Nanoscale modeling and simulation of interfacial bonding of single-walled nanotube reinforced composites

Owning to the extraordinary mechanical, electrical and thermal properties of single-walled nanotubes (SWNTs), SWNT reinforced composites can be used for various applications. In the development of SWNT reinforced composites, one of the fundamental issues that scientists and engineers are confronting is the SWNT-polymer interfacial bonding, which will determine the load transfer capability from the polymer matrix to the nanotube. In single-walled nanotube (SWNT) reinforced epoxy composites, the epoxy resin molecules and the nanotubes are at the nano scale. The interaction at the SWNT/epoxy resin interface is highly dependent on their local molecular structures and bonding. At this small length scale, the lattice structures of the nanotube and the epoxy resin cannot be considered continuous, and their interfacial properties cannot be determined through continuum mechanics. In this paper, the interfacial bonding of SWNT reinforced epoxy composites is investigated using molecular mechanics and molecular dynamics simulations based on a cured epoxy resin model, which is constructed by incorporating three-dimensional cross-links formed with Shell EPON 862 epoxy resin and EPI CURE W curing agent during polymerization. The interfacial bonding energy between the SWNT and the cured epoxy resin is analyzed using molecular mechanics. Furthermore, the pullout of a SWNT from the cured epoxy resin is investigated using molecular dynamics simulations. Based on the pullout simulation, the interfacial shear strength between the SWNT and the cured epoxy resin is calculated to be up to 75MPa. These analysis results indicate that there could be an effective stress transfer from the epoxy resin to the nanotube.