Search results
Results from the WOW.Com Content Network
The dynamic Wilhelmy method is a method for calculating average advancing and receding contact angles on solids of uniform geometry. Both sides of the solid must have the same properties. Wetting force on the solid is measured as the solid is immersed in or withdrawn from a liquid of known surface tension.
An alternative method for measuring the contact angle is the Wilhelmy method, which employs a sensitive force meter of some sort to measure a force that can be translated into a value of the contact angle. In this method, a small plate-shaped sample of the solid in question, attached to the arm of a force meter, is vertically dipped into a pool ...
The captive bubble method is a method for measuring the contact angle between a liquid and a solid, by using drop shape analysis. [1] In this method, a bubble of air is injected beneath a solid, the surface of which is located in the liquid, instead of placing a drop on the solid as in the case of the sessile drop technique.
Contact angle method is the standard surface energy measurement method due to its simplicity, applicability to a wide range of surfaces and quickness. The measurement can be fully automated and is standardized. [4] In general, as surface energy increases, the contact angle decreases because more of the liquid is being "grabbed" by the surface.
In fluid dynamics, the capillary number (Ca) is a dimensionless quantity representing the relative effect of viscous drag forces versus surface tension forces acting across an interface between a liquid and a gas, or between two immiscible liquids.
Universal bevel protractors are also used by toolmakers; as they measure angles by mechanical contact they are classed as mechanical protractors. [2] [3] The bevel protractor is used to establish and test angles to very close tolerances. It reads to 5 arcminutes (5′ or 1 / 12 °) and can measure angles from 0° to 450°.
Contact angle is a measure of static hydrophobicity, and contact angle hysteresis and slide angle are dynamic measures. Contact angle hysteresis is a phenomenon that characterizes surface heterogeneity. [15] When a pipette injects a liquid onto a solid, the liquid will form some contact angle.
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.