Palmitoyl hyperbranched polyglycerol as a nanoscale initiator for endothermic hydrocarbon fuels

• PHPG is applied as a novel nanoscale initiator for hydrocarbon fuels.
• Decomposition of PHPG starts above 200 °C.
• The cracking conversion and the heat sink of fuels are promoted in the presence of PHPG.

One of hyperbranched polymers is developed as a novel nanoscale initiator to enhance the heat sink of endothermic hydrocarbon fuels to meet the great cooling requirement of hypersonic aircrafts. In this work, the hyperbranched polyglycerol (HPG) is treated with palmitoyl chloride to obtain a fuel-soluble product, palmitoyl-hyperbranched polyglycerol (PHPG). The thermogravimetric analyses show that the long-alkyl chains rupture first from the matrix at about 200 °C, and then the HPG core breaks around 400 °C during the cracking of PHPG, which indicates a high decomposition temperature for this “macroinitiator”. The cracking processes of n-tridecane with PHPG in different molecular weights and addition quantities are performed in an electrically heated tube reactor under supercritical conditions (3.5 MPa, and 600–720 °C). PHPG can promote the cracking of n-tridecane with significant improvements of the conversion and heat sink. The conversion of n-tridecane is improved as high as 17.6% at 690 °C, and the corresponding heat sink is improved from 3.0 MJ/kg to 3.5 MJ/kg. Furthermore, the optimum addition quantity and molecular weight range of PHPG are chosen for the practical application to an aviation kerosene under 600–700 °C, and the increases of heat sink in comparison with those from the thermal cracking confirm the potential application of PHPG to endothermic hydrocarbon fuels.