Simulation and Experimental Study on the Incompatibility Issue between ADN and Isocyanate

Abstract Since solid composite propellants are composed of a high percentage of oxidizers, the search for green oxidizers such as ammonium dinitramide (ADN) as a substitute for non-eco-friendly ammonium perchlorate (AP) is an important issue. ADN/GAP propellants are good green candidates to replace conventional AP/HTPB propellants. The incompatibility issue of ADN with isocyanate curing agents is a well-known problem. In this research, from the perspective of molecular dynamics and solubility parameter concept, an attempt was made to select a suitable curing system for ADN/GAP composite propellants by examining the interaction energy between different isocyanate curing agents and ADN as well as GAP. The examined isocyanates include N100, IPDI, TDI, DDI, IPDI/N100, and DDI/N100. The interaction of the selected curing system with ADN was investigated using infrared spectroscopy at different time intervals and compared with the N100 as a conventional curing system. The results show significant improvement of the selected curing system.