Mechanical and burning properties of highly loaded composite propellants

The performance of solid rocket motors can be improved by increasing the oxidizer content of HTPB-based solid propellants. To minimize the adverse changes in the mechanical and rheological properties due to the increased amount of hard solid particles in the soft polymeric binder matrix, the optimum combination of the particle sizes and volume fractions of the bimodal ammonium perchlorate was obtained. Mechanical properties of the propellant samples were measured by using an Instron tester. The tensile strength and the burning rate increased, while the elongation at maximum stress decreased with increasing fine-to-coarse ratio of ammonium perchlorate.