Degraded axial buckling strain of multiwalled carbon nanotubes due to interlayer slips

A multiple-shell model is presented for infinitesimal axially compressed bu ckling of a multiwalled carbon nanotube embedded within an elastic matrix. In contrast to an existing single-shell model which treats the entire multi walled nanotube as a singlelayer elastic shell, the present model assumes t hat each of the nested concentric tubes is an individual elastic shell and the deflections of all shells are coupled through the van der Waals interac tion between adjacent nanotubes. By examining a doublewalled carbon nanotub e, it is found that the change in interlayer spacing has a negligible effec t on the axial buckling strain provided that the innermost radius is at lea st a few nanometers. Under this condition, a single equation is derived whi ch determines the deflection of the multiwalled carbon nanotube, and it is shown that infinitesimal axial buckling of a N-walled carbon nanotubes is e quivalent to that of a single layer elastic shell whose bending stiffness i s approximately N times the effective bending stiffness of a single walled carbon nanotube. As a result, the axial buckling strain of a N-walled carbo n nanotube is about 5 N times lower than that predicted by the existing sin gle-shell model. The degraded axial buckling strain is attributed to the in terlayer slips between adjacent nanotubes, which represents an essential fe ature of mechanical behavior of multiwalled carbon nanotubes. (C) 2001 Amer ican Institute of Physics.