Rajeev Kuma; Saroj Kumari;S. Das; D.P. Mondal; Shyam Birla; Amit Vishwakarma; Anisha Chaudhary
Abstract
In the present investigation, influence of micronsize cenosphere particles derived from fly ash on the properties of aluminum composites was investigated. Aluminum-cenosphere (AC) composite was fabricated by modified stir casting technique. The mechanical and electromagnetic interference (EMI) shielding ...
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In the present investigation, influence of micronsize cenosphere particles derived from fly ash on the properties of aluminum composites was investigated. Aluminum-cenosphere (AC) composite was fabricated by modified stir casting technique. The mechanical and electromagnetic interference (EMI) shielding properties of AC composites were investigated. The obtained composites with cenosphere (+100 µm) loading demonstrate the excellent compressive strength of 251.3 MPa. This enhancement is due to the smaller size of cenosphere size provides the finer surface of the cenosphere. The addition of cenosphere in aluminum matrix improved dielectric and microwave absorption properties of composites in X band frequency region (8.2-12.4 GHz). The AC composites possess good EMI shielding effectiveness of -32.7 to -44.3 dB with 30% loading of cenosphere with various sizes (+212, +150 and +100 µm). The incorporation of lower size cenosphere (+100µm) in aluminum matrix significantly increases the interfacial polarization which leads to a higher absorption EMI shielding effectiveness (SE) of -31.1 dB at 2.0 mm thickness. This technique is very simple, economical and highly reproducible, which may facilitate the commercialization of such composite and it can be used as microwave absorbing materials in defense and aerospace applications.
Jyoti Srivastava; Pawan Kumar Khanna; Priyesh V More; Neha Singh
Abstract
Silver/Polypyrrole/Polyvinylalcohol polymer nanocomposite films were prepared by in-situ polymerization of pyrrole with variable loading of silver nanoparticles from 0.5-10%. The conducting films prepared from the nanocomposite solution were flexible, light weight, thermally stable and showed high ...
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Silver/Polypyrrole/Polyvinylalcohol polymer nanocomposite films were prepared by in-situ polymerization of pyrrole with variable loading of silver nanoparticles from 0.5-10%. The conducting films prepared from the nanocomposite solution were flexible, light weight, thermally stable and showed high hydrophobicity/hydrophilicity ratio. X-Ray diffraction measurement showed formation of fcc silver nanoparticles with particle size in the range of about 20-40 nm. UV-visible spectroscopy revealed the characteristic bands of Ag nanoparticles and polypyrrole in the so obtained co-polymer nanocomposites. The SEM studies of the nanocomposite films showed that the filler material was well conjugated in the Polymer matrix. Vector Network Analyser showed Electromagnetic shielding efficiency (EMI) efficiency as high as -35 dB in the X band (8-12GHz).
M. Farukh;S.K.Dhawan
Abstract
The paper reports the designing of PEDOT grafted PU foam by in-situ emulsion polymerization of ethylene dioxy thiophene (EDOT) on polyurethane foam (PU) containing multi-walled carbon nanotube (MWCNT) and by coating PEDOT on PU foam and to study their antistatic and electromagnetic shielding behavior. ...
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The paper reports the designing of PEDOT grafted PU foam by in-situ emulsion polymerization of ethylene dioxy thiophene (EDOT) on polyurethane foam (PU) containing multi-walled carbon nanotube (MWCNT) and by coating PEDOT on PU foam and to study their antistatic and electromagnetic shielding behavior. Static decay time measurements reveal that PEDOT grafted PU foam shows static decay time ranging from 0.17 sec to 0.75 sec on going down from 5000 v to 500 volts. EMI shielding measurement of the foam in Ku-band shows a shielding attenuation of 8-10 dB which indicates that that the foam can find applications as antistatic encapsulation material in electronic packaging of high tech equipments. SEM studies of the foam shows a uniform coating of PEDOT on PU foam leading to better conductivity of the conducting foam which accounts for its better anti-static properties.
Rakesh Kumar; Seema Joon; Avanish P. Singh; Brij P. Singh; S. K. Dhawan
Abstract
In response to the striking research activity and publications in fabrication of multifunctional materials, the present work is an attempt to fabricate processible composite sheets of poly (o-anisidine)-carbon fiber (PoACF) by a facile, low cost method and find their use in electromagnetic interference ...
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In response to the striking research activity and publications in fabrication of multifunctional materials, the present work is an attempt to fabricate processible composite sheets of poly (o-anisidine)-carbon fiber (PoACF) by a facile, low cost method and find their use in electromagnetic interference (EMI) shielding in X-band (8.2-12.4 GHz). PoACF composite is synthesized by in-Situ oxidative emulsion polymerization and transformed into thin sheets by compression molding technique using different ratio of phenolic novolac resin as a binder. The prepared PoACF composites and sheets are characterized by SEM, TGA, UV-vis, & FT-IR techniques. PoACF sheets have conductivity of the order of 10 -3 to 10 -1 S/cm and maximum shielding effectiveness of 32.57 dB at 4 mm thickness. These sheets have flexural strength between 18.82 to 41.28 MPa. The sheets of PoACF composite have sufficient thermal as well as mechanical stability and may be accepted as an economical material for EMI shielding application.
Pradeep Sambyal; Avanish Pratap Singh; Meenakshi Verma; Ankit Gupta; Bhanu Pratap Singh; S.K. Dhawan
Abstract
Utilization of flyash which is produced at large scale in coal based thermal power plant is a challenge. In this regard, our investigation provides distinctive way of utilizing flyash for designing and preparing high-performance EMI shielding materials. Herein, we report synthesis and characterization ...
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Utilization of flyash which is produced at large scale in coal based thermal power plant is a challenge. In this regard, our investigation provides distinctive way of utilizing flyash for designing and preparing high-performance EMI shielding materials. Herein, we report synthesis and characterization of multiwalled carbon nanotubes (MWCNT) based multiphase composites. The multiphase composites were synthesized by in-situ co-precipitation with conductive filler (MWCNT) and magnetic filler (Ferrofluid). Scanning electron microscopy results confirm the presence of fly ash particles covered with Ferrofluid nanoparticles along with MWCNTs. Multiphase composites show total shielding effectiveness of 48 dB (>99.998 % attenuation) in the Ku-band (12.4–18 GHz) frequency range. The electromagnetic attributes, dielectric and permeability parameters have been calculated from the measured scattering parameters (S11, S22, S12, S21) using the Nicolson–Ross–Weir algorithm. The synthesized multiphase composites were characterized using XRD, FTIR, VSM and SEM. The results suggested that the MPC composites showed great potential as a radar absorbing material.
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