Sessile drop technique

About: Sessile drop technique is a research topic. Over the lifetime, 2827 publications have been published within this topic receiving 68943 citations.

Evaluation of Surface Tension and Adsorption for Liquid Fe-S Alloys

Abstract: Surface tension of liquid iron is strongly influenced by the adsorption of sulfur. In this study, surface tensions of liquid Fe-S alloys at 1823 K were measured by the sessile drop technique in a purified argon atmosphere. Experimental results were compared with the model based on Butler's equations considering the effect of size and interactions of the adsorbed elements assuming that the system was composed of Fe-"FeS" binary. The model could evaluate the surface tension and the adsorption of sulfur more reasonably rather than a simple ideal adsorption model. In the calculations, excess free energy expanded by Margules' series over the entire composition range of Fe-FeS system was used.

Surface Characterization of 2-Hydroxyethyl Methacrylate/Styrene Block Copolymers by Transmission Electron Microscopy Observation and Contact Angle Measurement

Abstract: The surface structures of poly(HEMA-block-styrene-block-HEMA)s and poly(HEMA-ran-styrene) (where HEMA denotes 2-hydroxyethyl methacrylate) are characterized by TEM observation and contact angle measurements using sessile drop method and Wilhelmy plate technique under the dry and wet conditions. One (T-60) of the triblock copolymers is produced by the addition reaction of telechelic polystyrene with isocyanate terminals and semitelechelic PHEMA with an amino group at one chain end, and the others (L-50, L-60) are synthesized by anionic living polymerization. The random copolymer (R-50) is prepared by radical polymerization. L-50, L-60, T-60, and R-50 contain 45, 61, 63, and 47 wt % of PHEMA segments, respectively. From the TEM observation, the outermost surface of the as-cast L-50 film is found to be completely covered with polystyrene layer, while the microdomains of polystyrene and PHEMA are mixed in the top surface area of the as-cast T-60 film. By use of the staining technique, the wet surface structures of L-60 and T-60 are also observed. At the hydrated top surface, the polystyrene microdomains wrapped with PHEMA segments are stretched toward the water side, while the microphase separated structure in bulk remains intact. The contact angle measurements elucidates that the hydrophobic surfaces are replaced with hydrophilic ones by soaking the L-50 and T-60 films in water and that the hydrated surface of L-50 reverts to the hydrophobic one again by annealing. The surface of R-50 does not show a drastic restructuring in response to the environmental change.

Surface properties of fused salts and glasses: i sessile-drop method for determining surface tension and density of viscous liquids at high temperatures *

Abstract: An apparatus is described which allows measurements to be made of the contact angle and the exact dimensions of a sessile drop of liquid resting on an electrode graphite surface in vacua or in nitrogen atmosphere. Temperatures up to 1100°C have been employed. Under these conditions, surface tension and gravity are the only forces acting on the drop, and the exact shape, surface, and volume may be computed from the tables of Bashforth and Adams. The method may be used with liquids having viscosities up to 600 poises, whereas the bubble-pressure method used by Jaeger is limited to liquids of viscosity less than 70 poises. On the basis of internal evidence, the surface-tension values obtained by the sessile-drop method are considered correct within 5%. They also agree with data by Jaeger, but are, roughly, twice as great as those of Washburn and Libmart, who used a ring method. The probable error in Washburn and Libman's work appears to be in their assumption of zero contact angle.