Development and Characterization of Macadamia Nutshell Fibre-Reinforced PLA Composite for Sustainable Structural Applications

Abstract

The quest for sustainable and eco-friendly materials has led to significant advancements in the field of natural fibre-reinforced composites. Macadamia nutshell fibres are rich in cellulose, making it a suitable candidate. The fibres were extracted through mechanical grinding, treated with alkali, and characterized for their composition and surface morphology. Composite filaments were fabricated via melt extrusion and evaluated for tensile strength and structural performance compared to pure PLA filaments. By incorporating 7.5% fibre into PLA, the composite achieves a balance of mechanical, environmental, and functional properties. Surface roughness analysis of the fabricated composite filament revealed an R_a value of 3.964 µm, tensile strength of 41.55 ± 2.11 MPa. Moisture content was limited to 1.6%, while water absorption reached 10%, reflecting the hydrophilic nature of the natural fibres and underscoring the importance of material design considerations for humid environments. The results suggest that macadamia nutshell fibre PLA reinforced composites offer an eco-friendly alternative for light to moderate load-bearing structural applications.