| Author | J. Suhr, N. Koratkar, P. Keblinski & P. Ajayan |
|---|---|
| Title | Viscoelasticity in carbon nanotube composites |
| Year | 2005 |
| Journal | Nature Materials |
| Volume | 4 |
| Pages | 134-137 |
| Editor | Nature Publishing Group |
| Abstract | Polymer composites reinforced by carbon nanotubes have been extensively researched1–4 for their strength and stiffness properties. Unless the interface is carefully engineered, poor load transfer between nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage1,2 and reduced performance. Interfacial shear, although detrimental to high stiff ness and strength, could result in very high mechanical damping, which is an important attribute in many commercial applications. We previously reported5 evidence of damping in nanocomposites by measuring the modal response (at resonance) of cantilevered beams with embedded nanocomposite fi lms. Here we carry out direct shear testing of epoxy thin fi lms containing dense packing of multiwalled carbon nanotube fi llers and report strong viscoelastic behaviour with up to 1,400% increase in loss factor (damping ratio) of the baseline epoxy. Th e great improvement in damping was achieved without sacrifi cing the mechanical strength and stiff ness of the polymer, and with minimal weight penalty. Based on the interfacial shear stress (~0.5 MPa) at which the loss modulus increases sharply for our system, we conclude that the damping is related to frictional energy dissipation during interfacial sliding at the large, spatially distributed, nanotube–nanotube interfaces |
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