Mechanism and kinetics of the stabilization reactions of itaconic acid-modified polyacrylonitrile

The structural evolution and thermal behavior of polyacrylonitrile (PAN) homopolymer and copolymer [P(AN-IA)] containing about 1.5 mol% itaconic acid (IA) during stabilization in air were studied by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TG). A new parameter Es=A1595cm−1/A2243cm−1 was defined to evaluate the extent of stabilization. The kinetic parameters, viz. activation energy (Ea) and pre-exponential factor (A) of the stabilization reactions were calculated by Kissinger method and Ozawa method. FTIR analysis indicated that the cyclization of nitrile groups was initiated at a lower temperature by the IA comonomer and the stabilization proceeded at a more moderate pace in P(AN-IA) than in PAN, while an IA additive was found to be decomposed and failed to initiate the cyclization at a lower temperature. The improvement effect of IA comonomer on the stabilization reactions was further confirmed by the dynamic thermal analysis and kinetic study.