Effective surface energy

Organized assemblies are useful to promote specialized features of a reaction, e.g., proximity effects, surface energy effects, or reactant organization. These features are useful in energy storage. As more is learned about these systems and their participation in reactions, it may be possible to obtain precise information on the effects of microscopic geometric arrangements of reactants on the subsequent course of reaction. Many assemblies are known many others are available but have not been studied as yet. 

At this point, however, we need to be careful. The reason is that for solids we have to distinguish between surface tension and surface energy. The work required to form a new surface depends on how this surface is formed plastically (as for a liquid) or elastically. In an experiment, usually both effects contribute. Therefore we should consider the surface energy obtained from adhesion experiments as an effective surface energy. Inserting Eq. (6.70) into Eq. (6.69) leads to... 

A final consequence of this reconciliation between the kinetic theory and fracture mechanics concepts, is that the effective surface energy S should vary somewhat as Regime I gives way to Regime II. In the former, the stress field is required to provide energy (in the absence of losses) of the order of AG upwards, since the balance of the activation energy G is provided by thermal fluctuations. In Regime II virtually the whole of G must be provided by the stress field so that we have. 

In this expression the effective surface energy, a, represents a specific (per unit area of a newly formed interface) work of fracture. This quantity, along with the true surface energy, a, includes the work of plastic deformation per unit area of a surface of crack, i.e. the energy of lattice distortions and damages that occur during the development of a crack. The value of a may... 

This standard description is inappropriate when the cluster (of radius r) is formed on surface of nanofiber. Due to enormous curvature of such system this surface cannot be considered to be flat (see Fig. lb) and the effective surface energy in (3) has to be modified [4] ... 

A rough substrate with cavities can show hydrophobic behavior if air remains trapped in the cavities after a liquid drop is deposited on it. The effective surface energy of the substrate depends on the equilibrium state of the liquid-air interface inside the cavities. In general, multiple stable equilibrium states are possible, which... 

On the time scale of the evaporation process, the water will evaporate into the cavities and the air will diffuse out of the cavities. Hence, the effective surface energy of the substrate could change and may reduce the hydrophobicity. The current theory can be extended to study this problem, which is not within the scope of this work. 

One of the first attempts was to obtain an expression for the ductile-to-brittle transition temperature [54] using certain simplifying assumptions with respect to the temperature dependence of yield stress and effective surface energy. The derived expression has the following form ... 

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