Electrical and Electrostatic Discharge Solid Rocket Booster Ignition

In missile propulsion technology it is conventional to employ solid rocket boosters. These boosters are loaded with solid propellants, which are energetic compositions where raw materials are comprised of solid particulates, such as fuel, and oxidizer particles, in which are dispersed and immobilized throughout a binder (polymeric) matrix. The processability of these compositions is not simple because it is difficult to incorporate a high percentage of solids in polymeric matrix. Its has been problematic to formulate a safe composition so as to prevent an accidental ignition of solid propellant or other device that uses energetic materials. Accidents and incidents with solid rocket motor, during production, handling and storage, without apparent causes, led to studies by independent groups [1,2,3,4]. These studies generated important conclusions on the realm of solid rocket motor safety; furthermore, subsequent investigations suggest that spontaneous motor ignition can be attributed to electrostatic discharge. The solid composite propellant grain can be considered in a microscale heterogeneous system in which conductive and nonconductive particles and different types of binders had direct influence in the grain electrical characteristics. Nonconductive particles have a geometrical effect to influence the spacing of the conductive particles [5]. The aim of this paper is to present the methodologies and the respective results of electrical and electrostatic discharge tests. These results allow us to choose a less ESD sensitive formulation of solid propellant increasing the reliability in manufacturing, handling and storage of solid rocket motor.