Impregnation systems

Fig. 4. Pitch impregnation system. Courtesy of UCAR Carbon Technology Corp.

The third method is the most efficient and effective. The details of these methods are given in Table 6.10. Figure 6.12 gives a comparison of untreated, sealed and silicone-impregnated systems. 

Figure 6.12 Comparison of (a) untreated (b) sealed (c) silicone-impregnated systems. The untreated system is non-repellent to water (solid arrows) and is permeable to water vapour (wavy lines) the sealed system is water-repellent but impermeable to water vapour the silicone-impregnated system is water-repellent and permeable to water vapour...

In this equation S is the coefficient of scatter of the solid phase and e the coefficient of absorption of the liquid component. The equation approximates the behaviour of the diffuse reflector in cases where the difference of intensity between the incident and the reflected rays is independent of the thickness of the structure. This is the case with the fibre-impregnated system, and hence the equation is an approximate description of its behaviour. 

The best catalytic performance was found to be the property of grafted/ impregnated systems having fp = 0.65-0.72 for aU the tested reactions. When fp >... 

The insulation needs to be superior to Class H (epoxy impregnation system). 

On the contrary, in the co-impregnated systems, a Cu distribution occurred on the dense Pd(lll) planes. It was reported that the formation of carvotanacetone is produced mainly on the Pd sites of high coordination where the desorption of the molecule is favored. The adsorption is stronger on low coordination sites, leading to a higher residence time of the molecule and then to further hydrogenation [82]. 

Research on the process technology for precast products using polymer-impregnated mortar and concrete and for field polymer impregnation systems [12, 50, 51]... 

Development of the practical manufacturing processes for field polymer impregnation systems... 

Uses Microbicide for solv.- or water-based coatings, caulks, sealants, leather, adhesives, wood protective coating and impregnation systems Features Broad-spectrum effective against bacteria and fungi Regulatory ERA registered... 

The step after impregnation is the elimination of the solvent. Typically, the impregnated system, spread in fine layers, is heated in an oven up to the boiling point of the solvent or at a lower temperature for gentle drying, in static conditions or under a flow of gas. The elimination of water from the pores leads to an increase of the precursor concentration up to saturation and crystallization, preferably on seeds resulting from the interactions with the support, if one wants to obtain a highly dispersed phase. However, hydrated salts like nitrates melt at moderate temperature [35, 36], which may cause the coalescence of their initially dispersed particles, or even their exclusion from the pores. 

Alongside the method just described as an example, different impregnation systems are available. In 1971, a company patented a system of impregnation based on resin injection with a drawing machine under 6 atm pressure. This system has been widely applied for the production of pipes wifli average mechanical properties, pigmented with a gel-coat layer. 

Schwartz and co-workers [52, 63] applied a silica layer on the inner surfaces of polymeric, copper, and steel capillaries of 4-400 m length and =0.5 mm inside diameter. The authors [62] ran into difficulties in using a suspension containing micron-size particles and therefore they decided in favor of true colloidal silica solutions. They used [52] 22% silica sol in [water-2-propanol] system commercially available under the trade mark Nal-coag 1092. Such colloidal silica sols are produced for preparing adsorption and antistatic impregnated systems. They have a low viscosity and therefore can readily pass through a capillary to form a thin... 

The dry reinforcement is then allowed to pass through this unit to get impregnated by the resin. There are three types of impregnation systems currently used (1) dip bath, (2) straight through bath and (3) resin injection system (Owens Coming, 2003). 

FIGURE 10.7 Left Comparison of the fuel cell performance of a standard Pt/C catalyst, shape-selected nanopar-tides from TTAB and PVP synthesis and an impregnated system, right comparison of power densities between a standard Pt/C catalyst and the impregnated shape-selected sample normalized by Pt content. 

There are two kinds of direction in cotton yam twisting - the S-twist and the Z-twist. In S-twist, the fiber bundle is twisted in the direction of the right screw, whereas in the Z-twist, it is twisted in the direction of the left screw. The method developed in the impregnation system uses the difference between the S-twist and the Z-twist. The steps of the resin impregnation method into cotton yam are shown in Figure 5.8. The case where jute fiber is used as the NF is especially illustrated here. This is because the productivity of jute fiber is high and it is inexpensive. Moreover, it is imported in stable condition and its mechanical properties are also excellent... 

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