A kinetic investigation of thermal decomposition of 1,1′-dihydroxy-5,5′-bitetrazole-based metal salts

Abstract

Three novel Co/Cu/Pb salts of 1,1′-dihydroxy-5,5′-bitetrazole (BTO) were prepared, and their thermal behaviors, decomposition reaction kinetics, thermal safety and thermodynamic parameters were investigated as potential energetic combustion catalysts for propellant. Thermogravimetric analysis and differential scanning calorimetry had been used to identify the changes in thermal and kinetic behavior of samples. The results outlined three mass loss stages in TG curves, and the major effect of the metal was observed at second stage for decomposition of organic groups. Thermal-kinetic evaluations were carried out by a model-free and a model fitting method. The model-free method indicated that the activation energy follows the order of BTO-Pb > BTO-Cu > BTO-Co. The model fitting analysis of this stage suggested: (1) the thermal decomposition of BTO-Co was an one-dimensional bounding process, and R1, n = 1. The integral form of the reaction mechanism was F(α) = α. (2) The thermal decomposition of BTO-Cu kept to the mechanism of nucleation and growth, respectively, in which n = 4/3. The integral form of the reaction mechanism was F(α) = [−ln(1 − α)]3/4. (3) The thermal decomposition of BTO-Pb was one-dimensional diffusion referring to the 1D, D 1 decelerating reaction mechanism. The integral form of the reaction mechanism was F(α) = α 2. The thermal safety evaluation and thermodynamic parameters were finally studied. The high value of both self-accelerating decomposition temperature (T SADT) (520–550 K) and enthalpy of activation (ΔH ≠) (200 kJ mol−1) for the three indicated that they were all of good thermal stability.