Evolution of HTPB/RDX/Al/DOA mixed explosives with 90% solid loading in resonance acoustic mixing process

Resonance acoustic mixing (RAM) technology is an attractive and safe mixing method for material mass and energy exchange. However, the mixing mechanism of this technology and the evolution law of the material in the container are complicated, and improper mixing conditions will make the material unable to reach uniformity quickly and efficiently. In this paper, a 90% solid polymer-bonded explosive (PBX) was prepared by RAM, and the evolution of materials in different mixing containers, mixing acceleration, and mixing time was studied. The binder system consisted of hydroxyl-terminated polybutadiene (HTPB)/dioctyl adipate (DOA) and was cured by isophorone diisocyanate (IPDI). Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) were used to observe the microcosmic change of the sample during the mixing process, and a rheometer was used to measure the viscosity change of the slurry at different stages. The results showed that the hemispherical bottom vessel could achieve uniform mixing of materials within 45 minutes, and the mixing efficiency was highest when the acceleration was 40 g. According to the evolution state of typical materials, the mixing process was divided into 3 stages: rough cladding stage, the stage of converging into a smooth ball, and the flat fluidization stage. In the range of shear rates from 0.1 to 100s−1, the apparent viscosity of the material tended to be flat with the extension of mixing time, and the rheological behavior index of the material had little change after the material aggregates into a smooth ball. The density test of the cured sample further proved that the PBX was very uniform.