Carbon fibers have emerged as a material of both economic and strategic importance because of their properties which make them useful as a composite reinforcement material. Manufacture of carbon fibers from polyacrylonitrile (PAN) and pitch involves an oxidative stabilization process at low temperatures (approx 250 deg C) folowed by a high tempderature (>1200 deg C) carbonization step. Significant changes of both physical and chemical nature occur during carbonization, with very large increases in the modulus and strength (tensile and compressive) of the fiber. Several investigations have bene conducted in order to relate the mechanical properties of carbon fibers to the discrenible aspects of their structure. The fibers examined are usually from the terminus of the carbonizawtion process, with commerically available fibers constituting the materials studied in most cases. Few reports have been published regading the evolution of structure and properties during the carbonization process itself.
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