Mechanical, thermal, and microstructural properties of FFF-printed graphene-reinforced PLA composites

This study investigates the mechanical, thermal, and microstructural properties of pure PLA and 0.5 wt% graphene-reinforced PLA composites fabricated by fused fillament fabrication. Under optimized parameters of 0.16 mm layer height, 200 °C, and 90 mm/s, neat PLA exhibited an ultimate tensile strength of 28.86 MPa. The addition of graphene increased the ultimate tensile strength to 41 MPa, representing a 41% improvement, achieved at 0.18 mm layer height, 220 °C, and 60 mm/s. Flexural strength followed a similar trend, while impact strength remained at 2.5 kJ/m² but with significantly improved consistency. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed uniform graphene dispersion and good interfacial bonding. Differential scanning calorimetry analysis revealed a slight increase in glass transition temperature from approximately 59 °C to 60.04 °C, reduced crystallinity with crystallization enthalpy changing from −35.91 to −14.07 J/g, and a lower melting point decreasing from 177.9 °C to 154.35 °C, indicating restricted polymer chain mobility. Fourier-transform infrared spectroscopy suggested molecular interactions between PLA and graphene. These enhanced properties expand the potential of PLA-graphene composites for engineering applications.