Defect engineering of carbon nanotubes and its effect on mechanical properties of carbon nanotubes/polymer nanocomposites: A molecular dynamics study

Molecular dynamics simulations have been performed to explore the effect of intrinsic defects of carbon nanotubes (CNTs) on the mechanical properties of CNTs/polyethylene (PE) composites. Three kinds of defects including single adatom defect, single vacancy defect and an adatom-vacancy pair defect have been considered here. The longitudinal Young's moduli of individual CNTs and CNTs/PE composites with different defects were calculated. On this basis, the interfacial interaction energy between CNTs and PE matrix and the adsorption behavior of PE molecular chains on the surface of CNTs were characterized. The results show that the elastic properties of individual CNTs and the interfacial characteristics between CNTs and matrix both contribute to the elastic properties of CNTs/PE composites. Meanwhile, due to different interaction energies, there exists three different adsorption modes of PE molecular chains on the surface of CNTs. Compared with the MD simulation results, the rule of mixture does not solidly hold in predicting the Young's modulus of composites for large defect degree.