Despite extensive studies on individual chemical treatments of date palm fibers, the combined and sequential effects of alkali, citric acid, silane, and methacrylic acid modifications on fiber powder surface chemistry and morphology remain insufficiently understood. This study systematically evaluates these sequential treatments on date palm mesh fiber powder using FTIR, XRD, SEM, AFM, and TGA, with epoxy composites (10 wt%) fabricated solely to illustrate filler applicability. FTIR confirmed the progressive removal of noncellulosic components and the introduction of ester, carbonyl, and mercapto functional groups. XRD revealed a crystallinity index of 24.1% for untreated powder, increasing to 26.2% after alkali treatment, while subsequent modifications preserved cellulose crystallinity at ~25%. SEM and AFM demonstrated progressive morphological evolution, with maximum surface height increasing from 0.55 µm to 3.3 µm after silane treatment. TGA showed that the main cellulose degradation temperature shifted from 349°C (UTFP) to 353–360°C in treated samples, indicating improved thermal stability. For the epoxy composites, alkali-treated fibers (EATF) yielded the highest tensile strength (~40 MPa) and stiffness (~2.63 GPa), while the USER formulation exhibited the lowest water absorption (~3%) and a moderate thickness swelling (~45–50%). These results provide a quantitative framework for optimizing sequential chemical treatments of date palm mesh fiber powder for bio-composite applications.
Ouaar et al. (Wed,) studied this question.