high permittivity
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2022 ◽  
Vol 310 ◽  
pp. 131423
Leilei Li ◽  
Junting Liu ◽  
Shuyao Cao ◽  
Jie Xu ◽  
Emilia Pawlikowska ◽  
Low Loss ◽  

Chillu Naresh ◽  
Gandluri Parameswarreddy ◽  
Asapu Vinaya Kumar ◽  
Rengaswamy Jayaganthan ◽  
Venkatachalam Subramanian ◽  

Abstract In the present study, hybrid composites are prepared by reinforcing various concentrations of high permittivity zirconia nanofiller into epoxy/CNT compositions to test their usability in EMI shielding applications in the X and Ku bands. ZrO2 nanofiller is added in different proportions to improve absorbance shielding while maintaining the composite conductivity uniform by adding constant CNT concentration to restrict the reflectance shielding. The microscopic studies have revealed an efficient dispersion of ZrO2 nanoparticles in the CNT networks and provided a smoother surface. The presence of zirconia nanofillers increased the dielectric properties, viz. the dielectric constant (194 at 0.1 Hz) and loss tangent (1.57 at 0.1 Hz), respectively, whereas the conductivity was found to be invariantly constant. The increased permittivity of composites enhanced the shielding by absorption, while the shielding by reflection is least influenced by the addition of zirconia nanofiller. The addition of zirconia nanofillers increased the permittivity and tan delta, allowing charges to accumulate at the interfacial areas for incoming EM radiations, resulting in increased absorbance shielding. Limiting the CNT concentration in all composites to the same level resulted in the formation of conductive networks, thus resulting in uniform reflectance shielding for all the hybrid composites in the present study. The dynamic mechanical analysis showed the improvement in the storage modulus and activation energy due to the enhanced interfacial adhesion and cross-linked polymer density.

2021 ◽  
Vol 119 (25) ◽  
pp. 252601
Daniel F. Santavicca ◽  
Marco Colangelo ◽  
Carleigh R. Eagle ◽  
Maitri P. Warusawithana ◽  
Karl K. Berggren

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7537
Yilin Huang ◽  
Weidong Xue ◽  
Xingwang Hou ◽  
Rui Zhao

In this paper, we will discuss the excellent broadband microwave absorption behaviors of Cu/CuO/carbon nanosheet composites: traces of copper and oxide embedded in a carbon nano-sheet not only cut down the high permittivity of adsorbs but also induce more interfacial polarization centers. The results showed that at a cracking temperature of 900 °C, the fabricated material has a unique ripple-like structure, which promotes the hierarchical interfacial polarization. The prepared material has a maximum absorption bandwidth of 4.48 GHz at an exceedingly thin thickness of 1.7 mm and a maximum reflection loss of −25.3 dB at a thickness of 2 mm. It is a relatively ideal material for electromagnetic wave absorption.

2021 ◽  
Vol 22 (12) ◽  
pp. 1655-1665
Shaopeng Pan ◽  
Mingtuan Lin ◽  
Lin Qi ◽  
Pan Chen ◽  
Yang Feng ◽  

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4202
Yingjie Jiang ◽  
Yujia Li ◽  
Haibo Yang ◽  
Nanying Ning ◽  
Ming Tian ◽  

The dielectric elastomer (DE) generator (DEG), which can convert mechanical energy to electrical energy, has attracted considerable attention in the last decade. Currently, the energy-harvesting performances of the DEG still require improvement. One major reason is that the mechanical and electrical properties of DE materials are not well coordinated. To provide guidance for producing high-performance DE materials for the DEG, the relationship between the intrinsic properties of DE materials and the energy-harvesting performances of the DEG must be revealed. In this study, a simplified but validated electromechanical model based on an actual circuit is developed to study the relationship between the intrinsic properties of DE materials and the energy-harvesting performance. Experimental verification of the model is performed, and the results indicate the validity of the proposed model, which can well predict the energy-harvesting performances. The influences of six intrinsic properties of DE materials on energy-harvesting performances is systematically studied. The results indicate that a high breakdown field strength, low conductivity and high elasticity of DE materials are the prerequisites for obtaining high energy density and conversion efficiency. DE materials with high elongation at break, high permittivity and moderate modulus can further improve the energy density and conversion efficiency of the DEG. The ratio of permittivity and the modulus of the DE should be tailored to be moderate to optimize conversion efficiency (η) of the DEG because using DE with high permittivity but extremely low modulus may lead to a reduction in η due to the occurrence of premature “loss of tension”.

2021 ◽  
Vol 119 (19) ◽  
pp. 193501
Mohammad Wahidur Rahman ◽  
Nidhin Kurian Kalarickal ◽  
Hyunsoo Lee ◽  
Towhidur Razzak ◽  
Siddharth Rajan

APL Materials ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 111101
Eric N. Jin ◽  
Brian P. Downey ◽  
Vikrant J. Gokhale ◽  
Jason A. Roussos ◽  
Matthew T. Hardy ◽  

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