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Carbon Nanotubes with Temperature-Invariant Viscoelasticity from –196° to 1000°C

Science  03 Dec 2010:
Vol. 330, Issue 6009, pp. 1364-1368
DOI: 10.1126/science.1194865

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Shake It to Wake It

Viscoelastic materials combine the recoverable stretchiness found in elastic materials with the slow-flowing behavior of a thick fluid, like honey. When subjected to an oscillatory motion, the response will depend on the frequency. At low frequencies, the viscous behavior will dominate and lead to a dissipation of the applied energy as heat, while at fast frequencies the elastic behavior dominates. Xu et al. (p. 1364; see the Perspective by Gogotsi) developed a viscoelastic material with an exceptionally broad operating temperature range, based on a network of carbon nanotubes. The responsiveness of the material was probably caused by the “zipping” and “unzipping” of the nanotubes at points of contact.

Abstract

Viscoelasticity describes the ability of a material to possess both elasticity and viscosity. Viscoelastic materials, such as rubbers, possess a limited operational temperature range (for example, for silicone rubber it is –55° to 300°C), above which the material breaks down and below which the material undergoes a glass transition and hardens. We created a viscoelastic material composed from a random network of long interconnected carbon nanotubes that exhibited an operational temperature range from –196° to 1000°C. The storage and loss moduli, frequency stability, reversible deformation level, and fatigue resistance were invariant from –140° to 600°C. We interpret that the thermal stability stems from energy dissipation through the zipping and unzipping of carbon nanotubes at contacts.

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