High surface tension

Another valuable property of mercury is its relatively high surface tension, 480.3 mN /m(= dyn/cm) at 0 °C, as compared to 75.6 mN /m for water. Because of its high surface tension, mercury does not wet glass and exhibits a reverse miniscus in a capillary tube. 

Inks. The main components of the inks ate typically water, colorants, and humectants. Additives ate used to control drying time, waterfastness, lightfastness, and consistency of drop formation. Water is an excellent vehicle for ink jet because of its high surface tension and safety in all environments. 

The principal physical properties influencing ink performance ate surface tension and viscosity. High surface tension is desired for good droplet formation and capillary refill in dtop-on-demand ink jet. Low viscosity is desired because less energy is required to pump and eject ink. Conductivity is also an important parameter. Continuous ink-jet inks must have some conductivity to allow for charging. Low conductivity is generally preferred for impulse, particularly thermal ink jet, because excess ions can cause corrosion of the printhead. 

Adhesion to Metals. For interaction between coating and substrate to occur, it is necessary for the coating to wet the substrate (107). Somewhat oversimplified, the surface tension of the coating must be lower than the surface tension of the substrate. In the case of metal substrates, clean metal surfaces have very high surface tensions and any coating wets a clean metal substrate. 

Thus apolar probe liquids of sufficiently high surface tension to yield finite contact angles against many surfaces are especially valuable for this purpose. Popular examples of these include diiodomethane, with a surface tension of 50.8 mN/m at 23°C, and a-bromonaphthalene, with a surface tension of 44.4 mN/m at the same temperature. One should be cautioned, however, that both are sufficiently volatile that the 7re-effects may not be negligible with their use. 

Hydrophobic Cannot be wetted by aqueous and other high surface tension fluids. 

Holes and Smaller With Water or High Surface Tension Liquids > om= Minimum Vapor Velocity Through Holes, ft./sec. 

Hole size is as important in perforated plates without downcomers as far the sieve tray. Published data limits a full analysis of the relationships however, the smaller holes, Ys-in., Me-in., 4-in. appear to give slightly higher efficiencies for the same tray spacing [47]. Unfortunately the data [69] for the larger %-in. holes was not evaluated for efficiencies. Experience has indicated efficiencies equal to or only slightly, 10-15%, less for M-in. holes w hen compared to Me-in. holes for some systems. Holes as small as Mfrin., %2-in. and Me-in. were considered unsatisfactory for high surface tension materials such as water [47]. 

The larger holes are recommended for high surface tension liquids. 

Property of liquid, whereby molecular forces at the surface tend to minimize the contained volume, hence water droplets. Water has high surface tension which makes it poor at wetting thus requiring use of surfactant materials for certain processes. 

The use of low flow rates allows the production of ions from mobile phases containing high percentages of water which, as noted previously, usually presents a particular problem because of its high surface tension and conductivity. The production of electrospray spectra from aqueous solution is possible at flow rates of less than 50 tLlmin ... 

High surface tension, coarse droplets, difficult to spray... 

The high potentials required for electrospray show that air at atmospheric pressure is not only a convenient, but also a very suitable ambient gas for ES, particularly when solvents with high surface tension, like water, are to be subjected to electrospray. The oxygen in the air, which has a positive electron affinity, captures free electrons and acts as a discharge suppressor. 

The mercury penetration approach is based on the fact that liquid mercury has a very high surface tension and the observation that mercury does not wet most catalyst surfaces. This situation holds true for oxide catalysts and supported metal catalysts that make up by far the overwhelming majority of the porous commercial materials of interest. Since mercury does not wet such surfaces, the pressure required to force mercury into the pores will depend on the pore radius. This provides a basis for measuring pore size distributions through measurements of the... 

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