Hindered Sedimentation of Tungsten Carbide Particles in a Hydroxyl-Terminated Polybutadiene-Based Polymer-Bonded Explosive Energetic Composite System

Energetic composite systems with uniform particle distributions are of considerable interest, but sedimentation is a persisting challenge. Tungsten carbide (WC, density: 15.36 g/cm³) particles are promising cemented carbide particles owing to their desirable properties. In this study, we investigated the mitigation of sedimentation in a polymer-bonded explosive (PBX) energetic composite by optimizing the viscosity and particle distribution using WC particles and a hydroxyl-terminated polybutadiene-based binder. A simulation based on a modified version of Stokes' law is used to study the sedimentation behaviors of the system at different viscosities, and the resistance coefficient of particle sedimentation is estimated. The PBX energetic composite system loaded with the WC particles is prepared and analyzed. In the early curing stages, when the resistance coefficient is 0.65-1.95 (×10⁹), the sedimentation rate is low, but increases rapidly as the viscosity of the system increases. When the effective viscosity is ≥11,510 MPa·s, the particle sedimentation is improved. The energetic components are tightly entangled within the binder, with no exposure or agglomeration, and the WC particles are evenly distributed. The system can reach a solid content of 91% and retain its pourability. Thus, an energetic composite system loaded with high-density metal particles is prepared, providing a reference for use in PBX formulation.