Development and characterization of novel polyurethane formulations for composite rocket propellants

Abstract. Composite rocket propellants are heterogeneous energetic mixtures based on crystalline oxidizers, metallic powders, and a polymeric matrix. Nowadays, these composite formulations incorporate hydroxyl-terminated polybutadiene (HTPB) as polymeric binder, a class of butadiene-terminated oligomer, to provide optimal thermal and mechanical behavior. Novel polyurethane binder formulations comprising commercial polyols, an aliphatic isocyanate as a cross-linking agent, an organic catalyst and various plasticizers are reported here. The developed polyurethanes were investigated by specific analytical techniques: thermogravimetric analysis (TGA-DTG) and dynamic mechanical analysis (DMA). Furthermore, to demonstrate their applicability as binder for energetic composites, the optimal polyurethane formulation was employed in the development of novel composite mixtures that were further ballistically characterized.