Fabrication of alginate-based microspheres with cellular structure for tuning ammonium dinitramide performance

Recently, an emerging category green of energetic material ammonium dinitramide (ADN) has exhibited promising application in propellants due to its outstanding merits in energy release and environmental friendliness. It can be considered to substitute traditional oxidizer of ammonium perchlorate (AP) in military systems and aerospace. In this paper, a novel spherical energetic composite ADN/copper alginate (CA) with a microporous structure was designed and prepared by the W/O gel emulsion method, and a desirable porous microsphere structure was obtained. Multiple characterization techniques were used to investigate the structure and properties of ADN/CA composites. The results showed that ADN crystals were homogeneously encapsulated in an alginate-gel matrix. Thermal decomposition temperature was reduced to 151.7 °C compared to ADN, while the activation energy of them was reduced from 129.73 kJ/mol (ADN) to 107.50 kJ/mol (ADN/CA-4). In addition, as-prepared samples had lower impact and frictional sensitivity than ADN. The mechanism of sensitivity reduction and decomposition are also discussed. Constant-volume combustion tests show that peak pressure of the ADN/CA-4 achieves 253.4 kPa and pressurization rate of 2750.4 kPa/s. Hence, this has a promising application in improving the combustion performance and safety performance of solid propellants.