For instance, I read that the Hercules X-265 rocket motor used in the Sprint missile was a solid double base propellant that used nitrocellulose with zirconium metal staples and nitroglycerin as a binder. How would sodium metal staples work instead of zirconium?
Or better yet, suppose one were to build an experimental solid/liquid rocket motor that used molten sodium metal with liquid oxygen. Due to extreme temperature difference there might need to be an igniter to get the combustion started. Sodium is abundant, has a melting point close to the boiling point of water (~ 208 degrees Fahrenheit). To my knowledge, such an experimental rocket engine like this has never been tested. The main problem would be that the highly toxic exhaust, NaO, would react with moisture to form NaOH (lye or caustic soda).