Keyu Chen

A novel ternary composite: fabrication, performance and application of expanded graphite/polyaniline/CoFe2O4 ferrite

Expanded graphite–polyaniline microparticles (EG/PANI), synthesized by the emulsion polymerization of aniline in the presence of expanded graphite, were coated with CoFe2O4 ferrite (CF) to form ternary composites of EG/PANI/CoFe2O4 (EG/PANI/CF). The phase composition, morphology, electrical and magnetic performances of the composites were characterized by means of modern measurement technology. The results indicated that the electrical and magnetic performances of the ternary composites were related to their composition, and were better than those of binary composites. The EG/PANI/CF composites with a mCF/mEG/PANI of 0.2 had the best conductivity (86.207 S cm−1) of all ternary composites. The EG/PANI/CF composites with a mCF/mEG/PANI of 0.8 at a thickness of 0.5 mm had the minimum reflection loss of −19.13 dB at 13.28 GHz and an available bandwidth of 5.94 GHz. Hence, the obtained composites had potential and valuable applications in microwave shielding and absorption fields.

A novel microwave absorber — BaAl 2 Fe 10 O 19 /poly( m -toluidine) composite: Preparation and electromagnetic properties

BaFe10Al2O19/poly(m-toluidine) (BFA/PMT) composites were synthesized by in-situ polymerization of m-toluidine in the presence of BaFe10Al2O19 particles. The structure, composition and morphology of the obtained samples were characterized by using XRD, FT-IR, UV-visible spectroscopy, SEM and TEM techniques. Their electrical conductivity, magnetic property and microwave absorbing property were measured by the four-probe meter, the vibrating sample magnetometer and the vector network analyzer, respectively. The results indicated that BFA particles were coated effectively by PMT polymer and some interactions between PMT and BFA particles existing in the composites. The conductivity of BFA/PMT composite is smaller than that of pure polymers and its saturation magnetization is a little smaller than that of pure BFA. The influence of the constitution and film thickness of absorbent on its microwave absorbing property is evident. The microwave absorbing properties of the BFA/PMT composites are better than those of pure BFA and PMT. When optimizing the mass rate of BFA/PMT to 0.3, the absorbent with 2 mm film thickness has the minimum reflection loss of −28.26 dB at approximate 14.24 GHz, and the maximum available bandwidth of 8.8 GHz, respectively. The results show that these composites can be used as advancing absorption and shielding materials due to their favorable microwave absorbing property.