Fabrication and evaluation of PLA/PA-HA filament for 3D printing: towards trabecular bone-compatible biomedical applications

Abstract The advancement of additive manufacturing has enabled the transition of 3D printing from a prototyping tool to a platform for producing functional, bioactive, and patient-specific implants. This study explores the fabrication and characterisation of polylactic acid (PLA) reinforced with polyamide 12 (PA12) and hydroxyapatite (HA) as composite filaments for fused deposition modeling (FDM), with a focus on bone scaffold applications. While reinforcements such as carbon, glass, and ceramic fillers have previously enhanced mechanical and thermal performance, PLA/HA composites remain hindered by brittleness. To overcome this limitation, PA12 was incorporated to improve ductility and fracture resistance while retaining the bioactivity of HA. Three formulations were prepared: PLA/20PA-10HA, PLA/30PA-10HA, and PLA/40PA-10HA, and systematically evaluated for density, functional groups (FTIR), thermal transitions (DSC), rheology, and tensile behaviour. Filament tensile testing revealed Young’s modulus values of 0.23 ± 0.06 GPa, 0.19 ± 0.06 GPa, and 0.28 ± 0.03 GPa, respectively. Among these, PLA/40PA-10HA demonstrated the most favourable balance of rheological stability and mechanical performance, leading to its selection for FDM printing. The printed cylindrical specimens achieved a compressive strength of 43.04 ± 2.78 MPa, a Young’s modulus of 0.84 ± 0.19 GPa, and a failure strain of 12.57 ± 1.18%. These properties fall within the range of human trabecular bone, indicating that the developed composite can sustain physiological loads. The findings establish a foundation for on-demand fabrication of load bearing, bioactive scaffolds through FDM, advancing the potential of chair-side manufacturing for bone tissue engineering.