Delamination toughening of carbon fiber/epoxy laminates by hierarchical carbon nanotube-short carbon fiber interleaves

In this study, hierarchical short carbon fibers (SCFs) synthesized with carbon nanotubes (CNTs) were used as CNT-SCF interleaves to increase the mode I delamination fracture energy GIC of carbon fiber/epoxy (CF/EP) composite laminates. Even at a relatively low CNT-SCF areal density, 1.0 mg/cm2, GIC (1.17 kJ/m2) was increased by 125% compared to the control laminates (0.52 kJ/m2), which is a very high value compared to those results obtained by other interleaving methods in CF/EP laminates. The toughening effects of SCFs in bulk epoxy and interleaved CF/EP laminates were also studied to better understand the failure mechanisms of the hierarchical CNT-SCF structure. SEM observations revealed synergistic toughening mechanisms in these CNT-SCF interleaved CF/EP laminates.