High-energy-density metallized gel propellant by hydrogen-bonded polymer-small molecules for enhanced stability and shear-thinning performance

Abstract

Metallized gel propellants with high metal content hold significant potential for enhancing the energy properties of hydrocarbon fuels. However, achieving an optimal balance between storage stability and atomization characteristics poses a significant challenge. In this study, we successfully synthesized metallized gel propellants that exhibit exceptional stability and remarkable shear-thinning properties by utilizing cooperative hydrogen bonding between polymer octanoyl cellulose and the small Thixatrol ST molecule. Through meticulous mixture design and formulation optimization, the metallized gel propellants demonstrated noteworthy characteristics, including a high calorific value of 48.48 MJ/kg, an impressive dynamic stability index of 89.12%, a surface tension of 23.21 mN/m, and sustained stability for at least six months under resting conditions. The metallized gel propellant, containing 50 wt% boron particles, exhibited a density 1.54 times higher than pure kerosene, meeting the requirements for enhancing specific impulse in rocket and ramjet engines. Moreover, optimized samples with varying boron concentrations were evaluated for their rheological properties and atomization behavior. The results revealed that the inclusion of boron particles increased the viscosity of the metallized gels. Consequently, the sample with 50 wt% boron exhibited modified viscosity-flow behavior, resulting in the formation of larger gel droplets during atomization. Finally, the metallized gel propellant demonstrated successful ignition in ramjet engine experiments. We anticipate that the cooperative hydrogen bonding between the polymer and small molecule will pave the way for the development of high-content metallized gel propellants with exceptional stability and superior shear thinning performance.