Comparative Molecular Dynamics Simulation Study of Mechanical Properties of Carbon Nanotubes with Number of Stone-Wales and Vacancy Defects

Abstract

Carbon nanotubes (CNTs) having pristine structure (i.e. structure without any defect) have very high mechanical properties. However, CNTs suffer from defects which can appear during purification, production or deliberately introduced by chemical treatment. The present study is based on comparative investigation of effects produced by Stone-Wales (S-W) and vacancy defects (VD) on the mechanical performance of single walled carbon nanotubes (SWCNT). The defects have been varied from 1 to 4 in both VD and S-W. In order to investigate the effect of both the defects on the material properties of CNT, molecular dynamics (MD) simulations have been used. In this study, a series of MD models (inclusion of number of S-W and VD) have been built to simulate the effects of defects on themechanical performance of SWCNTs. MD simulation has been carried out on a 42.59Å long armchair (6, 6) and (10, 10) SWCNTs by varying relative positions and orientations. Results show that the defects have reduced the tensile strength and strain more in VD as compare to S-W. This has been reduced by an average value of 23.48% and 28.2% respectively for 4 vacancy defects (4VD). Simulation results also show that more energy is required to stabilize the structure which comprises of VD. The increase in the energy value on an average is 35.52% for 4 VD as compared to pristine CNT. The Young's modulus of defected CNTs has also been calculated by increasing the lattice size in the successive increments of 25% by volume and it has been found that the Young's modulus of pristine CNT is weakened by 9.38% for S-W defects.