Characterization of carbon nanotube enhanced interlaminar fracture toughness of woven carbon fiber reinforced polymer composites

In this study, the effect of multi-walled carbon nanotubes (CNTs) on the Mode I Interlaminar fracture toughness or the strain energy release rate of woven carbon fiber reinforced composites has been investigated and characterized by double cantilever beam tests. The CNTs were uniformly dispatched on the surface of woven carbon fiber prepregs with the CNT loading ranging from 0-4.0 g/m2 by an increment of 0.5 g/m2. The prepregs were then layered and cured with an out-of-autoclave processing. SEM examination of the fractured surfaces revealed that the CNTs were uniformly distributed in the interlaminar surface. The experimental results demonstrate that a small CNT loading can increase the interlaminar fracture toughness because extra energy is required to break CNTs for crack propagating through. At the CNT loading of 1.0 g/m2, the fracture toughness of sample increases up to 32%. As the CNT loading is increased beyond 1.0 g/m2, a consistent decrease in the fracture toughness is observed, which can be attributed to the slippage among CNTs leading to initiation of micro-fracture in the matrix.