Jointed Capsule Model of Carbon Nanotubes and Its Applications in Polymer Nanocomposites

Bead-spring models of polymer chains have been widely adopted to study mechanical and thermal properties of polymers. For nanocomposites containing carbon nanotubes (CNTs), it is thus desirable to develop similar models for CNTs. However, a bead-spring representation of a CNT suffers from the corrugation nature of a bead-spring chain, which makes the model incapable of correctly capturing the load transfer, friction, and adhesion at the interface between the CNT and other components in the nanocomposite. To overcome the corrugation issue, we have developed a jointed capsule model of CNTs in which each bond connecting two neighboring beads in a usual bead-spring chain is replaced by a cylinder with a diameter equal to the bead diameter. Each segment thus appears as a capsule. We have confirmed that in the jointed capsule model the potential experienced by a bead sliding over the surface of a CNT is smooth and does not show corrugation any more. We use the jointed capsule model to study the adhesion and friction between CNTs and the mechanical properties of nanocomposites consisting of a polymer matrix with dispersed CNTs and/or CNT bundles.