Diffusion influence, liquid

The amorphous orientation is considered a very important parameter of the microstructure of the fiber. It has a quantitative and qualitative effect on the fiber de-formability when mechanical forces are involved. It significantly influences the fatigue strength and sorptive properties (water, dyes), as well as transport phenomena inside the fiber (migration of electric charge carriers, diffusion of liquid). The importance of the amorphous phase makes its quantification essential. Indirect and direct methods currently are used for the quantitative assessment of the amorphous phase. 

The influence of interfaeial potentials (diffusion or liquid junction potentials) established at the boundary between two different electrolyte solutions (based on e.g. aqueous and nonaqueous solvents) has been investigated frequently, for a thorough overview see Jakuszewski and Woszezak [68Jak2]. Concerning the usage of absolute and international Volt see preceding chapter. 

The large fluctuations in temperature and composition likely to be encountered in turbulence (B6) opens the possibility that the influence of these coupling effects may be even more pronounced than under the steady conditions rather close to equilibrium where Eq. (56) is strictly applicable. For this reason there exists the possibility that outside the laminar boundary layer the mutual interaction of material and thermal transfer upon the over-all transport behavior may be somewhat different from that indicated in Eq. (56). The foregoing thoughts are primarily suppositions but appear to be supported by some as yet unpublished experimental work on thermal diffusion in turbulent flow. Jeener and Thomaes (J3) have recently made some measurements on thermal diffusion in liquids. Drickamer and co-workers (G2, R4, R5, T2) studied such behavior in gases and in the critical region. 

Even when composition is fixed, viscosity and other rheological properties may depend on the size and arrangement of aligned domains within a sample of liquid crystalline material. No studies of this matter seem to have been made, however. Such structural characteristics do influence electrical conduction and diffusion in liquid crystals, as discussed further below. 

V. Linek, J. Mayrhoferova, J. Mosnerova, The influence of diffusivity on liquid phase mass transfer in solutions of electrolytes, Chem. Eng. Sci. 25 (1970) 1033-1045. 

Fredrickson3 has formulated expressions for the concentration depolarization of fluorescence in the presence of molecular rotation. A theoretical examination of diffusion influenced fluorescence quenching by nearest possible quenching neighbours in liquids has been made35. A modified version of Smoluchowski - Collins - Kimball formulation of the Stern - Volmer equations has been matched with experimental data for quenching of anthraquinone derivatives by N,N-dimethyl- -toluidine. Another paper discusses this work on the basis of the kinetics of partly diffusion controlled reactions3 . 

All moisture transport processes, on the other hand, affect heat transfer significantly. Evaporation and moisture sorption have a direct impact on heat transfer, which in turn is influenced by water vapor diffusion and liquid diffusion. The temperature rise during the transient period is caused by the balance of heat released during fiber moisture sorption and the heat absorbed during the evaporation process [40],... 

Let us consider a particular example of the effect of RS substances on the water resistance of adhesive-bonded joints. Adhesives based on imsaturated polyester resins, such as PN-1, are distinguished by low water resistance. The influence of water on a steel joint cemented by such an adhesive actually results in some initial increase of the specific electrical resistance along the adhesive-steel interface and then in an abrupt drop (Fig. 5.5). The increase is explained by more complete consumption of the monomer in the system. When ATG is added to the adhesive (which decreases the interphase tension) the specific electrical resistance stabilizes after a drop. The decrease seems to be related to the processes of relaxation of the internal stresses in the adhesive interlayer. The stresses facilitate the diffusion of liquids in polymeric materials, in particular the stress concentration at the polymer-metal interface. 

Kinetics under Varying Degree of Liquid Diffusion Influence... 

Fast activationless reactions, such as recombination of atoms and radicals, of course, occur more slowly in liquid than in gas because they are limited by the rate of particle self-diffusion, and diffusion in liquid occurs more slowly than in gas. Therefore, it is of interest to compare slow reactions, which are not limited by diffusion in liquid, to those with rate constants A < 1 o l/(mol s) in the gas phase. As we will see further, the solvation effects and formation of molecular complexes influence strongly on the chemical reaction in liquid. Since solvation is absent ftom the gas phase, for the correct comparison we have to consider reactions in which at least one reactant is a nonpolar particle, for example, hydrocarbon. Reactions of radicals with nonpolar C—H bonds are most suitable for this comparison. The data on such... 

With regard to the liqiiid-phase mass-transfer coefficient, Whitney and Vivian found that the effect of temperature upon coiild be explained entirely by variations in the liquid-phase viscosity and diffusion coefficient with temperature. Similarly, the oxygen-desorption data of Sherwood and Holloway [Trans. Am. Jnst. Chem. Eng., 36, 39 (1940)] show that the influence of temperature upon Hl can be explained by the effects of temperature upon the liquid-phase viscosity and diffusion coefficients. 

Next, the German Adolph Eick (1829-1901), stimulated by Graham s researches, sought to turn diffusion into a properly quantitative concept and formulated the law named after him, relating the rate of diflfusion to the steepness of the concentration gradient (Eick 1855), and confirmed his law by measurements of diflfusion in liquids. In a critical examination of the influence of this celebrated piece of theory, Tyrrell... 

Now, we should ask ourselves about the properties of water in this continuum of behavior mapped with temperature and pressure coordinates. First, let us look at temperature influence. The viscosity of the liquid water and its dielectric constant both drop when the temperature is raised (19). The balance between hydrogen bonding and other interactions changes. The diffusion rates increase with temperature. These dependencies on temperature provide uS with an opportunity to tune the solvation properties of the liquid and change the relative solubilities of dissolved solutes without invoking a chemical composition change on the water. 

The behavior of ionic liquids as electrolytes is strongly influenced by the transport properties of their ionic constituents. These transport properties relate to the rate of ion movement and to the manner in which the ions move (as individual ions, ion-pairs, or ion aggregates). Conductivity, for example, depends on the number and mobility of charge carriers. If an ionic liquid is dominated by highly mobile but neutral ion-pairs it will have a small number of available charge carriers and thus a low conductivity. The two quantities often used to evaluate the transport properties of electrolytes are the ion-diffusion coefficients and the ion-transport numbers. The diffusion coefficient is a measure of the rate of movement of an ion in a solution, and the transport number is a measure of the fraction of charge carried by that ion in the presence of an electric field. 

Glaser and Litt (G4) have proposed, in an extension of the above study, a model for gas-liquid flow through a b d of porous particles. The bed is assumed to consist of two basic structures which influence the fluid flow patterns (1) Void channels external to the packing, with which are associated dead-ended pockets that can hold stagnant pools of liquid and (2) pore channels and pockets, i.e., continuous and dead-ended pockets in the interior of the particles. On this basis, a theoretical model of liquid-phase dispersion in mixed-phase flow is developed. The model uses three bed parameters for the description of axial dispersion (1) Dispersion due to the mixing of streams from various channels of different residence times (2) dispersion from axial diffusion in the void channels and (3) dispersion from diffusion into the pores. The model is not applicable to turbulent flow nor to such low flow rates that molecular diffusion is comparable to Taylor diffusion. The latter region is unlikely to be of practical interest. The model predicts that the reciprocal Peclet number should be directly proportional to nominal liquid velocity, a prediction that has been confirmed by a few determinations of residence-time distribution for a wax desulfurization pilot reactor of 1-in. diameter packed with 10-14 mesh particles. 

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