanipulation system for tensile testing in order to handle an individual MWCNT on the device and to directly observe its deformation behavior. Consequently, we succeeded in obtaining force-displacement curves of MWCNTs. Young's moduli of MWCNTs were determined to be 360 to 450 GPa. The shear strength during interlayer sliding was also estimated at 60 MPa on the average, which was significantly larger than the previous reported shear strength of the high quality crystalline graphite. On the other hand, The MD results exhibited distinct stick-slip events of telescopic MWCNT models. The shear interaction strength was found around 33 MPa for extraction of inner shells regardless of the number of shells of MWCNT. Analytical shear strength is approximately close to the experiments. The reascension of tensile force after the stick-slip event was also demonstrated in the MD simulations, which was due to the “edge effect” of the extracted shell.