Composite solid rocket propellants, or composite propellants for short, are mainly composed of crystalline oxidizers, binder systems (fuel), and metallic fuels. Composite propellants are typically classified according to the binder and named based on the structural framework of the binder polymer and its chemically active groups. For example, carboxylated polybutadiene propellant (CTPB) has a binder with carboxyl COOH chemically active groups. Hydroxyl-terminated polybutadiene propellant (HTPB) has a binder with terminal hydroxyl OH chemically active groups.
Composite propellants possess high energy characteristics, with an actual specific impulse of 2256-2453 N/(kg/s), a density of approximately 1.75 g/cm³, and ease of solving raw material issues. They also have low pressure index and temperature coefficient, resulting in minimal performance variation of the engine under different operating temperatures; low critical pressure, leading to low combustion chamber pressure and a lightweight casing; and good mechanical properties even at low temperatures. Therefore, they have found wide application in various tactical and ballistic missiles.
