Wetting properties, flow

In porous and granular materials, Hquid movement occurs by capillarity and gravity, provided passages are continuous. Capillary flow depends on the hquid material s wetting property and surface tension. Capillarity appHes to Hquids that are not adsorbed on capillary walls, moisture content greater than fiber saturation in cellular materials, saturated Hquids in soluble materials, and all moisture in nonhygroscopic materials. 

In applications such as the preparation of tableting feeds and the manufacture of detergent powders, the aim is to produce small agglomerates (usually 2 mm diameter and less) with improved flow, wetting, dispersing or dissolution properties. This is accomplished by superficially wetting the feed powder, often with less than 5% of bridging liquid in the form of a... 

Capillary sealing effects are controlled by wetting phenomena which, for hydrocarbons in general, are poorly constrained. In real sub-surface situations, the assumption of a water-wet seal is reasonable for an initially hydrocarbon-free seal. This may be less likely in dynamic situations where capillary seals may leak periodically in the presence of active charge. The wetting properties of seals may change through time an initially water-wet seal may evolve into a hydrocarbon-wet seal, due to the adsorption of a variety of compounds from crude oil, such as asphaltenes (Anderson, 1986). This may ultimately result in a top seal which has no capillary seal capacity and leaks via two-phase flow. 

Mesoscopic roughness at the solid-liquid interface can greatly modify both interfacial flow and static wetting properties leading to two behaviors, either a decrease [45,64,102] or an increase [63,103] of surface slippage with roughness. 

Fillers are often useful in epoxy-polyamide adhesives (41). Fillers aid flow control—particularly at elevated temperatures. Other properties contributed by fillers are exhibited in the cured system. For example, they can increase the modulus of elasticity, modify the coefficient of thermal expansion, increase heat resistance, and even affect bond strength. Of course, the excellent wetting properties of polyamides Increase the dispersion efficiency of these fillers. The type of filler selected and the amount used also have a pronounced effect on adhesive quality. A few of these effects are illustrated in Tables VI and VII (37). (See also Table VIII.)... 

Tg and fp are invariants of geometry and physical properties. For other geometries the general formula (16.39) holds, but the characteristic length is replaced by a hydraulic diameter de= 4 x (cross-sectional area for flow) / (wetted perimeter). 

Chem. Descrip. Epoxidized soya oil acrylate Uses For use in inks and coatings on p r, plastics and wood Features Good flow, adhesion, and exc. pigment wetting Properties Gardner 10 color m.w. 1200 vise. 25,000 cps add no. 15 tens. str. 1000 psi tens, elong. 20%... 

Microfluidic generation of droplets is a method of droplet formation in microfluidic channels. It works by combining two or more streams of immiscible fluids and generating a shear force on the discontinuous phase causing it to break up into discrete droplets. In contrast to piezoelectric, pneumatic and acoustic forms of droplet generation, in this method, there is no need for an actuator to impose instabilities on the liquid jet. In the absence of an actuator, the size and polydisper-sity of the droplets are determined by the dimensions of microchannels, the flow rates of liquids, wetting properties of microchannels, etc. 

Coalescer pads ineffective temperature too hot/pH incorrect/fibers have the same charge as the droplets/surface tension negative system/wetting properties of fibers changed/fibers weathered and need to be replaced/flow rate too slow... 

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