Toward Eco-functional Materials: PLA/PBAT–Graphite Filaments with Enhanced Mechanical and Electrical Performance

Abstract The growing demand for sustainable materials in additive manufacturing has driven the development of biodegradable polymeric composites with functional properties. In this study, filaments based on a PLA/PBAT blend reinforced with different graphite contents (2.5–12.5 wt%) were produced and systematically characterized. The composite filaments were fabricated via melt extrusion and processed through 3D printing to evaluate their performance in mechanical, electrical, and flammability tests. Optical microscopy revealed good dispersion of graphite, while tensile testing indicated that graphite addition enhanced stiffness without compromising structural integrity. Impedance spectroscopy and volumetric resistivity measurements demonstrated a progressive reduction in electrical resistance, with percolative behavior emerging above 7.5% graphite, enabling antistatic functionality. Thermal stability and flammability tests (UL 94 HB) confirmed adequate performance for low-risk electronic and packaging applications. Additionally, soil burial biodegradation tests were conducted to assess the environmental stability of the developed filaments. The results showed gradual mass loss and mechanical degradation over time, indicating that the PLA/PBAT-graphite composites maintain biodegradability despite the presence of the conductive filler. From an environmental perspective, the use of a PLA/PBAT matrix—biodegradable and partially derived from renewable resources—positions these composites as promising candidates for sustainable additive manufacturing. Overall, the results demonstrate that PLA/PBAT-graphite filaments combine multifunctional performance with environmentally responsible behavior, making them suitable for applications in protective packaging, electronic enclosures, and technical components requiring both performance and ecological balance.