Development and Performance Evaluation of Flax–areca Hybrid Epoxy Composites with Zirconium Oxide for Lightweight Structures

Natural fiber hybrid composites incorporating flax fibers and additives have emerged as promising materials for lightweight structural applications. This study focuses on the development, characterization, and evaluation of epoxy composites incorporating flax fiber (FF) and areca fiber (AF), both with and without zirconium oxide (ZrO₂) nanoparticles. Hybrid composites (comprising 50 wt.% fibers in a 1:1 ratio) and single-fiber-reinforced composites (containing 50 wt.% fibers) were fabricated using a compression molding process. The composites contained 5–10 wt.% of additives. The X-ray diffraction (XRD) spectrum revealed the crystallinity index and crystallite size of all the composites. The crystal structure exhibited monoclinic symmetry, and the surfaces of both the fibers and fillers were irregular. Fourier-transform infrared (FTIR) spectroscopy was used to determine the chemical composition of the composites. Subsequently, the mechanical and thermal properties of the hybrid composites were evaluated. The results indicated that the concentration of ZrO₂ nanoparticles significantly influenced the tensile, flexural, and impact strengths of the composites. Notably, the hybrid composite with 7.5 wt.% filler exhibited a tensile strength of 105 MPa, a flexural strength of 690 MPa, an interlaminar stress of 255.1 MPa, and an impact energy of 4.82 J/m². Thermal analysis revealed that incorporating up to 7.5 wt.% filler improved composite stability by acting as a barrier to degradation. These findings indicate the potential application of the developed composites in lightweight structures.