Adjustable wetting

For many applications it is desirable to be able to adjust the wetting properties of a solid surface for aqueous solutions. One method is called electrowetting [303,304], In electrowetting an electric potential is applied between a metal surface and a liquid via an electrode (Fig. 7.24). The metal is coated with an insulating layer of thickness h. Fluoropolymer coatings turned out to be suitable materials though it is not fully understood why [305], The change in contact 

0o is the contact angle without applied voltage, is the dielectric permittivity of the insulating polymer film, and U is the applied voltage. Please note that the sign of the applied potential is not relevant. 

In a glass capillary of 1 mm diameter water rises 2.2 cm at 25°C. What is the difference in the surface tension between the glass-vapor and the glass-liquid interface  

In a classical paper Owens Wendt estimated the surface energy of polymers by measuring the contact angle with water and methylene iodide [272], They measured  

The dispersive and polar components of the surface tensions of the liquids were estimated to be 7 = 21.8 mN/m and 7 = 51.0 mN/m for water and 7 = 49.5 mN/m and 7 = 1.3 mN/m for methylene iodide. This estimation was done by measuring contact angles with various hydrocarbons and assuming that there are only nonpolar interactions. What are the surface energies, 7s, of the polymers  

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To further understand the action of the hydroxide ions on the primer properties, weight gain tests were undertaken on various, commercially available adhesives. We attempted to prepare neat samples of ten types of adhesive agents (ie top coats and primers) which had been recommended by the manufacturers as suitable for marine applications. The neat samples were prepared with the use of a commercial adjustable wet film applicator supplied by the Paul Gardner Company. This applicator will lay films up to 0.25inches... 

Any increase of the suspension injection, in order to realize an improved separation of the gas component which can be removed, is not possible. The maximum liquid and/or solvent injection into a fluidized bed is limited by the capacity of the fluidization gas. The maximum of the capacity is reached with the state of saturation of the gas. Figure 16.6 illustrates the dependence of the adjusting wetted surface and the absolute humidity on the spraying liquid mass flow. Clearly, a small deviation of... 

Fiberboard or hardboard is made of low grade wood and wood waste. In the wet production process, a sheet is produced on a papermaking machine, such as a fourdrinier. A Hquid resole is usually added to the beater section and precipitated onto the wood fibers by adjusting the pH. The moderately dry felt is further dried and cured in an off-line press. 

A blending system provides the kiln with a homogeneous raw feed. In the wet process the mill slurry is blended in a series of continuously agitated tanks in which the composition, usually the CaO content, is adjusted as required. These tanks may also serve as kiln feed tanks, or the slurry after agitation is pumped to large kiln feed basins. Dry-process blending is usually accompHshed in a silo with compressed air. 

In colorfastness to acid spotting, ISO 10S-E0S, drops of a solution of either acetic acid (300 g of glacial acetic acid per Hter of water), sulfuric acid (50 g of concentrated acid per Hter), or tartaric acid (100 g of crystalline acid per Hter) are spotted onto the test material, which is then dried and assessed. Colorfastness to alkaH spotting, ISO 10S-E06, is like E05 except that a solution of 100 g of anhydrous sodium carbonate per Hter of water is used. Colorfastness to water spotting, ISO 10S-E07, is like E05 but uses drops of water and assessment is made after 2 min wet and after drying. In colorfastness to hot water, ISO 10S-E08, the textile specimen and adjacents are wound around a glass rod and placed in water adjusted to pH 6 with acetic acid at 70°C... 

TABLE 12-4 Degree Adjustment to Be Applied to Leaving-Air Wet-Bulb Temperature to Find Cooled-Water Temperatures of Spray Ponds ... 

Coohng range, °F. Entering wet-bulb temp., f °F. Adjustment, °F. ... 

Current designs for venturi scrubbers generally use the vertical downflow of gas through the venturi contactor and incorporate three features (I) a wet-approach or flooded-waU entry sec tion, to avoid dust buildup at a wet-dry pmction (2) an adjustable throat for the venturi (or orifice), to provide for adjustment of the pressure drop and (3) a flooded elbow located below the venturi and ahead of the entrainment separator, to reduce wear by abrasive particles. The venturi throat is sometimes fitted with a refractoiy fining to resist abrasion by dust particles. The entrainment separator is commonly, but not invariably, of the cyclone type. An example of the standard form of venturi scrubber is shown in Fig. 17-48. The wet-approach entiy section has made practical the recirculation of slurries. Various forms of adjustable throats, which may be under manual or automatic control. 

When possible, gears should be run-in on initial startup. Speeds and loads should be inereased in pereentage inerements. Lube oil temperature, and pressure and bearing temperatures should be observed and adjustments made to the lube system as required. The number of adjustments made will depend on the eomplexity of the system. Oil pressure is of primary importanee. When an auxiliary pump has been provided, oil should be eireulated before the aetual start. If not, the pump should be primed, and the journals wetted with oil. Primer holes are sometimes provided or alternate journals ean be oiled through the holes provided for bearing temperature deteetors. 

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