Characterization of Solid Propellant and its Connection to Aging Phenomena

Abstract

Solid propellant characterization has been performed with the use of three Fourier transform infrared (FT-IR) techniques: FT-IR-microscopy (FT-IR-mic), attenuated total reflectance/FT-IR (ATR/FT-IR) spectroscopy, and desorption/gas chromatography/FT-IR (D/GC/FT-IR) spectroscopy as well as thermogravimetric analysis (TGA). Emphasis was placed on examination of the content and behavior of plasticizer (bis-2,2-dinitropropyl acetal/formal, BDNPA/F) in propellant samples characterized over a 300-day period. Levels of residual solvent and other desorbable materials were examined as well. The following conclusions were made: there are significantly higher levels of both plasticizer and polymeric binder at extruded surfaces than in the interior of propellant grains; the rate of plasticizer migration in binder alone depends on the CAB:NC (cellulose acetate butyrate: nitrocellulose) ratio; and plasticizer evaporation and diffusional migration are negligible for all but one of the samples analyzed, suggesting that plasticizer is probably not responsible for observed aging phenomena. Levels of residual solvent and other minor components were observed to decrease with time under both ambient and accelerated aging conditions and may be related to aging phenomena.