Fabrication and performance evaluation of sustainable flax fiber-reinforced HDPE bio-composites: A path toward reducing plastic waste

The escalating environmental crisis caused by non-biodegradable plastic waste has intensified the search for sustainable alternatives to petroleum-based polymers. This study fabricated and evaluated flax fiber-reinforced high-density polyethylene (HDPE) bio-composites as eco-friendly substitutes for conventional plastic materials. Flax fibers were alkali-treated with 5% NaOH for 24 hours to enhance interfacial adhesion with the hydrophobic HDPE matrix. Four formulations were prepared at fiber loadings of 0%, 5%, 10%, and 15% wt% and characterized by tensile testing, impact testing, and FTIR spectroscopy. The 5% fiber composite (Sample 2) yielded the best overall performance: impact strength increased by 30% to 132.32 ± 4.73 kJ/m 2 compared to neat HDPE (101.78 ± 13.88 kJ/m 2 ), tensile strength was maintained within 4% of neat HDPE (22.50 ± 0.76 MPa vs 23.41 ± 2.56 MPa), and Young’s modulus improved by 11.4% to 1330.93 ± 66.53 MPa. At 15% fiber loading, stiffness increased by 31.7% but impact strength declined catastrophically by 57.2%. These results demonstrate that 5 wt% alkali-treated flax fiber reinforcement produces bio-composites with balanced mechanical properties suitable for non-structural applications such as household containers, interior panels, disposable food service items, and agricultural packaging — offering a viable pathway to reduce dependence on petroleum-based plastics and minimize landfill waste accumulation.