Pritom J. Bora

Lightweight Polyaniline-Cobalt Coated Fly Ash Cenosphere Composite Film for Electromagnetic Interference Shielding

Thermal power plant’s solid environmental waste fly ash cenosphere (FAC) is cobalt coated chemically and functionalized by in situ synthesis of polyaniline (PANI) under nitrogen atmosphere at −30 ± 2 °C and characterized by various techniques. The electromagnetic interference shielding effectiveness (EMI SE) of free standing PANI/Co-FAC (PCC) films prepared by solution casting indicates an appreciable shielding. The most effective average EMI SE of ~ 30 dB was obtained for 89 ± 3 μm thicker flexible film over the frequency range of 12.4-18 GHz (Ku-band). Mechanistically, EMI shielding due to absorption was found to be dominant. The obtained shielding effectiveness due to absorbance (SEA) of PCC film is nearly two times higher than PC film. The microwave conductivity (σ) of PCC film (157-184 Sm−1) is much higher than PC film (118-142 Sm−1). Moreover, the high EM attenuation constant (α) value of PCC film indicates excellent suitability of EMI shielding due to absorption.

Outstanding electromagnetic interference shielding effectiveness of polyvinylbutyral–polyaniline nanocomposite film

In this study, we studied the electromagnetic interference (EMI) shielding property of a solution processed polyvinylbutyral-polyaniline nanocomposite (PVBPN) film in the X-band (8.2-12.4 GHz) and Ku-band (12.4-18 GHz) frequency. The polyaniline nanofibers were chemically synthesized at -30 +/- 2 degrees C and characterized by various techniques. The optimally prepared, free standing PVBPN film (sandwiched 0.78 +/- 0.02 mm) shows an outstanding EMI shielding effectiveness in the X-band and Ku-band frequency. In the X-band, similar to 26 dB EMI shielding effectiveness (shielding due to absorption SEA similar to 21 dB and shielding due to reflection SER similar to 5 dB) was obtained and was found to increase similar to 30 dB (SEA is similar to 26 dB and SER similar to 4 dB) for the Ku-band. The enhancement of shield conductivity, dielectric loss and EM attenuation constant with frequency results in the excellent EMI shielding property of the PVBPN film.

Influence of MnO2 decorated Fe nano cauliflowers on microwave absorption and impedance matching of polyvinylbutyral (PVB) matrix

In this work, a promising, polyvinyl butryl (PVB)-MnO2 decorated Fe composite was synthesised and microwave absorption properties were studied for the most important frequency ranges i.e., X-band (8.2-12.4 GHz) and Ku-band (12.4-18 GHz). The microwave absorption of Fe nano cauliflower structure can be enhanced by MnO2 nanofiber coating. 10 wt% Fe-MnO2 nano cauliflower loaded PVB composite films (2 mm thick) shows an appreciable increase in microwave absorption properties. In X-band, the reflection loss (RL) of this composite decreases almost linearly to -7.5 dB, whereas in the Ku-band the minimum RL was found to be -15.7 dB at 14.7 GHz. Here it was observed that impedance matching is the primarily important factor responsible for enhanced microwave absorption. Further, enhancement of EM-attenuation constant (a), dielectrics, scattering attenuation also bolsters the obtained results. This polymer composite can be considered as a novel microwave absorbing coating material.

Novel poly (vinyl butyral) (PVB) /polyaniline-cenosphere composite film for EMI shielding

in-situ synthesis ofpolyaniline (PANI)/fly ash cenosphere (hollow microspheres) composite was carried out under nitrogen atmosphere at -30 +/- 2 degrees C. Investigated electromagnetic shielding effectiveness (EMI SE) of ree standing PVB/PANI-cenosphere (PVBPC) composite films prepared by solution casting indicates an appreciable shielding. The most effective EMI SE of 30.3 dB was obtained for 197 +/- 3 mu m thicker flexible film over the frequency range 8.2-12.4 GHz. Mechanistically, absorption was found to be dominant. The obtained shielding effectiveness due to absorbance (SEA) of PVBPC film is more than two times higher than PVB/PAN I composite film. In the presence of hollow PAN I-cenospheres in PVB matrix the time average power of incident electromagnetic wave decreases resulting in an increase of absorbance.

Lightweight Microwave Absorber from Industrial Waste Fly Ash Cenosphere

The present investigation demonstrates the microwave absorption property of magnetic alloy nanoparticle-coated solid industrial waste fly ash cenosphere (FAC). Here, cobalt iron (CoFe) alloy nanoparticles were chemically coated over FAC, and a composite matrix was made from these particles using epoxy resin. Surface morphology of both CoFe-FAC and epoxy/CoFe-FAC composites was studied. The dielectric loss and reflection loss (RL) of this polymer composite were studied by rectangular waveguide transmission line method. A 10 wt% CoFe-FAC-loaded epoxy composite shows an excellent microwave absorption property in the X-band (8.2–12.4 GHz). The most effective RL value −29 dB was obtained for epoxy/CoFe-FAC composite, whereas a pristine epoxy/FAC composite combination exhibits −12 dB RL under same condition. The thickness dependency of RL was also studied, and it indicates that the standard −10 dB RL can be obtained for epoxy/CoFe-FAC composite at a minimum thickness of 2 mm. The enhancement of dielectric loss, EM attenuation constant and loss factor with frequency was found to be responsible for the obtained RL.