Effect of Nitrogen Atmosphere on the Structure and Properties of a PAN-Based Carbon Fiber

In general, carbon fibers are produced at high temperatures in nitrogen atmosphere. In this study, PAN fibers were carbonized at different temperatures in two carbonization furnaces. The results show that the two furnaces require different amounts of nitrogen during carbonization. The first stage of carbonization does not require a high purity nitrogen atmosphere, because the uncyclized chains in oxidized PAN fibers, which have only about 60% cyclized chains, continue to cyclize during the first stage of carbonization. When the first-stage furnace (a volume of 75 1) contains a nitrogen flow rate of 210 l/h, carbon fibers with excellent mechanical properties can be obtained.