Determining the Swelling Behavior and Tensile Strengths of Commercially Produced Buna‑N O‑Rings and Stereolithographic Additively Manufactured O‑Rings after Exposure to Mixtures Containing Jet Fuels, Synthetic Fuels, and Fuel Surrogate.

Synthetic fuels are among the portfolio of fuels that enable operational energy resilience. This work investigates the physical properties of mixtures of military jet propellant fuel JP-5 with synthetic paraffinic kerosene (alcohol-to-jet, ATJ-SPK), formulates a surrogate mixture for ATJ-SPK, and explores the swelling behavior and tensile strengths of commercially manufactured Buna-N O-rings and stereolithographic additively manufactured (SLA) acrylate O-rings after exposure to fuels, surrogate, and fuel mixtures with additives. An ATJ-SPK surrogate was formulated (0.185 mole fraction of iso-cetane in iso-dodecane isomers) whose density, speed of sound, viscosity, flash point, and swelling matched those of ATJ-SPK. ATJ-SPK and its surrogate swelled Buna-N (∼3%) and SLA (∼5%) O-rings less than did JP-5 (∼23% Buna-N, ∼18% SLA). Adding cyclic and aromatic compounds to mixtures of JP-5 with ATJ-SPK or its surrogate increased swelling and decreased the tensile strength of the O-ring. SLA O-rings had tensile strengths lower than those of Buna-N O-rings. The densities of some mixtures met military fuel specifications, while many flash points were too low. This work shows that SLA O-rings can produce adequate swelling behavior and that cyclic and aromatic compounds can be used to enhance swelling, but the fuel's physical properties must be examined to determine if they are adversely impacted.