Graphene-reinforced PETG composites: microstructural insights and mechanical evaluation using fused deposition modelling

Abstract This study reports on the development of a Polyethylene Terephthalate Glycol (PETG) composite incorporating graphene material, aiming to enhance microstructural and mechanical performance without compromising processability. The hybrid functional material demonstrates significantly improved tensile strength, load-bearing capacity, and fracture behaviour. Using Fused Deposition Modeling (FDM), composites were fabricated with varying graphene content (0.02, 0.2, and 0.4 wt%), nozzle temperatures (245 °C, 255 °C, and 265 °C), and build orientations (H1, H2, V1). The tensile testing results indicate that optimized parameters, particularly higher temperatures and horizontal orientations, lead to superior mechanical properties. The highest tensile strength of 45.1 MPa was achieved at 0.2 wt% graphene, H2 orientation, and 265 °C, showing a 129% improvement over the lowest value. Virgin PETG exhibited typical thermoplastic behaviour with 55–60 MPa strength and good ductility. Horizontal orientations (H1, H2) consistently outperformed vertical (V1), offering up to ~100% higher strength due to better interlayer bonding. Graphene reinforcement beyond 0.2 wt% notably enhances mechanical performance, strongly influenced by temperature and orientation. In addition, the coarse, fibrous fracture surface confirms ductile failure with good toughness retention in PETG/graphene composites. While GNPs were generally well-dispersed, moderate interfacial adhesion and some agglomeration may limit load transfer and strength.