Abstract:In this study, the microwave-absorption characteristics of multi-layered radar-absorbing structures (RASs) were investigated. Electrical-grade glass (e-glass)/epoxy composites containing modified multi-walled carbon nanotubes (MWCNTs) were fabricated. The poly aniline (PANI) coated MWCNTs was obtained by in-situ polymerisation of aniline in the presence of MWCNTs. The PANI-coated MWCNTs (PCNTs) were then used as reinforcements in the polymer matrix, and their morphologies, microstructures, thermal stabilities,… Show more
“…The formation of ferrite is further confirmed by EDAX analysis which showed the presence of Mn, Zn, Fe, O elements present in the nano ferrite powder synthesised. Thus, the EDAX result suggests the formation of spinel phase Mn 0.5 Zn 0.5 Fe 2 O 4 nano particles [68]. Figure 4 (a) SEM image of MnZn ferrite nano particle and (b).…”
Section: Resultsmentioning
confidence: 99%
“…FTIR spectra are used to monitor the structural changes of the nano ferrite particles from 400 to 4000 cm −1 , as shown in Figure 3. The characteristic bands at 484 and 567 cm −1 corresponding to the interactions between the metal ions and oxygen ions occupying the tetra and octahedral positions in the spinel crystal lattice of the ferrite [63] and the bands at approximately 3433, 2323, and 1629 cm −1 can be ascribed to the N-H, C-H, and C = O stretching vibrations, respectively [68]. The vibrations at 1629 cm −1 could be owing to the absorption bands originating from the carboxyl groups from the post combustion residue [28].…”
In this study, radar absorbing structures (RAS) containing MnZn ferrite/Polyaniline (Pani) coated multi-walled carbon nanotubes (PCNTs) were fabricated to observe their microwave absorption behaviour in X-band frequency range. The ferrite nano particles were prepared by sol-gel auto combustion method. The prepared nano ferrite powder was characterised using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). RAS filled with nano ferrite particles and PCNTs in different concentrations were fabricated to investigate their microwave absorption behaviour using a vector network analyzer (VNA) and later reflection loss (RL) is estimated. The minimum RL loss estimated for double-layered RAS are found to be −29.06 dB at 10.8 GHz for ferrite fixed samples and −33.07 dB at 9.6 GHz for PCNT fixed samples. Further, their mechanical behaviour is examined.
“…The formation of ferrite is further confirmed by EDAX analysis which showed the presence of Mn, Zn, Fe, O elements present in the nano ferrite powder synthesised. Thus, the EDAX result suggests the formation of spinel phase Mn 0.5 Zn 0.5 Fe 2 O 4 nano particles [68]. Figure 4 (a) SEM image of MnZn ferrite nano particle and (b).…”
Section: Resultsmentioning
confidence: 99%
“…FTIR spectra are used to monitor the structural changes of the nano ferrite particles from 400 to 4000 cm −1 , as shown in Figure 3. The characteristic bands at 484 and 567 cm −1 corresponding to the interactions between the metal ions and oxygen ions occupying the tetra and octahedral positions in the spinel crystal lattice of the ferrite [63] and the bands at approximately 3433, 2323, and 1629 cm −1 can be ascribed to the N-H, C-H, and C = O stretching vibrations, respectively [68]. The vibrations at 1629 cm −1 could be owing to the absorption bands originating from the carboxyl groups from the post combustion residue [28].…”
In this study, radar absorbing structures (RAS) containing MnZn ferrite/Polyaniline (Pani) coated multi-walled carbon nanotubes (PCNTs) were fabricated to observe their microwave absorption behaviour in X-band frequency range. The ferrite nano particles were prepared by sol-gel auto combustion method. The prepared nano ferrite powder was characterised using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). RAS filled with nano ferrite particles and PCNTs in different concentrations were fabricated to investigate their microwave absorption behaviour using a vector network analyzer (VNA) and later reflection loss (RL) is estimated. The minimum RL loss estimated for double-layered RAS are found to be −29.06 dB at 10.8 GHz for ferrite fixed samples and −33.07 dB at 9.6 GHz for PCNT fixed samples. Further, their mechanical behaviour is examined.
“…Usually, researchers use a combination of simulation and experimentation to comprehensively investigate the absorbing properties of absorbing composite [34][35][36]. They obtain simulation results by testing the electromagnetic parameters of the absorbents and experimental results by preparing samples, mixing the absorbent with resin and short-cut fiber [37].…”
In this paper, the glass-fiber-fabric-reinforced resin-based absorbing composites were prepared, and their microwave-absorbing properties were studied via simulation and experiment. The simulation results show that the absorption bandwidth of the absorbing material can cover the X\C\S band, respectively, at different thicknesses. The minimum reflection loss (RL) of the composite with a thickness of 2.2 mm is −27.4 dB at 5.95 GHz. However, the experiment results are quite different from those of the simulation. The metallographic results indicate that it is the change of the mass fraction of the absorbents in the composites after curing that causes the difference. According to the metallographic results, three shape approximation methods were proposed to calculate the real mass ratio of the absorbents in the composites, namely, parallelogram approximation, bows approximation, and elliptical approximation. Meanwhile, the structural parameter Kf was introduced to optimize the calculation results. The electromagnetic parameters of the material based on the calculation results were measured, and the results show that the simulation results obtained via bow approximation have a better coincidence to the experiment results, and the mass ratio of the absorbent raises by around 9.95%, which lays a foundation for the subsequent design of microwave-absorbing composites.
“…Even though CPs are considered to be promising electrode material individually, they suffer from low solubility, poor processability and low cyclic stability towards repeated oxidation and reduction cycle [22]. There have been extensive studies to counter the drawbacks associated with CPs and some of them, focussing on the synthesis of composites with metal oxides [3], carbon materials [1,23], metal nano-particles [4,14,24], co-polymerisation [25][26][27], using surfactants [28] and blending CPs with hydrogels and other polymer matrices [29].…”
Composites of polyaniline and polyvinyl alcohol were prepared through an in-situ polymerisation of aniline using ethanol as a coagulating agent and characterised for their applicability as supercapacitor electrode material. The thermally stable composites afford moderately high electrical conductivity. Composite with 0.03 mol aniline exhibited a high electrical conductivity of 0.371 × 10 −2 S/cm. The variation in electrical conductivity with an increase in aniline content is consistent with the band gap energies estimated from electronic spectra and IR drop. SEM analysis confirms coral-like nanowires of polyaniline (PANI) grown within the polyvinyl alcohol matrix. Cyclic voltametric studies revealed that the composites are highly electroactive as they allow easy diffusion of ions through the nanowires of PANI for efficient electrochemical reaction. The composite with 0.03 mol aniline has a superior specific capacitance of 302 Fg −1 at a scan rate of 5 mV/s. The composite exhibited a maximum energy density of 41.94 Whkg −1 and excellent stability even after storage of 18 months in ambient condition with 83.3% capacitance retention.
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