Non-isothermal kinetic analysis of oxidative stabilization processes in PAN fibers

Non-isothermal kinetic analysis of oxidative stabilization processes in polyacrylonitrile (PAN) fibers was studied with the use of the differential scanning calorimetry (DSC) data. PAN terpolymer fibers consisting of acrylonitrile, methyl acrylate and itaconic acid were studied. Kinetic parameters and kinetic models of nitrile cyclization and oxidative destruction of chain fragments and functional groups were obtained. On the basis of these kinetic models constant heat flow temperature programs with maximum heat flow of 0.11 mW/mg for PAN fiber and 0.09 mW/mg for pre-oxidized PAN fiber were calculated. It was shown that simulated degree of conversion coincides within errors with cyclization index (CD) for stabilized fiber. CD can be used as an estimation of degree of conversion in research and practical applications. Technique of kinetic analysis, that was used, allows optimization of conditions for thermal stabilization for any required cyclization index and degree of conversion for the oxidative stabilization process in PAN fibers.