Functionally Graded Nanofiber Interlayers for Hydrothermally Aged Glass/Epoxy Laminates: Mechanical Performance and Electromagnetic Attenuation

ABSTRACT Functionally graded Ag/Fe 3 O 4 ‐loaded polyacrylonitrile (PAN) nanofiber interlayers were placed between selected glass fabric plies to improve interlaminar damage resistance in glass fiber‐reinforced polymer (GFRP) laminates while adding a secondary electromagnetic interference (EMI) attenuation function. Unlike filler‐modified systems, the functional nanoparticles were carried by electrospun nanofiber mats and localized at ply interfaces instead of being dispersed throughout the epoxy matrix. PAN nanofiber mats and nanofiber/epoxy thin panels were first tested to compare Ag‐, Fe 3 O 4 ‐, and hybrid‐modified systems, and the selected graded architecture was then transferred to GFRP laminates. Neat and nanofiber‐interleaved laminates were tested before and after immersion in distilled water at 70°C for 21 days. In the unaged state, nanofiber interleaving increased tensile strength, flexural strength, apparent interlaminar shear strength, and Mode‐I fracture energy by 22.9%, 20.8%, 19.5%, and 25.1%, respectively. After aging, the same properties remained 30.7%, 32.5%, 27.0%, and 22.4% higher than aged neat GFRP. At 10 GHz, total shielding effectiveness increased from 1.79 to 9.72 dB and remained 5.78 dB after aging. The results show that graded nanofiber interlayers can improve the damage tolerance of GFRP laminates while providing an added moderate electromagnetic attenuation function.