Asphaltic thermoplastic propellants

A need has surfaced over the past several years for low-cost access to space. The two primary avenues for cost reduction are to lower propellant raw material costs and to lower processing costs. Thermoplastics and thermoplastic elastomers will help achieve these reductions. Several families of candidate thermoplastic materials have been evaluated, including acrylic resins and physically modified asphalts. These materials meet the criteria for continuous or alternate processing, are inexpensive, and have latent benefits with respect to oxidizer compatibility. The classes of thermoplastic elastomers explored consist of styrenic block copolymers. These materials provide cost benefits as well as desired mechanical and ballistic performance. These materials generally require a high-shear premix before propellant processing. The components required for ternary binder compositions are summarized, and current research is reported, and a view of proposed raw material costs and applications is given.