Multi-layered stack consisting of PVDF nanocomposites with flow-induced oriented MWCNT structure can supress electromagnetic radiation

Gebrekrstos, Amanuel and Biswas, Sourav and Menon, Aishwarya V and Madras, Giridhar and Poetschke, Petra and Bose, Suryasarathi (2019) Multi-layered stack consisting of PVDF nanocomposites with flow-induced oriented MWCNT structure can supress electromagnetic radiation. In: COMPOSITES PART B-ENGINEERING, 166 . pp. 749-757.

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Abstract

Polymeric nanocomposites have emerged as a potential material in the electronic world owing to its numerous advantages like ease of processing, design flexibility, light-weight, ease of embedding and integrating with the existing production line. Given the surge in electronic components, electromagnetic interference, which severely impairs the reliability of precise electronic devices, has emerged as a new challenge. Hence, technologically, viable design is the need of the day. However, the high concentration of fillers required to achieve the desired properties still remains a challenge with respect to the design of functional polymeric nanocomposites. In this context herein, we report as to how flow induced distribution of multi-walled carbon nanotubes (MWCNT) in poly-vinylidene (PVDF) matrix during mechanical rolling influence the texture, polymorphism and electromagnetic shielding properties. We demonstrate the flow induced orientation of MWCNT, polymorphism in PVDF and composites shielding performance by TEM, crystallographic texture and shielding effectiveness measurements, respectively. Further, mechanical and thermal properties of as pressed and mechanically rolled samples were investigated by DMA and DSC. TEM analysis revealed that MWCNT form small aggregate, however were aligned along the rolling direction. This observation is in sharp contrast to the random distribution for as pressed samples. Quantitatively, a strong texture was observed for rolled samples as compared to as pressed samples. Absorption of EM waves is the major shielding mechanism which is mechanistically discussed here through associated dielectric loss parameters. Interactions, alignment of MWCNTs, and polymorphism influence the shielding efficiency in these composites. In addition, stacking of such nanocomposite layers further enhances the overall shielding efficiency by absorption (up to 72%) due to the polarization, multiple internal reflections and interlayer charge storing capacity. A Bluetooth module was employed to successfully demonstrate the efficacy of this approach in supressing unwanted EM interference. This study comprehensively guides researchers as to how processing or flow-induced changes alter the distribution of MWCNTs in polymer composites and how this influences the overall shielding behaviour.

Item Type:	Journal Article
Publication:	COMPOSITES PART B-ENGINEERING
Publisher:	ELSEVIER SCI LTD
Additional Information:	The copyright for this article belongs to Elsevier Ltd
Keywords:	Polymer composites; Carbon nanotube; Mechanical rolling; EMI shielding effectiveness
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy) Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	03 Jul 2019 07:01
Last Modified:	03 Jul 2019 07:01
URI:	http://eprints.iisc.ac.in/id/eprint/62767

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