High-Density Polyethylene (HDPE) offers many possible uses in the field of biomedical, but using it successfully in 3D printing (additive manufacturing) has proven problematic due to challenges such as warping and printing instability during the printing process. In order to improve the ability to print HDPE successfully, this research explores creating an HDPE/nano-Hydroxyapatite (nHA) composite to enhance both the compressive performance of the material as well as its printability. Composite formulations consisting of pure HDPE and HDPE reinforced with 1, 3, and 5 wt.% nHA were prepared and compared with corresponding formulations containing 3 wt.% HDPE-g-MAH compatibilizer. The materials for each of these composite formulations were compounded using a twin-screw extruder into filaments, and then subsequently turned into pellets for further use in the printing of composite parts through the use of PioCreat G5 Ultra Pellet 3D Printing Technology. Results from compression testing indicate that pure HDPE has a compressive strength of approximately 9MPa, while the incorporation of 3 wt.% nHA resulted in the highest compressive strength of approximately 14.28 MPa, corresponding to an improvement of approximately 58.7% compared to pure HDPE. Developing a stable HDPE printing profile was accomplished through use of process optimization and customized print beds, showing how FGF technology can be effectively utilized to create high-quality HDPE biomedical composites that exhibit enhanced printability and compressive properties. In addition, the incorporation of HDPE-g-MAH with increased quantities of HDPE has also resulted in greater mechanical performance due to enhanced interfacial adhesion strength and improved surface area contact between both materials. However, excessive filler loading tended to cause clogging and/or agglomeration of filler particles thereby diminishing mechanical performance.

Keywords

HDPE composites, Hydroxyapatite (HA), 3D Printing, Fused Granulate Fabrication (FGF), Compressive strength, MAH compatibilizer, biomedical.