The Macrostructure

Fig. 26.1. The macrostructure of wood. Note the co-ordinate system (axial, radial, tangential]...

Fig.ll. SEM micrograph showing the macrostructure of CFCMS (scale bar represents lOOpm). 

The macrostructure of the boron nitride obtained here is porous with pores 2 pm in diameter. There is no evidence for microporosity and the BET surface area 1s 35 m2 g-1. Transmission electron micrographs (Figure 4) show regions of well developed crystallinity. The crystalling grains are 5—10 nm on a side and 30-40 nm long. The BN (002) lattice fringes are clearly visible. 

Numerous dendrimers, which contain coordination sites on the outer surface, within the macrostructure throughout all layers, and at the inner core have been prepared. In contrast,... 

Abstract. The subject of this research are the regularities of the particles motion in the electric and thermoelectric fields with distributed potential and the influence of temperature field to the particle motion trajectories in aggregate electric and thermal fields. The analytical solution of the problem of particle motion in thermoelectric field with distributed potential is produced. Common regularities of particle motion and trajectory changes in such fields are derived. It is shown that nonlinear curves give a nonconsiderable part of the trajectory within the macrostructures and so the trajectory shape doesn t considerably influence the electron flow transformation process. Conversely, the trajectory shape does influence the aforesaid processes in micro- and nanostructures defining the specific ways of transformation. 

A structure formed by the reversible association of am-phiphiles in apolar solvents. In inverted micelles, the polar portion of the amphiphile is concentrated in the interior of the macrostructure. Such association usually occurs with aggregation and is not typically characterized by a definite nucleation stage. Thus, inverted micelles (also referred to as inverse or reverse micelles) often fail to exhibit critical micelle concentration behavior. See Micelle... 

Details are given of the interaction between the macrostructure and morphology of PP structural foam mouldings made by the gas-counter pressure process. The morphology, orientation, and processes ofnon-isothermal... 

Heterogeneities exist on all spatial scales, from the micropores, the larger pores and particles to the macrostructure of the aquifer (Fig. 25.1). Therefore, the description of... 

Dementyev and Tarakanov 8 160) used another approach by adopting a macrostructural model of syntactic foam morphology161 to calculate the strength properties of an epoxy foam with phenolic microspheres. They made two restrictive assumptions, i.e. that the mechanical properties of the microsphere walls and the binder are the same, and that the volume fraction of filler is substantially smaller than that of the matrix. The macrostructural parameters of the syntactic foam are then defined in terms of the dimensions of the microspheres, and their displacements have the same nature as the deformations of the nodes and edges of an imaginary latice. We then get ... 

The macrostructure and microstructure of starch lead to the ready formation of inclusion complexes and surface adsorbates.1 Inclusion complexes form by involvement of the inner core of the amylose helix, the intergranular... 

The hydration of starch evokes thermal effects which are obviously also dependent on the starch variety. This is true because the external temperature does not affect426 the macrostructure and microstructure of starch below 140°C. An estimation of the heat of sorption is useful in determining the concentration of bound water.426-434 The heat of adsorption ranges from 0.255 to 0.100 kJ/mol and depends not only on the variety of starch, but also on the mode of drying of starch prior to measurement (Table XVIII).426... 

It is clear, however, that a s is not quantitatively equal to a because the macrostructural looseness (A) of the polymer in the two cases is not the same A for (Sty), x(DVB)x is given by [(1/x)1 3 — (l/x)o 3], as defined in Eq. 20, whereas A for the non-crosslinked polymer varies with the class of liquid, which determines y and the distribution of the self-associated domains that comprise y as noted above. It may be possible, however, to establish a quantitative relationship of a with oc9 for a given class of liquids, which could then be used in turn to establish the corresponding a/ocs for other P-L systems in that liquid classification. 

So far most of the pertinent literature interprets interactions between polymer and a second sorbed component on the basis of the colligative properties of the system. This information is summarized in Sect. 2 of this review. From those reports, I inferred that some sort of association of the small penetrant molecules with the repeat unit of the polymer is a prerequisite condition for the sequential changes described above. This implies that the magnitude of polymer swelling should be directly related to how well the molecular structure of the small molecule can be accommodated by the molecular structure of the polymer repeat unit in view of the macrostructure of that polymer (i.e. the crosslink density). The results obtained in our laboratory, which are summarized in Sect. 3 of this Review, are thoroughly consistent with that hypothesis. In Sect. 4 these interpretations are extended to correlate the colligative properties of Sect. 2. 

Neither of the above theories takes the macrostructure of carbon black into account in any quantitative way, although in practice this is crucial in selecting a material for a particular application. Sheng (1980) was, however, able to develop the first of these theories and extend its range of applicability. He noted the well-established model for hopping conduction by tunnelling... 

For a discrete molecule with a simple structure, a microstructure is sufficient to characterize the given molecule. For a complex system such as that of asphaltene, the information required for characterization has to include association as well as micelle formation. The microstructure has been chosen arbitrarily to refer to short-range bonding, that is, distances between 0.5 A-2.0 A whereas the macrostructure (bulk structure) pertains to molecular interactions or orders at larger distances (20 A-2000 A). 

Table II. Some Commonly Used Structural Parameters for the Macrostructure of a Petroleum-Derived Asphaltene...

Figure 3. The general features of the macrostructure of petroleum-derived asphaltenes and related substances...

Table IV. Parameters for the Characterization of the Macrostructure of Coal-Derived Asphaltenes and Related Derivatives...

In these studies, the possibility exists that the kinetics of gas formation have been modified or that they require a different mechanism of localized interaction within the macrostructure. The larger, more amorphous the structure, the greater the opportunity for product ratio inversion by the localized high temperature power input to specific bond types. Presently, gas output and composition are being studied as a function of shale grade, time, and power. Tentative results indicate the individual hydrocarbon components maintain a consistent relationship to each other but the C02 and CO content vary with grade of shale and time. 

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