Apparent layer thickness, determination

One of the principle analytical techniques for the analysis of laminates is the infrared microscope. This instrument is capable of recording transmission infrared spectra from sample down to 10 square microns in size. The approach is usually to prepare a section of the laminate by microtoming a section and then recording a spectrum of each layer aided by the masking off of the other layers. The sectioning is often undertaken obliquely in order to maximise the apparent layer thickness. The microscope also allows the thickness of each layer to be determined. 

RAT grinding operations. This surface layer was removed except for a remnant in a second grind. Spectra - both 14.4 keV and 6.4 keV - were obtained on the undisturbed surface, on the bmshed surface and after grinding. The sequence of spectra shows that nanophase Oxide (npOx) is eiu-iched in the surface layer, while olivine is depleted. This is also apparent from a comparison of 14.4 keV spectra and 6.4 keV spectra [332, 346, 347]. The thickness of this surface layer was determined by Monte-Carlo (MC)-Simulation to about 10 pm. Our Monte Carlo simulation program [346, 347] takes into account all kinds of absorption processes in the sample as well as secondary effects of radiation scattering. For the MC-simulation, a simple model of the mineralogical sample composition was used, based on normative calculations by McSween [355]. 

The number of layers and the approximate thickness of each layer were determined from SEM images of freeze-fractured cross-sections of the films (Figure 65). A diagram of the apparent film construction is presented in Figure 66. The composition and thickness of each layer are shown in Table 15. The center opaque polyethylene layer and the EVA heat seal layer could not be differentiated in the SEM images of the freeze-fractured cross-section of the... 

This occurs because, as the layer thickness is increased the van der Waals attraction is weakened, so that the superposition of attraction and repulsion will have a smaller minimum. For very small steric layers, may become deep enough to cause weak flocculation that would result in a weak attractive gel. Hence, it becomes apparent exactly how the interaction energies can also determine the dispersion rheology. 

To some authors, it seems to be apparent that the microlayer consists of a surface monolayer of adsorbed organic matter of thickness —20 A diluted by a vast excess, 10 —10 times as much, subsurface seawater. It should be noted that a monolayer thickness of this magnitude applies mostly to mono-layers of simple surfactants such as fatty lipids. Water-soluble surfactants of the wet variety (MacIntyre, 1974) can form monolayer films of much greater thickness, with hydrophobic parts of the molecule attached to the interface and hydrophilic parts extending by as much as —1 pm into the aqueous phase. The results of Baler et al. (1974), to be discussed shortly, show that films in a dry state on germanium prisms used for the Blodgett (1934, 1935) type of sampling method have thicknesses determined by ellip-... 

Such boundary layers exist in proximity to any interface solid-liquid, liquid-liquid, and liquid-air. In the vicinity of the apparent three-phase contact line (Fig. 3), those boundary layers overlap. The overlapping of boundary layers is the physical phenomenon which results in the existence of surface forces. Let the thickness of the boundary layers be 8. In the vicinity of the three-phase contact line, the thickness of a droplet/ meniscus, h, is small enough, that is, /i 8, and, hence, boundary layers overlap (Fig. 3), which results in the creation of disjoining pressure. A similar situation occurs at a contact of two particles in a liquid (Fig. 4). The abovementioned characteristic scale of boimdary layer thickness, 8 10 cm, determines the characteristic thickness where the disjoining pressure acts. 

Metallographic examination offers valuable information once the sample is sectioned, mounted, hand-p>olished, and KroU etched per recommended procedures outlined in Ref 37. The remaining metal sample thickness and the alpha-case layer thickness along the sample surface can be determined from the cross-sectioned mount. This alpha-stabilized layer is not visually discemable in a alloys, but should be readily apparent when heavier than a few tenths of a mil in ot/p and P alloys (see Fig. 11). Subscale or... 

The stagnant layer in electrokinetics, that is, the layer with an apparent infinitely high viscosity, is closely related to these density oscillations. Hence, the thickness of this layer is determined by the extension of these oscillations into the solution. 

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