The Thermal Decomposition of Azodicarbonamide

Abstract

The thermal decomposition of azodicarbonamide has been studied in solid state. Themal characteristics were examined by using differential thermal analysis and thermal gravimetric analysis. The kinds of decomposition products were identified by using the pyrolysis gas chromatography, infrared and mass spectrometries. Main gaseous products were N2 and CO, the amounts of CO, and NH3 were negligible, while cyanic acid and isocyanic acid were produced in various proportions. The residues were isocyanuric acid and biurea mixture. Cyamelide and ammonium cyanate were obtained as sublimation products.The rate of decomposition was measured by the gas evolution method over the range 181197°C, invacuum. The course of decomposition could be followed by the expression of the formwhere P., isthepressure, fgasev, lvedatc, mpletedec, mp, siti, n, Pthepressureatthetime theratecnstantandCtheconstant. Theactivationenergyandthepre-exponential factorwas, 31.6kca1/moland1.0×1013, respectively.On the base softheseresults, the decomposition mechanismhas been proposed which involved the elim natinofazo-radical and the subequentreaction soft herad icalsformed. The main reactionswerethetrimerization of isocyanic acid and the addition of the resulting radicals to theamide.