Defective vigna radiata waste as a functional reinforcement in polylactic acid composites for additive manufacturing

ABSTRACT This study investigates the use of defective Vigna radiata (Vr) powder derived from discolored, broken, or expired mung beans unsuitable for consumption as a natural filler to improve the properties of polylactic acid (PLA) for 3D-printing filaments. As an agricultural byproduct, Vr provides a biodegradable and sustainable alternative to synthetic fillers, aiming to enhance the mechanical and functional performance of PLA composites. Eco-friendly PLA/Vr filaments were developed for Fused Deposition Modeling (FDM). Vr powder was prepared by drying, grinding, and sieving, and incorporated into PLA at 1%, 2%, and 3% weight fractions using single screw melt extrusion. The extruded filaments were 3D-printed using FDM on an Ender 3 V2 with optimized settings (nozzle ~200°C, bed 60–70°C) to fabricate test specimens. Mechanical properties such as tensile, flexural, and compressive strength, hardness, and impact resistance were evaluated, while morphological and structural characteristics were analyzed using SEM, XRD, and FTIR. At 1% Vr loading, tensile strength increased by 8.14%, flexural strength by 9.75%, and compressive strength by 7.64% compared to neat PLA. SEM confirmed uniform filler dispersion, while XRD and FTIR indicated enhanced crystallinity. Overall, Vr-reinforced PLA composites demonstrate improved performance making them promising for biomedical and eco-friendly consumer applications.