Hydroxy-Terminated Polybutadiene Propellant Formulation

The polymeric hydrocarbon also acts as a binder of the particles, holding them together so as to formulate a propellant grain. Ammonium perchlorate (AP) is a typical crystalline oxidizer and hydroxy-terminated polybutadiene (HTPB) is a typical polymeric fuel. When AP and HTPB are decomposed thermally on the propellant surface, oxidizer and fuel gases are produced, which diffuse into each other and react to produce high-temperature combustion gases. 

Supercritical fractionation was investigated for the special-purpose polymers of both the diol and triol of a glycidyl azide polymer and a hydroxy-terminated polybutadiene. Hydroxy polybutadiene is used on a large scale as an ingredient in plastic bonded explosive (PBX) propellant formulations the hydroxy functionality of the polybutadiene reacts with an isocyanate functionality of another prepolymer to form a urethane. In the polysiloxanes section we referred to functionally terminated polymers as macromonomers in the terminology of the urethane industry, however, isocyanate-terminated polyester polymers are normally referred to as prepolymers in their reaction to form the urethane, even though the prepolymers are typically between 1,000 and 10,000 molecular weight. 

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