LLM-105 nanoparticles prepared via green ball milling and their thermodynamics and kinetics investigation

Abstract

2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) has drawn extensive attention because of its heat resistance and insensitivity properties. In this study, the LLM-105 nanoparticles were successfully prepared via ball milling method. The milled particles were characterized by scanning electron microscopy, X-ray diffraction, dynamic light scattering, differential scanning calorimetry and thermal sensitivity tests. Moreover, thermodynamics and kinetics parameters of LLM-105 samples were calculated by two kinetics equations. Results show that the milling process can significantly reduce the particle size of LLM-105 and the milling LLM-105 particles have the narrow particle size distribution ranging from 510 to 650 nm. The thermal decomposition peak temperatures of milling LLM-105 are decreased by over 14 °C than those of raw LLM-105 at the same heating rate. The apparent activation energy (E_a) of LLM-105 nanoparticles is calculated as 221.2 kJ mol⁻¹ and 221.4 kJ mol⁻¹ by Kissinger and Starink equation, respectively, which is lower a third than that of raw LLM-105 (339.9 kJ mol⁻¹, 339.7 kJ mol⁻¹). The thermodynamics parameters (ΔS^≠, ΔH^≠, ΔG^≠) of LLM-105 are also decreased in various degrees.