The Toughness of Composites: Nano vs Micro Reinforcement

H. Daniel Wagner Xiaomeng Sui
Department of Materials & Interfaces, Weizmann Institute of Science

The structural toughness arising from conventional energy dissipation mechanisms has the potential to be significantly higher in nanocomposites than in composites made of conventional micron-size fibers1-4. Of particular interest is the relationship between tube-matrix interfacial adhesion and nanocomposite toughness. Indeed, it was shown that it is possible to detach a nanotube from a polymer matrix and thereby measure their interfacial adhesion either using a drag-out configuration5, nano-pullout tests6-8, Raman tests9, and indirect tests on composites10. Numerical simulations are also available11. Here we consider how to quantify nano-toughness through a reanalysis of old concepts such as the Kelly-Tyson equation, the critical length and pullout energy dissipation of a nanotube, and discuss appropriate ways to compare energy dissipation at the nano and micro levels12.  

 References:

  1. H.D. Wagner, “Nanocomposites – Paving the way to stronger materials”, Nature Nanotechnology (News & Views) 2 (Dec 2007), 742-744.
  2. M. Wichmann, K. Schulte, H.D. Wagner, “On Nanocomposite Toughness”, Composites Science & Technology 68 (2008), 329-331.
  3. X.-M. Sui, H.D. Wagner, “Tough nanocomposites: The role of carbon nanotube type”, Nano Letters 9 (4), (2009), 1423-1426.
  4. N. Lachman, H.D. Wagner, “Correlation between interfacial molecular structure and mechanics in CNT/epoxy nano-composites”, Composites A 41 (2010) 1093–1098.
  5. C.A. Cooper, S.R. Cohen, A.H. Barber, H.D. Wagner, "Detachment of nanotubes from a polymer matrix", Applied Physics Letters, 80 (20)(2002), 3873-3875.
  6. A.H. Barber, S. Cohen, H.D. Wagner, "Measurement of carbon nanotube-polymer interfacial strength", Applied Physics Letters, 82 (23) (2003), 4140-4142.
  7. A.H. Barber, S.R. Cohen, A. Eitan, L.S. Schadler, H. D. Wagner, “Fracture transitions at carbon nanotube-polymer interfaces” Advanced Materials 18 (2006), 83-87.
  8. A.H. Barber, S. Cohen, S. Kenig, H.D. Wagner, “Interfacial fracture energy measurements for multi-walled carbon nanotubes pulled from a polymer matrix”, Composites Science and Technology, 64 (2004), 2283-2289.
  9. XD He, F Zhang, RG Wang, W Liu, “Preparation of a carbon nanotube/carbon fiber multi-scale reinforcement by grafting multi-walled carbon nanotubes onto the fibers”, Carbon 45 (2007) 2559–2563.
  10. F-H Zhang, RG Wang, XD He, C Wang, LN Ren, “Interfacial shearing strength and reinforcing mechanisms of an epoxy composite reinforced using a carbon nanotube/carbon fiber hybrid”, J Mater Sci (2009) 44:3574–3577.
  11. N. Lachman, B.J. Carey, D.P. Hashim, P.M. Ajayan, H.D Wagner, “Interfacial load transfer in carbon nanotube/carbon microfiber hybrid composites”, Composites Science & Technology, 72, (14) (2012), 1711-1717.
  12. H.D. Wagner, P. Ajayan, K. Schulte, “Nanocomposite toughness from a pull-out mechanism”, Composites Science & Technology, 83 (2013), 27-31.




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