Physical and mechanical properties of fused deposition modelling PLA/ carbon dot nanocomposites

This study explores the incorporation of carbon dots (CDs) into polylactic acid (PLA) filaments to improve their mechanical properties for fused deposition modelling (FDM). Known for their adjustable photoluminescence, high quantum yield, low toxicity, and biocompatibility, CDs are integrated into PLA at various concentrations (0.1, 0.3, 0.5, 0.7, 1.0, 3.0, and 5.0 wt%). Samples reinforced with 0.1-0.7 wt% CDs exhibit a tensile modulus ranging from 3.55 to 4.0 GPa and a tensile strength from 30 to 35 MPa. Meanwhile, those with 3.0 wt% achieve a higher tensile modulus (4.3 GPa) and strength (55 MPa), albeit with noted manufacturing challenges. The inclusion of 5.0 wt% CDs compromises the filament manufacturing process, resulting in a reduced tensile stress of 27 MPa, lower than pristine PLA, and exhibiting micro defects after 3D printing. Fluorescence analysis during tensile testing indicates that lower CD concentrations reduce fluorescence, while higher concentrations increase it, suggesting a correlation with the mechanical response. PLA reinforced with 0.5 wt% CDs not only offers improved mechanical properties but also facilitates easy manufacturing, showing promise for creating both solid and lattice 3D-printed products.