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.

Bubble point pressures of binary methanol/water mixtures in fine‐mesh screens

Abstract: Binary methanol/water mixture bubble point tests involving three samples of fine-mesh, stainless steel screens as porous liquid acquisition devices are presented in this article. Contact angles are measured as a function of methanol mass fraction using the Sessile Drop technique. Pretest predictions are based on a Langmuir isotherm fit. Predictions and data match for methanol mole fractions greater than 50% when pore diameters are based on pure liquid tests. For all three screens, bubble point is shown to be a maximum at a methanol mole fraction of 50%. Model and data are in disagreement for mole fractions less than 50%, which is attributed to variations between surface and bulk fluid properties. A critical Zisman surface tension value of 23.2 mN/m is estimated, below which contact angles can be assumed to be zero. Solid/vapor and solid/liquid interfacial tensions are also estimated using the equation of state analysis from Neumann and Good. Published 2013 American Institute of Chemical Engineers AIChE J 60: 730–739, 2014

Surface Testing of Dental Biomaterials—Determination of Contact Angle and Surface Free Energy

Abstract: The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens-Wendt, van Oss-Chaudhury-Good and Zisman's methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m2), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m2). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.

Effects of drop viscosity on oscillation dynamics induced by AC electrowetting

Abstract: The effects of drop viscosity on oscillation dynamics of a sessile drop, such as resonance frequency and oscillation amplitude, in response to different AC voltages (80 and 100 V rms , corresponding to the electrowetting number η of 0.25 and 0.39, respectively) and frequencies (frequency range of 20–110 Hz in which the first and second resonance frequencies exist) were investigated, based on both experiments and theoretical modeling. The results show that drop viscosity rarely affects resonance frequency, but strongly affects the oscillation amplitude and peak width of the resonance frequency. In addition, drop oscillation in the resonance mode is no longer observed, when the drop viscosity is over the critical value, which increases with applied AC voltage. A theoretical model predicts the oscillation dynamics of sessile drops within the error level of ±5%, except for the drop with high viscosity (60 mPa s). Moreover, the friction coefficient obtained by fitting the theoretical models is nearly proportional to the drop viscosity. Finally, an empirical relationship, in which the maximum amplitude is inversely proportional to the drop viscosity, is obtained.

Reactive wetting of alumina by Ti-rich Ni–Ti–Zr alloys

Abstract: Active brazing is a commonly used method for joining ceramic materials. In the present study, the wetting behavior of four Ti-rich ternary Ni–Ti–Zr alloys was investigated through sessile drop experiments on alumina disks of 96 and 99.9 % purity. The microstructure at the metal/alumina interface was analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Three of the analyzed alloys exhibited reactive wetting with final contact angles between 40° and 70°. The reaction phases at the metal/alumina interface had a thickness of about 1 µm and were of a similar composition for all alloys. Dilatometer measurements showed thermal expansion coefficients between 13.2 and 15.8 × 10−6 °C−1. The lowest wetting angle of 40° was achieved with the alloy 61Ti–20Zr–19Ni at temperatures above 980 °C.