Protection against electromagnetic interference (EMI) has remained a pervasive challenge for almost two decades. For these reasons, research efforts have focused on the design and fabrication of efficient EMI shielding materials. This chapter investigates the mechanisms of microwave absorption in microcellular foamed conductive composites designed for protection or shielding against electromagnetic interference. A multi-layered electromagnetic one-dimensional (1D) model mimicking the microcellular foam structure is built and validated using previous measurements on various fabricated composite foams. This model helps to perform a parametric analysis of the absorption behaviour in a foamed composite, using the following parameters: the size of the hollow cell, the thickness of the cell’s wall, its conductivity, the overall thickness of the composite, and the frequency. The foamed composite materials that serve as a reference for the validation of the proposed model were fabricated using a supercritical CO2 process. Three different polymer matrices were considered as examples in this work, i.e., polycarbonate (PC), poly-caprolactone (PCL), and polypropylene (PP). These investigations demonstrate that multiple reflections of the microwave signal between the cellular walls are not the main mechanism responsible for absorption. However, they are often reported as a cause of enhanced absorption in the literature. On the contrary, this work demonstrates that the enhancement of the absorption observed in the foamed conductive composite compared to the unfoamed composite is mainly due to the presence of air in the micro-cells of the composite. The associated electromagnetic shielding efficiency of the foams for practical applications is also discussed. As a whole, the chapter provides a comprehensive study of the performance of composite foams that can help to protect modern communications systems, IoT devices, and living systems from spurious electromagnetic radiations that can interfere with.
Author(s)
Details.
Isabelle
Huynen
Université Catholique de Louvain, Place du Levant 3, 1348
Louvain-la-Neuve, Belgium.
Please see the book here:- https://doi.org/10.9734/bpi/nhstc/v4/6070
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