AbstractPolyacrylonitrile (PAN) fibers pretreated with potassium permanganate have reduced the activation energy of cyclization and the oxidation time, and also improved the properties of the resultant carbon fibers. The activation energy of cyclization is reduced to 24 ± 1 kcal/mol from 30 ± 3 kcal/mol and the tensile strength of the carbon fibers increases by about 20−40. The method of measuring the “aromatization index” (AI) value is modified and is recommended in checking the oxidation process. All fully stabilized PAN fibers have almost the same AI value. However, the oxidation time is decreases by 30 min when oxidation temperature is raised
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