 It has been reported that carbon nanotube (CNT) buckypaper demonstrates frequency- and temperature-invariant viscoelastic properties [Xu et al., Science, 2010, 330, 1364]. In an attempt to provide microscopic insight, we performed coarse-grained molecular dynamics simulations on the viscoelastic properties of model CNT buckypaper. First of all, the model is shown to exhibit the observed frequency- and temperature-invariant viscoelastic features. Analyzing snapshots of the buckypaper under cyclic shear deformation, we furthermore confirm that a zipping.unzipping mechanism plays an important role in the molecular origin of the particular viscoelastic properties of buckypaper. Quantitative inspection of the amount of inter-tube entanglements per CNT, < Z >, reveals that CNT buckypaper is faced with reversible entanglement loss during the shear loading process; the equilibrium < Z > is fully recovered if shear loading is removed. The variation of < Z > during a loading. unloading.reloading cycle is found to be insensitive to both frequency and temperature. Our study highlights an energy dissipation mechanism for carbon nanomaterials, which can help us design new energy-adsorption coatings/damping devices under extreme conditions, and seems to rule out a recently proposed scenario of unstable detachments.attachments.
for LaTeX users @article{YLi2012-8,
author = {Y. Li and M. Kr\"oger},
title = {Viscoelasticity of carbon nanotube buckypaper: Zipping-unzipping mechanism and entanglement effects},
journal = {Soft Matter},
volume = {8},
pages = {7822-7830},
year = {2012}
}
\bibitem{YLi2012-8} Y. Li, M. Kr\"oger,
Viscoelasticity of carbon nanotube buckypaper: Zipping-unzipping mechanism and entanglement effects,
Soft Matter {\bf 8} (2012) 7822-7830.YLi2012-8
Y. Li, M. Kr\"oger
Viscoelasticity of carbon nanotube buckypaper: Zipping-unzipping mechanism and entanglement effects
Soft Matter,8,2012,7822-7830 |
mk@mat.ethz.ch
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