Environmentally-Benign Oxidizers for Propulsion

Ammonium perchlorate (AP) is the most commonly used oxidizing ingredient in solid propellant formulations. It carries a sufficient excess of oxygen to allow for the combustion of the required binder and added metal, such as aluminum. One major drawback of AP is its chlorine content which results in the formation of hydrochloric acid (HCl) as a combustion product and can cause environmental problems. Available halogen-free oxidizers, such as ammonium nitrate (AN) or ammonium dinitramide (ADN) provide less available oxygen, than AP and, therefore, result in significantly reduced performance of their formulations. A second major drawback to AP is its high solubility in water (20g/100g water at 0°C) and subsequent contamination of ground water. Further, it is highly mobile and persistent in ground-water systems. An objective of the Phase I STTR program is to conceive potential candidate compounds and screen them based on their theoretical performance and other parameters. Experimental approaches to synthesize and characterize promising new ingredients will be designed. Ideally, sufficient amounts of target compounds will be prepared to allow determination of structure and permit necessary ingredient stability and sensitivity tests to be conducted. If the reaction scheme is complex, performance on Phase I may be limited to demonstration of feasibility of the key steps.