MECHANICAL AND THERMAL-PROPERTIES OF CARBON NANOTUBES

This chapter discusses some aspects of the mechanical and thermal prop erties of carbon nanotubes. The tensile and bending stiffness constant s of ideal multi-walled and single-walled carbon nanotubes are derived in terms of the known elastic properties of graphite. Tensile strengt hs are estimated by scaling the 20 GPa tensile strength of Bacon's gra phite whiskers. The natural resonance (fundamental vibrational frequen cy) of a cantilevered single-wall nanotube of length 1 micron is shown to be about 12 MHz. It is suggested that the thermal expansion of car bon nanotubes will be essentially isotropic, which can be contrasted w ith the strongly anisotropic expansion in ''conventional'' (large diam eter) carbon fibers and in graphite. In contrast, the thermal conducti vity may be highly anisotropic and (along the long axis) perhaps highe r than any other material. A short discussion of topological constrain ts to surface chemistry in idealized multi-walled nanotubes is present ed, and the importance of a strong interface between nanotube and matr ix for formation of high strength nanotube-reinforced composites is hi ghlighted.