Processing–Structure–Property Relationship in Solvent‐Blended PLA ‐Graphite‐ PEG Filaments: Influence of Graphite Concentration

There has been an increasing demand for carbon allotropes‐based composites in 3D printing. Thus, synthesis of carbon allotrope‐polymer composite filaments is important for achieving consistent extrusion and reliable fabrication by fused filament fabrication (FFF). In this work, a solvent blending approach was used to prepare polylactic acid‐based composite filaments with graphite concentration varying up to 40 wt.%. A binary solvent consisting of dichloromethane and chloroform facilitates effective dispersion of graphite, while polyethylene glycol improved filament flexibility and printability. The extruded filament was evaluated for dimensional deviation, revealing reduced die swell with increase in filler loading. The thermal stability, crystallinity, and microstructural homogeneity of fabricated composite filaments were also investigated. Mechanical and thermomechanical analyses were further performed on 3D printed specimens to assess stiffness, strength, and viscoelastic behavior. Percolation threshold was reached at 20 wt.% graphite doping and is found to give optimal mechanical properties. An increase in graphite concentrations increased the thermal as well as the electrical conductivity. The results demonstrated that solvent blending enables effective incorporation of higher graphite concentrations while maintaining adequate processability and structural integrity for additive manufacturing applications in the domain of 4D printing of structures, polymeric sensors, and energy storage.