Spreading of Liquid Droplets on Cylindrical Surfaces: Accurate Determination of Contact Angle.

1989 ◽  
Vol 170 ◽  
Author(s):  
H. Daniel Wagner ◽  
E. Wiesel ◽  
H. E. Gallis
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Glass Fibers ◽  
Accurate Determination ◽  
High Strength ◽  
Contact Angles ◽  
Liquid Droplets ◽  
Liquid Polymers ◽  
Solid Liquid Interface ◽  
Solid Liquid

AbstractThe wetting of cylindrical monofilaments by liquid polymers is a problem of much scientific and technological importance. In particular, the characterization of the physicochemical nature of interfaces is a key problem in the field of advanced fibrous composites. The macroscopic regime contact angle, which reflects the energetics of wetting at the solid-liquid interface, is difficult to measure by usual methods in the case of very thin cylindrical fibers.In the present article a numerical method is proposed for the calculation of macroscopic regime contact angles from the shape of a liquid droplet spread onto a cylindrical monofilament. This method, which builds on earlier theoretical treatments by Yamaki and Katayama [1], and Carroll [2], very much improve the accuracy of the contact angle obtained. Experimental results with high-strength carbon, para-aramid, and glass fibers, are presented to demonstrate the high degree of accuracy of the method proposed.

Mass-Area Method to Measure the Contact Angle on Hydrophilic Surfaces

2011 ◽  
Author(s):  
Hie Chan Kang ◽  
Anthony M. Jacobi
Keyword(s):  
Contact Angle ◽  
Present Method ◽  
Contact Angles ◽  
Solid Materials ◽  
Spherical Cap ◽  
Present Measurement ◽  
Area Method ◽  
Hydrophilic Surfaces ◽  
Solid Liquid Interface ◽  
Solid Liquid

A mass-area method is proposed to overcome problems in the measurement of the equilibrium contact angles for rough and hydrophilic surfaces. A goniometer usually measures the contact angle at the top plane of a rough surface, not the contact line of the solid-liquid interface. The present method estimates the contact angle indirectly from the volume of the liquid and the size of the contact area, assuming a spherical cap and consistent with a minimization of the free energy. The present method shows a roughly linear relationship with measurements by a goniometer for smooth surfaces of various solid materials with various liquids, but the goniometer measurements are smaller. An example test and the error of the present measurement method are presented and discussed.

Role of titanium on the reactive spreading of lead-free solders on alumina

2006 ◽  
Vol 21 (12) ◽  
pp. 3222-3233 ◽  
Author(s):  
Laurent Gremillard ◽  
Eduardo Saiz ◽  
Velimir R. Radmilovic ◽  
Antoni P. Tomsia
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Triple Line ◽  
Contact Angles ◽  
Liquid Interface ◽  
Liquid Front ◽  
Wide Variability ◽  
Solid Liquid Interface ◽  
Lead Free Solders ◽  
Solid Liquid

The wetting of Sn3Ag-based alloys on Al2O3 has been studied using the sessile-drop configuration. Small additions of Ti decrease the contact angle of Sn3Ag alloys on alumina from 115° to 23°. Adsorption of Ti-species at the solid–liquid interface prior to reaction is the driving force for the observed decrease in contact angle, and the spreading kinetics is controlled by the kinetics of Ti dissolution into the molten alloy. The addition of Ti increases the transport rates at the solid–liquid interface, resulting in the formation of triple-line ridges that pin the liquid front and promote a wide variability in the final contact angles.

scholarly journals Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

2021 ◽  
Vol 1 (1) ◽  
pp. 10
Author(s):  
Lukman Hakim ◽  
Irsandi Dwi Oka Kurniawan ◽  
Ellya Indahyanti ◽  
Irwansyah Putra Pradana
Keyword(s):  
Molecular Dynamics ◽  
Contact Angle ◽  
Liquid Droplet ◽  
Center Of Mass ◽  
Contact Angles ◽  
Surface Wettability ◽  
Dynamics Simulation ◽  
Potential Models ◽  
Surface Hydrophilicity ◽  
Dynamics Simulations

The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

Dependence of the Contact Angle on Adsorption at the Solid-Liquid Interface

2010 ◽  
Author(s):  
C. A. Ward
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Pressure Range ◽  
Line Tension ◽  
Liquid Interface ◽  
Fluid Interfaces ◽  
Phase Line ◽  
Three Phase ◽  
Solid Liquid Interface ◽  
Solid Liquid

A method for determining the surface tension of solid-fluid interfaces has been proposed. For a given temperature and fluid-solid combination, these surface tensions are expressed in terms of material properties that can be determined by measuring the amount of vapor adsorbed on the solid surface as a function of xV, the ratio of the vapor-phase pressure to the saturation-vapor pressure. The thermodynamic concept of pressure is shown to be in conflict with that of continuum mechanics, but is supported experimentally. This approach leads to the prediction that the contact angle, θ, can only exist in a narrow pressure range and that in this pressure range, the solid-vapor surface tension is constant and equal to the surface tension of the liquid-vapor interface, γLV. The surface tension of the solid-liquid interface, γSL, may be expressed in terms of measurable properties, γLV and θ: γSL = γLV(1 − cosθ). The value of θ is predicted to depend on both the pressure in the liquid at the three-phase, line x3L, and the three-phase line curvature, Ccl. We examine these predictions using sessile water droplets on a polished Cu surface, maintained in a closed, constant volume, isothermal container. The value of θ is found to depend on the adsorption at the solid-liquid interface, nSL = nSL(x3L,Ccl). The predicted value of θ is compared with that measured, and found to be in close agreement, but no effect of line tension is found.

Temperature-Dependent Wettability of Water on a Nickel Surface at Pressurized Condition: A Molecular Dynamics Study

2019 ◽  
Author(s):  
Dong-Lei Zeng ◽  
Biao Feng ◽  
Jia-Wen Song ◽  
Li-Wu Fan
Keyword(s):  
Contact Angle ◽  
Hydrogen Bonds ◽  
Average Energy ◽  
Contact Angles ◽  
Nickel Surface ◽  
Free Energies ◽  
Water Droplets ◽  
Temperature Dependent ◽  
Interfacial Free Energies ◽  
Solid Liquid

Abstract Temperature-dependent wettability of water droplets on a metal surface in a pressurized environment is of great theoretical and practical significance. In this paper, molecular dynamic simulation is used to study this problem by relating the temperature-dependent apparent contact angles to the changes in solid-liquid and solid-vapor interfacial free energies and hydrogen bonds in the nano-sized water droplets with increasing the temperature. The temperature range of interest is set from 298 K to 538 K in a 20 K interval under a constant pressure of 7 MPa. The results show that the contact angle in general decreases with raising the temperature and decreasing trend can be divided into two sections with different slopes. The contact angle drops slowly when the temperature is below 458 K as a critical point. Beyond this point, the contact angle shows a much steeper decrease. The difference between solid-vapor and solid-liquid interfacial free energies is found to decrease slightly with temperature. Combining with that the surface tension drops with increasing the temperature, a decreasing trend of the contact angle is expected according to the Young’s equation. As the temperature increases, the number and average energy of the hydrogen bonds both decrease, and the hydrogen bonds tend to aggregate at the bottom of the nano-droplets.

scholarly journals Amphiphobic Nanostructured Coatings for Industrial Applications

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 787 ◽  
Author(s):  
Federico Veronesi ◽  
Giulio Boveri ◽  
Mariarosa Raimondo
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Friction Reduction ◽  
Hybrid Coatings ◽  
Wetting Behavior ◽  
Wide Range ◽  
Solid Liquid

The search for surfaces with non-wetting behavior towards water and low-surface tension liquids affects a wide range of industries. Surface wetting is regulated by morphological and chemical features interacting with liquid phases under different ambient conditions. Most of the approaches to the fabrication of liquid-repellent surfaces are inspired by living organisms and require the fabrication of hierarchically organized structures, coupled with low surface energy chemical composition. This paper deals with the design of amphiphobic metals (AM) and alloys by deposition of nano-oxides suspensions in alcoholic or aqueous media, coupled with perfluorinated compounds and optional infused lubricant liquids resulting in, respectively, solid–liquid–air and solid–liquid–liquid working interfaces. Nanostructured organic/inorganic hybrid coatings with contact angles against water above 170°, contact angle with n-hexadecane (surface tension γ = 27 mN/m at 20 °C) in the 140–150° range and contact angle hysteresis lower than 5° have been produced. A full characterization of surface chemistry has been undertaken by X-ray photoelectron spectroscopy (XPS) analyses, while field-emission scanning electron microscope (FE-SEM) observations allowed the estimation of coatings thicknesses (300–400 nm) and their morphological features. The durability of fabricated amphiphobic surfaces was also assessed with a wide range of tests that showed their remarkable resistance to chemically aggressive environments, mechanical stresses and ultraviolet (UV) radiation. Moreover, this work analyzes the behavior of amphiphobic surfaces in terms of anti-soiling, snow-repellent and friction-reduction properties—all originated from their non-wetting behavior. The achieved results make AM materials viable solutions to be applied in different sectors answering several and pressing technical needs.

Adsorption of azacrown ethers at solid–liquid interface. Contact angle and neutron reflectivity study

2009 ◽  
Vol 256 (1) ◽  
pp. 274-279 ◽  
Author(s):  
Kamil Wojciechowski ◽  
Anna Brzozowska ◽  
Sebastien Cap ◽  
Witold Rzodkiewicz ◽  
Thomas Gutberlet
Keyword(s):  
Contact Angle ◽  
Liquid Interface ◽  
Neutron Reflectivity ◽  
Azacrown Ethers ◽  
Interface Contact ◽  
Solid Liquid Interface ◽  
Solid Liquid

Ring-Shaped Sessile Droplet

2011 ◽  
Author(s):  
Svyatoslav S. Chugunov ◽  
Douglas L. Schulz ◽  
Iskander S. Akhatov
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Liquid Structure ◽  
Solid Substrate ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Sessile Droplet ◽  
System Equilibrium ◽  
Energy Consideration ◽  
External Forces

It is recognized that small liquid droplet placed on the solid substrate forms equilibrium contact angle that can be obtained from well-known Young’s law. Previously, deviations from Young’s law were demonstrated for the droplets exposed to external fields (gravity, electric, etc) and for the droplets on non-homogeneous substrates. This work reveals that the Young’s equilibrium contact angle can be altered by geometrical reasons only. We consider a ring-shaped droplet on a solid substrate as a test structure for our discussion. We use the global energy consideration for analysis of system equilibrium for the case of freely deposited liquid with no external forces applied. The theoretical analysis shows that steady ring-shaped liquid structure on a solid substrate does exist with contact angles on both contact lines to be different from the Young’s equilibrium contact angle.

Hydrophobicity of Teflon Coated Well-Ordered Silver Nanorod Arrays

2012 ◽  
Vol 1389 ◽  
Author(s):  
Arif S. Alagoz ◽  
Wisam J. Khudhayer ◽  
Tansel Karabacak
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Hierarchical Structures ◽  
Silicon Substrates ◽  
Nanorod Arrays ◽  
Water Contact ◽  
Glad Technique ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Angle Deposition

ABSTRACTFrom wings of flies to plant leafs, hydrophobic surfaces are well-common in nature. Many of these surfaces have micro and nano hierarchical structures coated with low surface energy layer. In this work, we mimicked similar structure by fabricating Teflon coated periodic and well-ordered silver nanorod arrays and investigated the effect of nanorod separation on water contact angle (WCA). The silver nanorod arrays were deposited on patterned and flat silicon substrates using glancing angle deposition (GLAD) technique. Then a thin layer of Teflon was deposited on the silver nanorods by small angle deposition (SAD) technique. A systematic increase in water contact angle was observed with increasing nanorod separation which is attributed to the decreased area fraction of solid-liquid interface.

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