Crystallisation Behavior of ADN Droplets in Microfluidic Emulsion Crystallisation Process

Since ammonium dinitramide (ADN) is a future-oriented green oxidizer in solid rocket propellants and a promising candidate to replace the environmentally harmful ammonium perchlorate, the focus of the current research lies on propellant formulations with ADN. For its implementation in a rocket propellant matrix, a spherical shape of the crystal is required.
To achieve good control of crystallization in favor of prill quality, it is necessary to understand the crystallization kinetics of ADN melt droplets. Parameters like droplet size, supercooling temperature and addition of surfactants and additives have an impact on the crystallization behavior. The technique of microfluidics, as a powerful tool to investigate these parameters individually, was applied in this work to build a suitable observation setup. Initial experiments were performed with supercooling, showing that additional crystallization aids are required to stimulate crystallization of ADN melt droplets.