Microwave–Materials Interactions and Dielectric Properties: From Molecules and Macromolecules to Solids and Colloidal Suspensions

Stuerga, D.

doi:10.1002/9783527651313.ch1

Cited by 11 publications

(35 citation statements)

References 143 publications

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“…The decrease in dielectric constant with frequency can be explain due to the effect of polarization taking place in the composites due to the continuous varying of electric field. It is this component or field of the microwave that is responsible for the interaction of the material with the electromagnetic waves [30]. Figures 4-6 showed some form of oscillation in the dielectric constant, loss factor, and loss tangent of the composites.…”

Section: Resultsmentioning

confidence: 99%

The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

Meli

Abbas

Zaid

et al. 2019

Advances in Polymer Technology

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RS-4050 is a rigid epoxy based magnetic castable microwave absorbing material; it has been used in many areas of waveguide application as a microwave waveguide terminations and dummy loads. In recent years, there is a demand for composites material with lower dielectric constant higher loss factor for microwave application. This research, the effect of soda lime silica (SLS) on structural and complex permittivity of soda lime silica-high density polyethylene (SLS-HDPE) composites was conducted in order to explore the possibility of substituting RS-4050 with SLS-HDPE composites as a microwave waveguide terminations and dummy loads. Elemental weight composition of the SLS glass powder and HDPE was identified through scaling of different percentage of SLS and HDPE. X-ray diffraction (XRD) was used to investigate the crystallinity behavior of SLS-HDPE composites. The proposed SLS-HDPE composites material was studied at frequencies 8 to 12 GHz. The study was conducted using waveguide Agilent N5230A PNA technique. The effect of microwave frequency on complex permittivity properties for SLS-HDPE composites of different percentages of SLS and HDPE (10% SLS-90% HDPE, 20% SLS-80% HDPE, 30% SLS-70% HDPE, 40% SLS-60% HDPE, and 50% SLS-50% HDPE) were investigated. Results showed the diffraction patterns reveal good amorphous quality with a genuinely properties structure. The microwave frequency and composites percentages significantly influenced the complex permittivity (real and imaginary) properties of the composites. Moreover, the complex permittivity increased as the percentage of SLS filler increased in the host matrix HDPE as a result of increased in composite density due to less volume being occupied by the filler as the percentage increased. The complex permittivity of the smallest and largest percentages of SLS (10% and 50%) was (2.67-j0.05) and (3.45-j0.35), respectively. The study revealed that the best sample for waveguide application as microwave terminator is 50% SLS as it has the highest dielectric constant, highest loss factor, and highest loss tangent as compared to 10% SLS to 40% SLS. Also 50% SLS has the highest absorption properties as compare to 10% SLS, 20% SLS, 30% SLS, or 40% SLS. The XRD physical structure of the SLS-HDPE composites revealed the absorption characteristics of different percentages of the materials. The SLS-HDPE composites can be applied in the area of waveguide as a microwave waveguide terminations and dummy loads.

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Section: Resultsmentioning

confidence: 99%

The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

Meli

Abbas

Zaid

et al. 2019

Advances in Polymer Technology

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“…The term microwave radiation refers to electro-magnetic radiation with a frequency of 300 MHz to 300 GHz, corresponding to wavelengths of 1 m to 1 mm. [70][71][72][73][74][75] Microwaves therefore have a lower frequency than infrared radiation, but a higher frequency than radio waves. Photons at 2.45 GHz, the frequency most often used for microwave heating, have an energy of approximately 0.01 meV.…”

Section: Introduction To Microwavesmentioning

confidence: 99%

“…Photons at 2.45 GHz, the frequency most often used for microwave heating, have an energy of approximately 0.01 meV. 73 In comparison, Brownian motion at 200 K has an energy of approximately 17 meV, hydrogen bonds up to 440 meV, and a typical C-H bond is approximately 4510 meV. 73 Microwave radiation is therefore non-ionizing, meaning that it does not possess enough energy to directly break molecular bonds and thereby create ions.…”

Section: Introduction To Microwavesmentioning

confidence: 99%

“…73 In comparison, Brownian motion at 200 K has an energy of approximately 17 meV, hydrogen bonds up to 440 meV, and a typical C-H bond is approximately 4510 meV. 73 Microwave radiation is therefore non-ionizing, meaning that it does not possess enough energy to directly break molecular bonds and thereby create ions. [70][71][72][73][74][75] Reactions under microwave heating therefore do not (in the vast majority of cases)…”

Section: Introduction To Microwavesmentioning

confidence: 99%

“…rely on microwave radiation directly breaking or altering chemical bonds; microwaves energy is usually simply converted into thermal energy. [70][71][72][73][74][75] Microwave radiation has extremely wide-ranging applications, from satellite communication to radar to medicine. 71,73 In fact, the discovery of microwave heating in 1945 was due to heating observed in proximity to a high-powered radar station.…”

Section: Introduction To Microwavesmentioning

confidence: 99%

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Iron-catalyzed cross-coupling of arylboronic acids with unactivated N-heterocycles and quinones under microwave heating

2021

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The iron-catalyzed direct arylation of a variety of N-heteroarenes, quinones, and hydroquinones with arylboronic acids is investigated under microwave heating. The reaction proceeds at 70 °C under air using K2S2O8 as an oxidant and FeSO4 as a catalyst. Under microwave heating reaction rates increased by 14 to 115 times. Reaction scope with N-heteroarenes and quinones is comparable to or slightly expanded when compared to previous reports, but the scope of arylboronic acid utility was slightly limited due to previously unobserved arylboronic acid hydroxydeboronation.

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Solvatochromism in Mixtures of Hydrogen Bond Acceptor (HBA) Solvents with Water

Spange,

Seifert

2024

ChemPhysChem

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The UV/Vis absorption energies νmax of Reichardt's dye B30 with respect to ET(30) and 4‐nitroaniline (NA) are investigated as a function of the solvent composition Nav,z. in co‐solvent/water mixtures. Nav,z. is the average molar concentration of the solvent mixture at a given solvent fraction z. The z can be the mole, the volume or the mass fraction. The co‐solvents considered were acetonitrile, acetone, tetrahydrofuran, pyridine, piperidine and 2‐(diethylamino)‐ethanol. Acetone and acetonitrile can be expected to slightly enhance the water structure at low co‐solvent concentrations. This interpretation is supported by the analysis of the refractive index as a function of the solvent composition. In general, it can be stated that the structural complexity of the binary solvent mixtures is mainly responsible for the evolution of the absorption energies ET(30) or νmax(NA) as a function of the mixture composition. In particular, the endothermic solvation of NA in co‐solvent/water mixtures and its effect on the νmax(NA) is highlighted.

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Microwave–Materials Interactions and Dielectric Properties: From Molecules and Macromolecules to Solids and Colloidal Suspensions

Cited by 11 publications

References 143 publications

The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

Iron-catalyzed cross-coupling of arylboronic acids with unactivated N-heterocycles and quinones under microwave heating

Solvatochromism in Mixtures of Hydrogen Bond Acceptor (HBA) Solvents with Water

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