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Diameter-dependent bending modulus of individual multiwall boron nitride nanotubes
Adrienne E Tanur1, Jiesheng Wang, Arava L M Reddy
1Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
The Journal of Physical Chemistry. B
|January 29, 2013
Summary
This study reveals multiwall boron nitride nanotubes (MWBNNTs) possess exceptional mechanical strength, with bending moduli increasing as nanotube diameter decreases. This finding is attributed to a low shear modulus, offering insights into MWBNNTs
Area of Science:
- Materials Science
- Nanotechnology
- Mechanical Engineering
Background:
- Multiwall boron nitride nanotubes (MWBNNTs) are advanced nanomaterials with potential applications.
- Understanding their mechanical properties is crucial for material design and utilization.
Purpose of the Study:
- To investigate the mechanical properties of individual MWBNNTs.
- To determine the bending modulus and its dependence on nanotube diameter.
- To elucidate the underlying reasons for observed mechanical behaviors.
Main Methods:
- Synthesis of MWBNNTs using a growth-vapor-trapping chemical vapor deposition method.
- Mechanical testing via a three-point bending technique using atomic force microscopy.
- Analysis of boundary conditions and application of Timoshenko beam theory.
Main Results:
- Exceptional mechanical properties confirmed with an average bending modulus (EB) of 760 ± 30 GPa for 20 MWBNNTs.
- First-time observation of increasing bending moduli with decreasing diameter (100 ± 20 GPa to 1800 ± 300 GPa).
- Determined Young's modulus of 1800 ± 300 GPa and a low shear modulus of 7 ± 1 GPa.
Conclusions:
- The bending modulus of MWBNNTs is diameter-dependent, primarily due to their low shear modulus.
- Interwall shearing between nanotube structures likely causes the observed diameter dependence.
- These findings highlight the unique mechanical characteristics of MWBNNTs for advanced applications.
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