Fused Granular Fabrication of 2D Material-Reinforced Polymer Matrix Composites: Effects on Printing Quality, Mechanical Properties, and Tribological Performance

This study investigates the incorporation of 2D materials as solid lubricant filler, particularly MoS ₂ (in particle sizes of 1.5 and 12.5 µm), WS ₂ , and Ti ₃ C ₂ T _x MXenes, into polylactic acid (PLA) for mechanically and tribologically enhanced polymer matrix composites (PMC) using a simplified feedstock preparation method. Thereby, dry powder-pellet mixing process followed by Fused Granular Fabrication (FGF) is employed to avoid filament extrusion, aiming for scalable and thermally efficient production. Mechanical and tribological performance is assessed across varying filler concentrations (0.5–1.5 wt.%). While all reinforced samples exhibit improved tensile strength and hardness, these effects are mainly attributed to enhanced interlayer adhesion due to improved processability. In contrast, tribological testing reveals that the fillers influenced wear and friction behavior via material-specific mechanisms. Notably, the 1.5 wt.% MXene and small-particle MoS ₂ composites achieve substantial reductions in coefficient of friction (up to 30%) and wear rate (up to 40%), attributed to the formation of stable, shearable transfer films. However, WS ₂ shows detrimental effects, likely due to particle agglomeration and poor film formation. The absence of clear trends with concentration indicates a saturation limit in the dry mixing approach. This work validates the dry-mixing-FGF pathway as a viable route for functionalized PLA composites but highlights the need for process optimization and filler-specific tailoring to unlock the full potential of 2D materials as tribo-fillers.