The Mode I interlaminar fracture toughness of chemically carbon nanotube grafted glass fabric/epoxy multi-scale composite structures

A novel and simple chemical route was successfully applied to graft carbon nanotubes (CNTs) onto silanized plain weave glass fabric (PWGF) mats, as confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The CNTs grafted PWGF mats were used to reinforce epoxy matrix for multi-scale composite production due to their potential for increasing interlaminar fracture toughness by bridging the ply interfaces. Grafting CNTs onto PWGFs improved both initial and steady-state toughness more than double as measured by Mode I interlaminar fracture testing. Failed specimens were visualized to determine the failure modes using fractography. The key findings indicated that the covalent interactions created between CNTs and fibers lead fibers bridging the interface region like “barbed wires”, which are mainly responsible for increased fracture toughness as a result of improved interfacial adhesion.