Investigating the effects of printing temperatures and deposition on the compressive properties and density of 3D printed polyetheretherketone

Abstract

Polyetheretherketone (PEEK) is a biocompatible high-performance thermoplastic that can be processed through material extrusion (ME) additive manufacturing (AM) for load-bearing implant applications. In this work, density measurements and compression testing were used to investigate the relation between printing temperatures and deposition patterns of PEEK 3D printed samples. Different deposition patterns were tested with different nozzle and zone heater temperatures to observe how the heat input from the printing process influenced the deposition stability with different nozzle paths. Compression test results showed that samples with concentric-based deposition patterns resulted in higher compressive yield strength and modulus than the rectilinear samples. These results were correlated with the samples’ void contents estimated from density measurements. Both the highest 0.2% offset yield strength of 100.3 MPa and the highest modulus of 3.58 GPa were obtained with an interlayer offset deposition which resulted in reductions in estimated void contents between 48 and 72% in relation to concentric deposition. Different printing temperatures and deposition sequences were tested, where higher printing temperatures resulted in lower yield strength and stiffness. Alternating deposition between the outer and inner lines of the concentric pattern resulted in a reduction of about 43% in void contents and increased elastic modulus and yield strength from 3.12 to 3.40 GPa and 94.4 to 95.2 MPa respectively. The results from this work suggest that the relation between printing temperatures and deposition strategy for different print geometries plays a significant role in the ME-AM of PEEK for high-performance applications.