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Anisotropic nanomechanical properties of Nephila clavipes dragline silk

Published online by Cambridge University Press:  01 August 2006

Donna M. Ebenstein
Affiliation:
Code 6176, United States Naval Research Laboratory, Washington, DC 20375
Kathryn J. Wahl*
Affiliation:
Code 6176, United States Naval Research Laboratory, Washington, DC 20375
*
a) Address all correspondence to this author. e-mail: kathryn.wahl@nrl.navy.mil
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Abstract

Spider silk is a material with unique mechanical properties under tension. In this study, we explore the anisotropic mechanical properties of spider silk using instrumented indentation. Both quasistatic indentation and dynamic stiffness imaging techniques were used to measure the mechanical properties in transverse and longitudinal sections of silk fibers. Quasistatic indentation yielded moduli of 10 ± 2 GPa in transverse sections and moduli of 6.4 ± 0.5 GPa in longitudinal sections, demonstrating mechanical anisotropy in the fiber. This result was supported by dynamic stiffness imaging, which also showed the average reduced modulus measured in the transverse section to be slightly higher than that of the longitudinal section. Stiffness imaging further revealed an oriented microstructure in the fiber, showing microfibrils aligned with the drawing axis of the fiber. No spatial distribution of modulus across the silk sections was observed by either quasistatic or stiffness imaging mechanics.

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Articles
Copyright
Copyright © Materials Research Society 2006

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