Development of Eco-Friendly Prosopis Juliflora Fiber-Reinforced Epoxy Composites with Mg (OH) ₂ and TiO₂ Nanofillers for Improved Mechanical and Fire-Retardant Properties

Abstract

Natural fiber–reinforced polymer composites are emerging as viable alternatives to synthetic materials, especially in heat- and fire-resistant applications, due to increasing environmental consciousness and the need for biodegradable options. Eco-friendly epoxy composites reinforced with 20 wt. % alkali-treated Prosopis juliflora fibers and Mg(OH)₂/TiO₂ nanofillers (2–6 wt.%) were fabricated using the hand lay-up method to enhance mechanical, thermal, fire-retardant, and moisture resistance properties. XRD analysis confirmed increased crystallinity after alkali treatment (71.86% to 72.98%), indicating removal of amorphous constituents, while FTIR spectra validated improved interfacial compatibility. SEM micrographs revealed enhanced fiber–matrix adhesion and minimal void formation at 4 wt. % filler loading, whereas 6 wt. % caused nanoparticle agglomeration. The optimum composition exhibited a tensile strength of 64.60 MPa (30.29% improvement) and flexural strength of 21.89 MPa (54.86% improvement) compared to the control (49.58 MPa). Impact strength increased to 21.67 kJ m⁻² (71.2% enhancement). Cone calorimetry demonstrated a reduction in peak heat release rate from 420 kW m⁻² to 402 kW m⁻² (4.3% reduction), while the burning rate decreased below 35 mm min⁻¹ for nanoparticle-filled composites. TGA results showed improved onset degradation temperature up to 348.6 °C and increased char residue to 11.5%. Water absorption decreased by up to 8.18% due to the barrier effect of nanofillers. The synergistic incorporation of Mg(OH)₂ and TiO₂ significantly improved multifunctional performance, making the composites suitable for lightweight structural and fire-resistant applications.