ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER DOVER NJ LARGE CALIBER WEAPON SYSTEMS LAB
A constant volume - constant pressure combustion calorimeter for measuring the heat generated by burning small samples of explosives at any fixed test pressure to 68,900 kPa 10,000 psi is described. The heat-of-reaction measurement is determined within 345 kPa 50 psi of the test pressure. The explosive beta-HMX is shown to undergo a reaction transition between 20,700 and 34,500 kPa 3000 and 5000 psi during which its heat-of-reaction Q increases 427000 Jkg 102 or - 6 calg. This transition occurs in the same pressure region as the discontinuity in burning rate previously observed for experimental gun propellants containing this explosive. The presence of this transition may lead to an explanation of this phenomenon.