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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

(a) Pristine surface of a VACNT array. Exemplary, some bunches of CNTs are surrounded by circles. (b) Clustered surface of the same sample after the friction experiment (same magnification as in (a)). Note that all bunches are condensed to one large single cluster.
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RSFS20150026F2: (a) Pristine surface of a VACNT array. Exemplary, some bunches of CNTs are surrounded by circles. (b) Clustered surface of the same sample after the friction experiment (same magnification as in (a)). Note that all bunches are condensed to one large single cluster.

Mentions: In the pristine condition, the single nanotubes are supposed to be bundled together more or less uniformly to parallel bunches, each of which contains quite a large number of tubes fixed together (figure 2a). The base end of every tube, and of a bunch, is stationary and fixed to the substrate. The only degree of freedom remaining for a bunch is to rotate with respect to the fixation point. When an external force deflects the bunch, it tends to return to its original vertical orientation.Figure 2.


Modelling clustering of vertically aligned carbon nanotube arrays.

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

(a) Pristine surface of a VACNT array. Exemplary, some bunches of CNTs are surrounded by circles. (b) Clustered surface of the same sample after the friction experiment (same magnification as in (a)). Note that all bunches are condensed to one large single cluster.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

RSFS20150026F2: (a) Pristine surface of a VACNT array. Exemplary, some bunches of CNTs are surrounded by circles. (b) Clustered surface of the same sample after the friction experiment (same magnification as in (a)). Note that all bunches are condensed to one large single cluster.
Mentions: In the pristine condition, the single nanotubes are supposed to be bundled together more or less uniformly to parallel bunches, each of which contains quite a large number of tubes fixed together (figure 2a). The base end of every tube, and of a bunch, is stationary and fixed to the substrate. The only degree of freedom remaining for a bunch is to rotate with respect to the fixation point. When an external force deflects the bunch, it tends to return to its original vertical orientation.Figure 2.

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