Boron based fillers as char enhancers of EPDM based heat shielding materials for SRMs: A comparative analysis

Solid Rocket Motors (SRMs) are used to launch satellites and other civilian or military payloads in orbit. Due to their low density and outstanding insulation capability, EPDM/aramid fibers ablatives represent the state of the art of Elastomeric Heat Shielding Materials (EHSMs) SRMs. However, this class of polymeric ablatives tend to exhibit a limited ablation resistance induced by thermo-oxidation and mechanical erosion due to the propellant combustion byproducts. In order to increase the thermo-oxidation resistance, char retention, and insulation index, boron based fillers can be considered in the material formulation of the SRM insulation liner. In this work we systematically studied the effect of different boron containing fillers embedded in EPDM based EHSMs. The heat capacity, thermal stability, mechanical properties, ablation resistance, pre- and post-oxy-acetylene torch testing morphology of these materials were analyzed evidencing the clear benefits of these fillers.