Additive manufacturing and mechanical performance of short fiber reinforced PEEK (polyether ether ketone) thermoplastic composites in a vacuum environment

Abstract

Short fiber reinforced thermoplastic composites (SFRTC) have gained popularity in the material extrusion (MEX) method, which is an additive manufacturing (AM) technology, allowing for the simpler and more cost-effective production of polymer composites. However, parts produced using MEX 3D printing technology often exhibit poor mechanical properties and surface quality compared to products manufactured using injection molding, which is one of the main disadvantages of this method. Various methods are used to overcome these challenges, such as production in a vacuum environment, heat-based processes, ultrasonic vibrations, and others. The objective of this study was to achieve parts with lower porosity and improved mechanical properties when printed in a vacuum environment compared to an atmospheric environment. Additionally, an investigation into the optimization of printing parameters was conducted to determine the parameters that yield the highest mechanical properties. For this purpose, SFRTC parts were printed at different vacuum levels (0.5, 10, 100 mbar), and they were subjected to flexural tests to determine their mechanical properties. The results showed that the flexural stress and elastic modulus of the samples produced in a 0.5 mbar vacuum environment increased by 79.75% and 39.41%, respectively, compared to samples produced in an atmospheric environment. Furthermore, the cross-sectional images of the samples were examined using an optical microscope, revealing the lowest porosity in the samples printed in 0.5 mbar vacuum environment.