Session A28: Focus Session: Carbon Nanotubes and Related Materials: Fundamentals and Applications

8:00 AM–11:00 AM, Monday, March 21, 2011
Room: C156

Sponsoring Unit: DMP
Chair: Mark Hersam, Northwestern University

Abstract ID: BAPS.2011.MAR.A28.5

Abstract: A28.00005 : Load transfer mechanisms in cross-linked DWNT fibers

9:12 AM–9:24 AM

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  T. Filleter
  M. Naraghi
  A. Moravsky
  R. Bernal
  R.O. Loutfy
  H.D. Espinosa

The application of carbon nanotubes (CNT) to macroscopic composite fibers has been limited by weak shear interfaces between adjacent CNT shells and composite matrix elements. A fundamental understanding of load transfer at multiple length-scales is needed to identify how the exceptional mechanical properties of CNTs can be scaled to produce high-performance fibers. Through in-situ electron microscopy tensile testing we have elucidated load transfer mechanisms across multiple scales of cross-linked double-walled nanotube (DWNT) fibers. A low density of polymer cross-links is found to increase the total energy dissipated at failure and ductility of fibers by 5 and 10X, respectively, without reducing strength. This mutiscale approach has identified a need to enhance shear interactions between individual DWNTs within the hierarchical DWNT fiber structures. Through in-situ TEM electron irradiation studies we have shown that load can be effectively transferred to inner DWNTs within bundles by covalently cross-linking the interfaces of adjacent DWNTs and shells. We have observed order of magnitude increases in strength and modulus and identified their dependence on irradiation dose. In future a combined approach of irradiation induced covalent and polymer cross-linking may lead to high-performance DWNT-based fibers and composites with tunable mechanical properties.

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