Development and Characterization of S-glass Fiber/Bi₂O₃-reinforced Epoxy Hybrid Composites for Enhanced Mechanical Performance and Gamma Radiation Shielding

Abstract

Conventional epoxy composites offer low weight and good processability but provide limited gamma-ray attenuation and mechanical resistance, while lead-based shields are heavy and toxic. This study develops a lead-free multifunctional composite by combining silane-treated S-glass fibres and chemically precipitated Bi₂O₃ nanoparticles within an epoxy matrix. The composites were fabricated using mechanical mixing, ultrasonication, vacuum degassing, ambient curing, and post-curing. Their chemical, morphological, thermal, mechanical, and gamma-shielding characteristics were evaluated using FTIR, SEM, TGA, DSC, impact and three-point bending tests, and a cobalt-60/NaI(Tl) attenuation setup. The optimized composites achieved an impact strength of 8.4 kJ/m² and a maximum flexural strength of 195 MPa, representing improvements of approximately 171% and 112%, respectively, over neat epoxy. The EP/SGF-20/Bi₂O₃-25 composite exhibited the lowest HVL of 5.4 cm, compared with 9.9 cm for neat epoxy, confirming improved gamma-ray attenuation. These improvements resulted from the combined effects of strong fibre reinforcement, high-density Bi₂O₃ nanoparticles, and enhanced interfacial bonding produced by silane treatment. The developed composites provide a lightweight, lead-free material with integrated structural, thermal, and radiation-shielding functions, offering potential for medical shielding components, nuclear facilities, aerospace structures, and radiation-protection systems.