Electrical Properties of Solids. VIII. Dipole Moments in Polyvinyl Chloride-Diphenyl Systems<sup>*</sup>

Fuoss, Raymond M.; Kirkwood, John G.

doi:10.1021/ja01847a013

Cited by 743 publications

(207 citation statements)

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“…Dielectric losses have a lower maximum and persist over a wide range of frequency. Fusoos and Kirwood [106] have successfully described this behavior. It is widely believed that a dispersion caused by Brownian motion of the polymer chain whereas the b dispersion is because of oscillatory motion or intramolecular rotation of side groups.…”

Section: 15 (Arrows Indicate Values Of Dielectric Losses At 245 Ghz)mentioning

confidence: 90%

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Stuerga¹

2006

Microwaves in Organic Synthesis

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The main focus of the revised edition of this first chapter is essentially the same as the original -to explain in a chemically intelligible fashion the physical origin of microwave-matter interactions and, especially, the theory of dielectric relaxation of polar molecules. This revised version contains approximately 60% new material to scan a large range of reaction media able to be heated by microwave heating. The accounts presented are intended to be illustrative rather than exhaustive. They are planned to serve as introductions to the different aspects of interest in comprehensive microwave heating. In this sense the treatment is selective and to some extent arbitrary. Hence the bibliography contains historical papers and valuable reviews to which the reader anxious to pursue particular aspects should certainly turn.It is the author's conviction, confirmed over many years of teaching experience, that it is much safer -at least for those who rate not trained physicists -to deal intelligently with an oversimplified model than to use sophisticated methods which require experience before becoming productive. Because of comments about the first edition, however, the author has included more technical material to enable better understanding of the concepts and ideas. These paragraphs could be omitted, depending on the level of comprehension of the reader. They are preceded by two different symbols -k for TOOLS and j for CONCEPTS.After consideration of the history and position of microwaves in the electromagnetic spectrum, notions of polarization and dielectric loss will be examined. The orienting effects of electric fields and the physical origin of dielectric loss will be analyzed, as also will transfers between rotational states and vibrational states within condensed phases.Dielectric relaxation and dielectric losses of pure liquids, ionic solutions, solids, polymers and colloids will be discussed. Effect of electrolytes, relaxation of defects within crystals lattices, adsorbed phases, interfacial relaxation, space charge polarization, and the Maxwell-Wagner effect will be analyzed. Next, a brief overview of 1 thermal conversion properties, thermodynamic aspects, and athermal effects will be given.

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Section: 15 (Arrows Indicate Values Of Dielectric Losses At 245 Ghz)mentioning

confidence: 90%

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Stuerga¹

2006

Microwaves in Organic Synthesis

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“…In order to characterize and analyse the observed relaxations in the mechanical spectrum, it is convenient to choose a model which appropriately reproduces the experimental data. A reliable model to represent the secondary relaxations in polymers is the Fuoss and Kirkwood equation [37]. This semi-empirical model has extensively been used in the representation of the mechanical relaxations and can be written in the temperature dependence as…”

Section: Dynamic Mechanical Measurementsmentioning

confidence: 99%

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

Redondo-Foj¹,

Carsí²,

Ortiz-Serna³

et al. 2013

J. Phys. D: Appl. Phys.

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A poly(vinylpyrrolidone-co-butyl acrylate) (60VP-40BA) membrane has been synthesized as a tractable and hydrophilic material, obtaining a water swelling percentage around 60%. An investigation of molecular mobility by means of Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Broadband Dielectric Relaxation Spectroscopy (DRS) has been fulfilled in the dry membrane. Dielectric and viscoelastic relaxation measurements have been carried out on the 60VP-40BA sample at several frequencies between -150ºC to 150ºC .The dielectric spectrum shows several relaxation processes labelled as γ, β and α in increasing order of temperature, whereas in the mechanical spectrum only the β and α relaxation processes are completely defined. In the dielectric measurements, conductive contributions overlap the α-relaxation. The apparent activation energies have similar values for the β-relaxation in both, the mechanical and the dielectric measurements. The β process is related to the local motions of the pyrrolidone group and the γ process is connected with the butyl units motions, both located in the side chains of the polymer.

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“…6,7 In a similar way the logarithmic moments can be calculated if the relaxation is defined by a function (t) in time domain. The negative derivative of ͑6͒ with respect to ln t can be written as…”

Section: Calculation Of Logarithmic Momentsmentioning

confidence: 99%

Logarithmic moments of relaxation time distributions

Zorn¹

2002

The Journal of Chemical Physics

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In this paper a novel way to quantify ''nonexponential'' relaxations is described. So far, this has been done in two ways: ͑1͒ by fitting empirical functions with a small number of parameters, ͑2͒ by calculation of the underlying distribution function g(ln ) of ͑exponential͒ relaxations using regularization methods. The method described here is intermediate, it does not assume a specific functional form but also does not aim at the complete distribution g(ln ) but only its logarithmic moments ͗(ln ) k ͘. It is shown that these exist ͑in contrast to the linear moments͒ and can be calculated analytically for all currently used empirical descriptions of nonexponential relaxations. Therefore, the logarithmic moments represent a common basis for comparing literature data from authors which prefer different empirical formulas ͑e.g., those of Kohlrausch and Havriliak-Negami͒. The logarithmic moments are also shown to be related in a simple way to the ͑linear͒ moments of an underlying distribution of activation energies giving them a physical significance.

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Electrical Properties of Solids. VIII. Dipole Moments in Polyvinyl Chloride-Diphenyl Systems^*

Cited by 743 publications

References 0 publications

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

Logarithmic moments of relaxation time distributions

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Electrical Properties of Solids. VIII. Dipole Moments in Polyvinyl Chloride-Diphenyl Systems*

Cited by 743 publications

References 0 publications

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

Logarithmic moments of relaxation time distributions

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Product

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Electrical Properties of Solids. VIII. Dipole Moments in Polyvinyl Chloride-Diphenyl Systems^*