Electromagnetic Interference Shielding Effectiveness of Clay, Alumina, and Carbon Nanotubes Based on Epoxy Nanocomposites

Reis, Felipe Carlos dos; Opelt, Carlos Vinicios; Coelho, Luiz Antonio Ferreira; Baldan, Maurício Ribeiro; Ribeiro, Bruno; Rezende, Mirabel Cerqueira

doi:10.1590/1980-5373-MR-2024-0036

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Article • Mat. Res. 27 • 2024 • https://doi.org/10.1590/1980-5373-MR-2024-0036 copy

Electromagnetic Interference Shielding Effectiveness of Clay, Alumina, and Carbon Nanotubes Based on Epoxy Nanocomposites

Authorship SCIMAGO INSTITUTIONS RANKINGS

In this work, epoxy resin-based composites reinforced with nanoclays, nanoalumina, carbon nanotubes (CNTs) (0.15, 0.50, and 1.50% vol were submitted to morphological characterization by scanning (SEM) and transmission (TEM) electron microscopies, electrical tests through electrical impedance spectroscopy, and electromagnetic analyses (scattering parameters), in the frequency range of 8.2 to 12.4 GHz. SEM images of the CNT composite revealed nanotube clusters in the matrix. The proximity between the CNTs is corroborated by the increase in the electrical conductivity of the composite due to the formation of a long-range electron transport network, which favored the polarization effect, absorption losses (SE_A = 1.33 dB), reflection (SE_R = 3.38 dB) and reflection loss (RL = -6.61 dB at 10.8 GHz). Composites with nanoclays and nanoalumina showed no significant electrical and electromagnetic results.

Keywords:
EMI shielding; CNTs; epoxy composites; nanoalumina; nanoclays; microwave absorption

Sample code	Type of filler	Polymer matrix	vol. [%]
E	-	Epoxy Resin Araldite LY 5052	-
Al_0.15	Al₂O₃	Epoxy Resin Araldite LY 5052	0.15
Al_0.50			0.50
Al_1.50			1.50
CNT_0.15	MWCNTs	Epoxy Resin Araldite LY 5052	0.15
CNT _0.50			0.50
CNT _1.50			1.50
MMT B _0.15	MMT-30B	Epoxy Resin Araldite LY 5052	0.15
MMT B _0.50			0.50
MMT B _1.50			1.50
MMT A _0.15	MMT-Na⁺	Epoxy Resin Araldite LY 5052	0.15
MMT A _0.50			0.50
MMT A _1.50			1.50

Samples	𝜎_{AC (S/cm)}	ε_r
E	1.68 x 10^-9	3.02
MMT A _1.50	2.67 x 10^-9	4.80
MMT B _1.50	2.53 x 10^-9	4.54
Al_1.50	1.17 x 10^-9	2.10
CNT_0.15	3.47 x 10^-8	62.33
CNT _0.50	5.59 x 10^-8	100.46
CNT _1.50	1.25 x 10^-7	224.95

Sample	R	T	A	ε'	ε"	ε"/ ε'	ε_r
E	0.28	0.67	0.05	2.85	0.11	0.04	2.85
MMT A _1.50	0.31	0.63	0.05	3.04	0.12	0.04	3.04
MMT B _1.50	0.30	0.65	0.05	2.94	0.11	0.04	2.95
Al_1.50	0.31	0.64	0.05	3.00	0.12	0.04	3.00
CNT_0.15	0.35	0.56	0.09	3.32	0.20	0.06	3.33
CNT _0.50	0.45	0.45	0.10	4.08	0.35	0.08	4.09
CNT _1.50	0.54	0.34	0.12	5.33	0.70	0.13	5.37

Sample	SE_A (dB)	SE_R (dB)	SE_T (dB)	SE_T (%)	RL (dB)	RL (%)
E	0.31	1.43	1.75	33.2	-0.94 at 12.4 GHz	19.5 at 12.4 GHz
CNT_0.15	0.65	1.89	2.55	44.4	-1.81 at 12.4 GHz	34.1 at 12.4 GHz
CNT _0.50	0.90	2.61	3.51	55.4	-4.28 at 12.1 GHz	62.7 at 12.1 GHz
CNT _1.50	1.33	3.38	4.71	66.2	-6.61 at 10.8 GHz	78.2 at 10.8 GHz

Material	Thickness (mm)	EMI SE / RL (dB)	Band	Reference
		EMI SE
Epoxy/CNTs (15 wt%)	2	25	8.2-12.4 GHz	⁵⁷57 Huang Y, Li N, Ma Y, Du F, Li F, He X, et al. The influence of single-walled carbon nanotube structure on the electromagnetic interference shielding efficiency of its epoxy composites. Carbon. 2007;45(8):1614-21. http://doi.org/10.1016/j.carbon.2007.04.016. http://doi.org/10.1016/j.carbon.2007.04....
Epoxy/CNTs (2.5 wt%)	2	8	8.2-12.4 GHz	⁵⁸58 Khodadadi Yazdi M, Noorbakhsh B, Nazari B, Ranjbar Z. Preparation and EMI shielding performance of epoxy/non-metallic conductive fillers nano-composites. Prog Org Coat. 2020;145:105674. http://doi.org/10.1016/j.porgcoat.2020.105674. http://doi.org/10.1016/j.porgcoat.2020.1...
Epoxy/CNTs (1.5 vol%)	3	4.5	8.2-12.4 GHz	This work
		Reflection loss (RL)
Epoxy/CNTs (20.7 wt%)	1.75	−19	8.2-12.4 GHz	⁵⁹59 Singh BP, Bharadwaj P, Choudhary V, Mathur RB. Enhanced microwave shielding and mechanical properties of multiwall carbon nanotubes anchored carbon fiber felt reinforced epoxy multiscale composites. Appl Nanosci. 2014;4(4):421-8. http://doi.org/10.1007/s13204-013-0214-0. http://doi.org/10.1007/s13204-013-0214-0...
Epoxy/CNTs (2.0 wt%)	3	−10.5	8.2-12.4 GHz	⁶⁰60 Che BD, Nguyen BQ, Nguyen LTT, Nguyen HT, Nguyen VQ, Van Le T, et al. The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites. Chem Cent J. 2015;9(1):1-13. http://doi.org/10.1186/s13065-015-0087-2. http://doi.org/10.1186/s13065-015-0087-2...
Epoxy/CNTs (1.5 vol%)	3	-6.6	8.2-12.4 GHz	This work

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