Mechanical and electrical properties of additive manufactured high-performance continuous glass fiber reinforced PEEK composites

This work aims to examine the additive manufacturing process, mechanical properties and electrical properties of continuous glass fiber-reinforced PEEK composites (CGFRPCs). A dual-stage heating nozzle with a preheating function is designed to promote the melt of filaments and then enhance the mechanical properties of finished specimens because of the low thermal conductivity of continuous glass fiber composites. The influence of traction speed on the morphology and mechanical properties of the composite filaments in preparation is first examined to obtain high-strength composite filaments. Additionally, the influence of preheating temperature on the heating effect of the filament and the evolution of the temperature field of the filament during the heating process are analyzed via thermal imaging and finite element approaches. Based on the printing device with a dual-stage heating nozzle, the cuboid-shaped tensile, flexural, interlaminar shear, and impact specimens with zero raster angles are also prepared and tested, and the influences of preheating temperature, printing speed, filament traction speed, hatch spacing, and fiber content on their strengths are discussed. Finally, the ring and cuboid-shaped samples are printed with parameters having better strength, and their electrical properties at various temperatures and frequency bands are tested by the probe, airline, and waveguide methods. The obtained results reveal that a lower traction speed is beneficial to improving the fiber dispersion in filaments, and the roundness and strength of the filaments. Preheating is also helpful to enhance the tensile and flexural strengths of the composite specimens, and the maximum strengths are obtained at a preheating temperature of 405 °C and printing speed of 1.5 mm/s, with an increase of 3.5% and 25.84%, respectively, compared with the no-preheated case. By process optimization, the tensile, flexural, interlaminar shear, and impact strengths of the specimens in order reach 524.33 MPa, 598.57 MPa, 46.28 MPa, and 173.91 kJ/m².