Electrical Properties
The p electrons of carbon atoms in CNTs form extensive delocalized π bonds. Due to the significant conjugation effect, carbon nanotubes possess some unique electrical properties.
CNTs have a one-dimensional hollow tubular structure, with the tube walls composed of single or multiple layers of graphene sheets. The tube diameter is on the nanometer scale, and the length is on the micrometer scale, resulting in a huge aspect ratio. Their properties vary depending on the way the graphene sheets are rolled up, exhibiting metallic or semiconductor properties.
Mechanical Properties
Because the carbon atoms in CNTs adopt sp2 hybridization, compared to sp3 hybridization, the s orbital component in sp2 hybridization is larger, giving carbon nanotubes high modulus and high strength.
CNTs exhibit excellent mechanical properties. Their tensile strength reaches 50-200 GPa, 100 times that of steel, while their density is only 1/6 that of steel, at least an order of magnitude higher than conventional graphite fibers. Their elastic modulus can reach 1 TPa, comparable to that of diamond, and approximately 5 times that of steel.
Thermal Conductivity
CNTs possess excellent heat transfer properties. Due to their very large aspect ratio, CNTs exhibit high heat exchange performance along their length, but relatively lower heat exchange performance perpendicular to their diameter. Through appropriate orientation, carbon nanotubes can be synthesized into highly anisotropic thermally conductive materials.
Adsorption Properties
CNTs possess an extremely large specific surface area and strong adsorption capacity; they also exhibit good electromagnetic wave absorption properties.
