Evaluation of Mechanical, Rheological, Thermal and Ballistic Properties of GAP Based Composite Solid Propellants

Abstract. Binder is a vital component that determines the mechanical integrity, energetic output and ballistic performance of the propellant grain in composite solid rocket propellants. Hydroxyl-terminated polybutadiene (HTPB) has been widely used as a conventional binder. However, it is non-energetic due to its inert nature. On the other hand, energetic polymers such as glycidyl azide polymer (GAP) can release additional chemical energy during combustion due to energetic azide groups in its structure. The incorporation of GAP enables the binder to serve as both structural matrix and energetic component in the propellant. However, GAP based binder systems generally exhibit poor mechanical characteristics in comparison with HTPB based counterparts. Recent studies have focused on improving the mechanical properties of GAP based binder systems. In this study, the effects of different plasticizers and crosslinking agents on GAP-based composite solid propellants are investigated in terms of their mechanical properties. Mechanical strength and elastic properties are measured to determine structural integrity. Moreover, rheological characterization is performed by evaluating viscosity under different shear rates at various temperatures to analyze the pouring process of the propellant slurries. Physicochemical properties such as density are also examined. Thermal behavior is analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Ballistic performance is assessed by measuring burning rate at different pressure, calorific value and specific impulse of propellants. The results of this study are expected to provide the development of composite solid propellants having proper mechanical, rheological, physicochemical, thermal, and ballistic properties.