Thermistors Based on Polyethylene Composites with γ-Fe2O3/Multiwalled Carbon Nanotube Hybrid Fillers for Protection of Electronic Circuits

The objective of this research is to develop and characterize polyethylene composites with randomly and partially oriented hybrid filler (HF) based on multiwalled carbon nanotubes (MWCNTs) decorated with gamma iron (III) oxide (γ-Fe₂O₃) nanoparticles (Fe₂O₃/MWCNTs). The structure of Fe₂O₃/MWCNTs hybrid is determined by X-ray diffraction (XRD), Raman spectroscopy, and microscopy techniques (scanning electron microscopy–energy-dispersive X-ray spectroscopy, transmission electron microscopy). A low-density polyethylene (LDPE) matrix is filled with 5 and 10 vol% HF. The effect of external magnetic field on the distribution of Fe₂O₃/MWCNTs in LDPE composites comparing to filler distribution without magnetic field is studied. The XRD and differential scanning calorimetry results confirm an increasing trend in the degree of crystallinity of LDPE matrix with increasing HF content and as an additional result of magnetic field application. The presence of more ordered Fe₂O₃/MWCNT particles in the matrix has enhanced the nucleation effect for LDPE crystallization process in composites under magnetic field. The effect of magnetic treatment on thermal, electrical, and thermoresistive properties of HF-LDPE composites is studied. The highest thermoresistive response (723%) and fastest recovery are detected for the HF-LDPE composite with 10 vol% magnetically oriented filler with the perspective to be applied as a critical temperature resistor.