Fiber‐Reinforced Bio‐Epoxy Composites: Degradation Mechanisms in Saline Environment

ABSTRACT

This study examines the degradation behavior of bio‐epoxy composites reinforced with glass, basalt, carbon, and flax fiber yarns in a simulated saline environment. Fiber yarns and composite samples were exposed to 3.5% NaCl solution at 60°C for up to 3000 h. Mechanical degradation was evaluated through tensile strength and interfacial shear strength (IFSS), while chemical and microstructural changes were assessed using SEM/EDS. The results demonstrated that fiber type significantly affected durability. Glass fibers exhibited the lowest tensile strength retention (49%), followed by basalt fibers (57%), due to aqueous corrosion and silane‐based sizing degradation associated with siloxane hydrolysis and silica leaching. Carbon fibers showed higher retention (89%), mainly due to sizing removal with limited chemical alteration, while flax fibers showed considerable reduction (34%) due to moisture‐induced swelling and microcracking. Single‐yarn composites with carbon, basalt, and flax fibers retained approximately 100% of their IFSS after 3000 h, whereas glass fiber composites retained at least 95%. Failure was dominated by matrix failure in carbon and basalt composites, interfacial debonding in glass composites, and fiber pull‐out in flax composites. Overall, the bio‐epoxy composites demonstrated stable performance under saline aging, supporting their potential as sustainable alternatives to conventional composites in saline environments.