A comprehensive analysis on the processing-structure-property relationships of FDM-based 3-D printed polyetheretherketone (PEEK) structures

Poly-ether-ether-ketone (PEEK) is a high-performance polymer with outstanding mechanical properties. Primarily, PEEK parts are developed by conventional manufacturing techniques that are complicated, expensive, and labor-intensive. In contrast, Fused Deposition Modeling (FDM), a form of 3-Dimensional (3D) printing, is a simple, cost-effective, and competent manufacturing technique that can efficiently develop design-specific structures. However, FDM of PEEK is challenging as PEEK has a high melting point and melt viscosity, and therefore it is critical to optimize the FDM process to yield PEEK parts with favorable mechanical properties. This paper explores the effect of various FDM parameters on the mechanical properties of 3D printed PEEK and establishes a processing-structure-property relationship for FDM-developed PEEK parts. Specifically, the influence of the nozzle, bedplate and chamber temperature, layer height, print speed, and annealing are analyzed on the mechanical properties (tensile, compressive, and flexural strengths) of 3D printed PEEK. Our results indicate nozzle and chamber temperature, layer height, and print speed are critical for developing robust PEEK structures. Moreover, annealing helps in achieving PEEK parts with excellent tensile (97.34 MPa), compressive (118.26 MPa), and flexural (104.65 MPa) strengths; notably, the strengths were comparable to those of injection molded parts. SEM and stereomicroscope images of the parts’ cross-sections and fracture surfaces provide interesting insight into the influence of 3D printing parameters on the parts’ mechanical properties at a microstructural level and suggest ways to minimize mechanical properties degradation. Overall, this study provides the essential knowledge required for developing FDM-based 3D printed design-specific PEEK parts with excellent mechanical properties.