Effects of gamma-ray irradiation on M1 propellant

Abstract

Samples of M1 single-base propellant were exposed to 10{sup 5}, 10{sup 6}, and 10{sup 7}r of Co{sup 60} gamma rays. Burning rates were determined over a pressure range of 600 to 2600 psi at -40{degrees}, 21{degrees}, and 71{degrees}C. A statistical study indicated no significant change in the burning rate and a small but statistically significant increase (6%) in the exponential factor n after the 10{sup 7}r dose. Visible deterioration resulted, as the color changed from yellow to dark brown and the surface became uneven. In view of these marked visible effects, the slight change in burning rate is surprising. One sample exposed to 5 {times} 10{sup 8}r showed severe blistering, swelling, and contraction, and embrittlement causing fracture. Nitrogen Taliani tests conducted at 110{degrees}C indicated that the decomposition rate is decreased by exposure to 10{sup 5}r, is decreased less by 10{sup 6}r, and remains unchanged after 10{sup 7}r exposure. Chemical analysis showed that the percentage of 2-nitrodiphenylamine increases with dose by a factor of 7 at 10{sup 7}r, while, at the same time, the nitrogen content of the nitrocellulose decreases with increasing dose. This indicates that a substantial part of the nitrocellulose decomposition product had reacted with the diphenylamine stabilizer. It is remarkable that propellant strands obviously modified by exposure to 10{sup 7}r showed little or no change in burning rate.