Reduced surface

Nonpolar sihcaUte, F-siUcahte, other high siUca content crystalline molecular sieves, activated carbons with reduced surfaces. 

Cake Dewatering. Dewatering (qv), identified as a separate entity in filtration, is used to reduce the moisture content of filter cakes either by mechanical compression or by air displacement under vacuum pressure or drainage in a gravitational or centrifugal system. Dewatering of cakes is enhanced by addition of dewatering aids to the suspensions in the form of surfactants that reduce surface tension. 

Sihcone surfactants are used to assist in controlling cell size and uniformity through reduced surface tension and, in some cases, to assist in the solubilization of the various reactants (52,53). 

Numerous avenues to produce these materials have been explored (128—138). The synthesis of two new fluorinated bicycHc monomers and the use of these monomers to prepare fluorinated epoxies with improved physical properties and a reduced surface energy have been reported (139,140). The monomers have been polymerized with the diglycidyl ether of bisphenol A, and the thermal and mechanical properties of the resin have been characterized. The resulting polymer was stable up to 380°C (10% weight loss by tga). 

Aluminum, the most common material used for contacts, is easy to use, has low resistivity, and reduces surface Si02 to form interfacial metal-oxide bonds that promote adhesion to the substrate. However, as designs reach submicrometer dimensions, aluminum, Al, has been found to be a poor choice for metallization of contacts and via holes. Al has relatively poor step coverage, which is nonuniform layer thickness when deposited over right-angled geometric features. This leads to keyhole void formation when spaces between features are smaller than 0.7 p.m. New collimated sputtering techniques can extend the lower limit of Al use to 0.5-p.m appHcations. 

Numerous modifications of chromium-based catalysts have been made through the introduction of various additives, the most effective of which are titanium alkoxides (38,39). These additives apparentiy reduce surface silyl chromate moieties to chromium titanates, which are then oxidized to titanyl chromates. These catalysts offer a better control of the resin molecular weight (39). 

Dicylopentadiene Resins. Dicyclopentadiene (DCPD) can be used as a reactive component in polyester resins in two distinct reactions with maleic anhydride (7). The addition reaction of maleic anhydride in the presence of an equivalent of water produces a dicyclopentadiene acid maleate that can condense with ethylene or diethylene glycol to form low molecular weight, highly reactive resins. These resins, introduced commercially in 1980, have largely displaced OfXv o-phthahc resins in marine apphcations because of beneficial shrinkage properties that reduce surface profile. The inherent low viscosity of these polymers also allows for the use of high levels of fillers, such as alumina tfihydrate, to extend the resin-enhancing, fiame-retardant properties for apphcation in bathtub products (Table 4). 

MethylceUulose reduces surface and interfacial tension. MethylceUulose forms high strength films and sheets that are clear, water-soluble, and oU-and grease-resistant, and have low oxygen and moisture vapor transmission rates (see Barrier polymers). 

Like the methylceUuloses, water solutions of HPC display greatly reduced surface tension. A 0.1% solution of HPC at 25°C has a surface tension of about 44 mN/m(=dyn/cm) (water is 74.1 mN/m) and interfacial tension of about 12.5 mN/m(=dyn/cm) against mineral oil. The molecular weight of the HPC has only a slight effect on the surface tension. 

High heat transfer to reduce surface area. 

Reduced surface finish quality of work pieces... 

In general, organic contaminants induce foaming and inorganics increase surface tension, although clearly there are exceptions. For example, sugar increases surface tension, while tannins, lignosulfonates, car-boxymethyl cellulose (CMC), phosphinocarboxylic acids (PCAs), and other dispersants reduce surface tension and help destabilize foams. 

Figure 8.4 shows the steady-state effect of po2 and imposed catalyst potential Uwr on the rate of C2H4 oxidation and compares the results with the open-circuit kinetics. The sharp rate decline for high po2 values is due to the formation of surface Rh oxide.13 Increasing UWr causes a significant increase in the oxygen partial pressure, po2, where oxide forms and thus causes a dramatic increase in r for intermediate (1 to 2.5 kPa) Po2 values. For low P02 values (reduced surface) the effect of Uwr is moderate with p values up to 2. For highp02 values (po2>Po2 > oxidized surface) Uwr has practically no effect on the rate. 

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