CNT PROPERTIES

CHEMICAL -- SP2 bonding structure, stronger than that of SP3 bonding in diamonds.  Are considered anisotropic
ELECTRICAL -- In theory, metallic nanotubes can carry an electrical current density of 4 × 109 A/cm2 which is more than 1,000 times greater than metals such as copper.  It has also recently been reported that SWNTs can route electrical signals at high speeds (up to 10 GHz) when used as interconnects on semi-conducting devices.  
Source: azonano.com
MECHANICAL -- Since CNTs have a low density for a solid of 1.3 to 1.4 g•cm−3, its specific strength of up to 48,000 kN•m•kg−1 is the best of known materials, compared to high-carbon steel's 154 kN•m•kg−1.
THERMAL –- It is predicted that CNTs will be able to transmit up to 6000 W•m−1•K−1 at room temperature; compare this to copper, a metal well-known for its good thermal conductivity, which transmits 385 W•m−1•K−1. The temperature stability of CNTs is estimated to be up to 2800 °C in vacuum and about 750 °C in air.
OPTICAL -- Graphene, a single layer of carbon atoms in sheet form (imagine a CNT unrolled) is transparent but exhibits the most extreme properties of any known material.
U.N.O. Source: Wikipedia (various, please see associated bibliography)