Influence of Thrower–Stone–Wales defects on the interfacial properties of carbon nanotube/polypropylene composites by a molecular dynamics approach

A molecular dynamics (MD) simulations study is performed on Thrower–Stone–Wales (TSW) defected carbon nanotube (CNT)/polypropylene (PP) composites. We identify the degradation of the CNT and the improvement of the interfacial adhesion between the defected CNTs and PP molecules considering different CNTs with different numbers of TSW defects. By embedding the CNTs into a PP matrix, the effect of the TSW defects on the transversely isotropic elastic stiffness of polymer composites is calculated by MD simulations. Even if the TSW defects degrade the elastic properties of the CNTs, the transverse Young’s modulus and the transverse and longitudinal shear moduli of the composites increase due to the stronger interfacial adhesion between the defected CNTs and matrix, whereas the longitudinal Young’s modulus of the composites decreases. To elucidate the improved interfacial load transfer between the CNTs and the matrix, random polymer chain crystallization onto the surface of CNTs is simulated. The simulation shows that PP chains are wrapped more uniformly onto the surfaces of defected CNTs than onto the pristine CNT. The non-bond adhesion energy between the PP chains and the defected CNTs is greater than that between the PP chains and the pristine CNT.