The crystal characteristics of octahydrol, 3,5,7-tetranitro-l,3,5,7-tetrazocine (HMX), i.e. density, porosity of internal crystal, morphology, size and size distribution, have vital important influence on the sensitivity of HMX-based pressed PBXs. To improve the safety properties of HMX-based polymer bonded explosives (PBXs), the ordinary quality HMX was replaced by the high-quality HMX in pressed HMX-based compositions. The reaction characteristics of HMX-based PBXs were tested by using Susan Test. The influences of the particle characteristic parameters (e.g. crystal quality, size and shape) of HMX on the Susan sensitivity of the PBX were investigated thoroughly. Results show that the threshold velocity for initiation of the PBX was increased while the quality of HMX crystal was improved. The threshold velocity of the PBX in Susan test increased from 37 m·s-1 to 45 m·s-1 while the internal porosity of HMX crystal (δ value) decreased from 0.30 % to 0.16 %. The threshold velocity of PBX in Susan test increased from 45m·s-1 to 53 m·s-1 when the particle size of high-quality HMX increased from 20 μm to 105 μm, and the brisance of the latter was less than that of the former.
HMX, Pressed PBX, reaction, Susan impact test, crystal quality