Influence of starch treatment on the dimensional stability and mechanical properties of date palm leaf fiber laminate-epoxy composites
Year: 2026
Type: article
Abstract: The hydrophilicity of date palm leaf fiber (DPF), combined with inadequate interfacial adhesion under moist conditions, limits the structural reliability of DPF mats as reinforcement in epoxy laminates. To address these limitations, this study reports a fully bio-based, non-toxic, and cost-effective surface treatment: starch coating. Untreated and starch-coated biocomposites were systematically compared. The starch coating, which does not require hazardous chemical reagents, generates a rough, granular, hydroxyl-rich interphase that promotes strong hydrogen-bonded networks and mechanical interlocking without introducing new covalent groups, as confirmed by scanning electron microscopy and Fourier transform infrared analyses. The modified interphase substantially improved the dimensional stability of the biocomposites during a 50-day water immersion test, as evidenced by a threefold reduction in equilibrium water absorption (from 14.5% to 4.5%) and a 50% decrease in thickness swelling (from 41% to 20%), attributed to surface hydroxyl masking and physical barrier effects. Thermomechanical properties were also enhanced, with a 77 °C increase in the onset temperature of primary thermal degradation and a 10°C rise in the glass transition temperature, indicating restricted epoxy chain mobility at the reinforced interface. Consequently, ultimate tensile strength and Young’s modulus increased by 11% (from 41.17 to 45.68 MPa) and 15.7% (from 1.214 to 1.405 GPa), respectively, reflecting improved stress-transfer efficiency. The starch-modified interphase exhibited only a 14% reduction in surface hardness (from 88.33 to 75.92 Shore D). Collectively, these results demonstrate that starch coating is an effective, eco-friendly alternative to conventional silane or alkali treatments, providing a sustainable approach to converting agricultural waste into robust biocomposites suitable for semi-structural applications in humid environments.
Institutions: University of Biskra, University of Skikda, University of Ha'il
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,640
OpenAlex ID: W7204173577