Dielectric spectroscopy of microwave-absorbing materials

Poplavko, Yuriy

doi:10.1016/b978-0-12-823518-8.00005-0

Cited by 5 publications

(11 citation statements)

References 10 publications

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“…When a polymeric material is found in an external electric field, its response is governed by different polarization mechanisms . Generally, the polarization of any material comes from four different contributions: dipolar, atomic, electronic, and interfacial polarization 9 . In polymers with dipole groups, the mechanism of orientation of dipole side groups or dipole segments corresponds to Debye's relaxation polarizations 10 .…”

Section: Introductionmentioning

confidence: 99%

“…Generally, the polarization of any material comes from four different contributions: dipolar, atomic, electronic, and interfacial polarization. 9 In polymers with dipole groups, the mechanism of orientation of dipole side groups or dipole segments corresponds to Debye's relaxation polarizations. 10 The dipolar segmental relaxations or dipolar group relaxations correspond to β-relaxations.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric properties of epoxy/graphite flakes composites: Influence of loading and surface treatment

Maletić,

Jović Orsini,

Milić

et al. 2023

J of Applied Polymer Sci

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Epoxy‐rich carbon‐based composites are well recognized materials in industries owing to their good mechanical properties and thermal stability. Here, dielectric properties of composites based on bisphenol‐A‐epoxy resin loaded with 5, 6, 10, and 15 wt% of graphite flakes (GF) have been studied. The frequency and temperature dependence of the dielectric permittivity, dielectric loss, and ac conductivity have been examined in temperature (−103 to 97°C) and frequency (20 Hz–200 kHz) range. Influence of the filler surface chemistry have been studied for composites loaded with 5 wt% GF obtained: (i) under wet milling, without or with adding Triton‐100x as a surfactant, or (ii) under dry milling in the presence of KOH. The composite made of epoxy loaded with 5 wt% exfoliated expanded graphite flakes (EEG), was also prepared. The surface treatment with KOH notably increased dielectric constant of the composite, keeping low dielectric loss, while treatment with Triton‐100x significantly increased tanδ. The composite loaded with exfoliated expanded graphite shows higher ac conductivity than those obtained with flaky graphite, GF. Possibility to change dielectric properties of the composites without changing the loading content can be used as an approach in tailoring one with desired dielectric properties.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dielectric properties of epoxy/graphite flakes composites: Influence of loading and surface treatment

Maletić,

Jović Orsini,

Milić

et al. 2023

J of Applied Polymer Sci

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show abstract

“…where C is the measured capacitance, d is the thickness of samples (m), ε 0 is the permittivity of free space, and A is the electrode area (m 2 ). 43 2.4. Touch-Screen System.…”

Section: Sample Characterizationmentioning

confidence: 99%

“…The real part of the dielectric constant was then calculated from the dielectric measurements taking into consideration the geometrical characteristics of the samples (1) where C is the measured capacitance, d is the thickness of samples (m), ε 0 is the permittivity of free space, and A is the electrode area (m 2 ). 43 2.4. Touch-Screen System.…”

Section: Sample Characterizationmentioning

confidence: 99%

Direct-Ink Writing Processing of High-k Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) and Its Integration into an All-Printed Capacitive Touch-Sensing Device

Pereira,

Pinto,

Gonçalves

et al. 2023

ACS Appl. Electron. Mater.

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Direct-ink writing (DIW) printing technology represents a suitable and efficient additive manufacturing technique for producing intricate designs and structures directly on the application surface. This work has demonstrated the potential of combining DIW and screen printing to fabricate an all-printed 7 × 7 capacitive touch sensor based on high dielectric constant (high-k) poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)�P(VDF-TrFE-CFE). The printed device allows a maximum detection signal-to-noise ratio (SNR) of 20 dB, a large touch sensitivity that demonstrates the touch sensor's ability to detect and respond precisely to user input. Furthermore, by demonstrating the processability of P(VDF-TrFE-CFE) with DIW printing, this research also opens the way for the low-cost fabrication and integration of sensing devices based on this high dielectric constant polymer.

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“…The absorption EM wave in nonmagnetic material is characterized by the attenuation coefficient (see Poplavko, 2021):…”

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confidence: 99%

Iron Oxide Fe3O4 Nanoparticles with Intrinsic Conducting Polymers and Biochar to Improve the Electromagnetic Shielding Performance of Light Weight Absorption-Type Materials

Carolina Sparavigna

2023

ijSciences

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Magnetic iron oxide nanoparticles (Fe3O4) can be dispersed in a supporting material so that the composite can better respond to electromagnetic fields, absorbing a part of their energy. In the discussion here proposed we will consider the role of these nanoparticles in applications for electromagnetic interference (EMI) shielding. Inserted in intrinsically conducting polymers (ICPs) for instance, the nanoparticles are increasing EMI shielding effectiveness of polymer, producing light weight "absorption-type" shields, which are specifically relevant for absorbing microwaves. Encapsulation of Fe3O4 nanoparticles with polypyrrole and polyaniline will be described in detail and the recent biochar-based composites, Fe3O4@biochar, will be discussed too.

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Dielectric spectroscopy of microwave-absorbing materials

Cited by 5 publications

References 10 publications

Dielectric properties of epoxy/graphite flakes composites: Influence of loading and surface treatment

Dielectric properties of epoxy/graphite flakes composites: Influence of loading and surface treatment

Direct-Ink Writing Processing of High-k Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) and Its Integration into an All-Printed Capacitive Touch-Sensing Device

Iron Oxide Fe3O4 Nanoparticles with Intrinsic Conducting Polymers and Biochar to Improve the Electromagnetic Shielding Performance of Light Weight Absorption-Type Materials

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