Compounding of glycidyl azide polymer with nitrocellulose and its influence on the properties of propellants

Currently formulated propellants comprise RDX and polymeric binders, such a s hydroxy-terminated polybutadiene (HTPB) and cellulose-acetate butyrate (C AB) as well as the energetic substances glycidyl azide polymer (GAP) and ni trocellulose (NC). Propellants based on GAP are often brittle if they are f ormulated with a high content of cyclotrimethylene trinitramine (RDX) and d ue to the usually insufficient mechanical properties of GAP. On the other h and formulations based on RDX and NC may exceed the tolerable burning tempe rature with increasing RDX concentration. Therefore, in this study propella nts with a high force and with relatively low burning temperature has been formulated by using a compound of NC and GAP as energetic binder. According to thermodynamic calculations GAP/NC composite propellants can be formulat ed with up to 15 percent more specific energy than seminitramines at the sa me burning temperature. By choosing appropriate polymerization conditions c hemical stable compositions can be produced. ARC experiments give evidence that at temperatures from 120 degreesC to 160 degreesC the binder decompose s similar to NC. At higher temperatures the behaviour switches from NC type to GAP type decomposition. In comparison to GAP bound propellants the comp ressive strength of propellants bound by the GAP/NC compound can be signifi cantly increased by up to 420 percent at room temperature. Although the exa mined seminitramine propellants bound with NC show a compressive strength w hich is about 10 percent higher at room temperature, the GAP/NC composition s are quite superior at elevated temperature.