Effects of cyclic absorption–desorption of model fuels by aerospace‐grade carbon/epoxy composites

Abstract The aviation industry is in the process of using several alternative fuels sourced from renewable sources to decrease its impact on the environment. These alternative fuels are mostly comprised of aliphatic hydrocarbons and have low to no aromatic content. The Federal Aviation Administration (FAA) has approved several drop‐in fuels, in which alternative fuels are typically blended with conventional Jet A fuel. Because of blending, the drop‐in fuels consist of both aliphatic and aromatic components. To achieve a fundamental understanding of how individual aliphatic and aromatic components interact with the aerospace‐grade composites, we have considered four model fuels, three aliphatic with varying chain lengths and one aromatic. The absorption of these model fuels by composites in three absorption/desorption cycles was captured and compared to the conventional Jet A fuel. The equilibrium weight gain by the composites due to absorption was low but was different for each model fuel, and the trend could be validated using Hansen solubility parameters. The absorption of model fuels decreased the glass transition temperature of composites. The change in glass transition temperature was not significantly different between the model fuels and the conventional fuel. These results can be translated to alternative fuels, making them a possible substitute for Jet A in the aviation industry.