Effect of moisture on the stabilization of PAN fibers

The effect of moisture in the oxidative stabilization of polyacrylonitrile fibers was investigated. The results showed that moisture plays two different roles in the stabilization process of acrylic precursors. Moisture was found perfoming as plasticizer under low temperature heat treatment. In the case of the high temperature treatment process, however, it was concluded that it is hydrogen bonds between H2O and oxygencontaining groups formed in the oxidation reaction that prevent the occurrence of cyclization reactions. Both factors favored the diffusion of oxygen into the core of the PAN fibers and improved the properties of both oxidized fibers and final carbon fibers. However the moisture effect was retarded when temperature was high.