Microwave Makes Carbon Nanotubes Less Defective

An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes (CNTs). Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ∼35% and ∼65%, respectively, in tensile strength (∼0.8 GPa) and modulus (∼90 GPa) during tensile testing; an ∼20% improvement in electrical conductivity (∼80000 S m−1) was also reported. The mechanism of the microwave response of CNTs was discussed.