Propellants Explosives Pyrotechnics, Vol.45, No.7, 1018-1025, 2020
Synthesis and Characterization of Gelled High-Density Fuels with Low-Molecular Mass Gellant
The demand for high performance and safer fuels has led to an ever increasing interest on gelled fuels. Here we report the synthesis and characterization of gelled high-density fuels with low-molecular mass gellants (LMMGs). This LMMG is synthesized simply by one step reaction and shows excellent gelling ability with the critical gellant concentration less than 1 %. Scanning electron microscopy studies reveal that LMMGs self-assemble into fibrous structures and create a 3D network structure by crosslink of these fibers, which constructs the basic network of gel. The basic physical and thermal properties of gelled fuels such as gel transition temperature (T-G), density, centrifugal stability and heat of combustion were investigated. Thermal characterizations reveal that the gels are thermally reversible and the T-G increases with the concentration of gellant. Physical stability determined by the ratio of gel-liquid separation under high speed centrifugation shows that gelled quadricyclane (QC) and exo-tetrahydrotricyclopentadiene (HDF-T1) exhibit good physical stability. Rheological measurements show that the gels are shear-thinning and the viscosity increases with an increasing amount of gellant. The viscosity of gelled QC is the highest among four gelled fuels, followed by gelled HDF-T1. The strain sweep tests and frequency-sweep tests show that gelled QC also has superior mechanical strength while the gelled kerosene (RP-3) has the lowest strength. Gel with higher strength has a higher viscosity and better physical stability due to a more stable internal structure and stronger resistance to deformation.