Co-authors​ :

 Zaki ECHCHERKI (UNITED KINGDOM), Yasith Sanura PERERA (UNITED KINGDOM), Chamil ABEYKOON (UNITED KINGDOM) 

Over the years, 3D printing has gained wide popularity in rapid prototyping as a fast and less expensive alternative to traditional manufacturing techniques. Fused deposition modelling is one of the predominant 3D printing techniques, and polylactic acid (PLA) is a widely used polymeric material for producing 3D-printed parts under this technique. This study investigates the mechanical properties of 3D-printed PLA composites reinforced with milled carbon fibre (mCF) and graphene nanoplatelets (GNP). The composites were produced through melt blending using a twin-screw extruder with different filler fractions (i.e., 3 wt.%, 5 wt.%, 8 wt.%, 10 wt.%, and 15 wt.%) of mCF and GNP. 3D-printing filaments manufactured using the developed composites were used to produce 3D-printed specimens using the fused deposition modelling technique. During 3D printing, specimens were produced with three different raster angles (i.e., [0°], [45°], and [0°, 90°]) to evaluate their effect on the mechanical properties of the specimens. Under mechanical properties, the tensile and flexural properties of the specimens were evaluated. The results indicated that the addition of mCF and GNP fillers resulted in a significant improvement in both tensile and flexural properties of PLA, with mCF-reinforced PLA exhibiting better mechanical performance than GNP-reinforced PLA. In general, the tensile and flexural strength of the specimens were found to increase as the filler fraction increased. Moreover, the raster angle was also found to have a significant influence on the mechanical properties, where a raster angle of [0°] generally exhibited the highest tensile modulus and ultimate tensile strength, followed by raster angles of [0°, 90°] and [45°]. The highest tensile modulus was observed with the 15 wt.% GNP-reinforced PLA specimen printed with a raster angle of [0°], while the highest flexural modulus was reported by the 15 wt.% mCF-reinforced PLA specimen printed with a raster angle of [0°]. However, the strain at break was found to reduce with the increasing filler fraction, with the 3 wt.% mCF-reinforced PLA specimen printed with a raster angle of [0°] demonstrating the highest strain at break during both tensile and flexural testing. The findings of this study provide insight into how the filler type, filler percentage, and raster angle collectively affect the mechanical properties of PLA composites reinforced with carbon-based fillers and this should be invaluable for optimising and tailoring 3D-printed parts for a wide range of engineering applications.