Effect of Fe₃O₄ nanoparticle loading on the mechanical and thermal properties of injection-molded PETG nanocomposites for smart functional applications

Abstract Magnetic nanoparticle-reinforced polymer nanocomposites have attracted considerable attention from researchers for their applications in advanced engineering and smart materials. However, systematic studies on injection-molded PETG/Fe 3 O 4 nanocomposites and their processing-structure-property relationships remain limited. In this research, polyethylene terephthalate glycol (PETG) mixed with Fe 3 O 4 nanoparticles (0.5-4 wt.%) was fabricated by injection molding to investigate the mechanical, thermal, structural, and morphological properties of the nanocomposites. This research explores a processing-structure-property correlation and determines an appropriate filler loading of 2 wt.%, which balances mechanical enhancement with nanoparticle agglomeration. Mechanical test findings indicated a substantial enhancement in strength and stiffness with rising Fe 3 O 4 content, maximum at an ideal loading of 2 wt.%, where the tensile strength attained 54.5 MPa and Young’s modulus elevated to 674.15 MPa, signifying a remarkable improvement relative to pristine PETG. Thermal characterization revealed enhanced thermal stability, as evidenced by an increase in the glass transition temperature from 86.5 ℃ to 91.5 ℃, and thermogravimetric analysis indicated a rise in the degradation onset temperature from 352 ℃ to 381 ℃. The heat deflection temperature increased to 56 ℃, indicating enhanced load-bearing capacity under thermal conditions. Laser flash study indicated that thermal diffusivity and conductivity increased with higher nanoparticle weight percentages. Morphological examination confirmed consistent nanoparticle distribution at reduced filler concentrations, whereas agglomeration occurred at elevated loadings of Fe 3 O 4 . XRD and FTIR measurements confirmed the effective integration of Fe₃O₄ nanoparticles without modifying the polymer’s chemical structure. The results demonstrate that PETG/Fe 3 O 4 nanocomposites exhibit markedly enhanced multifunctional capabilities, suggesting potential applications in smart structures, thermal management components, sensors, and other advanced additive manufacturing processes.