3D Printed Gun Propellants based on GAP-ETPE

Additive manufacturing techniques are based on the principle of adding material selectively only in the place where it is needed as opposed to subtractive techniques where material is removed until the desired shape is obtained. This has several advantages, most notably little limitations regarding the shape of the product as well as little waste. The burning behaviour of gun propellants is governed by the shape of the propellant grain as well as the material composition. Additive manufacturing techniques are therefore a promising approach to influence these characteristics. In a first step to produce complex gun propellants by 3D printing, cylindrical grains with a single perforation have been produced by material extrusion. GAP-ETPE based formulations have been chosen due to their relatively low processing viscosities which enables precise dosing of the material by the printer. Although filler contents of up to 70 percent by weight could be achieved the viscosity of the mixture did not become a limiting factor. The produced propellant grains showed good reproducibility and little printing errors.