Measurements of Nitrile Rubber Absorption of Hydrocarbons: Trends for Sustainable Aviation Fuel Compatibility

The commercial aviation sector is seeking to reach netzero CO2 emissions by 2050, with sustainable aviation fuel(SAF) beingthe most important lever. However, SAF is currently limited by ASTMspecifications to a maximum of 50%v blending with conventional jetfuel. One reason for the current blend limit is motivation to maintaino-ring swelling consistent with 100% petroleum fuel. This work exploresthe relationships between o-ring swelling of SAF blend components,model compounds, and various blends in nitrile rubber compared toconventional fuel swelling. Specifically, optical dilatometry measurementswere used to gather swell propensity data for 39 different hydrocarbondopants at 8%v in an iso-alkane solution, 4 dopantsat 7 different concentrations, and 19 different fuels or fuel blends.This study also highlights the advantages of using swell measurements,such as those employed here, as a quality control metric instead ofthe current 8%v aromatics requirement. Notably, the potential is shownto maintain swelling in the conventional fuel range with fuels composedof less than 8%v aromatics.