Mechanical performances of printed carbon fiber-reinforced PLA and PETG composites

In this study, the 3D printing technology was adopted to produce carbon fiber-reinforced polylactic acid and polyethylene terephthalate glycol composites. Fused deposition modeling process was conducted at different settings of printing parameters, specifically, raster angle, printing speed, and extrusion temperature. Each of the selected printing parameters has a key role in making the best-printed part in terms of layer-by-layer deposition quality and mechanical performance. To examine how these process parameters affect the behavior of the printed parts, tensile tests were performed and mechanical properties were assessed. It was reported that the printing orientation, characterized by the raster angle, can be identified as the determining factor to define the fracture mode. Composite parts printed with 0° raster angle, aligning with the tensile loading path, exhibit the highest levels of stiffness and ductility. Ductile and brittle fractures corresponding to 0° and 90° raster angles, respectively, were illustrated through optical observations of failure profiles. Furthermore, the tensile test indicates that higher printing speed leads to a significant deterioration in mechanical performances, notably reducing the stiffness of the printed structures. Scanning electron microscopy analysis confirmed that increasing the printing speed results in greater porosity within the structure, thereby weakening its mechanical strength. Regarding the extrusion temperature, it was shown that elevating it enhances the mechanical characteristics of the printed parts, particularly in terms of strength and ductility. Referring to microstructural observations, this outcome is attributed to the improved adhesion between the deposited layers and the reduction in porosity at high extrusion temperature.