Microencapsulation of hydrocarbon fuels for monopropellant creation with hydrogen peroxide

Abstract

Monopropellant systems are used in rocket engines when high reliability and low technical complexity is demanded. However, they usually have lower specific impulses compared to bipropellants. A mixture of oxidizer and fuel from typical bipropellant systems is generally difficult to convert into a monopropellant as they are normally immiscible and would constitute a potentially explosive mixture. Microencapsulation of one of the two components of a bipropellant could be a possible way to create an insensitive mixture of the two substances together in the same tank while creating a monopropellant. This approach would bring together the advantages of both monopropellant and bipropellant, a high specific impulse combined with low technical complexity. In this work we present a new concept of microencapsulated hydrocarbon fuels for the creation of a monopropellant with hydrogen peroxide as green oxidizer component. Hydrocarbon filled microcapsules were synthesized by interfacial polymerization and analyzed by thermogravimetry, optical and electron microscopy as well as infrared spectroscopy. Additionally, the compatibility of the polyamide capsule wall with rocket grade hydrogen peroxide (up to 98%) and vice versa was studied and was found to be suitable.