Spectroscopic analysis of the degradation of solid propellant stabilizer

Stabilizing additives are added to solid rocket propellant systems to slow the break-down of energetic nitrogen-based compounds utilized in solid rocket propellants. Over time this results in a reduction of stabilizers and an increase of inert compounds, which decrease propellant performance. Raman spectroscopic techniques can detect changes in chemical concentrations due to the strong spectrum that these compounds demonstrate. In this study, two wavelengths, 532 nm, and 785nm are used to analyze the Raman spectra of samples to characterize the changes to compounds over time. Computational techniques are demonstrated to mitigate fluorescence and improve the signal-to-noise ratio of chemical peaks specific to stabilizer compounds. Fluorescence in the 532 nm Raman spectrum is examined as a method for characterizing propellant compounds, as 2-Nitrodiphenylamine (2-NDPA) traditionally has more fluorescence than Nmethyl- 4-nitroaniline (MNA), and the 532 nm Raman system traditionally detects more fluorescence than the 785 nm Raman system. Detection of the stabilizer, MNA, in concentrations ranging from 0.38% to 0.75% is demonstrated. Raman spectroscopy is shown to provide a rapid method for analyzing high and low concentrations of stabilizer compounds to determine the remaining viability of the propellant.