The objective of this project is to investigate solid rocket motor propellant formulations that meet mission requirements for U.S. Department of Defense (DoD) tactical missile systems while reducing environmental risk through the elimination of isocyanate curatives and ammonium perchlorate.
Environmentally benign cure chemistry based on thiol-ene or other “click” reactions will be incorporated into ammonium perchlorate-free tactical solid rocket motor formulations that rely on added energy from plasticizers (and potentially binders) to maintain volumetric specific impulse characteristics that are comparable with current formulations. These chemistries have demonstrated feasibility in ammonium perchlorate-containing propellants, and show promise for translation to perchlorate-free systems. The effort will involve four major focus areas:
- propellant formulation development, in which alternative ingredient sets will be screened on the basis of compatibility, reactivity, burning rate, and calculated performance characteristics in order to down-select the most promising candidates;
- aging studies, in which approaches for minimizing polymer decomposition will be tested and performance as a function of service conditions for notional motors will be calculated;
- small motor demonstration, in which performance calculations will be validated at -45, 75, and 145 °F, and;
- long-range risk reduction, in which the fundamental physics and chemistry of the system will be determined so as to maximize the reliability of performance models, and an assessment of the human health, environmental, and safety impacts of the system will be completed.
If successful, these efforts will facilitate the complete elimination of isocyanate curatives and ammonium perchlorate, and their associated environmental, safety, and occupational health risks, from solid rocket motor propellant formulations for DoD tactical missile platforms, without introducing significant new environmental, safety, or occupational health concerns, and without sacrificing propellant safety or performance. The effort will advance the technical readiness level of environmentally-friendly binder chemistries in perchlorate-free propellant formulations, while delivering improved safety, reduced environmental risk, and performance data that will advance the scientific understanding of alternatives to isocyanate cure. The data will also facilitate engineering design and demonstration of tactical motors that meet both current and emerging performance requirements. The project will also provide key aging data that will facilitate the introduction of solid rocket motor propellant formulations with longer service lifetimes, thus reducing the cost, environmental impact, and safety risks associated with fielding and maintenance of solid rocket motors.