Plateau Burning of AP/HTPB-Based Solid Rocket Propellants Applying a Copper-Based Metal-Organic Framework Additive

This study explored the influence of a copper-based, metal-organic framework additive on the burning behavior of an AP/HTPB-based composite solid rocket propellant. This MOF (HKUST-1) is a copper-based organometallic complex that has the capability to provide energetic benefits along with tailored burning rates to composite solid rocket propellants. These characteristics were evaluated through a parametric study incorporating chemical equilibrium analysis, scanning electron microscopy, and ballistics testing within a constant-volume bomb. Formulations were evaluated at 1-5% HKUST-1 integrated within and 80% solids loading fuel matrix. Results demonstrated that HKUST-1 provides an energetic benefit that is rather promising when compared to traditional propellant burning rate modifiers. CEA calculations showed an AFT and Isp increase up to 22% and 13% respectively compared to baseline formulations with equal composition of Fe2O3. Additionally, ballistics tests evaluated from 500-3000 psi indicated that this MOF has the unique capability to produce plateau propellant burning rates for an extended range of pressures from 1000-3000 psi higher than other plateau-inducing formulations. Pressure exponents as low as 0.016 and average burning rates as high as 0.412 in/s highlight HKUST-1’s potential as a high-performance burning rate modifier that can provide increased stability within solid rocket applications.