Research on propellant components: I. Vibrational spectroscopy correlations in energetic materials. II. Aging studies of hydroxyl-terminated polybutadiene based binder

This dissertation consists of two research projects dealing with the chemistry of rocket propellant components.; The first project is an investigation of the vibrational spectroscopy of fifty-nine energetic nitro and nitramino compounds. The geometries were optimized and the vibrational frequencies were calculated using density functional theory (B3LYP/6-31+G*). Detailed descriptions of the molecular motions were assigned to the observed infrared spectra. Trends in the vibrational modes of the nitro group were sought. A previously unreported correlation was found between the nitro group internal bonding angle and its asymmetric stretching frequency. The concept of meta and ortho/para directing groups was found to apply to trends in coupled motions in the nitroaromatic compounds.; The second project concerns the aging of hydroxyl-terminated polybutadiene (HTPB) based solid rocket propellant. One-dimensional aging profiles were developed at temperatures low enough to be considered actual storage temperatures. FT-IR spectroscopy was used to follow chemical changes in the HTPB binder associated with aging. Success was marginal, but the first evidence of the peroxyl group was obtained. Extraction of the soluble fraction of the binder enabled profiles to be developed based on crosslinking. A new concept of in situ oxygen sensors was used to investigate diffusion of O2 into the propellant. Results for samples aged at two temperatures led to the hypothesis that increased concentrations of dissolved O2 at lower temperatures lead to increased reaction rates of aging at higher temperatures. This finding has potentially important ramifications for storage of propellant and how aging studies are interpreted.