Investigation of the Physico‐Mechanical and Morphological Characteristics of Alkali and Acid‐Treated Jute, JuCo , and Glass Fiber‐Reinforced Epoxy Composite
Abstract
Natural‐fiber‐reinforced epoxy composites often suffer from limited mechanical performance and poor moisture resistance due to weak interfacial adhesion between hydrophilic fibers and the hydrophobic epoxy matrix. To overcome these limitations, chemical surface treatments are commonly applied to modify the fiber surface, reduce hydrophilicity, and improve fiber–matrix adhesion. This study investigates the physico‐mechanical and morphological behavior of Jute/JuCo/Glass/JuCo/Jute epoxy laminates treated with 5% NaOH and 1% H 2 SO 4 for 24 h, evaluated through tensile, flexural, and impact testing, water absorption analysis, FTIR spectroscopy, and SEM fractography. Acid‐treated composites achieved the best mechanical performance, with tensile and flexural strengths of 74.57 and 76.06 MPa, representing increases of approximately 6.85% and 11.22% over untreated samples, respectively. In contrast, alkali treatment reduced tensile strength by around 20% despite a marginal 1.32% gain in flexural strength. Both treatments lowered impact resistance relative to the untreated composite (77.18 kJ/m 2 ), reflecting a trade‐off between stronger interfacial bonding and reduced energy‐dissipation capacity during fracture. NaOH treatment was most effective at limiting moisture uptake, reducing long‐term water absorption by about 20.63%, while acid treatment gave an intermediate reduction. FTIR spectral changes were consistent with partial removal of hemicellulose and lignin after chemical modification, and SEM revealed reduced surface irregularities, less fiber pull‐out, and improved fiber–matrix adhesion in acid‐treated samples, corroborating the mechanical trends. Overall, the findings show that H 2 SO 4 treatment is preferable for maximizing strength, whereas NaOH treatment is better suited for applications demanding moisture durability, offering practical guidance for tailoring surface treatments in hybrid natural‐synthetic fiber composites.