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Surface tension is an important factor in the phenomenon of capillarity. Surface tension has the dimension of force per unit length, or of energy per unit area. [4] The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to ...
This method is especially used to compare and measure the critical surface tension of low-energy solids (mainly plastics) very quickly and easily. Figure 4 in ZIsman's published article from 1964 [1] shows the critical surface tension as a measure of wettability of Polyethylene. Zisman published this analysis in 1964 and used a variety of ...
Water at room temperature has a surface tension of around 0.07 N/m and a viscosity of approximately 10 −3 Pa⋅s. So even variations of a few percent in the surface tension of water can generate Marangoni flows of almost 1 m/s. Thus Marangoni flows are common and easily observed.
Droplet formation mostly depends on momentum, viscosity and surface tension. [2] In inkjet printing for example, an ink with a too high Ohnesorge number would not jet properly, and an ink with a too low Ohnesorge number would be jetted with many satellite drops. [3]
Properties of surface chemicals can be investigated by measuring pressure/area isotherms, as the two-dimensional analog of Boyle's law, πA = k, at constant temperature. Surface tension is another example of surface pressure, but with a reversed sign, because "tension" is the opposite to "pressure".
When the surface excess of a component is positive, increasing the chemical potential of that component reduces the surface tension. Next consider the example of water with salt. The water surface is less salty than bulk, so whenever the water's surface area is increased, it is necessary to remove salt molecules from the new surface and push ...
Yet when the diameter is ~3 μm, the bubble has an extra atmosphere inside than outside. When the bubble is only several hundred nanometers, the pressure inside can be several atmospheres. One should bear in mind that the surface tension in the numerator can be much smaller in the presence of surfactants or contaminants.
This relationship is the basis of a convenient method of measuring surface tension, commonly used in the petroleum industry. More sophisticated methods are available to take account of the developing shape of the pendant as the drop grows. These methods are used if the surface tension is unknown. [3] [4]