Influence of Fused Deposition Modelling Nozzle Temperature on the Rheology and Mechanical Properties of 3D Printed β-Tricalcium Phosphate (TCP)/Polylactic Acid (PLA) Composite

The primary goal of this study is to develop and analyze 3D printed structures based on a well-known composite known as β-Tricalcium Phosphate (TCP)- polylactic acid (PLA). There are some interesting aspects of this study. First, we developed 3D printable TCP-PLA composite filaments in-house, with high reproducibility, by a one-step process method using a single screw extruder. Second, we explored the physicochemical properties of the developed TCP-PLA composite filaments. Third, we investigated the effect of an FDM-based nozzle temperature of 190 °C, 200 °C, 210 °C, and 220 °C on the composite's crystallinity and rheological and mechanical properties. Results confirmed the successful development of constant-diameter TCP-PLA composite filaments with a homogeneous distribution of TCP particles in the PLA matrix. We observed that a higher nozzle temperature in the FDM process increased the crystallinity of the printed PLA and TCP-PLA structures. As a result, it also helped to enhance the mechanical properties of the printed structures. The rheological studies were performed in the same temperature range used in the actual FDM process, and results showed an improvement in rheological properties at higher nozzle temperatures. The bare polymer and the composite polymer-ceramic melts exhibited lower viscosity and less rigidity at higher nozzle temperatures, which resulted in enhancing the polymer melt flowability and interlayer bonding between the printed layers. Overall, our results confirmed that 3D printable TCP-PLA filaments could be made in-house, and optimization of the nozzle temperature is essential to developing 3D printed composite parts with favorable mechanical properties.