HYDROPEROXIDES IN POLYACRYLONITRILE AND THEIR ROLE IN CARBON-FIBER FORMATION

The oxidation of polyacrylonitrile (PAN) has been studied by a combination of chemiluminescence (CL) and infra-red methods. Various hydroperoxide structures have been created by preferential oxidation of PAN with specific agents, and the CL emission from their decomposition measured. The structure of the products from hydroperoxide decomposition has been studied by FTIR. An oxidation mechanism is proposed, whose main steps are cyclization of CN groups, initiated by OH radicals, and the oxidation of the resulting hydronaphthiridine ladder through a stepwise formation of hydroperoxides and acridones. The mechanism accounts for the high CL emission at 160 degrees C observed with both thermally 'stabilised' and reagent-oxidised PAN, as well as for the observed high concentration of acridone rings.