Development of graphite‐reinforced <scp>PLA</scp> / <scp>PBAT</scp> composite filaments

Abstract Additive manufacturing, particularly Fused Deposition Modeling (FDM), has been increasingly used due to its ability to create complex and personalized products. Besides, this processing technique can be performed with biodegradable polymers such as polylactic acid (PLA), a pioneer polymer in additive manufacturing profiles. Despite having a good set of desirable properties, the low impact strength and heat resistance of PLA limit its applications, which leads to studies on the use of different biodegradable polymers and additives. This study developed PLA/PBAT composite filaments with graphite (2.5%–12.5%) for FDM, evaluating their printability, microstructure, thermal, and mechanical properties. Morphological analysis showed homogeneous graphite dispersion, with the 7.5% graphite formulation (EC/7.5G) exhibiting optimal interlayer adhesion and minimal voids, yielding denser parts with superior printability. FTIR confirmed characteristic functional groups, while TGA indicated enhanced thermal stability, with the 12.5% graphite formulation (EC/12.5G) achieving the highest onset degradation temperature (T5 at 337.3°C). Tensile tests revealed the 2.5% graphite formulation (EC/2.5G) had the highest elongation at break (815.57%), though the elastic modulus decreased with increasing graphite content. DMA showed improved storage modulus at lower temperatures, with the 7.5% graphite formulation balancing stiffness and ductility. Printed parts demonstrated high dimensional accuracy and surface finish. The 7.5% graphite formulation (EC/7.5G) emerged as the optimal composition, offering enhanced thermal stability, mechanical performance, and printability, making it a promising candidate for sustainable, functional 3D printing applications. Highlights Novel composite filament developed by combining PLA, PBAT, and graphite. Graphite incorporation enhanced the thermal stability of the composite filaments. Sustainable and versatile filament alternative to conventional options. Printability that allows high dimensional regularity.