3D Printing of Hemp‐Reinforced Polylactic Acid and Acrylonitrile Styrene Acrylate Filaments: Mechanical Strength Evaluation

ABSTRACT The growing demand for sustainable materials in additive manufacturing highlights the need for biocomposites that are both environmentally friendly and industrially viable. However, most prior research on hemp fiber‐reinforced filaments has relied on chemically treated fibers and low fiber concentrations, limiting scalability, increasing production costs, and reducing industrial relevance. This study addresses that gap by developing 3D printing filaments using untreated hemp fibers combined with polylactic acid (PLA) and acrylonitrile styrene acrylate (ASA) polymer matrices, enhanced with bio‐based plasticizers. Filaments were produced via single‐screw extrusion and tested through fused deposition modeling (FDM) printing of ASTM D638 and D695‐compliant specimens. The results showed that incorporating 10% w/w hemp fiber with 2.5% w/w ESO in PLA led to a notable improvement in tensile strength and stiffness compared to the composition without plasticizer, while also enhancing printability. Excessive fiber or plasticizer content caused fabrication issues and performance degradation due to fiber agglomeration and poor interfacial bonding. In terms of plasticizers, ESO outperformed glycerin in mechanical reinforcement, though high ESO levels caused material buildup during extrusion. Importantly, when compared to some published data on chemically treated hemp composites, the developed untreated‐fiber formulations achieved comparable or superior mechanical performance, offering a more scalable and cost‐effective alternative for industrial applications. PLA‐based composites outperformed ASA‐based ones in mechanical metrics, but ASA composites offered better dimensional stability and surface finish. This study demonstrates a practical, scalable approach for producing biocomposite filaments without requiring fiber pretreatment, highlighting a cost‐effective pathway for sustainable 3D printing materials suitable for industrial‐scale use.