ScholarWorks@경상국립대학교

초록

Sealants used in aerospace fuel systems must suppress interfacial void formation while maintaining airtight sealing performance under prolonged exposure to hydrocarbon fuels. Polyurethane-based sealants (PUS) exhibit rapid curing, high strength, and excellent toughness; however, their resistance to fuel-induced swelling remains limited. In this study, silica-reinforced PUS composites were developed to enhance oil resistance via surface-engineered silica nanoparticles. Hydrophilic and hydrophobic silica particles were functionalized with mercapto groups, and the surface sulfur content was systematically controlled to tailor polymer–filler interfacial interactions. Mechanical properties and oil resistance were evaluated under aviation kerosene immersion conditions. The optimized composite (0.004S-PB-PUS) exhibited a kerosene swelling ratio of 15–18%, representing a reduction of >40% compared with neat PUS (∼26%) while maintaining stable mechanical performance during immersion. After 7 days of kerosene exposure, the tensile-strength reduction stabilized at approximately 30%, indicating improved resistance to fuel-induced degradation. The improved oil resistance is attributed to the combined effects of tortuous diffusion pathways and restricted polymer chain mobility in the silica–polyurethane interphase, which suppress solvent transport within the polymer matrix. However, excessive nanoparticle loading or imperfect interfacial packing may induce micro-void formation, potentially altering oil penetration pathways and influencing adhesion durability. These findings demonstrate that surface-engineered silica nanoparticles can significantly enhance the bulk oil resistance of polyurethane sealants while maintaining acceptable mechanical stability, although interfacial adhesion durability remains sensitive to nanoparticle dispersion and interfacial microstructure. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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