Structural parameters microstructure

Comparing the alteration in a values with the established changes in fine structure parameters presented in Table 12, it can be seen that the alteration in a values does not correlate with variations in any particular structure parameter. This leads to the conclusion that the ascertained alternation in a must be evoked by a complex change in different substructure, microstructure, and orientation parameters of the fiber. 

It should be emphasized that for Markovian copolymers a knowledge of the values of structural parameters of such a kind will suffice to find the probability of any sequence Uk, i.e. for an exhaustive description of the microstructure of the chains of these copolymers with a given average composition. As for the composition distribution of Markovian copolymers, this obeys for any fraction of Z-mers the Gaussian formula whose covariance matrix elements are Dap/l where Dap depend solely on the values of structural parameters [2]. The calculation of their dependence on time, and the stoichiometric and kinetic parameters of the reaction system permits a complete statistical description of the chemical structure of Markovian copolymers to be accomplished. The above reasoning reveals to which extent the mathematical modeling of the processes of the copolymer synthesis is easier to perform provided the alternation of units in macromolecules is known to obey Markovian statistics. 

Figure 6 shows the reconstructed microstructure of a typical non-woven, carbon paper GDL with porosity around 72% and thickness of 180 ixm along with the structural parameters in terms of... 

The presence of insoluble materials in the polymerization mixture may have some control on the structure of the polymeric skeleton. Seidl et al. reported that the micro structure of skeletons of ion-exchange resins, based on the copolymers of styrene and DVB, can be controlled by carrying out the polymerization in presence of an inert material and by adjusting the reaction conditions and concentration of DVB. The micro structure depends on the parameter of interaction and on the molar volume of the inert material. In the case of copolymers modified by an inert component with high molar volume and interaction parameters, microstructures with small measureable surfaces and pores with relatively large radii are obtained. 

Microstructure. By using a group of structural parameters obtained through a number of physical methods (such as x-ray, NMR, MS, IR, VPO, DTA, densimetric methods, EM, and SAS) and chemical methods (such as oxidation, alkylation, and halogenation), the structure of petroleum asphaltene has been gradually revealed. As an example, the structural parameters of an asphaltene derived from a Laquinillas crude oil from Venezuela (API gravity 20°, Conradson carbon number 13.39, Miocene Age) are listed in Table I. An empirical formula can be deduced. 

Table I. Examples of the Structural Parameters for the Microstructure of a Petroleum-Derived Asphaltene...

These properties are affected by structural parameters [102], e. g., molecular weight, molecular weight distribution, long chain branching, microstructure, and crystallization behaviour, which are mainly determined by the catalyst system used (see Table 2). 

All in all, the WPPM approach can provide a simultaneous structure and microstructure refinement, based on physical models of the phases under study, without using any arbitrary profile function. Considering the terms of Equation (26), refinement parameters to be optimized in a least-squares analysis are relatively few, namely, mean (p) and variance (cr) of a suitable distribution of coherent domain sizes, dislocation density (p), effective outer cut-off radius (R ) and character (/e, effective fraction of edge dislocations), twin fault (P), deformation fault (a) and APB (y) probabilities. 

Note that in addition to the standard Dirichlet boundary data for the displacements, Dirichlet boundary data for the microstructural parameter also have to be prescribed. Experimentally [24, 37] the local mechanical properties in the interphase depend on both the polymer and the substrate. The possibility of prescribing additional boundary conditions for k is utilized to describe the variations of the mechanical properties in the interphase depending on the substrate. If on the one hand ic = ko is chosen as Dirichlet data for the structural parameter, no interphase is predicted by the model. If on the other hand, ic > Kq or K < Ko is chosen, an interphase is predicted which is either stiffer or weaker than the bulk material, respectively. The thickness of the interphase is mainly governed by the material parameters a and yS. 

ABSTRACT Based on low-temperature nitrogen adsorption principle, the pore structure of coal particles is tested and adsorption isotherms of coal particles with different size are obtained by Quantachrome Autosorb-iQ automatic specific surface area and pore size distribution analyzer. Then, microstructure characteristic parameters such as specific surface area, pore volume and average pore size of coal particles are calculated. Besides, fractal dimension of the internal surface of coal particles is calculated with FHH fractal theory. The relationship between fractal dimension and pore structure parameters together with the adsorption capacity of coal particles is analyzed. Studies show that fractal dimension can characterize the variation of characteristic parameters such as specific surface area and total pore volume of coal particles. In addition, with the increase of fractal dimension, the surface heterogeneity of pore structure is strengthened and so is adsorption capacity. The findings can provide a certain theoretical foundation for mechanism study on coal gas adsorption, desorption and seepage. 

M. Luz Granizo, M.T. Blanco-Varela, S. Martinez-Ramirez, Alkali activation of metakaolins parameters affecting mechanical, structural and microstructural properties, J. Mater. Sci. 42 (2007) 2934-2943. 

The properties for porous ceramics can be tailored for specific environmental application by controlling the composition and microstructiue of the porous ceramic. Changes in open and closed porosity, pore size distribution and pore morphology can have a major effect on a material s properties. All of these microstructural features are in turn highly influenced by the processing route used for the production of the porous material. For the mechanical properties, porous ceramics are determined by their structure parameters, such as porosity, pore size, and pore structure (DeviUe, S et al, 2006 Gough, J. E et al, 2004). Additionally, the... 

Various synthesis methods of mesoporous carbon based on different mesoporous silicate or aluminosilicate templates have been developed [5,7]. The first report on the synthesis of OMC used mesoporous silica MCM-48 with the bicontinuous cubic Ia3d symmetry as the template the as-prepared OMC was denoted as CMK-1. Thereafter, various OMCs with different pore topologies have been actively investigated. For these OMCs, the imiform mesopores are interconnected, resulting in the appearance of distinct X-ray diffraction lines below 2 theta of 5. Meanwhile, they have a large siu ace area and high pore volume. The other structural parameters such as pore diameters, particle morphologies and sizes, and microstructures of carbon frameworks could be tuned by... 

For a quantitative description of the internal granule structure the differentiation between macro- and microstructure is useful. Table 11.2 provides an overview over possible structural parameters. 

All, except point (b), are parameters depending on the possibility of controlling the preparation process in all its aspects, from purity of raw materials to homogeneous distribution of main components and dopants, and from crystalline structure to microstructure and porosity. 

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