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Eyring’s model

As in Eyring s model, only intrasegmental forces are taken into account. [Pg.375]

The TSM for elementary processes in condensed systems [58] employs the traditional tenets of Eyring s model [20,23], although it follows from the nature of the condensed state that the driving force of the process is ensured by thermofluctuation excitations of the medium, and not by the translational motion of the particles. In the transition state, an AC reacts with the neighboring particles. The parameter of their interaction - differs from the parameter of interaction between the initial reactant i which the AC is formed from and the neighboring particle j. [Pg.365]

As discussed in Sect. 3.2, once a mature fibril is created, further thickening occurs by a viscoplastic drawing mechanism which involves intense plastic deformation at the craze/bulk interface [32], Instead of using a non-Newtonian formulation as in [32] or a formulation based on Eyring s model [45], but on the basis of a preliminary study of the process [36], the craze thickening is described with a similar expression as the viscoplastic strain rate for the bulk in Eq. 3 as [20]... [Pg.214]

Figure 14.13 Eyring s model, (a) Before applying the stress, the positions of the segments identified as 1 and 2 are separated by an energy barrier AE. The jump between the two is equally probable in both directions, 1 2. (b) After application of the stress the energy barrier drops by AE — in such a way that the jump from position 1 to 2 is favored, therefore causing jumping over the barrier to occur preferentially in the direction of the stress. (From Ref. 36.)... Figure 14.13 Eyring s model, (a) Before applying the stress, the positions of the segments identified as 1 and 2 are separated by an energy barrier AE. The jump between the two is equally probable in both directions, 1 2. (b) After application of the stress the energy barrier drops by AE — in such a way that the jump from position 1 to 2 is favored, therefore causing jumping over the barrier to occur preferentially in the direction of the stress. (From Ref. 36.)...
While the stress relaxation studies in Chapter 10 emphasized the presence of a single relaxation time, or at most a few relaxation times, real plastics undergoing extensive deformation display a broad distribution of relaxation times. Eyring s model of holes and flow. Section 8.6, can also be used to predict the time and temperature effects of shear yielding. [Pg.566]

Note 1.4.- It is worth noting that Eyring s model, for the partition function (relation [1.90]) is tantamount to mixing Guggenheim s (section 1.3.1) and Mie s (section 1.3.2) models. These models gave a good account of the properties of liquids respectively in the vicinity of a gaseous state and of a solid state. [Pg.32]

Figure 1.10. Comparison between the experimental value and that calculated by Eyring s model for the radial distribution function of Argon at 84.4K (data from [YOO 81])... Figure 1.10. Comparison between the experimental value and that calculated by Eyring s model for the radial distribution function of Argon at 84.4K (data from [YOO 81])...
Certain data appear in Table 1.2 for Lennard-Jones and Devonshire s model (see section 1.4). Others are given for the solids of rare gases in Table 1.3, and pertain to Eyring s model (see section 1.5). [Pg.34]

Note that both models yield satisfactory results on this point. However, it is important to apply the comparison to several types of results. For example. Figure 1.11 shows that, for the representation of the distribution function, Lennard-Jones and Devonshire s model, Eyring s model and the calculations performed by numerical simulation are very similar. Meanwhile, Figure 1.12, which gives the variation of the compressibility coefficient as a function of a reduced volume, illustrates the significant behavioral difference between the molecular dynamics simulation and Eyring s model, on the one hand, and Lennard-Jones/Devonshire s, Guggenheim s (see section 1.3.1)... [Pg.34]

Fig. 8. Schematic of the energy landscape for an unstrained polymer for Eyring s model of viscous flow. Fig. 8. Schematic of the energy landscape for an unstrained polymer for Eyring s model of viscous flow.
Several attempts to relate the rate for bond scission (kc) with the molecular stress ( jr) have been reported over the years, most of them could be formally traced back to de Boer s model of a stressed bond [92] and Eyring s formulation of the transition state theory [94]. Yew and Davidson [99], in their shearing experiment with DNA, considered the hydrodynamic drag contribution to the tensile force exerted on the bond when the reactant molecule enters the activated state. If this force is exerted along the reaction coordinate over a distance 81, the activation energy for bond dissociation would be reduced by the amount ... [Pg.112]

Although the formulation of such a theory has never been achieved, Eyring s absolute reaction rate model [123] has several features in common with such theory. [Pg.493]

Mathematical formulation of Eyring s surface-burning model is given by Cook on... [Pg.581]

The differences are easily seen even between A B. This is in agreement with Cook s geometrical model but not with the Jones nozzle theory or Eyring s curved-front theory, since in the latter theories... [Pg.722]

Based on the Nernst-Planck flux equation and Eyring s rate theory, a simple theoretical model was evolved for the description of the transport of ions through thick carrier membranes5 (see also Ref. 15). The primary... [Pg.295]

Cohen and Price s model was applied to several HMX propint formulations with the results shown in Figs 6, 7 and 8. The model information is represented by the solid line plot 58) D. Price A.R. Clairmont, Jr, Explosive Behavior of Simplified Propellant Models , Comb Flame 29, 87-93 (1977) CA 87, 55269 (1977) [The objective of the study was to determine deton vel (D), detonability and shock sensy as functions of loading d (p0) and (critical) charge diameter (dc) for a model proplnt compn contg AP/Al/wax/HMX (50/15/ 15/20%). From the data the authors conclude that (1) D varies directly (or linearly) with po (2) dc increases with increasing p0, (3) deton is diffusion controlled, (4) the proplnt cannot be dead-pressed (it will always detonate), (5) the proplnt is a group 2 expl, and (6) addn of 20% HMX to a proplnt model without expin at 55% theoretical max d lowers the relative Eyring reaction time (to deton) from 1.0 to 0.45 units]... [Pg.590]

Different approaches were used to describe the yielding of polymers quantitatively. Some theories took into account the free volume fraction. Eyring considered thermally activated mechanisms, and Robertson s model was based on changes of chain conformations. Argon s and Bowden s models were based on a metallurgical approach and a dislocation theory. A brief summary of the existing yielding theories is presented. [Pg.372]

The macroscopic upper yield stress is lineary related to Tg — T for a given strain rate, and can be adjusted with Argon s, Bowden s, and Kitagawa s models. The influence of strain rate is well represented by the phenomenological Eyring s equation. [Pg.380]

Chapter 8 provides a unified view of the different kinetic problems in condensed phases on the basis of the lattice-gas model. This approach extends the famous Eyring s theory of absolute reaction rates to a wide range of elementary stages including adsorption, desorption, catalytic reactions, diffusion, surface and bulk reconstruction, etc., taking into consideration the non-ideal behavior of the medium. The Master equation is used to generate the kinetic equations for local concentrations and pair correlation functions. The many-particle problem and closing procedure for kinetic equations are discussed. Application to various surface and gas-solid interface processes is also considered. [Pg.7]

There are two models that quantitatively describe the relationship between temperature and rate constants, the Arrhenius theory and the Eyring theory [2, 3], Engineers prefer the Arrhenius equation because it is slightly simpler, while kineti-cists prefer the Eyring equation because its parameters (entropy and enthalpy of activation, AS and AH, respectively) can be interpreted more directly. Here, we will use Eyring s equation. [Pg.254]

Equation (10) was shown to follow from a thermally activated model of Eyring s type, that is a stress-assisted thermally activated process for viscous flow [154]. For rough surfaces the area of true molecular contact is very small and, hence, the adhesion contribution to the total friction force is usually negligible, as manifested by a zero friction at zero load [148]. Yet in the microscopic limit of the SFM experiment employing a comparatively sharp... [Pg.117]

Girault and Schiffrin [60] pointed out the multistep character of the ion transport across the liquid-liquid interface, and hence they referred to Eyring s multistep model [108]. The ion was considered to diffuse toward the interface over a sequence... [Pg.322]

However, Eq. (14.20) fails when it tries to describe the yield behavior of polymers over a wide range of temperatures. This has led to a modification of the model (20,21) that assumes that the deformation process involves two different flow processes that have different values of AE and V. Finally, another simple modification of Eyring s equation [Eq. (14.20)] (22) is to include the effect of hydrostatic pressure. This modification reflects the different yield behavior of polymers observed in tension and those in compression. [Pg.602]


See other pages where Eyring’s model is mentioned: [Pg.322]    [Pg.58]    [Pg.189]    [Pg.172]    [Pg.209]    [Pg.35]    [Pg.322]    [Pg.58]    [Pg.189]    [Pg.172]    [Pg.209]    [Pg.35]    [Pg.515]    [Pg.301]    [Pg.174]    [Pg.416]    [Pg.288]    [Pg.101]    [Pg.93]    [Pg.350]    [Pg.322]    [Pg.26]    [Pg.457]    [Pg.17]   
See also in sourсe #XX -- [ Pg.598 ]

See also in sourсe #XX -- [ Pg.12 ]




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