Thermal decomposition behavior and kinetics for nitrolysis solution from the nitration of hexamethylenetetramine

Abstract

In order to understand better thermal safety of the nitrolysis solution from the nitration of hexamethylenetetramine, its decomposition behavior was studied. The nitrolysis solution prepared was analyzed using isoperibolic experiments, differential scanning calorimetry (DSC), differential thermal analysis-thermogravimetry, and fourier transform infrared spectroscopy. An accurate kinetic model was proposed to describe the decomposition in the nitrolysis solution by applying an ordinary differential equation fitting method to isothermal DSC data and non-isothermal DTA data. We found that the thermal decomposition in the mixed solution is attributed to pyrolysis of organic nitrates in acid solution. The process is coupled with rapid reaction rate, great heat release, and huge amounts of reddish-brown gas produced. The decomposition in the nitrolysis solution follows a 1.162th Prout-Tompkins equation with autocatalysis, with a differential kinetic mechanism function of f(α) = (1 − α)1.162·α0.4189. The thermal safety evaluation and safety parameters were finally studied based on four criteria and isoperibolic experiment data. The thermal safety margin is less than 164.57 K and the bursting point of pyrolysis is 338.43 K at 5 min of delay time. These results show that the nitrolysis solution is hazardous and the thermal sensitivity is higher than that of 2-ethylhexyl nitrate and hexogen.