Effect of Fiber Orientation on the Properties of Continuous Glass Fiber Reinforced PLA Composites Produced via Nozzle‐Impregnation 3D Printing

ABSTRACT In this study, continuous glass fiber‐reinforced PLA composites were fabricated via a custom‐designed dual‐feed FDM system using a nozzle‐impregnation method. PLA filament and glass fiber tow were co‐fed into the extruder, where fiber impregnation occurred before deposition through a rounded steel nozzle. Specimens with fiber orientations of 0°, 0/90°, 90°, ±45°, and ±20° were printed using a 0.5 mm layer height and 2 mm line width. Thermogravimetric analysis revealed that fiber addition slightly decreased the onset degradation temperature of the matrix. Ignition loss measurements confirmed that fiber orientation had no effect on fiber volume fraction (~12.5 vol.%). Tensile and flexural strengths increased significantly as fiber alignment approached 0°, reaching 82.75 MPa and 48.04 MPa, respectively, while 90°‐oriented samples showed the lowest values. Scanning Electron Microscope analysis revealed poor impregnation and interfacial bonding in off‐axis configurations. Finite element simulations showed a strong correlation with experimental modulus values for both 0° and 90° orientations. Furthermore, increasing fiber volume fraction was found to enhance stiffness along the fiber axis, confirming the anisotropic nature of the material and emphasizing the importance of fiber alignment. This study provides a scalable approach for tailoring mechanical performance in additively manufactured continuous fiber composites.