Solid texture properties

Solid Texture Properties - These properties often are a result of further treatment of the matrix and film as discussed in the previous section. They have to be treated separately because of the distinct methods of their assays (79-91). 

The XRD patterns demonstrated that the MCM-22 zeolites were well crystallized and pillars have been created in the MCM-36 sample, respectively. Thus, the last material exhibited a typical intense peak at 29 2°, corresponding to a Aspacing of 4 nm. The textural properties of solids (Table 1) indicated that the pillaring in MCM-36 resulted in increases in BET specific surface area and external surface area compared with the MCM-22 zeolite. 

Chemical composition of fresh HTs was determined in a Perkin Elmer Mod. OPTIMA 3200 Dual Vision by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline structure of the solids was studied by X-ray diffraction (XRD) using a Siemens D-500 diffractometer equipped with a CuKa radiation source. The average crystal sizes were calculated from the (003) and (110) reflections employing the Debye-Scherrer equation. Textural properties of calcined HTs (at 500°C/4h) were analyzed by N2 adsorption-desorption isotherms on an AUTOSORB-I, prior to analysis the samples were outgassed in vacuum (10 Torr) at 300°C for 5 h. The specific surface areas were calculated by using the Brunauer-... 

General methodology includes preparation of the solid texture. The measurement techniques may be the application of forces such as pure stress (also strain), shear, or their combinations and the measurement of the resistance to this procedure (Table III). Also used are special methods such Table III. Measurable Properties of Texture... 

Chapter H2 describes the measurement of textural properties of solid-like foods. The first unit in that chapter, unit H2.i, describes a general procedure commonly used to evaluate the texture of solid foods. This method involves the compression of the food material between two parallel plates. There are a number of empirical textural parameters which can be evaluated with this technique. Simple compressive measurements do not provide a complete textural picture of some foods untthi.i presents variations to the parallel plate compression method with the use of special fixtures. For example the use of a puncture probe or a wire cutting device provide data that may relate more directly to the consumer s evaluation of texture for products like apples and cheese, unit m.3 describes a general protocol for the evaluation of a number of sensory texture parameters. This protocol is... 

The solid-like properties may be measured by non-destructive dynamic rheology analysis or by destructive methods using a Penetrometer, Jelly Tester, Instron instruments, or other types of texture analyzers. The latter methods are the most useful due to their simplicity and speed. Texture analysis of whippable emulsion must always be compared with the amount of air incorporated into the foam, which is known as percentage overrun and is calculated as follows ... 

In contrast to the mechanical and rheological properties of materials, which have defined physical meanings, no such definitions exist for the psychophysical assessment of equivalent textural properties of foods. To identify material properties, or combinations of these, which are able to model sensory assessments requires a mixture of theory and experimentation. Scientific studies of food texture began during the twentieth century by the analysis of the rheological properties of liquid or semi-solid foods. In particular Kokini14 combined theoretical and experimental approaches in order to identify appropriate rheological parameters from which to derive mathematical models for textural attributes of liquid and semi-solid foods, namely, thickness, smoothness and creaminess. 

SolcovaO., Snajdaufova H., Hejtmanek V., Schneider P. (1999) Textural properties of porous solids in relation to gas transport. Chemistry Papers 53(6), 396 102. 

The main properties of these materials were characterized by means of x-ray diffraction (Siemens D-500 with A.Cu radiation of 1.54 A), Transmission Electron Microscopy (Phillips-CM200) and N2 adsorption (Micromeritics ASAP-2000), 29Si-NMR(MAS). As the textural properties of the catalytic materials, for example the inner pore structure, is a key parameter for their performance, in the present work the N2 adsorption isotherms of the calcined mesoporous Si02-based solids were determined. The solids were prepared using different CTAB surfactant and some co-surfactants based in the light alcohols, i.e. MeOH, EtOH and PrOH. Thus, Figure 15.5 shows the isotherms of the mesoporous solids prepared with MeOH (co-surfactant). In all... 

FIGURE 15.5 Textural properties of mesoporous solids prepared with different concentration of co-surfactant (Methanol), along 4th column of a 6 x 8 library. 

In the last decade, a variety of microporous and mesoporous materials have been developed for applications in catalysis, chromatography and adsorption. Great attention has been paid to the control of (i) pore surface chemistry and (ii) textural properties such as pore size distribution, pore size and shape. Recently, a new field of applications for these materials has been highlighted [1-3] by forcing a non-wetting liquid to invade a porous solid by means of an external pressure, mechanical energy can be converted to interfacial energy. The capillary pressure, Pc p, required for pore intrusion can be written from the Laplace-Washbum relation,... 

In Table 2 the textural properties of all the composites heat-treated at 150°, 500°C and 850°C are presented. The sample designation is the same as that used for the raw materials with the addition of the letter m to indicate that the results refer to monolith composites. The total pore volume is the sum of the micro- and mesopore volumes (0-2 nm and 2-50 nm) calculated from the corresponding nitrogen adsorption/desorption isotherms, and the macroporosity (50 nm - 100 pm) determined from MIP, respectively. The threshold diameter was that at which in the MIP analysis there was a sudden upswing in the cumulative volume curve where a large part of the porous network became filled. This pore size can be considered as that which controls any transport phenomena through the solid sample. 

In this work, a comparative study of the textural properties developed by the intercalation and pillaring of a saponite with various aluminium oligomers is presented. The adsorption models above summarized have been applied to the nitrogen adsorption at 77 K results in order to evaluate the effect of the oligomer nature and the calcination temperature on the MPSD of the prepared solids. 

The microporous structure of the PILCs is characterised by the distance between the clay layers and the distance between the intercalated units (pillars), the interlayer spacing and the interpillar spacing respectively [6]. Several phenomena can influence these distances such as the elimination of organic moieties from the polycations and the dehydration or sintering of the pillars. Regarding the MPSDs presented in Figures 2-4, more information about the distribution of the aluminium fixed and the evolution of the textural properties with the calcination temperature is required in order to achieve a better knowledge of the microporous structure of these solids. 

The overall performance of a catalyst is known to depend not only on the inherent catalytic activity of the active phase but also on the textural properties of the solid. The ability to control the specific surface area and the pore size distribution during the synthesis of amorphous silica-aluminas has been described for both surfactant micelle templated syntheses (M41-S (1), FSM-16 (2), HMS (3), SBA (4), MSU (5), KIT-1 (6)) and cluster templated sol-gel syntheses (MSA (7), ERS-8 (8)). 

The study of the textural properties of catalyst supports is of primary importance in terms of understanding the catalytic phenomena involved in petrochemical and refining industry processes. In fact, characteristics, such as the specific surface area, pore size or total porous volume will be useful in various stages of a catalyst s existence its preparation (deposition of active phases), its use in catalysis and its regeneration. They directly influence the physicochemical properties of the solid as well as surface reactivity, shape selectivity and hydrodynamic properties. 

The crystallinities were determined by XRD (Phillips PW1830 spectrometer, CuK< radiation) in reference to the parent TEA-beta sample. Textural properties were determined by nitrogen adsorpticm at 77 K in a Mictomeritics ASAP 2400. Before experiments, the samples were treated in vacuum at 573 K for three hours. The acidity of the samples was measured by IR spectroscopy combined with pyridine adsorption/desorption experiments on a Nicolet 710 FTIR Spectrometer equipped with data station. The solid state Si and A1 NMR spectra were collected by using a Varian spectrometer, VXR-300 FT NMR, at 7.05 T and equipped with a Varian CP-MAS probe. A 38% ethanolic solution of acetylacetone (ACAC) was used for impregnation of the samples before Al NMR analyses in order to complex all the EFAL including the NMR "invisible" species. The XPS data were collected by a VG-Scientific Escalab MKII spectrometer operated with a MgKa x-ray source. 

Ceria is effective in the removal of trace amounts of toxic metal species and radionuclides from aqueous solutions and contaminated soils [17], The behaviour of hydrous ceria as selective anion exchanger has also been described in the literature [18] For these applications the preparation of high surface area, thermally and chemically stable ceria phases as well as the study of the parameters which control structural and textural properties of the solid are of particular interest, as they are in the case of the automobile exhaust catalysts... 

Fat crystallization has been extensively studied in bulk fats and, to a lesser extent, in emulsified fats. It has been shown that the crystallization behavior of a fat will proceed quite differently, depending on whether it is in bulk or emulsified form (4,5). Authors have examined the effect of the state of dispersion on the crystallization mechanisms (nucleation, crystallization rate) and polymorphic behavior (6-11) of partial- and triglycerides in bulk and emulsified form. Understanding the mechanisms of emulsion nucleation and crystallization is one of the first steps in understanding the destabilization of emulsions and partial coalescence, e.g., stabilization of liquid fat emulsions by solid particles (fat) or control of the polymorphic form of crystals during the process of partial coalescence to control the size of aggregates and textural properties. 

The textural properties of the hybrid materials are also strongly dependent upon the hydrolysis conditions and the nature of the linker. After hydrolysis in a homogeneous medium, nitrogen adsorption and TEM measurements indicate the formation of non-porous solids with BET specific surface areas lower than 7 m except for 2g. Variation of the precursor concentration does not strongly affect these values. In contrast, hydrolysis under microemulsion conditions leads to a significant increase in the specific surface areas, mainly in the case of the flexible alkylene linker (Table 3.2.5). 

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