Effect of magnetite nanoparticles on the structure, thermal and magnetic properties of the high-density polyethylene

High-density polyethylene (HDPE) nanocomposites with Fe3O4 nanoparticles were synthesized and analyzed for structural, thermal, and magnetic properties. X-ray diffraction showed an increase in Fe3O4 crystallite size from 5.14 nm to 12.01 nm, while the HDPE crystalline size decreased from 14 nm to 4.88 nm for HDPE + 3% Fe3O4 and HDPE + 40% Fe3O4, respectively. Thermogravimetric analysis showed improved thermal stability, with the onset temperature increasing from 243.78°C (HDPE) to 395.13°C (HDPE + 40% Fe3O4). Differential scanning calorimetry indicated a crystallinity rise from 44.45% to 51.95% (HDPE + 40% Fe3O4), while melting and crystallization temperatures remained near 104°C and 94°C, respectively. Magnetic characterization revealed that the saturation magnetization increased from 49.61 × 10−3 emu for HDPE +1% Fe3O4 to 52.98 × 10−3 emu for HDPE +10% Fe3O4, while the coercivity decreased from 17.76 G for HDPE + 5% Fe3O4 to 6.30 G for HDPE + 1% Fe3O4. This reduction in coercivity suggests a transition from a single-domain to a multi-domain state, likely due to nanoparticle aggregation at higher concentrations. These results demonstrate the potential of HDPE/Fe3O4 nanocomposites for thermally stable and magnetically tunable applications.