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Modelling clustering of vertically aligned carbon nanotube arrays.

Schaber CF, Filippov AE, Heinlein T, Schneider JJ, Gorb SN - Interface Focus (2015)

Bottom Line: Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties.To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters.The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

View Article: PubMed Central - PubMed

Affiliation: Functional Morphology and Biomechanics, Zoological Institute , Kiel University , Am Botanischen Garten 1-9, 24118 Kiel , Germany.

ABSTRACT
Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

No MeSH data available.


Related in: MedlinePlus

Typical evolution of the time-depending values in presence of clustering during five friction cycles. (a) Transformation of the array xj = xj(t). (b) Friction force (the force value averaged over each current scan is shown by the bold line). (c) Mean size (bold line) and length of the cluster. (d) Number of clusters.
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RSFS20150026F4: Typical evolution of the time-depending values in presence of clustering during five friction cycles. (a) Transformation of the array xj = xj(t). (b) Friction force (the force value averaged over each current scan is shown by the bold line). (c) Mean size (bold line) and length of the cluster. (d) Number of clusters.

Mentions: The time-dependent scenario of the clustering can be recorded and quantitatively described by accumulation and plotting the complete set of time-depending arrays xj = xj(t). Figure 4a shows a typical result of this procedure. One can see directly how the initially equidistant trajectories xj(t) evolve to the dense bundles corresponding to the clusters. Figure 4b shows the time-dependent friction force.Figure 4.


Modelling clustering of vertically aligned carbon nanotube arrays.

Schaber CF, Filippov AE, Heinlein T, Schneider JJ, Gorb SN - Interface Focus (2015)

Typical evolution of the time-depending values in presence of clustering during five friction cycles. (a) Transformation of the array xj = xj(t). (b) Friction force (the force value averaged over each current scan is shown by the bold line). (c) Mean size (bold line) and length of the cluster. (d) Number of clusters.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590422&req=5

RSFS20150026F4: Typical evolution of the time-depending values in presence of clustering during five friction cycles. (a) Transformation of the array xj = xj(t). (b) Friction force (the force value averaged over each current scan is shown by the bold line). (c) Mean size (bold line) and length of the cluster. (d) Number of clusters.
Mentions: The time-dependent scenario of the clustering can be recorded and quantitatively described by accumulation and plotting the complete set of time-depending arrays xj = xj(t). Figure 4a shows a typical result of this procedure. One can see directly how the initially equidistant trajectories xj(t) evolve to the dense bundles corresponding to the clusters. Figure 4b shows the time-dependent friction force.Figure 4.

Bottom Line: Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties.To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters.The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

View Article: PubMed Central - PubMed

Affiliation: Functional Morphology and Biomechanics, Zoological Institute , Kiel University , Am Botanischen Garten 1-9, 24118 Kiel , Germany.

ABSTRACT
Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

No MeSH data available.


Related in: MedlinePlus