• Title/Summary/Keyword: Magnetic composites

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The Functionalization and Preparation Methods of Carbon Nanotube-Polymer Composites: A Review (탄소나노튜브-폴리머 복합체의 기능화와 제조방법)

  • Oh, Won-Chun;Ko, Weon-Bae;Zhang, Feng-Jun
    • Elastomers and Composites
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    • v.45 no.2
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    • pp.80-86
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    • 2010

  • Carbon nanotubes (CNTs) exhibit excellent mechanical, electrical, and magnetic properties as well as nanometer scale diameter and high aspect ratio, which make them an ideal reinforcing agent for high strength polymer composites. The functionalized CNTs are believed to be very promising in the fields such as preparation of functional and composite materials. CNT-Polymer composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. However, since CNTs usually form stabilized bundles due to Van der Waals interactions, are extremely difficult to disperse and align in a polymer matrix. The biggest issues in the preparation of CNT-reinforced composites reside in efficient dispersion of CNTs into a polymer matrix, and the alignment and control of the CNTs in the matrix. There are several methods for the dispersion of nanotubes in the polymer matrix such as solution mixing, bulk mixing, melt mixing, in-situ polymerization and chemical functionalization of the carbon nanotubes, etc. These methods and preparation of high performance CNT-polymer composites are described in this review.

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Characteristics of Electromagnetic Wave Absorber Sheet for 2.4 GHz Wireless Communication Frequency Bands Using Fe Based Alloy Soft Magnetic Metal Powder (Fe-계 연자성 금속분말을 이용한 2.4 GHz 대역 무선통신용 전파 흡수체의 특성 평가)

  • Kim, ByeongCheol;Seo, ManCheol;Yun, Yeochun
    • Korean Journal of Materials Research
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    • v.29 no.9
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    • pp.532-541
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    • 2019

  • Information and communication technologies are developing rapidly as IC chip size becomes smaller and information processing becomes faster. With this development, digital circuit technology is being widely applied to mobile phones, wireless LANs, mobile terminals, and digital communications, in which high frequency range of GHz is used. In high-density electronic circuits, issues of noise and EMC(Electro-Magnetic Compatibility) arising from cross talk between interconnects or devices should be solved. In this study, sheet-type electromagnetic wave absorbers that cause electromagnetic wave attenuation are fabricated using composites based on soft magnetic metal powder and silicon rubber to solve the problem of electromagnetic waves generated in wireless communication products operating at the frequency range of 2.4 GHz. Sendust(Fe-Si-Al) and carbonyl iron(Fe-C) were used as soft magnetic metals, and their concentrations and sheet thicknesses were varied. Using soft magnetic metal powder, a sheet is fabricated to exhibit maximum electromagnetic attenuation in the target frequency band, and a value of 34.2dB(99.9 % absorption) is achieved at the target frequency.

  • https://doi.org/10.3740/MRSK.2019.29.9.532 인용 PDF KSCI