Effect of microstructure induced by microcellular injection molding on electromagnetic interference shielding properties

Silver (Ag)/carbonyl iron particles (CIPs) were prepared by electroless plating successfully to improve the electromagnetic interference (EMI) shielding and antioxidation properties of CIPs. The microstructure, phase composition, thermogravimetric (TG), electromagnetic and EMI shielding properties were analyzed respectively. Experimental results show that Ag particles were uniformly distributed on the surface of CIPs. TG results show the apparent weight gain temperature of Ag/CIPs was deferred compared with the weight gain temperature of CIPs. The total EMI SE value of Ag/CIPs/EP composite reaches about 36 dB with thickness 1.5 mm, which is far superior to the value of CIPs/EP composite. The EMI shielding result shows such Ag/CIPs composite material has an outstanding EMI shielding effect in the measured frequency band (8.2 GHz–12.4 GHz).

Stretchability and multifunctional heating abilities are highly desired for wearable electromagnetic interference (EMI) shielding fabrics to tackle the growing electromagnetic pollution for special crowd, such as pregnant women. Herein, we fabricated stretchable MXene-coated thermoplastic polyurethane (TPU) fabrics by simple uniaxial prestretching and spraying methods. The obtained unique wrinkled structure endowed the film with effective strain-invariant electrical conductivity and EMI shielding properties. Specifically, the prepared stretchable film with an extremely low MXene loading (0.417 mg cm-2) exhibited a stable EMI shielding effectiveness of approximately 30 dB under 50% tensile strain and durability during stretching and bending cycles. More importantly, owing to the high electrical conductivity and localized surface plasmon resonance (LSPR) effect of the MXene layer, the stretchable fabrics exhibited excellent Joule heating (up to 104 °C at a voltage of 5 V) and superior photothermal conversion abilities. Moreover, the unique wrinkled MXene-coating layer not only endows the fabrics with stretchable heat abilities but also enhances the photothermal conversion performance by increasing the light absorption area and travel path. We believe that this study offers a novel strategy for the versatile design of stretchable and multifunctional wearable shielding fabrics.

Multilayer composite films with enhanced electromagnetic interference shielding and thermal management properties based on bamboo cellulose nanofibers.

Tunable electromagnetic interference shielding performance of polypropylene/carbon black composites via introducing microcellular structure

Highly conductive carbon nanotubes-boron nitride-thermoplastic polyurethane composite thin films with ultra broadband and efficient electromagnetic interference shielding up to 110 GHz and heat dissipation abilities

Electroless nickel coated carbon fibers (ENCF) were blended with acrylonitrile-butadiene-styrene (ABS) to prepare composites for electromagnetic interference (EMI) shielding. The effects of processing parameters, such as additives, temperature, and fiber loading amount, on EMI shielding effectiveness (SE) were researched. The thermal stability of EMI SE of ENCF/ABS composites was tested by heat treating composites in a drying oven at 60°C, and SE was measured at an interval of one week to consider the degradation of SE. The best SE of ENCF/ABS composites could be reached was 44 dB at optimum processing parameters. The thermal stability of ENCF/ABS composites for EMI shielding was steady without obvious degradation after 60°C heat treatment for five weeks. © 1997 John Wiley & Sons, Inc.

Comparative study of electromagnetic interference shielding properties of injection molded versus compression molded multi-walled carbon nanotube/polystyrene composites

A waste material which is collected from palm oil mill called POFA is used as cement replacement in plastering work to overcome electromagnetic interference issue.In the experiment, variables involved POFA admixture percentage (weight %), topcoat powder-to-binder ratio, water-to-binder ratio, latex agent content (weight%), particle size of POFA (µm) and curing conditions.The EMI shielding effectiveness (SE) is mainly dependent on all variables, especially POFA admixture percentage and particle size of POFA.A hybrid Taguchi design and flower pollination algorithm (FPA) method was used to optimize the best approaching high EMI SE based on experimental data.The experimental results found that plaster mortar can shield -23dB of electromagnetic wave (EMW) while using FPA method was shielded -24.68dB.The interaction model of EMI SE was derived from regression analysis and the truth found that the EMI SE is dependent on the water-to-binder ratio followed by latex agent content, particle size of POFA and curing conditions.From the FPA process, targeted EMI SE were suggested 30.012% of POFA admixture percentage, 0.3 of topcoat powder-to-binder ratio, 1.03 of water-to-binder ratio, 10% of latex agent content, 45µm particle size of POFA and air curing condition were optimal variables.

Synergistically-enhanced flexible electromagnetic interference shielding nanocomposites

The aim of this study is to discuss the effect of moisture absorption on electrical conductivity and electromagnetic interference of the carbon fiber (CF) reinforced bioplastic composite. The composites were prepared by the hot press machine, and immersed in water for 20 and 40 days. The electrical conductivity measurements were carried out as a function immersed time. The electrical conductivity of CF with two layers is greater than that of one layer, because the electrical conductivity increases with increasing the volume filler of CF. The electrical conductivity slightly increases with increasing the immersion time. The EMI SE (electromagnetic interference shielding effectiveness) of the composite was examined with the frequency from 500 MHz to 2000 MHz. The EMI SE of the CF increases with increasing the content of the CF, and the EMI SE result of composite is around 50 dB to 60 dB. There is scarcely significant effect of orientation on composite on the EMI SE.

Lightweight and flexible Ni-Co alloy nanoparticle-coated electrospun polymer nanofiber hybrid membranes for high-performance electromagnetic interference shielding

It is important but challenging to develop high‐performance electromagnetic interference (EMI) shielding materials with customizable structures, tailorable properties, light weight, and high‐efficiency EMI shielding effectiveness (SE). Herein, a facile approach is proposed to customize aramid nanofiber (ANF) based EMI shielding aerogels with pre‐designed architectures through ultra‐malleable ANF jellies. By precisely regulating the interfiber interactions between ANF and constructing a robust 3D skeleton, ANF jelly can be ‘kneaded‐frozen‐heated’ like dough to produce ultralight, elastic and porous ANF aerogels with special structures, such as aerogel sandwich, spring, fabric, etc. Benefiting from the interconnected porous structure, conductive fillers such as silver nanowires (AgNW) can easily cover the aerogel skeleton by dip‐coating to form highly conductive paths. With an ultra‐low loading (7.5 wt.%) of AgNW, a 5.2 mm‐thick AgNW/ANF aerogel exhibit an average EMI SE of 75.4 dB in the X‐band. Aerogels with additional functions can be customized according to the actual application environment. A customized sandwich aerogel with fire‐retardant outerlayer and EMI shielding interlayer can be used in high‐temperature environments. A flexible aerogel fabric as an EMI shielding gasket can effectively block wireless power transmission. This work provides a forward‐looking strategy for constructing high‐performance EMI shielding materials with tailored properties.

Interfused core-shell heterogeneous graphene/MXene fiber aerogel for high-performance and durable electromagnetic interference shielding.

Wood‐derived carbon has great potential in building sustainable, lightweight electromagnetic interference (EMI) shielding materials. However, developing a straightforward method for fabricating materials that exhibit both high EMI shielding effectiveness (SE) and multifunctionality remains a challenge. Herein, the carbonized wood/epoxy/iron composite (C/EP/Fe) with hierarchical porous architecture is synthesized by encapsulating magnetic nanoparticles inside the conduits of wood‐derived carbon materials through via a simple two‐step process. Hot pressing is used to convert the conductive pathways, the inherent 3D honeycomb structure into a 2D grid. This structural transition, synergized with the magnetic nanoparticles, markedly enhanced the EMI SE. At a density of 392.26 mg cm −3 and a thickness of 1.05 mm, the C/EP/Fe‐4 achieved an EMI SE of 95.3 dB in the X‐band and allowed for tunable EMI shielding performance through adjustments in rotation angles. Furthermore, the material demonstrated shielding efficiency exceeding 99.999999% across the C‐K bands, with excellent EMI SE values consistently above 89 dB. In addition to its superior EMI shielding performance, the C/EP/Fe exhibited a suite of multifunctional properties, including rapid Joule heating, excellent thermal stability, flame retardancy, hydrophobicity, and reliable mechanical strength.

Preparation and EMI shielding performance of epoxy/non-metallic conductive fillers nano-composites