Thermal safety assessment and thermo-kinetic parameters of 5,5′-dinitramino-3,3′-bi[1,2,4-triazolate] carbohydrazide salt (CBNT)

Abstract

The differential scanning calorimetry (DSC) was used to investigate the specific heat capacity of 5,5′-dinitramino-3,3′-bi[1,2,4-triazolate] carbohydrazide salt (CBNT) from 25 to 55 °C. The relationship can be described as Cp = 1.26324 + 0.0014 × T, 25 °C ≤ T ≤ 55 °C. Moreover, the thermal characteristics and kinetics of CBNT were studied using DSC and accelerating rate calorimetry (ARC). DSC results showed that the thermal decomposition occurred at 200.03, 203.75, 206.25 and 208.54 °C at different heating rates (0.5, 1.0, 1.5 and 2.0 °C min−1), respectively. The apparent activation energy (Ea) and pre-exponential factor (A), calculated using the Kissinger method, were 303.01 kJ mol−1 and 2.37 × 1032 s−1, respectively. The apparent activation energy, calculated using the Ozawa equation, was 295.64 kJ mol−1. ARC test indicated that the self-decomposition reaction of CBNT started at 180.8 °C and lasted for 497 min, during which the maximum temperature rise rate was 0.08 °C min−1 and the pressure rise rate was 2.04 kPa min−1. Moreover, rate constant method and mechanism functions method were applied to calculate kinetic parameters, among which the most possible mechanism functions were (1 − α)2. The values of Ea for the decomposition of CBNT calculated by these two methods were 420.78 and 420.73 kJ mol−1. The values of A were 5.13 × 1043 and 3.04 × 1045 s−1, respectively. In addition, the self-accelerating decomposition temperature of CBNT based on ARC data in the packages of 25, 50 and 75 kg was 195.23, 194.10 and 193.10 °C, respectively.