Carbon a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known. Graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is
Carbon nanotube springs being subjected to and the architecture of the rest of the system. The material selected for the structure should have high strength because the added mass and volume of the support contribute to reducing the energy density of the entire system. Analysis is performed on CNTs subject to tensile loads. A hollow cylindrical structure of CNT of length L, diameter d and mean radius r is considered. The tube has thickness n.h, where n is the number of layers in the CNT and h=0.34 nm is the thickness of one shell. The Young's modulus of the material of the CNT