Complex sentence: Often, the ingredients of a double-base propellant have multiple roles such as RDX which is both a fuel and oxidizer or nitrocellulose which is a fuel, oxidizer, and plasticizer.
Split into simpler sentences: Often, the ingredients of a double-base propellant have multiple roles. For example, RDX is both a fuel and oxidizer while nitrocellulose is a fuel, oxidizer, and plasticizer.