Energetic plasticizers for GAP-based formulations with ADN: compatibility and performance evaluation of a...

Glycidyl azide polymer (GAP) diol is an energetic binder with azide-functionalized side chains that offer a high enthalpy of formation. When formulated with ammonium dinitramide (ADN), GAP-based systems exhibit promising energetic and ballistic performance. However, GAP suffers from poor mechanical properties compared to inert binders such as hydroxyl-terminated polybutadiene (HTPB). As a result, plasticization is essential to lower the glass transition temperature of GAP. Energetic plasticizers can enhance both mechanical and energetic performance. In this study, we evaluated the compatibility of a novel nitrofurazanyl ether-based energetic plasticizer, NFPEG3N3, with key formulation components: GAP diol, HMX, Desmodur N100, and ADN. Compatibility was assessed using heat-flow microcalorimetry (HFMC) and thermogravimetry (TG), in accordance with STANAG 4147. NFPEG3N3 was found to be compatible with GAP diol, HMX, and N100. Although the NFPEG3N3-ADN mixture passed the HFMC (remaining below the 1% heat of explosion threshold), it failed TG, indicating potential concerns with long-term thermal stability. Performance calculations showed that replacing 15 wt% of GAP with NFPEG3N3 in a composite propellant increased the volume-specific impulse by 77 N s dm^-3. Additionally, formulations incorporating NFPEG3N3 demonstrated a superior oxygen balance and higher volume-specific impulse compared to those using the widely adopted energetic plasticizer Bu-NENA.