Aluminum Particles Concentration Effects on Electrical Properties of Metal-Loaded Dielectrics

The Hydroxyl-terminated polybutadiene (HTPB) based composite solid propellants are widely used in rocket and missile propulsion applications. The conductive particles, Aluminum, was dispersed in the composites to improved performance of the solid propellants due to their excellent physicochemical properties. Even though solid propellants are generally considered to be safer than liquid propellants, they are still liable to experience breakdowns under an intense electric field, which may lead to a detrimental loss of properties in their operation. This work is made to understand influence of Aluminum particles concentrations on electrical breakdown, electrical and dielectric properties of HTPB based composites. HTPB based composites with four different concentrations of small size (5 μm) Al particles were prepared. The DC breakdown electric field decreases with increasing the Al particles concentration. Moreover, the presence of these conductive particles induces an increase of permittivity. This fluctuation follows the Maxwell-Garnett approach. However, a decrease of HTPB based composites conductivity was induced by adding metal inclusions, due to the charge trapping effect of Al particles.