Mechanical properties of nanotube sheets: Alterations in joint morphology and achievable moduli in manufacturable materials

TLDR

Nanotube sheets, or “bucky papers,” have been proposed for actuating, structural, and electrochemical systems because of their promising mechanical properties. The study investigates how joint morphology influences the mechanical properties of nanotube sheets through detailed simulations. The authors simulate three‑dimensional joint deformation to parameterize torsion‑spring models in two‑dimensional Euler beam‑network simulations, establishing upper bounds on sheet moduli. Simulations and experiments suggest that moduli of HiPco‑ and laser‑ablated nanotube sheets could be increased 2–30×, and that adding more interrope connections is the most effective way to enhance stiffness in sheets with straight segments.

Abstract

Nanotube sheets, or “bucky papers,” have been proposed for use in actuating, structural and electrochemical systems, based in part on their potential mechanical properties. Here, we present results of detailed simulations of networks of nanotubes/ropes, with special emphasis on the effect of joint morphology. We perform detailed simulations of three-dimensional joint deformation, and use the results to inform simulations of two-dimensional (2D) networks with intertube connections represented by torsion springs. Upper bounds are established on moduli of nanotube sheets, using the 2D Euler beam-network simulations. Comparisons of experimental and simulated response for HiPco-nanotube and laser-ablated nanotube sheets, indicate that ∼2–30-fold increases in moduli may be achievable in these materials. Increasing the numbers of interrope connections appears to be the best target for improving nanotube sheet stiffnesses in materials containing straight segments.