Hierarchical carbon fibre composites incorporating high loadings of carbon nanotubes

Neptun Yousefi, Sandra J. Fisher, Christoph Burgstaller, Milo S.P. Shaffer, Alexander Bismarck

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Uncured solid bisphenol-A epoxy resins containing up to 20 wt% carbon nanotubes (CNTs) were prepared using melt blending in a high shear mixer. The extrudate was ground to produce fine nanocomposite (NC) powders. This simple method produced well-dispersed NC, with CNT agglomerate sizes below 1 μm. Consolidated NCs displayed improved tensile moduli and strengths up to 3.3 GPa (+32%) and 78 MPa (+19%), respectively at 15 wt% CNT, compared to the pure cured epoxy matrix. The relatively high Tg of 39 °C for the uncured NC powders simplified the manufacture of composite prepregs using wet powder impregnation. The prepregs were laminated into hierarchical carbon fibre reinforced composites with improved through-thickness properties. Interlaminar shear strength improved for intermediate CNT loadings in the matrix up to 65 MPa (10 wt% CNT, +19%) but decreased at higher concentrations. Compression moduli remained constant irrespectively of CNT loading but compression strength increased with a CNT loading of 2.5 wt% to 772 MPa (+31%). The mechanical properties of the hierarchical composites reflect good consolidation (void content <3%) and excellent fibre alignment (<±0.8°). In addition to the improved mechanical properties, incorporation of CNTs improved the through-thickness electrical conductivity up to 115 S/m.

Original languageEnglish
Article number109369
JournalComposites Science and Technology
Publication statusPublished - 3 May 2022
Externally publishedYes


  • A. Carbon fibres
  • A. Carbon nanotubes
  • B. Mechanical properties
  • E. Powder processing


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