Compact energetic crystals@urea-formaldehyde resin micro-composites with evident insensitivity

To improve the safety of nitramine explosives, two compact urea-formaldehyde (UF) resin coating micro-composites were fabricated via poly-condensation of urea and formaldehyde on the surfaces of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazisowurtzitane (HNIW) in this study. The two core-shell composites were characterized by several methods and their sensitivities were also studied. The results indicated that the UF resins were compactly coated on the surfaces of HMX and HNIW crystals with low contents, and the UF resin coating can stabilize the polymorphs and change the thermal properties of energetic crystals remarkably. In addition, the impact sensitivity of core-shell energetic composites reduced significantly comparing with pure explosives and corresponding explosive coated by other amino-resins, attributing to the buffering effect and better flexibility of UF resin.