Characterization and Properties of Desensitized Octogen

A kind of desensitized octogen(D-HMX) was characterized with various analysis methods,including Optical Microscopy with Matching Refractive Index(OPM),Scanning Electron Microscopy(SEM),Laser Particle Sizer,High Performance Liquid Chromatography(HPLC),density gradient technique and X-ray Diffraction(XRD).The thermal properties of D-HMX were investigated by Differential Scanning Calorimetry(DSC) and Vacuum Thermal Stability test(VST).The sensitivities of D-HMX against friction,impact and shock were studied.Compared with conventional octogen(C-HMX),D-HMX has better morphology,lesser crystal defects,better thermal properties and takes great effect on reducing shock sensitivity in both cast and pressed PBX formulations.Which are incarnated from the following aspects.First,the D-HMX has no twinned crystals or congeries,which shape is regular polyhedron and nearly spheric.Second,there are no inclusions in D-HMX crystals,the purity of D-HMX is(99.6±0.1)% and the mean particle density is great 1.9016 g·cm-3.Third,the results of DSC and VST show that the β→δ phase transition of D-HMX is shifted to high temperatures about 6 ℃ and that the amount of gas evolution of D-HMX is obviously less after being heated for 48 h at 120 ℃ compared with C-HMX.Fourth,the results of shock sensitivities demonstrate that the aluminium gap thicknesses of cast and pressed PBXs based on D-HMX are lesser 10%~23% than that of PBXs based on C-HMX.Additional,the impact sensitivity of D-HMX appears lower sensitivity than C-HMX.Especially for the fine grain D-HMX(FD-HMX),the drop-height of 72.2 cm and initiation probabilities of 24% indicate there are significantly higher resistance to impact than the fine grain C-HMX(FC-HMX) of 16.8 cm and 88%.