Effects of Additives on the Flowability of a Propellant Formulation Intended for Material Extrusion

In recent years a gun propellant formulation intended for 3D printing based on material extrusion has been developed at Fraunhofer ICT. The viscosity of the formulation is currently mainly adjusted by controlling the amount of solvent which is present in the paste as well as the temperature of the print head and nozzle. Due to high filler content and small particle sizes the extrusion pressure can be high and nozzle clogging may occur under certain circumstances. To alleviate these challenges two possible solutions are being investigated, the substitution of part of the current filler by new meltable fillers or filler combinations on one hand and the use of dispersants on the other hand. The rheology of the newly obtained formulations is characterized first to assess the impact of the changes in composition before 3D printing tests will show if these formulations are still suited for the material extrusion and if the above-mentioned issues can be eliminated in this way.