The influence of pre‐carbonization on the properties of PAN‐based carbon fibers developed by two‐stage continuous carbonization and air oxidation

Abstract The Properties of three kinds of carbon fibers, which were pre‐carbonized at 500, 550, and 600°C during two‐stage continuous carbonization, were measured after being air oxidized for periods of 1 to 6 min at 550°C. The effects of precarbonization temperatures on mechanical properties, density, morphology, elemental compositions, and microstructure of the carbon fibers are discussed. The pre‐carbonization process affected strongly the surface properties and mechanical properties of the final carbon fibers, as measured after air oxidation. Carbon fibers measured one to six min after air oxidation showed a different oxidation behavior in the surface morphology for each pre‐carbonization temperature. Optimum conditions not only improved the tensile strength and modulus by over 50%, but also increased the density and oxygen content.