Advancements in Photocurable Solid Propellants for Additive Manufacturing

The conventional mix-cast-cure method for producing composite solid propellants faces two significant challenges: the use of toxic thermocuring additives and the necessity for a mandrel. The mandrel not only poses a risk of unintended ignition as a result of electrostatic charge buildup during removal but also restricts the potential geometries of the propellant grains. Recent research has aimed to address these issues through additive manufacturing technologies. This innovative method eliminates the need for a mandrel and uses photocurable propellants, which are less toxic and more suited for 3D printing. This article provides a comprehensive overview of seven years of research conducted collaboratively by Politecnico di Torino and Politecnico di Milano, detailing the advancements in developing a photocurable propellant and the corresponding 3D printing technology for its production. The resulting UV-curable propellant exhibits a rapid curing process, favorable rheological properties, and mechanical strength comparable to that of traditional propellants. X-ray tomography has confirmed satisfactory layer adhesion, and successful ballistic tests have been conducted. In addition, a prototype 3D printer has been developed, with initial printing tests currently in progress.