Spatial network

The brass-colored PdTel consists of Jahn-Teller distorted PdTe2/2l4/4 octahedra, which are interconnected by common edges and corners to afford a loose, spatial network. The compound is considered to be ionic, containing Pd and Te , although the observed diamagnetism, electronic conduction, and color suggest some metallic character. 

Subsurface Defects in Ingots, The precipitation of REpOpS and rH as solid pariicles in the liquid steel immediately after the adSi ion is conducive to inclusion clustering, the forming of large — up to inches in diameter — spatial networks of small —... 

In order to prepare wood substitutes and materials with open-cell structures, the so-called water-filled oligomeric foams are used These foams are obtained by mixing the OFM-monomeric composition with water until an emulsion is formed which is hardened after the addition of an initiator and activator. As a result, a white rigid material is obtained which is a spatial network copolymer with uniformly distributed micro-inclusions of water (2—5 nm). Optimal strength is reached at 50-60% of water, although the amount of water may be as high as 90%. At optimal water concentration, the cell walls withstand cryolitic destruction till 34 K. At 7 mass % of water the apparent denaty of the material reaches 250—9(X) kg/m and it resembles natural wood in appearance and in some properties. 

Fig. 7. Schematic representation of ordered Ag nanostructures formed as (a) nanoclusters in LTA zeolite, (b) spatial network in LTA, and (c) wires in a mesoporous matrix.

The basis of the system (order I) is a local spatial network (Cacoh et al., 1987) which can be thickened with vertical and horizontal micro-networks (order II). The highest accuracy is obtained with the equipment employed in relative measurements, e.g. extensometers, inclinometers, feeler gauges. 

The local spatial network as a multifunctional geodetic network (in Polish), Zeszyty Naukowe AR Wroclaw, s.Geodezja IV, 167, 97-92. 

FIGURE 38 The kinetic curves for the system EPS-4/DDM at T 383 (1), 393 (2) and 403 K (3). The shaded lines are tangents to the initial parts of curves Q(t). Horizontal arrows indicate completion of microgels formation, vertical arrows indicate spatial network of entire sample formation. 

It is obvious that the system EPS-4/DDM proposed curing mechanism corresponds completely to the notions about gel formation phenomena as gel formation period , but not gelation poinf [48]. This period occupies the temporal range A-B in the curve h (Fig. 37). Strictly speaking, gelation is the critical stractural transition and it should be identified as spatial network formation... 

Rx gardless of the way of obtaining, the. system network polymer (. P)- -LMWL, whore the polymer forms a spatial network-crosslinked structure, will also be called a gel. 

The sites form a spatial network [56] on which the gas molecules can jump through the dense structure. This i twork comprises the spatial connectivity of the sites and the residence times X] of the solute there. 

Physicochemical properties of polymer surfactants that present macromolecules with both hydrophobic and hydrophilic fi agments are to be considered as stabilizers of ultradispersed state in all the above-cited processes. Along with the topochemistry, interactions which condition the morphology of future nanocomposites must also be considered. The stabilization mechanism is based on structural and mechanical constituents of stability in dispersed systems and spatial networks of the coagulation structure type and formation of adsorption-solvate structured films on nanoparticle surface. 

Under the action of strong enough mechanical stresses the macromolecular network decomposes into diradicalic fragments which within a short time behave as molecules of a micromolecular fluid, suffering a relative shifting under the action of the mechanical stresses and fixing then again in a spatial network of a structure similar to the first but which differs from these by a new macroscopic form of the polymeric product. 

FIGURE 2.23 The parallelepiped unit cell (left) and the spatial network that it generates (right), after Chiriac-Putz-Chiriac (2005). 

FIGURE 4.5 Deduction of the interstitial sphere radius with CN=8 from AA cubic spatial network. 

When the contacts between the particles in a free-disperse system are established, the transition of the system into a connected-disperse state takes place. This transition is associated with the development of a spatial network of particles in which the cohesive forces between the particles forming a network are sufficiently strong to resist thermal motion and the action of external forces. As a result of the transition, the system acquires a set of new structnral-mechanical (rheological) properties that characterize the ability of the syston to resist deformation and separation into individual parts. That is, the system acquires mechanical strength, which is the principal and universal characteristic of all solid and solid-like materials. For many materials, their mechanical strength defines the conditions of their use. 

The structure formation that takes place in disperse systems is the result of spontaneous, thermodynamically favorable processes of particle cohesion, leading to a decrease in the free energy of the system, such as particle coagulation or substance condensation at the points of particle contact. The development of spatial networks of various types is the foundation for the ability of a disperse system to transform into a material. As a result of such a transformation, the system acquires new characteristics and properties that are completely different from those in the original state. 

Coconut and pahn kernel oil, pahn oil, traditional rapeseed oil and cottonseed oil, beef tallow and butter tend to preferentially crystallise in the metastabile 3 -modification, which has characteristic small needle-Hke crystals. These triacylglycerols characteristically form clusters and aggregates to form the crystal spatial network, ideally they form a gel structure, which shows thixotropy. Fats... 

The process of polymerization of bifimctional monomers (e.g., diacrylates) can be divided into two steps (scheme 33). The first step yields a linear combshaped polymer with a degree of stereoregularity that depends on the natme of the metal ion. The second step results in a spatial network polymer. In this step, chain growth involves predominantly the C=C sidechains of the macroradicals. Chain growth occurs under conditions of severe steric hindrance and with an increasing level of internal (shrinkage) stresses and results in the formation of an atactic structure. 

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