Permitivity relative

The dielectric constant is a property of a bulk material, not an individual molecule. It arises from the polarity of molecules (static dipole moment), and the polarizability and orientation of molecules in the bulk medium. Often, it is the relative permitivity 8, that is computed rather than the dielectric constant k, which is the constant of proportionality between the vacuum permitivity so and the relative permitivity. 

Another way to obtain a relative permitivity is using some simple equations that relate relative permitivity to the molecular dipole moment. These are derived from statistical mechanics. Two of the more well-known equations are the Clausius-Mossotti equation and the Kirkwood equation. These and others are discussed in the review articles referenced at the end of this chapter. The com-... 

The effect of relative permitivity D on the cyclo-trimerization of phenyl isocyanate was studied in the solvent system acetonitrile (AN) - ethylacetate (EA) using cyclic sulfonium zwitterion VI as catalyst. It was found that the rate constant increased with the increase of relative permitivity D of the solvent system, the experimental data correlate well with the Kirkwood equation ... 

Similar effects of relative permitivity D on the cyclotrimerization were also observed in the case of substituted ammonium carboxylate catalysts. It was also observed that, besides relative permitivity, the specific solvation of reactants by aprotic dipolar solvents had a considerable effect on the rate constant of cyclotrimerization of isocyanates (see Table II). 

Figure 1. Effect of relative permitivity D of the solvent system on cyclotrimeriza-tion of isocyanates Catalyst cyclic sulfonium zwitterion VI 25°C solvent system, acetonitrile (D = 37.5) and ethyl acetate (D = 6.02).

Evidently, solvent polarity , as so-defined, is badly described in a quantitative manner by means of individual physical constants such as relative permittivity, dipole moment, etc. It is no surprise therefore, that the macroscopic relative permittivities are an unsuitable measure of molecular-microscopic interactions. This has often been demonstrated experimentally. One reason is that the molecular-microscopic relative permit-... 

The dipole moments were determined at 25 °C in benzene (five solutions, weight fraction 1.8x10 to 1.lxlO 3), showing the 3.84 D value for (1), 5,47 D for (2), 5.49 D for (3) and 5.34 D for (4). Relative permitivities were measured at 6 MHz on a homemade DK-meter with direct frequency reading,8 and refractive indices were measured... 

Re Entry [86], Ref. [2]) Special Relativity permits arbitrarily fast superluminal phenomena that transmit no mass-energy or information, as well as mutual velocities up to 2c see pp. 56 and 70 of Ref. [2], Section 2.10 of Ref. [2] states that the speed U of transmission of information must not exceed c if violation of causality is to be prevented in Special Relativity. But Eqs. (2.21) and (2.22) in Sect. 2.10 of Ref. [2] at least suggest the possibility that Special Relativity may be consistent with a somewhat less conservative limit, namely U < c2/v, where v is the relative velocity between the transmitter and receiver. Of course to guarantee causality Nature must then have a method to checkmate any attempt by the transmitter and/or receiver to "cheat" by increasing v while a signal is en route. 

The effect of solvents on the kinetics of the phenol-phenyl isocyanate reaction is seen in Table V. The reactivity increased in the following order dioxane < toluene < DMF (1 3.3 92). The difference in reactivity is due to the combined effects of the relative permitivity and the specific solvation. 

The observed increase in the reactivity is due to the combined effects of the relative permitivity and the specific solvation of the reactants by the solvents. 

It was found that the reactivity of isocyanates in the cyclotrimerization reactions increased with the presence of the electron withdrawing groups in the vicinity of the isocyanate group, with the increased nucleophili-city of a catalyst and relative permitivity of the solvent system. 

The solvents used in the cyclotrimerization of isocyanate had a very strong effect on the reaction rate with the increase of the relative permitivity of the solvent system, the cyclotrimerization rate constants increased. The experimental data... 

Besides the relative permitivity, the specific solvation of reactants by solvents affected the cyclotrimerization reaction. It was observed that in the solvent systems with the constant relative permitivity, the reaction rate decreased with the increasing solvation of reactive groups. (8)... 

At the beginning of this section it was stated that the propensity of a textile polymer to accumulate static electrical charges is related to their electrical resistance. It has al.so been said that electrical resistance is related to the relative permittivity of the material. Relative permitivity or permittivity is sometimes (now incorrectly) called dielectric constant, as this used to be the common term before SI units became the fashion. Relative permittivity is therefore often used as a shorthand method of indicating the static electrical propensity of fibers and filaments. Its measurement is discussed in lEC 250. 

Relative permitivity e is the ratio of the capacitance between pairs of electrodes with the material as the dielectric to the capacitance between the electrodes without the material (air being the dielectric). So... 

Using a surface tension of y = 37 mN m and a relative permitivity of Yj. = 2.2, Taylor found the critical potential for transformer oil in his experimental apparatus to be ... 

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