Surface layer, thickness

Fig. 8. Residual impression depth against reciprocal long period for two series of lamellar PE samples with surface layer thicknesses of 80 (O) and 200 A (A) respectively5Sa)...

Figure 1. Dependence of surface layer thickness onMjjtPDMS)...

We could not conclude at the moment whether the solvent dependent surface properties are to be explained only by the difference in the depth of graft layer. Another possibility is the change in polar group orientation in graft layer as suggested by Hoffman(18). This arguement will be settled by direct determination of the thickness of graft layer prepared under various conditions. Clarification of the surface layer thickness - sur-... 

Tsukahara, Y., Takeuchi, E Hayashi, E., and Tani, Y. (1984). A new method of measuring surface layer-thickness using dips in angular dependence of reflection coefficients. IEEE 1984 Ultrasonics Symposium, pp. 992-6. IEEE, New York. [214] Tsukahara, Y Nakaso, N., Kushibiki, J., and Chubachi, N. (1989a). An acoustic micrometer and its application to layer thickness measurements. IEEE Trans. UFFC 36, 326-31. [213-215]... 

Additional H20 surface layers. Thickness depends on temperature and relative humidity. 

Fig. 23. Variation of surface layer thickness with molecular weight of the stabilizing polydimethylsiloxane (PDMS) chain. Hydrodynamic thickness <5109) PMMA particles (O), PS particles ( ), micellar dispersions (A) from viscosity data x, thickness h from surface coverage data of PMMA particles assuming a prolate ellipsoid model for the...

The standard method of treating the electric dipole contribution from the surface region is to view the nonlinear polarization as a dipole sheet which can be described by the surface susceptibility tensor, xf. This is equivalent to considering the three layer system shown in Fig. 3.1 with the dipole sheet placed just below the surface at z = 0+ and allowing the surface layer thickness, d, to approach zero. The surface contribution to the polarization can then be written as... 

Figure 2. Dependence of surface layer thickness on Mn (PDMS) (O) PMMA particles ( , A) particles (6)...

Donnan potentials (Eqs. (28.14) and (28.15)) are independent of the surface layer thickness and therefore the membrane potential depends httle on provided that... 

Fig. 41. (top) Model of surface layer formed during plasma etching of silicon with chlorine, (bottom) Surface layer thickness as a function of the DC bias voltage (ion energy). After [212]. 

Fig. 6. Effect of the solvent quality on the PDMS surface layer thickness and particle-particle interaction force a) PDMS surface layer swelling due to good solvency of the liquid medium b) compression of PDMS layer due to low solvency of the liquid medium.

Calculations show that the model of a non-equilibrium surface layer is an alternative to kinetic-controlled adsorption models. On the basis of the purely diffusion-controlled adsorption mechanism the proper consideration of a non-equilibrium diffusion layer leads to a satisfactory agreement between theory and experimental data for various studied systems, systematically demonstrated for the short-chain alcohols [132], The non-equilibrium model is applicable in the concentration range from 10 to 10 mol/cm at different values of the Langmuir constant at- For l < 10 mol/cm a consideration of non-equilibrium layer effects is not necessary. For ai > 10 mol/cm and large surfactant concentration the Ay values calculated from the proposed theory do not compensate the discrepancy to the experimental data so that other mechanisms have to be taken into account. An empirical formula also proposed in [132] for the estimation of the non-equilibrium surface layer thickness leads to a better agreement with experimental data, however this expression restricts the validity of the non-equilibrium surface layer model as alternative to non-diffusional adsorption kinetics. 

The annealing temperature dependence of such a surface mobile layer will now be discussed. At 370 K, the thickness of the surface mobile layer was 10 2.8 nm. It should be of interest to compare the thickness with the chain dimension. Twice the radius of gyration (2/fg) of an unperturbed PS with Mn of 29k is calculated to be 9.3 nm. This value is comparable to the surface layer thickness. At 365 and 355 K, the interfacial thicknesses similarly increased with time at first and then became invariant with respect to the annealing time, as shown in Fig. 8c, d. The evolved interfacial thickness at 365 and 355 K were 9.6 2.5 and 11.4 0.9 nm, respectively. Half of these values, namely surface mobile layer thicknesses, are much... 

Fig. 9 Molecular weight dependence of surface layer thickness at 365 K...

In the majority of mechanical applications of materials, their surfaces experience contact with another material and take the external load before the bulk of the material is influenced. In some cases, surface interactions influence the bulk (e.g., propagation of cracks dislocations or point defects from the surface in depth). In many cases, only the outermost surface layer is affected by the surface contact with no detectable changes in the bulk of the material. This is like a storm that is frightening and destructive on the ocean surface, but does not have any influence on deep-water life. We are primarily concerned in this review with that kind of interaction. The surface layer thickness affected by external mechanical forces ranges from nanometers to microns. Thus, in our case, the definition of surface is different from the one used by surface scientists, that is, physicists and chemists. We introduce here an engineering definition of surface the outermost layer of the material that can be influenced by physical and/or chemical interaction with other surfaces and/or the environment. In this chapter, we consider only mechanical effects, but both mechanical and chemical interactions are possible and their synergy can lead to mechanochemical alteration of a material surface. 

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