Aging-Induced Electrical Resistance Changes in an RDX-Loaded Nitrate Ester Propellant with Polyglycol Adipate (PGA) and Polyethylene Glycol (PEG) Cross-Linked Binders Subject to Various Thermal and Moisture Environmental Conditions

Two Cyclotrimethylenetrinitramine (RDX)-loaded nitrate ester propellant formulations with polyglycol adipate and polyethylene glycol binders, respectively, are subjected to accelerated aging at 70°C in various humidity environments ranging from 0 to 100% relative humidity (RH). The electrical resistance of each sample is monitored throughout aging, along with high-performance liquid chromatography (HPLC) and gas chromatography (GC) used to measure the mass fraction of the stabilizers and nitroso/nitro derivatives at the beginning and end of aging. Stabilizer and nitroso/nitro derivative dimethyl sulfoxide (DMSO) solutions are used to evaluate the electrical resistance of these species as a function of mass fraction. The results indicate a weak correlation of the sample electrical resistance with stabilizer and nitroso/nitro mass fraction and a strong correlation with the moisture content of the sample. Moisture is postulated to affect the electrical resistance of the samples predominately by acid induced hydrolytic decomposition of the nitrate esters present and then further the cross-linked polymeric binders, causing an elevation of the mass fraction of acid species and a decrease in the sample pH.