Sessile drop, contact angle

Analytical Techniques. Sessile drop contact angles were measured with a NRL C.A. Goniometer (Rame -Hart, Inc.) using triply distilled water. The contact angles reported are averages of 2-8 identically treated samples with at least three measurements taken on each sample. ESCA spectra were obtained on a Kratos ES-300 X-ray Photoelectron Spectrometer under the control of a DS-300 Data System. Peak area measurements and band resolutions were performed with a DuPont 310 Curve Resolver. 

Far from a wellbore, the velocity of reservoir fluids is about one linear foot per day. Near a wellbore, the velocity can increase one-hundred fold. A static or quasi-static test such as the sessile drop (contact angle) test may not represent the dynamic behavior of the fluids in the field. The dynamic Wilhelmy device gives results which are comparable in interface velocity to the field displacement rate. The interface in the Wilhelmy test described here moved at a steady rate of 0.127 mm/sec or 36 ft/day. The wetting cycle for a hybrid-wetting crude oil system was not affected by moving at a rate less than 1 ft/day. 

There are a number of techniques that can be used to measure the degree of hydrophobicity of a surface. Direct techniques such as water uptake measurements and sessile drop contact angles are often supplemented with spectroscopic studies using FTIR and NMR to provide evidence of structural groups present in aerogel samples and to quantitate the relative number of those groups. These methods are described below. 

Values were experimentally obtained from the sessile drop contact angle measurements. ... 

Figure 14.2. Schematic of a sessile drop contact angle system...

Fig. 4 Comparison between single-fiber Wilhelmy, static sessile drop, and dynamic sessile drop contact angles for plain Toray TGP-H paper. The substrate on which the water droplet is sitting top-left comer) is plain TGP-H paper, with a single approximately 10 pm diameter TGP-H fiber penetrating the water droplet (the fiber was extracted from the paper substrate)...

Fig. 10 Before and after comparison of static sessile-drop contact angles of SGL SIGRACET GDL 24BC aged for 1,006 h in 80°C deionized water with air sparging gas Bars on left represent the MPL surface and bars on right represent the non-MPL sirrface...

Modeling of Heterogeneous Sessile-Drop Contact Angles... 

To understand the differences between single-fiber contact angles discussed in Sect. 3.2 and sessile-drop contact angles discussed in Sects. 3.3 and 4.1, a more advanced equation is needed than the Young equation to explain the phenomena. 

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