Morphology Structural Models

Membrane Morphology Structural Models Cluster-Network Models of Ion Aggregation... 

On the basis of this prior knowledge, it was no surprise for us to find a whole plethora of (catalytically very active) metal nanoparticles with tunable size, morphology, and structure when we applied modern analytical tools including structure modelling to revisit Ziegler s classical findings [305-307]. 

Pacheco-Sanchez, J. H. Alvarez-Raimrez, F., and Martmez-Magadan, J. M., Morphology of Aggregated Asphaltene Structural Models. Energy Fuels, 2004. 18 pp. 1676-1686. 

First of all let us consider the morphological structure of an agglomerate electrode [6] by way of example of the model shown in Figure 1. This schematic represents a multiphase system with no fixed connection between its components. As a rule, the active mass of an electrode is a mixture of Nickel hydroxide (oxyhydroxide) with conductive carbon or a metal, which are well dispersed mechanically in the matrix. 

Properties of peroxide cross-linked polyethylene foams manufactured by a nitrogen solution process, were examined for thermal conductivity, cellular structure and matrix polymer morphology. Theoretical models were used to determine the relative contributions of each heat transfer mechanism to the total thermal conductivity. Thermal radiation was found to contribute some 22-34% of the total and this was related to the foam s mean cell structure and the presence of any carbon black filler. There was no clear trend of thermal conductivity with density, but mainly by cell size. 27 refs. 

The microstructure and morphology of thick single-phase films have been extensively studied for a wide variety of metals, alloys, and refractory compounds. The structure model first proposed is shown in Figure 6 (10). It was subsequently modified as shown in Figure 7 (10,11). 

The microstructure and morphology of thick single-phase films have been extensively studied for a wide variety of metals, alloys, and refractory compounds. Structural models have been proposed (12,13). Three zones with different microstructure and surface morphology were described for thick (tens of micrometers) deposits of pure metal. At low temperature (< 0.3 Tm ), where Tm is the melting point (K) of the deposit metal, the surface mobility of the adatoms is reduced, and the deposit was reported to grow as tapered crystallites. The surface is not full density (Zone 1). At higher substrate temperature (0.3-0.45 Tm ), the surface mobility increases. The surface... 

Figure 3.27 Schematic drawing of a structural model of individual particles of chiral mesoporous silicas with an outer helix-like morphology (left), showing three channels inside these particles, which are mnning along the long axis of the particle and are twisted around each other, and (right) the respective cross-sections. (Adapted from Reference 303.)...

Figure 21.8 Structural models for lamellar PEP-fr-PEO-b-PHMA block copolymer-aluminosilicate composite morphologies with a small PEP block. In the absence of the PEP block, the PEO (black) and PHMA (light grey) chains stretch into their respective domains while the aluminosilicate particles (white) partition into the hydrophilic PEO domain (a). Possible domain structures discussed in the text are illustrated as follows In the balls-in-lamellae structure the small PEP block (dark grey) forms round micellar domains (b). Dimple structure with PEP micelles at the PHMA/PEO-aluminosilicate interface (c). In the pillared-lamellae structure the PEP domains form pillars spanning across the PEO-aluminosilicate domain (d).37 (Reprinted with permission fiomG.E. S.Toombesetal., Chem. Mater. 2008,20,3278-3287. Copyright 2008 American Chemical Society.)...

Figure 21.12 Structural models for PEP-fr-PEO-fr-PHMA block copolymer-aluminosilicate lamellar morphologies with a small PEP block. Top (a) and side (b) views of the pillared-lamellae structure.37 (Reprinted with permission from G. E. S. Toombes et al., Chem. Mater. 2008, 20, 3278-3287. Copyright 2008 American Chemical Society.)...

Figure 5. Structural models for the morphology of open-wedge, round, and oval filaments spun from mesophase pitch.

It is interesting to note that the (L-N-B)-model leads to similar expressions for the moduli like the VTG-model apart from the first summand of Eq. (38). However, contrary to the semi-empirical weighting functions W(y6) of the VTG-model, the corresponding density distribution function/la(y) in the (L-N-B)-model is related to the morphological structure of the filler network, i.e., the distribution of singly connected bonds in a percolation network. Unfortunately, this distribution function is not known, exactly. Therefore, a simple exponential... 

Figure 7. Proposed model of the local morphological structure in the PTMO-TEOS hybrid systems, in which 1/s is an estimate of the correlation distance, (Reproduced from reference 7. Copyright 1987 American Chemical...

Nearly all zeolite structure models, often seen in laboratories and in the literature, show only the general structure, just the morphology or topology, of the zeolite fiamework. It is only for these neutral zeolite fiameworks that those models can be complete. (Even then, the model is not complete unless all of the elements in the fiamework are labelled, to indicate, for example, their ordering.) For all other zeolites, much more must be added (the positions of the labile cations, at least) for the model to be considered complete. In general, these models are only convenient starting points for discussions of structure and properties. 

For a few decades now cellular and porous systems have been classified in morphological terms by simulating the real systems by one or another imaginary, and always simplified, geometrical or stereometrical scheme using an artificially ordered-structure model. Such classifications have always been based on the concept that in any cellular or porous system it is possible to isolate a structural element (cell or pore). However, the diversity of pore and cell types even in small-sized real foamed systems does, in most cases, not permit a definition by only one single geometrical structural parameter, as for other types of solids (type and volume of elementary cell, interplanar or interatomic distances, etc.)... 

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