Specific internal surface

The specimens of porous glass had a specific internal surface of ca. 100 m /g and were shaped into planparallel plates 3 mm thick. The specific surface of the granular silicagel (spheric particles 2-5 -3 5 mm in diameter) was 400 m /g. 

It should be noted that in the initiation of the cryochemical reactions observed, what is important is the very fact of formation of a new crack (or zone cut by such cracks), and not the increase in the specific internal surface of the sample. Indeed, slow heating of a monolithic sample, or of a sample... 

Shea et al. [281] have also succeeded in making a low-density aerogel from tetramethoxysilane and p-di(triethoxysilyl)benzene in one step using supercritical CO2 as a solvent. The highly porous monolithic samples exhibited a specific internal surface area over 700 m g. 

Cellulose Relative Internal surface (P A Specific internal surface (m g ) Conditions Reference... 

Oxidation increases with increasing fineness of coal and the rate of oxidation of coal with oxygen of air is proportional to the specific internal surface. The proportional coefficient at low temperatures is the cube root but analysis also shows that both rate and extent of oxidation increase with the decrease in particle size, until a critical particle diameter is reached, below which the rate remains fairly constant. 

Here, S = 5 gj is the surface stress, f r the external body force per unit mass of material surface, Sa- the specific internal surface energy, q . = q a the surface heat flux vector, rjg. the surface entropy density, So- = i a the surface entropy flux vector, and h /d the surface entropy production. 

The specific internal surface, Abet (m is then easily calculated by ... 

To be able to model the processes of diffusion and reaction, one needs to know some parameters describing the porous catalyst structure. One characteristic parameter is the internal surface area, that can be determined with adsorption experiments. This is frequently expressed as units of area per gram of catalyst. In this text the specific internal surface area a. is used, with dimension m/tti or m ... 

Hereby P denotes the Porod coefficient which is directly related to the specific internal surface Oac (the area per unit volume of the interface separating crystalline and amorphous regions), by... 

It is to be recognized that application of these relations is not restricted to the ordered periodic system but can be extended, with slight modifications, to real systems that may show variations in the thicknesses of the crystalline and amorphous regions, and may also possess diffuse phase boundaries. The changes in K z) resulting from a successive perturbation of the initial system are schematically indicated in Figs. A.2(b)-(d). All structures in this sequence are understood as having equal crystallinities and equal specific internal surfaces. 

Porosity characterizes the volumetric aspect of the pore system. Specific internal surface characterizes the surface area of the pore space or the area of interface solid-fluid. Thus, with the specific internal surface, a second pore geometrical property is defined and has particular importance for... 

The magnitude of the specific internal surface depends on the resolution of the method of determination. In most cases, specific internal surface is determined by the BET method (after Brunauer et al., 1938) based on nitrogen gas adsorption with an extremely high resolution. 

TABLE 2.6 Specific Internal Surface of Some Earth Materials... 

Mesri and Olson (1971) measured the permeability of pure clay (see Revil and Cathles, 1999). Permeabilities show a correlation with the specific internal surface area of the clay minerals with increasing surface area, a larger amount of water does not take part at the fluid flow and reduces permeability. 

For this modified a pore channel porosity, specific internal surface and permeability can be calculated. For permeability results ... 

The simple geometry of the model opens the way to transform the fundamental problem of permeability dependence on pore radius into the problem of dependence on specific internal surface. With this step, a permeability estimate from logs becomes possible. 

For the simple capillary model, pore radius can be expressed by specific internal surface ... 

For the modified capillary model (Fig. 2.28), the specific internal surface is ... 

Equations (2.58) and (2.60) express the controlling effect of the pore dimension by the specific internal surface. There are two ways to implement the effect of specific internal surface (in addition to porosity) in techniques for permeability estimate ... 

Thus, the ratio BVI/BVM is a measure for the specific internal surface 5por-... 

The right-hand side of the equation indicates that the term k/4> is controlled by specific internal surface or pore size, tortuosity, pore shape, and pore-throat to pore-body ratio. Thus, it covers all textural properties that control permeability except porosity. A reservoir quality index (RQI) can be defined as (Altunbay et al, 1997) ... 

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