A Study on the Toughening Effects of Two Types of Nano Carbon Fillers on Carbon/Epoxy Composites

The effect of two types of carbon nano fillers with different topology characteristics were studied on the toughness of imidazole/epoxy (IMI/EP) resin system. The influence of nano particles on fracture toughness (KIC), energy (GIIC), thermal mechanical properties (DMA), and curing behaviors were investigated. Both KIC and GIIC were increased after the addition of nano fillers. The improvement of GIIC was different by the nano carbon fillers Topology. The dispersion and enhancement effect improved as nano particle dimensions decreased. The mechanisms of these improvements in toughness were explored using optical microscopy (OM) and scanning electron microscopy (SEM). It was revealed that the improvement of fracture toughness with addition of nano particles was due to debonding and deformation of the nano particles. Subsequently, the crack growth was hindered by the nano particles, and the stress energy at crack tip was released by crack deflections, particles deformation and particles rupture. Finally, the curing behavior of the epoxy resin with different types of nano particles were studied using DSC. The crosslinking reaction rate slowed down with the addition of Carbon nano fibers (CNF), but increased with graphene oxide (GO).