Interface elasticity parameter

He and Hutchinson (1989) considered a crack approaching an interface as a continuous distribution of dislocations along a semi-infinite half space. The effect of mismatch in elastic properties on the ratio of the strain energy release rates, Gi/Gj, is related to two non-dimensional parameters, the elastic parameters of Dundurs, a and /f (Dundurs, 1968) ... 

High-resolution TEM (HRTEM) has now shown more details on such interfaces. The position of the misfit dislocation actually depends on the elasticity parameters of the two materials. The schematic diagram in Eigure 15.20... 

The interface region in a composite is important in determining the ultimate properties of the composite. At the interface a discontinuity occurs in one or more material parameters such as elastic moduli, thermodynamic parameters such as chemical potential, and the coefficient of thermal expansion. The importance of the interface region in composites stems from two main reasons the interface occupies a large area in composites, and in general, the reinforcement and the matrix form a system that is not in thermodynamic equiUbhum. 

As demonstrated, Eq. (7) gives complete information on how the weight fraction influences the blend viscosity by taking into account the critical stress ratio A, the viscosity ratio 8, and a parameter K, which involves the influences of the phenomenological interface slip factor a or ao, the interlayer number m, and the d/Ro ratio. It was also assumed in introducing this function that (1) the TLCP phase is well dispersed, fibrillated, aligned, and just forms one interlayer (2) there is no elastic effect (3) there is no phase inversion of any kind (4) A < 1.0 and (5) a steady-state capillary flow under a constant pressure or a constant wall shear stress. 

Luo and Domfeld [110] introduced a fitting parameter H , a d5mamical" hardness value of the wafer surface to show the chemical effect and mechanical effect on the interface in their model. It reflects the influences of chemicals on the mechanical material removal. It is found that the nonlinear down pressure dependence of material removal rate is related to a probability density function of the abrasive size and the elastic deformation of the pad. 

Our goal is to develop a property-performance relationship for different types of demulsifiers. The important interfacial properties governing water-in-oil emulsion stability are shear viscosity, dynamic tension and dilational elasticity. We have studied the relative importance of these parameters in demulsification. In this paper, some of the results of our study are presented. In particular, we have found that to be effective, a demulsifier must lower the dynamic interfacial tension gradient and its ability to do so depends on the rate of unclustering of the ethylene oxide groups at the oil-water interface. 

The rheological properties of a fluid interface may be characterized by four parameters surface shear viscosity and elasticity, and surface dilational viscosity and elasticity. When polymer monolayers are present at such interfaces, viscoelastic behavior has been observed (1,2), but theoretical progress has been slow. The adsorption of amphiphilic polymers at the interface in liquid emulsions stabilizes the particles mainly through osmotic pressure developed upon close approach. This has become known as steric stabilization (3,4.5). In this paper, the dynamic behavior of amphiphilic, hydrophobically modified hydroxyethyl celluloses (HM-HEC), was studied. In previous studies HM-HEC s were found to greatly reduce liquid/liquid interfacial tensions even at very low polymer concentrations, and were extremely effective emulsifiers for organic liquids in water (6). 

Surfactants form semiflexible elastic films at interfaces. In general, the Gibbs free energy of a surfactant film depends on its curvature. Here we are not talking about the indirect effect of the Laplace pressure but a real mechanical effect. In fact, the interfacial tension of most microemulsions is very small so that the Laplace pressure is low. Since the curvature plays such an important role, it is useful to introduce two parameters, the principal curvatures... 

The main issue is to attempt to provide a better interpretation of the results in terms of skin parameters. The friction coefficient depends on several parameters microrelief, vertical pressure, skin elastic properties, hydration of the surface, presence (or not) of a greasy film at the interface between skin and the measuring pad, nature of the pad. Several publications describe the influence of all these parameters on the measurement of friction coefficients but results are only qualitative because of the complexity of the phenomenon. 

The second important assumption in the analysis is that interfacial failure occurs only in shear, i.e. that any peeling stress, normal to the interface, is negligible. Analysis of an elastic bilayer (5) shows that, for the experimental parameters employed here, the peeling stress is, in fact, an order of magnitude less than the shear stress. Furthermore, finite element analysis (6) shows that the normal stress is compressive rather than tensile for the thicknesses of PET and Ni used here. Finally, it will be shown that the experimental results are consistent with the one-dimensional analysis presented above. 

For set B, craze thickening is faster and the craze critical thickness is attained at K / (so r ) 1.32, which is significantly smaller than the value K / (so rt) 1.71 for set A. During crack propagation, some plasticity confined to the craze/crack interface is observed (Fig. 12) but the bulk remains mostly elastic. Therefore, the craze parameters B of Table 3 result in a more brittle response compared to that predicted for the craze parameters A (see Fig. 8b). 

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