Fabrication and multiscale analysis of chromium-filled PETG composites using material extrusion 3D printing: effects on thermal stability and mechanical properties

Purpose This study aims to fabricate a metal filler-based 3D-printed thermoplastic composite and investigate the effect of filler variation (0%, 2.5%, 5.0% and 7.5%) on thermal and mechanical properties. Design/methodology/approach PETG/Cr composite filaments were prepared via melt compounding and extrusion, followed by 3D printing of standardized specimens. The fabricated composites were evaluated for thermal behaviour, hardness (Shore D) and mechanical performance (tensile, flexural and compressive tests). Morphological analysis was conducted using optical microscopy and scanning electron microscopy. Findings The thermal analysis revealed that the addition of 5.0% Cr enhances interfacial bonding and improves thermal stability. PETG/5.0 Cr exhibited the highest tensile strength of 26.6 ± 1.33 MPa and a maximum load-bearing capacity of 426 ± 21.3 N, which is 13.19% higher than neat PETG. It also demonstrated superior flexural strength and modulus, along with the highest compressive strength, attributed to uniform Cr dispersion and improved interlayer adhesion. Overall, PETG/5.0 Cr showed the best combined thermal and mechanical performance among all compositions. Research limitations/implications The study focuses only on Cr contents up to 7.5 Wt.% and non-functional (non-biomedical) applications due to safety considerations. Long-term durability and environmental exposure were not explored. Originality/value To the best of the authors’ knowledge, this is the first known study to explore chromium (Cr) powder as a reinforcement in PETG for 3D printing. The results provide a novel approach to developing metal–polymer composites with tailored properties suitable for structural applications.