Additive manufacturing of PLA/HNT nanocomposites for biomedical applications

Additive manufacturing has been of great interest of research in various applications due to their ease in processability, cost effectiveness and adaptability. In this study Poly Lactic Acid (PLA) was used as the base polymer which was reinforced with Halloysite Nanotubes (HNT) powder as they are known to be biodegradable and has high mechanical properties individually. HNT loadings with 3% and 5% were added to PLA by the method of twin screw extrusion and pelletized. For comparison, the PLA on its own was also extruded and pelletized. The resultant homogeneous pellets was extruded successfully into filaments of 1.75±0.10 mm diameter using twin screw extruder with specialized die fixed to the extruder for the manufacture of production grade 3D printing filament. This resultant filament was utilized for Fused Filament Fabrication (FFF) into standard tensile test bars and 25mm medical implants using a standard FFF printing machine. The 3D printed samples were characterized for mechanical properties by uniaxial tensile test and thermal stability by Differential scanning calorimetry. Interestingly there was no significant change in the mechanical properties of the 3D printed tensile bars due to the processing parameters during FFF. However, the decrease in cold crystallization temperature by DSC indicates the nucleating effect of the HNT on the PLA matrix which in turn increases the mechanical properties. We could successfully 3D print model medical implants.