Permittivity fluids

Dielectric films Dielectric fluids Dielectric insulators Dielectric masking Dielectric materials Dielectric permittivity Dielectrics... 

Unlike charges attract and like charges repel each other, so there is a high concentration of counterions attracted to the particle surface whilst co-ions (those with the same sign charge as that of the surface) are repelled. Thermal motion, i.e. diffusion, opposes this local concentration gradient so that the counterions are in a diffuse cloud around the particle. Of course particles which have a like charge will also repel each other but the interaction of the particle surfaces will be screened by the counterion clouds between the particles. The interaction potential is a function of the surface potential, i]/o, and the permittivity of the fluid phase, e = r80, where r is the relative permittivity.12,27... 

As its name suggests, a liquid crystal is a fluid (liquid) with some long-range order (crystal) and therefore has properties of both states mobility as a liquid, self-assembly, anisotropism (refractive index, electric permittivity, magnetic susceptibility, mechanical properties, depend on the direction in which they are measured) as a solid crystal. Therefore, the liquid crystalline phase is an intermediate phase between solid and liquid. In other words, macroscopically the liquid crystalline phase behaves as a liquid, but, microscopically, it resembles the solid phase. Sometimes it may be helpful to see it as an ordered liquid or a disordered solid. The liquid crystal behavior depends on the intermolecular forces, that is, if the latter are too strong or too weak the mesophase is lost. Driving forces for the formation of a mesophase are dipole-dipole, van der Waals interactions, 71—71 stacking and so on. 

ASTM D1531, 2001. Standard test methods for relative permittivity (dielectric constant) and dissipation factor by fluid displacement procedures. 

Liquid insulators are required for circuit breakers, transformers, and some cable applications. Natural hydrocarbon mineral oils are commonly-used, as well as chlorinated aromatic liquids (desirable because of nonflammability). For high-temperature situations, silicone fluids may be used. Permittivities range between 2 and 7. Insulating liquids function both as electrical insulators and heat-transfer media. See also Dielectric Theory. 

Guillot and Guissani [56] and Weiss and Schroer [221] went one step further. Guillot and Guissani considered the effect of unscreened DD interactions on the FL theory. They also performed an approximate treatment of unscreened DD interactions in the framework of the MSA. In contrast, Weiss and Schroer theory (WS) considers ionic screening of the DD interactions by the remainder of the fluid, the change of the dielectric permittivity caused by... 

Models 1 and 2 were applied to simple nonassociated polar liquids. Wideband Debye relaxation + FIR spectral dependencies of the permittivity s (v) and absorption ot(v) were successfully described. Usually only one quasiresonance absorption band (at v between 10 cm-1 and 100-200 cm-1) and one non-resonance Debye loss e" peak (at microwaves) arise in these fluids. Although a spatial model gives, unlike a planar one, a correct value of the integrated absorption J ° ve"(v)dv, the calculated spectral dependencies resemble those found for motion in a plane. 

If the concentration of an electrolyte is rather low, then at least three elementary types of motion stipulate dispersion of the complex permittivity in this polar fluid ... 

The method used in determining the dense dielectric permittivity of a definite material consists in defining a fluid in which the material cannot dissolve and further to measure the effective permittivity of various particulate media/fluid mixtures corresponding to various porosity. The interception point of the curves representing the variation of the permittivity of the material with porosity (through the effective medium equation, see section 3.2) gives the dense state permittivity. 

We now consider the same parallel-plate condenser immersed in the dielectric medium. The charges on the two plates are represented again by the symbols +Q and — Q. The permittivity of the fluid, s, is defined by... 

Notation o=e1ectrical conductivity, ic-real relative permittivity, subscripts mix, f and p denote soil-flu id mixture, fluid, and particle, respectively, /-ionic valence, c-ionic concentration, u=ionic mobility is, F =96485.3 C/mol is Faraday s constant, TDS= total dissolved salts in [mg. L], n=porosity, p=density, =surface conduction, S,=specific surface, a=degree of saturation, m=cementation factor, Gv=volumetric water content... 

It is well known that the permeability of a clay soil is not only a function of its porosity, but also of the concentration of ions in the pore fluid, and the permittivity of the pore fluid. While this may be well known, an explanation for the behaviour is not well known. In fact, in a recent paper Hueckel identified the explanation for this behaviour as one of the outstanding problems in soil mechanics ([4]) The controversy over these two inconsistent data sets (i.e., increased... 

Electric-force mixing is adequate for mixing flows at very low Reynolds number (-1). By lamination of two fluids with different electric conductivity and/or permittivity in a micro mixer, a steep cross-sectional gradient of the respective properties can be established [91]. The electric field may be parallel or perpendicular to the fluid interface, which is also a boundary where electric properties abruptly... 

One of the fluids was pure Mazola corn oil and the other was the same oil colored with oil-based Teal dye and doped with oil-miscible antistatic Stadis 450 to increase the conductivity and permittivity [91]. The latter values were measured with a broadband dielectric spectrometer in a spatially uniform low electric field for frequencies of 0.5-1 kHz. 

Anisotropic fluids, of which nematic liquid crystals are the most representative and simplest example, are characterized by an anisotropic dielectric permittivity. The nematic phase has D,yuh symmetry, and in a laboratory frame with the Z axis parallel to the C , symmetry axis (the director) the permittivity tensor has the form ... 

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