3D printing filaments from plasticized Polyhydroxybutyrate/Polylactic acid blends reinforced with hydroxyapatite

This research focused on the fabrication of bio-composite filament from polymer blending between Polyhydroxybutyrate (PHB) and Polylactic acid (PLA) while using hydroxyapatite (HA) and polypropylene glycol (PPG) as a reinforcing agent and plasticizer, respectively, targeting to be an alternative material used in 3D printing utilization stead of using commercial PLA. PHB/PLA blend containing 10, 20, and 30 phr HA, with equal PPG content were prepared using a melt-extrusion process via a twin-screw extruder. Herein, the thermal properties and flowability were investigated to optimize the 3D printing conditions. The results showed that adding PPG improved the processability during the filament extrusion and 3D printing process. The bio-composite with 10 phr HA and 10 phr PPG (HA-PPG 11) showed a consistent flow, leading to an excellent 3D printability, however, the flowability decreased with an increase in HA loading. Furthermore, the morphological and mechanical properties of the 3D printed specimens were characterized. Mechanical testing exhibited that HA-PPG 11 occupied excellent mechanical properties, which included impact strength (1.85 kJ/m2), flexural modulus (3.20 GPa), and flexural stress at 2% strain (42.5 MPa); especially, elongation at break which higher than commercial PLA, all of which are attributed to the high-level of HA dispersion within the bio-composite.