Effect of a Warm, Moist Environment on JA2 Gun Propellant.

Grains and sticks of JA2 propellant downloaded from a 1 2O-mm tank round that had been subjected to conditioning at high temperature and humidity were observed to be discolored and covered with an unknown liquid. Analysis of the propellant indicated a decrease in the nominal diethylene glycol dinitrate DEGDN plasticizer content. The nitroglycerine NG content was not observed to deviate significantly from its nominal level. The cause of the discoloration of the propellant was traced to its high moisture content. The liquid covering the material was determined to be a mixture of water and DEGDN. in follow-up experiments, it was determined that JA2 propellant can absorb an excess of 13 wt- moisture. It was also learned that graphite glaze can reduce the tendency of a grain to absorb moisture for grains immersed in water. When conditioned in a high-humidity environment, graphite glaze appeared to have no effect on the level of moisture absorbance. It is suspected that graphite serves to plug pores on the surface of the propellant and thereby inhibit, but not prevent, moisture absorption.