Carbon Fiber Morphology: Wide-Angle X-Ray Studies of Pitch- and Pan-Based Carbon Fibers.

摘要

Carbon fibers are extremely important components in high performance composites as they are the preliminary reinforcing material. Because the mechanical properties of fibers are dependent on their structures, the structure of carbon fibers has been examined by many researchers. A continued interest in this area results from the emergence of new carbon fibers with improved properties. Pitch-based fibers traditionally had high stiffnesses but had weak tensile strengths. Pan-based fibers were strong but lacked high moduli. Recent developments have improved these fibers' properties, and more work is focusing on the comprehensive properties as well. These property changes result from structural differences created during the fiber manufacture. This report describes the wide-angle x-ray diffraction techniques used to examine carbon and graphite fibers and the results of several fibers. A series of commercial PAN- and pitch-based carbon fibers whose tensile moduli spanned the generally available range were examined. Crystal perfection, size, orientation, and degree of graphitization correlated well with tensile moduli but less well with tensile and compressive strength. Keywords: Carbon fibers; Crystals; Crystallite size; Graphite fibers; Graphitization; Orientation; X-ray diffraction. (KT)