Mechanism and Kinetics of Stabilization Reaction of Polyacrylonitrile and Related Copolymers II. Relationships between Isothermal DSC Thermograms and FT-IR Spectral Changes of Polyacrylonitrile in Comparison with the Case of Acrylonitrile/Methacrylic Acid Copolymer

Abstract

The relationship between thermal behavior and structural change has been studied by an organized combination of isothermal DSC thermograms and FT-IR spectra measured for the stabilization reaction of polyacrylonitrile (PAN) in comparison with the case of acrylonitrile/methacrylic acid (AN/MAA) copolymer. The isothermal DSC exothermic thermogram of PAN is much broader and the structural changes proceed much more slowly than the case of AN/MAA copolymer. On the stabilization of PAN, at first, some nitrile groups change into amide groups, which initiate the dehydrogenation and cyclization reactions. This dehydrogenation reaction proceeds rather faster than the cyclization. The comonomer MAA was considered to accelerate the dehydrogenation reaction more effectively than the cyclization reaction.