%0 Journal Article
%T Permittivity and Electromagnetic Interference Shielding Investigations of Activated Charcoal Loaded Acrylic Coating Compositions
%A Sharief ud Din Khan
%A Manju Arora
%A M. A. Wahab
%A Parveen Saini
%J Journal of Polymers
%D 2014
%R 10.1155/2014/193058
%X Acrylic resin (AR) based electromagnetic interference (EMI) shielding composites have been prepared by incorporation of up to 30£¿wt% activated charcoal (AC) in AR matrix. These composites have been characterized by XRD, Raman spectroscopy, scanning electron microscopy, dielectric, and EMI shielding measurement techniques. XRD patterns and Raman studies confirm the incorporation of AC particles inside AR matrix and suggest possible interactions between phases. The SEM images show that incorporation of AC particles leads to systematic change in the morphology of composites especially the formation of porous structure. The dielectric measurements show that 30£¿wt% AC loading composite display higher relative permittivity value (~79) compared to pristine AR (~5). Further, the porous structure, electrical conductivity, and permittivity value contribute towards EMI shielding effectiveness value of £¿36£¿dB (attenuation of >99.9% of incident radiation) for these composites, thereby demonstrating their suitability for making efficient EMI shielding coatings. 1. Introduction Electromagnetic (EM) interference (EMI) is an offshoot of explosive growth of electronics and telecommunication in the modern society [1¨C3]. The EMI among electronic instruments/appliances may lead to degradation of device performance and may even adversely affect human health [4, 5]. Due to possible hazards of EMI only, the use of EM wave receipting/emitting electronic gadgets is prohibited inside sensitive zones, for example, during flight or inside hospital¡¯s ICUs [1, 5, 6]. Therefore, systematic strategies and suitable counter measures are essential to prevent/suppress EMI so as to ensure uninterrupted performance of appliances [1¨C9]. The primary mechanism of shielding is based on reflection and the material used for shielding by reflection requires mobile charge carriers; that is, shield should have conducting property [9, 10]. Consequently, metals (in the form of filler, coatings, or laminates) are the most common shielding material which uses primarily reflection mechanism for shielding along with minor absorption component. However, metals suffer from problems like poor wear/scratch resistance, corrosion susceptibility, high density, difficult processing, and high cost [1, 6, 9]. The secondary shielding mechanism is absorption for which shield material should have electrical or magnetic dipoles [9¨C12] along-with finite electrical conductivity. For such purpose materials with high dielectric constant like ZnO, SiO2, TiO2, BaTiO3, or high magnetic permeability, for example, carbonyl iron,
%U http://www.hindawi.com/journals/jpol/2014/193058/