Safe Operating Temperatures for Pressurized Alkaline Hydrolysis of HMX-Based Explosives

Alkaline hydrolysis is used to convert high explosives to nonenergetic, aqueous compounds. Base hydrolysis of high explosives is exothermic (Delta H-RXN = 2.3 kJ/g), and thermal runaway of the reaction is a possibility at elevated temperatures (>120 degrees C) where the rate of reaction is large. Thermal runaway could result in an accidental detonation of the energetic material being treated, so safe operating parameters for base hydrolysis need to be determined. To measure the safe operating temperature, base hydrolysis was performed at temperatures ramped from 20 to 300 degrees C. The results show that PBX 9501 molding powder detonates at a 185 degrees C bulk temperature in 1.5 hi NaOH with a 4.5 degrees C/min linear temperature ramp and no agitation. The reaction of pressed PBX 9501 with 0.75, 1.5, and 3.0 M NaOH and water and both pressed and nonpressed PBX 9404 with 0.75, 1.5 M, and 3.0 M NaOH and water aid not produce a detonation with a 4.5 degrees C/min linear temperature ramp. A previously developed reaction rate model was used to show that thermal runaway should occur when the base hydrolysis reaction rate reached a maximum at a bulk temperature between 185 and 225 degrees C.