Surface modification and hydrophilicity control in JUCO fiber-reinforced epoxy composites: Mechanical and morphological evaluation

This study investigates the efficacy of alkali treatment on JUCO fabric-reinforced epoxy composites to improve their structural integrity and environmental resilience. JUCO fibers were treated with sodium hydroxide (NaOH) at varying concentrations (1–5 wt. %) for 48 hours. To date, JUCO fiber has not been subjected to alkali treatment in different NaOH concentrations. Using a hand lay-up and cold press method, composites were fabricated using four layers of fabric and epoxy resin. The mechanical characteristics, hydrophilicity, and long-term aging were evaluated in three different mediums. Fick’s law was applied to analyze water diffusion kinetics, while finite element modeling (FEM) was used to validate tensile and flexural behavior. The alkali treatment significantly improved the mechanical strength of the composites. This enhancement is attributed to superior fiber-matrix interfacial adhesion, which is supported by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses. In addition, X-ray diffraction (XRD) revealed that composites made with NaOH-treated fibers exhibited higher crystallinity compared to those with untreated fibers. The 3% NaOH treatment demonstrates a significant reduction in moisture uptake from 4.92% to 0.82% in distilled water and a corresponding decrease in diffusion rates. The findings confirm that the surface modification of JUCO-based composites by NaOH treatment presents a sustainable and effective strategy for developing moisture-resistant materials appropriate for structural applications. An ideal balance between improved performance and long-term durability is offered by the 3% NaOH treatment.