F.B. Setiawan, P.H. Setyarini, Y.S. Irawan
Natural fiber composites provide a sustainable alternative to synthetic reinforcement; numerous region-specific fibers, such as doyo (Curculigo latifolia), remain under-investigated for engineering applications. This research investigates the impact of alkali treatment on the chemical, structural, thermal, mechanical, and morphological properties of woven doyo fibers and their epoxy composites. Alkali treatment with 5–10 % NaOH for 120 min altered the fiber surface by selectively reducing hemicellulose, lignin, and extractives, as confirmed by Fourier transform infrared spectroscopy, which showed attenuation of characteristic absorption peaks. X-ray diffraction revealed a slight increase in cellulose crystallinity following treatment, while contact angle measurements demonstrated markedly improved wettability, decreasing from approximately 74.7° for untreated fibers to around 31.0° after treatment. Thermogravimetric analysis indicated increases in degradation onset temperature and residual char content, suggesting enhanced thermal stability. Mechanical testing showed that untreated fibers yielded the highest tensile strength, about 216 MPa, whereas alkali-treated fibers produced a higher tensile modulus (up to 3.36 GPa) but reduced elongation. Field emission scanning electron microscopy (FESEM) observations further confirmed increased surface roughness, fiber fibrillation, and changes in fracture morphology associated with treatment severity. Overall, the results confirm the suitability of doyo fiber as an effective natural reinforcement and reveal that alkali treatment critically modulates both composite performance and fiber-matrix interfacial interactions. , © 2026, Setiawan F. B., Setyarini P. H., Irawan Y. S. Licensed under Creative Commons Attribution-Noncommercial 4.0 International License
University of Brawijaya, 167, Jl. MT. Haryono St., Malang, 65145, Indonesia
