Extrusion-based additive manufacturing of PEEK for biomedical applications

There has been a trend in recent years to develop polyetheretherketone (PEEK)-based medical devices due to the excellent cell biocompatibility and desirable mechanical properties of PEEK, which has elastic modulus comparable to cortical bone. Different manufacturing techniques such as injection moulding, particulate leaching, compression moulding, and selective laser sintering (SLS) have been used to produce porous PEEK for biomedical applications. Despite a large number of publications on extrusion-based additive manufacturing (AM) of porous structures using various materials, there have been very few general reports on extrusion AM of low quality small PEEK parts without defects such as warpage and delamination and no further assessment of mechanical properties. Successful low-cost 3D printing of PEEK structures using filament-based extrusion AM process is reported in this paper for the first time. Hot extrusion head design, extrusion temperature, and ambient temperature were identified as important factors need to be taken into consideration for printing PEEK structures without warpage, delamination, and polymer degradation. Compression and tensile tests were conducted to investigate mechanical properties of these new 3D printed PEEK structures. The air gap between infill pattern and entrapped micro-bubbles inside filaments were identified as the main source of mechanical properties reduction. In addition, three-point flexural test was performed on the 3D printed PEEK and compared with flexural specimens printed using other AM materials and techniques.