Processing–property relationships in 3D printed PLA/graphene composites for synergistic enhancement of mechanical strength and electrical conductivity

The integration of nanofillers such as graphene into polylactic acid (PLA) has attracted significant attention for enhancing the performance of fused filament fabricated (FFF) components. Despite these advances, the electromechanical properties of PLA–graphene composites remain insufficient for many functional applications, particularly in electronics and other industrial sectors. To address this limitation, the present study investigates how a broad range of fused filament fabrication (FFF) process parameters, including print orientation, raster angle, infill pattern, layer height, infill density, and printing speed, collectively influence the electromechanical performance of PLA-graphene composites. Using a Taguchi L18 orthogonal array, the study systematically evaluates and optimizes tensile, flexural, impact, and electrical conductance responses. The results demonstrate that a cubic infill pattern yields superior mechanical and conductive properties. At the same time, flat printing orientation enhances tensile and impact strength, and on-edge orientation improves impact strength and conductance. Optimal infill densities of 70 %, 80 %, and 90 % were identified for maximizing tensile, flexural, and impact strengths, respectively. The optimized specimen achieved a tensile strength of 51.91 MPa, flexural strength of 62.6 MPa, impact strength of 59.38 J/m, and conductance of 19.12 μS. Grey relational analysis further identified the most effective parameter combination for simultaneous multi-response optimization. Overall, this research provides a comprehensive understanding of process–property relationships in PLA–graphene composites and establishes a pathway for fabricating multifunctional FFF parts with improved electromechanical performance.