Thermal decomposition mechanism and hazard assessment of di-tert-butyl azodicarboxylate (DBAD)

In this work, we used C80 Micro-calorimeter and STA-FTIR-MS instrument to analyze decomposition mechanism of DBAD and evaluated the thermal hazard by the key index on self-accelerating decomposition temperature (SADT). Based on C80 data, the heat release per unit mass of DBAD is 699.85 +/- 52.88 kJ kg(-1), and the activation energy calculated by Friedman method ranges from 28.58 to 52.03 kJ mol(-1). Besides, the thermal decomposition reaction of DBAD can be described by Zhuralev-Lesokin-Tempelman equation. In summary, the decomposition mechanism of DBAD is as follows: the C-O bond cracks firstly, separating center dot C(CH3)(3) out, then the C-C bond cracks, separating center dot CH3 out; the N=N double bond, C-N bond and C-O bond crack subsequently, separating: N-CO, center dot O-CO-N:, HO-CO-N: and center dot N=N-CO out, and these radical groups gradually decompose or oxidize into center dot CH=CHCH3, center dot O-CO/CO2, center dot COOH, etc.; finally, all these radical groups dissociate and oxidize into H2O, CO2 and N-2. The SADT calculated by Semenov model of DBAD under 25 kg standard package is 63.95 degrees C.