Effect of CNT length and structural density on viscoelasticity of buckypaper: A coarse-grained molecular dynamics study

Carbon nanotube (CNT) buckypapers, having exceptional mechanical and electrical properties, have been reported to demonstrate frequency-invariant and temperature-invariant viscoelastic properties. In an attempt to provide an in-depth insight into the viscoelasticity of buckypapers with (5, 5) single-walled CNTs (SWCNTs), we perform coarse-grained non-equilibrium molecular dynamics simulations to investigate the effects of oscillatory shear strain amplitude, buckypaper's density, and length of individual SWCNTs on the viscoelastic properties. SWCNT buckypapers exhibit linear viscoelasticity over shear strain amplitude from 0.03 to 0.05. Higher density SWCNT buckypapers can result in larger dynamic stiffness and a higher loss factor of up to ∼0.29. In the frequency-independent regime (≤1 GHz), increasing the length of individual SWCNTs causes a very slight decrease of elastic properties and has minor influence on the viscous mode. Thus, this study provides deep insight into the viscoelasticity of (5, 5) SWCNT buckypapers and demonstrates controllability of the excellent energy dissipation potential of buckypapers, and can thus help us design new energy dissipation devices from carbon nanomaterials.