Study on oxidative stabilization of polyacrylonitrile fibers

The changes of volume density, linear density, mechanical properties, surface composition, the amount of cyclization and crosslinking in fibers during oxidative stabilization in air were investigated. Results show that the amount of crosslinkiing, cyclization and volume density of oxidized PAN fibers increase, while linear density, elastic modulus, tensile strength and elongation to failure decrease with increasing oxidation temperature. The fibers were densified during stabilization. The content of carbon, hydrogen and nitrogen and the ratios of hydrogen and nitrogen to carbon decrease while the total oxygen and the ratio of oxygen to carbon increase from the outside to inside of the oxidized PAN fiber. The amount of silicon decreases sharply at first, then levels off during stabilization. The oxygen content in the surface of the fiber remains unchanged during stabilization, and is always greater than that in the core.