Bio-based and biocompatible poly(butylene succinate)/natural rubber composites for enhanced ductility in material extrusion additive manufacturing

This study addresses the intrinsic brittleness and poor dimensional stability of poly (butylene succinate) (PBS) in material extrusion 3D printing by developing a bio-based composite filament reinforced with talc and toughened with epoxidised natural rubber (ENR). Unlike previous binary blends, this ternary system was engineered to optimise the trade-off between melt processability and mechanical performance. The composite filaments were fabricated via twin-screw extrusion and systematically characterised in terms of thermal, rheological, mechanical, and printing performance. Rheological analysis revealed that the incorporation of talc and ENR increased melt elasticity and complex viscosity at low frequencies, thereby improving extrusion stability and shape retention during printing. The developed composites exhibited significantly enhanced ductile behaviour, achieving an elongation at break of up to 43.1%, while maintaining good toughness and dimensional fidelity. Printed specimens demonstrated high dimensional accuracy, with a mean absolute percentage error (MAPE) as low as 4.70% and a reduced warping degree of 1.11%. Furthermore, cytotoxicity assays confirmed excellent material safety, with cell viability exceeding 96%, supporting the potential of these bio-based PBS/talc/ENR composite filaments for semi-rigid biomedical applications such as orthotic components. • Bio-based PBS/talc/ENR composite filament developed to improve ductility and dimensional stability of PBS for material extrusion 3D printing. • ENR increased ductility, raising elongation at break to ∼43% and enabling a balance between toughness and printability. • Thermal, rheological, and mechanical analyses confirmed improved melt elasticity, dimensional fidelity, and reduced warping in optimised blends. • Cytotoxicity evaluation showed excellent biocompatibility (>96% viability), supporting use in semi-rigid biomedical and additive manufacturing applications.