Fused granular fabrication of 2D material-reinforced polymer matrix composites: Effects on printing quality, mechanical properties, and tribological performance

Abstract

This study investigates the incorporation of 2D materials as solid lubricant filler, particularly MoS2 (in particle sizes of 1.5 and 12.5 μm), WS2, and Ti3C2Tx 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. All reinforced samples exhibit improved tensile strength and hardness, attributed primarily to enhanced interlayer adhesion from improved processability. Tribological performance is filler-specific: MXene and fine MoS2 achieve substantial reductions in coefficient of friction (up to 30%) and wear rate (up to 40%) via stable transfer film formation, while WS2 shows detrimental effects. The absence of clear concentration trends suggests a saturation limit in the dry mixing approach. This work supports the feasibility of the dry-mixing-FGF pathway for functionalized PLA composites under a fixed, preliminarily selected PLA processing baseline. At the same time, it highlights that systematic, material-specific FGF parameter optimization is required to distinguish intrinsic filler effects from parameter-dependent processing effects.