Thermal hazard evolution on guanidine nitrate

Abstract

Due to thermally reactive hazards, guanidine nitrate (GN) has caused numerous serious accidents involving manufacturing, storing, and transporting processes. Differential scanning calorimetry and thermogravimetry (TG) were used to study the thermal reactive hazards of GN and the influence of adding water, nitric acid, ammonium nitrate (AN), and urea on GN thermal decomposition in air. The results indicated that the exothermal onset temperature and peak temperature rose with the heating rates. According to the Kissinger method, Ozawa method, as well as Friedman method, the apparent activation energy of GN in the peak temperature is 121.1, 123.0, and 126.0 kJ mol−1, respectively. The thermal decomposition of GN consisted of four stages. The mass loss rate of GN reached the maximum at 300 °C, and this temperature was in line with the exothermic peak temperature. The TG curve of GN in nitrogen atmosphere has a certain hysteresis compared to the air atmosphere. The thermal hazard of GN was inversely proportional to the size of the particles. Water had little effect on the decomposition of GN. Furthermore, nitric acid can promote the decomposition of GN more vigorously and increase the hazards of thermal runaway of GN. With the growth of the amount of AN and urea, the decomposition reaction of GN was more likely to initiate and more difficult to govern. These results could be used as a reference guide to the actual manufacturing, storing, and transporting processes for GN.