Strategically designed macromolecules as additives for high energy-density hydrocarbon fuels

To improve oxidative stability and heat sink of hydrocarbon fuels, a series of versatile macromolecular additives, BHPEI and CBHPEI, were synthesized by modification of hyperbranched poly(ethyleneimine) (HPEI). These macromolecules were used as circumstance-dependent additives in JP-10, a high energy–density hydrocarbon fuel. Each strategically designed macromolecule serves not only as a radical scavenger to improve the thermal-oxidative stability of hydrocarbon fuels at relatively low temperature, but also as a cracking initiator for heat sink enhancement as the temperature rises. According to the ASTM E1858, with the addition of BHPEI-10K at 500 ppm, the oxidation induction time of JP-10 under 175 °C could increase from 9.3 min to 14.8 min. The insoluble deposits could be reduced by 73% with the addition of 500 ppm BHPEI-10K according to accelerated oxidation tests. The superior antioxidation capability of macromolecular antioxidants were further elucidated by density functional theory (DFT) calculations. Furthermore, the BHPEI-10K performed decently as a macromolecular initiator for supercritical cracking of JP-10, with a dosage of 0.1 wt%, the conversion of JP-10 at 675 °C can be elevated from 16.4% to 33.4% and the corresponding heat sink can be improved from 1.98 MJ/kg to 2.15 MJ/kg.