The influence of oxygen on the chemical reactions during stabilization of pan as carbon fiber precursor

DTA measurements were used for studies of the kinetics of the cyclization and oxidation of PAN during the thermal treatment in air and nitrogen. The cyclization is a first order reaction with an activation energy of about 30 kcal/mole in nitrogen and about 34 kcal/mole in air. For copolymer PAN (5% methylacrylate) lower activation energies were found. Oxygen promotes the initiation of the cyclization but does not catalyze the cyclization reaction itself. The sequence of cyclization and oxidation reactions is discussed in detail.