THERMAL-DECOMPOSITION OF HMX AND MIXTURES

Thermal decomposition of pure HMX shows DSC endothermic peaks at 210-degrees-C from beta to gamma phase transformation and at 285-degrees-C from the HMX melting followed by an instantaneous exothermic decomposition leading to a strong peak at 290-degrees-C and a very strong DTG peak at 325-degrees-C with a mass loss of 95%. However, the GS-2 mixture shows two DSC exothermic peaks at 225-degrees-C and 270-degrees-C assigned to nitroguanidine etc. and HMX decomposition. Addition of NH4ClO4 to HMX causes the decomposition to take place before melting and decomposition peak is lowered to 230-degrees-C. However in the case of GS-2, a strong effect was observed and the amount of the mixture was to be decreased to obtain a reasonable DSC curve. This shows that the addition of NH4ClO4 to HMX increases the decomposition of HMX, however this effect is more pronounced in GS-2 mixture. Even the minimum concentration of NH4ClO4 tested (10%) shows strong effect. The addition of NH4NO3 to HMX and GS-2 shows DSC exothermic decomposition peaks at 272-degrees-C and 245-degrees-C, showing a contribution from NH4NO3. This is supported by the fact that very strong DTG peaks at 310-degrees-C and 285-degrees-C from these mixtures respectively, are observed. Although NH4NO3 decomposes near to the decomposition of HMX, it does not show a strong effect on the decomposition of HMX/GS-2 as compared to NH4ClO4. Addition of KClO4, NaClO4 and KNO3 don't show any effect in these thermoanalytical studies.