Impact of Ammonium Perchlorate Content on Electrically Controlled Gel Polymer Electrolyte Monopropellants

A group of five electrically controlled monopropellants were developed, and their fundamental rheological, electrochemical, thermal, and combustion properties were characterized. A baseline monopropellant was composed of lithium perchlorate complexed with polyethylene glycol to form an ionically conductive gel polymer electrolyte. Subsequent candidates were supplemented with varying amounts of ammonium perchlorate at a fixed polymer-to-oxidizer ratio to determine the effects of shifting oxidizer content on the fundamental properties. The ignition of the gel monopropellants using an applied DC voltage potential at atmospheric conditions was observed and determined to be primarily the result of an electrolytic reaction. Time-resolved infrared thermography confirmed initial heating and initiation of the gels at the cathode once temperatures had reached the decomposition temperature of the polymer. Fourier transform infrared analysis of collected residue from experiments halted before ignition revealed lithium deposition on the cathode, supporting electrochemical activity. It was found that the electrolytic ignition delay time was affected by the oxidizer content, the magnitude of the applied voltage, and the distance between the electrodes supplying the voltage.