Enhancing Kevlar Fiber–Matrix Adhesion in <scp>3D</scp> Printed Composites via Nd: <scp>YAG</scp> Laser Treatment

ABSTRACT The highest rates of landfilling of waste poly(aramid) fabric (PAF) are reported in European countries, where only a limited amount is reused or recycled. In contrast, waste poly(para‐aramid) fiber, known as Kevlar, is converted into environmentally friendly and cost‐efficient functional composites that facilitate recycling. Kevlar fiber‐reinforced plastics (KFRPs) composite materials are distinguished by their high specific strength and stiffness. The designation “Kevlar” pertains to the extended molecular structures originating from poly para‐phenylene terephthalamide, which exhibit considerable alignment along the fiber axis due to strong interchain covalent bonds, while showing comparatively weaker hydrogen bonding in the perpendicular orientation, thus resulting in anisotropic characteristics. Researchers are looking at a variety of modification techniques, including oxidation, plasma treatment, x‐ray irradiation, and monomer grafting. The use of Nd:YaG laser treatment, which alters surface roughness and free energy to enhance the adhesion between discarded Aramid fibers and an additively manufactured matrix, is one significant area of study. In this work, ABS/Kevlar sandwich composites covered by direct ink writing (DIW) and made using fused deposition modeling (FDM) were investigated for their mechanical properties and surface morphology. This work carefully assessed the effects of several laser parameters, particularly energy levels (10 and 20 mJ), pulse frequencies (5 and 10 Hz), and contact periods. Characterization methods include field emission scanning electron microscopy (FESEM), Izod impact testing, tensile testing, and interlaminar shear strength (ILSS) measurements used to evaluate energy absorption, modulus, strength, and interfacial bonding. The findings showed that from sample F10P10 (A2) to sample F20P20 (B1), increasing laser power and exposure time resulted in improvements in tensile strength of 31.13%, ILSS of 29.03%, and Izod impact resistance of 31.95%. These results demonstrate how important laser processing settings are for improving the functionality of composite materials that are 3D printed.