Dynamic Wilhelmy plate apparatus

The sessile drop method has several drawbacks. Several days elapse between each displacement, and total test times exceeding one month are not uncommon. It can be difficult to determine that the interface has actually advanced across the face of the crystal. Displacement frequency and distance are variable and dependent upon the operator. Tests are conducted on pure mineral surfaces, usually quartz, which does not adequately model the heterogeneous rock surfaces in reservoirs. There is a need for a simple technique that gives reproducible data and can be used to characterize various mineral surfaces. The dynamic Wilhelmy plate technique has such a potential. This paper discusses the dynamic Wilhelmy plate apparatus used to study wetting properties of liquid/liquid/solid systems important to the oil industry. 

Figure 1. Schematic diagram of the dynamic Wilhelmy Plate Apparatus.

The dynamic advancing and receding contact angles of modified PU sheets were evaluated with a Wilhelmy plate contact angle apparatus (WET-TEK FlOO, Biomaterials Int.) in double-distilled water at constant temperature (20 °C) and humidity (30X RH) The velocity of the translation stage was 20 mm/min. 

---