| Abstract: | While 4 distinct endothermal processes are known to accompany the thermal decomposition of Ammonium Perchlorate (AP), the DTA thermograms show one endotherm corresponding to the structure transition at 240°C, and two exotherms. The different characteristic points of the DTA thermograms change with the thermal history of the sample and even with aging at ambient temperature. Periods of preheating at 150° lower the initial temperature of self-heating at a later heating from about 300° for freshly recrystallised AP to about 210° after preheating for 4 days at 150°C. Heating-cooling cycles above 200° (lower limit) up to 320° (upper limit) show for the first 2-3 cycles the influence of the known “limited decomposition” of AP. On cooling there is a temperature delay in the structure transition cubic → orthorhombic, up to a constant limit of about 15°, and an apparent comminution of grains. |
