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 systemusing a nozzle-impregnation method. PLA filament and glass fiber tow were co-fed into the extruder, where fiber impregnationoccurred 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 slightlydecreased the onset degradation temperature of the matrix. Ignition loss measurements confirmed that fiber orientation had noeffect on fiber volume fraction (~12.5 vol.%). Tensile and flexural strengths increased significantly as fiber alignment approached0°, reaching 82.75 MPa and 48.04 MPa, respectively, while 90°-oriented samples showed the lowest values. Scanning ElectronMicroscope analysis revealed poor impregnation and interfacial bonding in off-axis configurations. Finite element simulationsshowed a strong correlation with experimental modulus values for both 0° and 90° orientations. Furthermore, increasing fibervolume fraction was found to enhance stiffness along the fiber axis, confirming the anisotropic nature of the material and em-phasizing the importance of fiber alignment. This study provides a scalable approach for tailoring mechanical performance inadditively manufactured continuous fiber composites.