Effect of granulometric distribution on electromagnetic shielding effectiveness for polymeric composite based on natural graphite

Abstract

In this study, the electromagnetic interference (EMI) shielding effectiveness (SE) of polymer composites based on natural graphite in flakes (NGF) and silicone rubber was investigated with the aim to contribute to the development of the technology of electromagnetic shielding materials. This topic has attracted great attention to the aeronautical and aerospace applications, due to the serious problems that EMI can cause to the functioning of electronic devices. According to this, the present work has produced samples of composite materials with variations on the sizes of the filler particles and composition of the samples. The electromagnetic characterization of the samples is given by the Vector Network Analyzer (VNA) in the X-band frequency range (8.2 – 12.4 GHz). The results indicate that the variation of particle sizes is determinant to the SE performance along with the X-band frequency range. Furthermore, the expansion of the range of granulometry allows controlling the curves of the peaks along the X-band.

Cobalt Ferrite/Polyetherimide Composites as Thermally Stable Materials for Electromagnetic Interference Shielding Uses

“…It can be remarked that when the frequency was higher, the EMR absorption loss tended to be higher, whereas the reflection was diminished. This is in agreement with the literature data for other polymer composites [ 64 , 65 ], which states that the magnitude of conductivity and permeability is extremely important such that reflection effectiveness is impacted by the ratio σ/μ and the absorption is influenced by their product [ 66 ]. The deviation of the waves via reflection by the PEI/CoFe 2 O 4 films is caused by the distinct impedance of the shielding layer and the surrounding free space, while EMR attenuation occurs when unreflected waves penetrate the interior of the nanocomposite and is slightly stopped by dielectric and magnetic characteristics.…”

Progress in polymers and polymer composites used as efficient materials for EMI shielding

“…Finally, the authors stated that PP/GR composites can be used in Significant enhancement in electrical properties suggests that the prepared composites may be useful for EMI shielding applications particularly at high temperatures. Portes et al [41] investigated EMI SE of composites based on silicone rubber and natural graphite flakes (NGRF) in the X-band frequency range. The authors claim that the concentration, variation and combination of the particle sizes of NGRF showed a considerable impact on its electromagnetic characteristics.…”

“…Based upon the outlined formulations it can be stated that efficiency of shielding by absorption is a function of σ.μ, whereas shielding by reflection is dependent on the ratio of both parameters σ/μ [14,31,41,42].…”

Low frequency electromagnetic shielding efficiency of composites based on ethylene propylene diene monomer and multi‐walled carbon nanotubes

“…[18][19][20] A lot of works concerning the application of carbon based fillers into polymer matrices in order to prepare composite materials with the effect of EMR shielding have been published, as for example. 12,[21][22][23][24][25][26][27][28][29] Only few of them have been devoted to the incorporation of carbon based fillers into rubber matrices. 22,26,29 The shielding effectiveness of the prepared composites has been usually tested at high frequencies, mostly in the X-band frequency range…”