Investigation of CNT Defects on Mechanical Behavior of Cross linked Epoxy based Nanocomposites by Molecular Dynamics

Although carbon nanotubes (CNT) have been employed as reinforcements in nanocomposites, presence of nano scale defects such as Stone-Wales and vacancy defects in carbon nanotubes (CNT) weakens the mechanical properties of these materials. In this paper the effects of defects in CNTs on nanocomposite elastic behavior are investigated using molecular dynamics. Stiffness matrices of CNT and nanocomposite indicated the transversely isotropic behaviour of nanocomposite molecular model. Longitudinal and transverse Young's moduli for both perfect and defected CNT/epoxy nanocomposites are determined. A comparison between the results illustrates that the number and type of CNT defects have significant effects on mechanical behaviour of nanocomposite. Based on molecular dynamics results, CNT defects significantly affect the Young's modulus particularly in the transverse direction. Comparison between molecular simulation predictions and rule of mixtures results indicates that some correlation factors must be incorporated when using the micromechanical theories at nano scales.