Fracture mechanisms of polyacrylonitrile-based high-strength type carbon fibers

The fracture morphologies of various high-strength type polyacryonitrile (PAN)-based carbon fibers were examined by emission scanning electronic microscopy (SEM) observation, and analyzed based on the Griffith-Irwin's criterion. The results showed the fracture morphologies of PAN-based high strength carbon fibers were largely controlled by the rate of crack propagation. The fracture mechanisms for the high-strength type carbon fibers were proposed. The role of magnitude of surface defects on determining the fractography was discussed according to the mechanism.