Superstretchability and stability of helical structures of carbon nanotube/polymer composite fibers: Coarse-grained molecular dynamics modeling and simulation

Super-stretchable helical structures made from carbon nanotube (CNT) fibers are promising candidates for applications in stretchable and wearable devices. A multi-scale model of the helical structures of CNT/polymer composite fibers is presented to gain more insight into their deformation properties and damage mechanisms. By imitating the practical preparation process, a suitable model for the helical structures is obtained, which reflects the features of both the macro-scale geometric construction and the micro-scale structure. An interpretation of the stress-strain curves, various potential energies caused by micro-structural evolution, and the fracture morphology are conducted. In addition, the role of the strain rate on the mechanical behavior of the helical structures is investigated. It is found that the elongation of the helical composite fibers can reach 100%-300%, depending on the pitch of the helix and the tensile strain rate. The specific strength of the helical composite fibers greatly decreases for a decreasing helix pitch. The deformation mechanisms are divided into four types according to different predominate factors, for different strain rates. This work contributes to the understanding of the deformation and damage mechanisms behind the superstretchability and great stability of the helical structures of CNT/polymer composite fibers.

By imitating the practical preparation process, a suitable model for the helical structures is obtained, which reflects the features of both the macro-scale geometric construction and the micro-scale structure. An interpretation of the stress-strain curves, various potential energies caused by micro-structural evolution, and the fracture morphology are conducted. This work contributes to the understanding of the deformation and damage mechanisms behind the superstretchability and great stability of the helical structures of CNT/polymer composite fibers.281