Foamed propellants: Insights in the foaming process
Foamed propellants are based on crystalline explosives like nitramines bonded in inert or energetic polymers. Due to their porous structures they show high burning rates in comparison to conventional gun propellants based on nitrocellulose. Energy content and material characteristics such as burning behaviour can be varied by using different energetic fillers, energetic polymers and porous structures. Therefore the foaming process has a great influence on the material properties and quality of the foamed propellants. This paper outlines results received by various measurements using a specific laboratory equipment to characterise the foaming process. Parameters as rise height and rise profile are the classic methods. Additional informations can be derived measuring the temperature of the exothermic crosslinking reaction, the rise pressure and the dielectric polarisation during foam formation.