Preparation of the PBOPy/PPy/Fe3O4 composites with high microwave absorption performance and thermal stability

A microwave absorption composite is prepared by polypyrrole (PPy) coated Fe3O4 magnetic nano-particles and pyridine-based polybenzobisoxazole (PBOPy) by the means of solution blending. Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy-energy dispersive spectrometer, vibrating-sample magnetometry, and thermogravimetric analysis are employed to investigate properties of the prepared composites. Composites behave good thermal stability (high char yield above 60 wt%, 800 °C, in nitrogen). The magnetic saturation of PPy/Fe3O4 is 17.94 emu/g, and that of PBOPy/PPy/Fe3O4 composite is 0.36 emu/g. Vector network analyzer is used to measure electromagnetic parameters of PBOPy/PPy/Fe3O4 composite. Reflection losses (RL (dB)) are calculated in the frequency range of 2-18 GHz. PBOPy/PPy/Fe3O4 composite with 8 wt% PPy/Fe3O4 behaves a minimum RL value of −23.3 dB and below −10 dB in 11.6-13.84 GHz at the film thickness with 3.5 mm.