Advanced thermal decomposition kinetics, cook-off behavior, and shelf life assessment of modified low-sensitive explosive composition

A modified low-sensitivity explosive composition (LSX) based on DNAN/NTO/RDX had been previously synthesized and characterized, and its thermal decomposition kinetics were preliminarily investigated using Friedman and Ozawa–Flynn–Wall isoconversional methods. In the present work, the kinetic evaluation was extended using the Kissinger–Akahira–Sunose (KAS) and Vyazovkin isoconversional approaches. The slow cook-off response of LSX explosive was numerically simulated using COMSOL Multiphysics. Furthermore, the conversion-dependent kinetic parameters derived from the Vyazovkin model were further implemented in AKTS Thermokinetics software to assess the shelf life of the formulation. Differential scanning calorimetry and thermogravimetric analysis confirmed that the thermal decomposition of LSX proceeds through two distinct stages. The first decomposition stage exhibited mean apparent activation energies of 219 and 224 kJ mol −1 according to the Vyazovkin and KAS methods, respectively, whereas the second stage showed higher values of 257 and 272 kJ mol −1 . Kinetic compensation effect analysis showed superior linearity and reliability for the Vyazovkin model in determining the decomposition kinetic parameters. The COMSOL simulation predicted the onset of thermal runaway at approximately 183 °C at the center of the LSX charge after 6.89 h of slow heating. Isothermal simulations indicated negligible decomposition at 25–75 °C over 120 months, while approximately 50% conversion was predicted at 100 °C after 55 months. Under worldwide climatic conditions, the reaction progress remained on the order of 10 –2 in warm regions and of 10 –3 in cooler regions after 20 years. STANAG climatic simulations predicted conversion levels on the order of 10 –2 over the same period under all tested categories. These findings confirm that the LSX formulation possesses excellent thermal stability and strong long-term storage reliability under diverse thermal environments.