Cyclization reaction in poly(acrylonitrile/itaconic acid) copolymer: An isothermal differential scanning calorimetry kinetic study

The kinetics of the cyclization reaction in the poly(acrylonitrile/itaconic acid) (PAN) copolymer in the temperature range 175-200degreesC was studied by isothermal differential scanning calorimetry (DSC). The reaction conforms to an eta(th)-order autocatalytic model, with an overall order of 2. The kinetic parameters were derived by multiple regression analysis. The activation energy is 110.3 kJ/mol for the acid-catalyzed reaction and 153.2 kJ/mol for the autocatalytic part. The autocatalysis indicates the catalysis of the nitrile group cyclization by the initially formed pyrimidine groups. The kinetic parameters were used to predict the reaction profile at a given temperature. (C) 2003 Wiley Periodicals, Inc.