Filler size effect in graphite/paraffine wax composite on electromagnetic interference shielding performance
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pISSN: 0256-1115 eISSN: 1975-7220
INVITED REVIEW PAPER
INVITED REVIEW PAPER
Filler size effect in graphite/paraffine wax composite on electromagnetic interference shielding performance Sosan Hwang, Chae Lin Kim, Yongha Kim, Min Gyu Song, Jaewon Lee, Sung-Hyeon Baeck, Sang Eun Shim†, and Yingjie Qian† Department of Chemical Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, Korea (Received 13 November 2019 • Revised 29 February 2020 • Accepted 24 March 2020) AbstractGraphite exhibits electromagnetic wave attenuation and high electrical conductivity. In this study, we analyzed the electromagnetic interference shielding effectiveness (EMI SE) performance and electric conductivity of composites fabricated by varying the size (mean size: 6-100 m) of graphite fillers and explained resulting attributes through the relative permittivity and geometrical characteristics of the filler. When the graphite/paraffine wax composite was fabricated using large-sized graphite (KS150), the spacing between the graphite fillers became widened, enabling electromagnetic waves to leak through the gap. The analysis results indicated that KS150 graphite exhibited an EMI SE performance of under 10 dB when the filler content was 30 wt%. However, when the content was increased to 50 wt%, the EMI SE performance improved sharply to 40 dB. In contrast, when the composite was filled with small-sized graphite (KS6), having a high ratio of surface to volume, the EMI SE performance was greater than that with the largesized graphite at low loading. The results related to the EMI shielding performance of graphite-filled composites revealed that the size of the filler greatly affects the EMI SE. The composite using KS75 showed an EMI SE performance of 53.0 dB and electrical conductivity of 2,000 S/m. Keywords: Graphite, Electromagnetic Interference Shielding, Electrical Conductivity, Relative Permittivity, Geometrical Characteristics
which are the most conventional materials used for EMI shielding, suffer from easy-corrosion, high weight density, poor scratch resistance, and processing difficulty [8-11]. Meanwhile, the interest in conducting carbon-based fillers has been particularly elevated due to the difficulties in resolving the inherent problems of metalbased fillers as well as the demands for advanced EMI attenuating materials. Carbon materials are expected to exhibit high-performance EM wave attenuation due to their thermally activated carrier hopping associated with defect states [12-18]. Recently, several carbon-based materials such as carbon nanotube (CNT), carbon nanofiber (CNF), and graphene have been reported as alternatives for EMI shielding additives owing to their corrosion resistance and low density. Li et al. fabricated a reduced graphene oxide (rGO)/ polystyrene segregated composite having EMI shielding effectiveness (EMI SE) of 45 dB at only 3.47 vol% [19]. Wei et al. prepared a multifunctional material (CNT-graphene) that exhibits ultrahigh EMI shielding performance of an EMI SE of 47.5 dB in X-band at 1.6 m
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