A molecular dynamics investigation of the torsional responses of defective single-walled carbon nanotubes

The buckling behavior of defective single-walled carbon nanotubes (CNTs) under torsion is investigated by using molecular dynamics simulations. Various kinds of defects including vacancy defects (monovacancy, bivacancies and line) and topological defects such as Stone-Thrower-Wales are considered. The effect of initial defects on the torsional properties is closely examined. The simulation results show that the torsional capacity is strongly dependent of the type of defects, chirality and temperature. The reduction in the torsional capacity is greater for CNTs with vacancy defects than CNTs with topological defects. Armchair CNTs have higher shear modulus and critical torques and are less sensitive to the presence of defects when compared to their zigzag counterparts. Higher temperatures trigger bond reconstructions in defective CNTs and bring relief to the negative effects of the defects, thereby improving the torsional capacities of the defective CNTs. Thus, the deterioration of the torsional capacity induced by defects can be mitigated through thermal treatment.