What is the tensile strength of carbon nanotubes?
Carbon nanotubes are one of the strongest and stiffest materials known, in terms of tensile strength and elastic modulus respectively. This strength results from the covalent sp2 bonds formed between the individual carbon atoms. In 2000, a multi-walled carbon nanotube was tested to have a tensile strength of 63 GPa.[24] In comparison, high-carbon steel has a tensile strength of approximately 1.2 GPa. CNTs have very high elastic moduli, on the order of 1 TPa.[25] Since carbon nanotubes have a low density for a solid of 1.3-1.4 g/cm³[26], its specific strength of up to 48,462 kN·m/kg is the best of known materials, compared to high-carbon steel’s 154 kN·m/kg.
Under excessive tensile strain, the tubes will undergo plastic deformation, which means the deformation is permanent. This deformation begins at strains of approximately 5% [27] and can increase the maximum strain the tube undergoes before fracture by releasing strain energy.
CNTs are not nearly as strong under compression. Be
