scholarly journals Surface energy relations in liquid/solid systems I. The adhesion of liquids to solids and a new method of determining the surface tension of liquids

1942 ◽  
Vol 180 (981) ◽  
pp. 151-173 ◽  
Keyword(s):  
Surface Tension ◽  
Solid Surface ◽  
Adsorbed Layer ◽  
Contact Angles ◽  
New Method ◽  
Receding Contact ◽  
The Difference ◽  
Energy Relations ◽  
Work Done ◽  
Stationary Contact

A new method for determining the surface tension of liquids has been derived. This involves the consideration of the advancing and receding contact angles of a liquid drop on a tilted solid surface. The theory has been tested by an improved optical projection technique for a variety of liquid/ solid systems and the results obtained are in agreement with the accepted values. It is shown that the advancing and receding contact angles are characteristic constants of liquid/solid system s and the calculated and measured values of the minimum receding angles are in agreement. The prevailing views of ‘hysteresis’ effects or ‘stationary’ contact angles which have arisen to account for the data available are incorrect and the discordant experimental results reported are due to inadequate technique. The difference between the adhesions corresponding to the advancing and receding angles is ascribed to the work done in removing an adsorbed unimolecular layer. The work done in gcal./mol. in forming this adsorbed layer is in reasonable agreement with that expected from studies in gas/solid systems and the forces involved are van der Waals’. Further, different solids that might be expected to show similar surface structures yield similar values for the work done. The variation in the value of the advancing angle in some liquid/solid systems and its constancy in others is reconciled with the polar character of the solid surface, i.e. it is suggested that short-range forces are involved. It has been found that monolayers of ferric stearate on glass are orientated with their hydrocarbon tails away from the interface in agreement with electron diffraction measurements. It is suggested that the methods may be useful for investigating the structure of monofilms and built-up layers of monofilms.

scholarly journals Derivation of Generalized Young’s Equation for Wetting of Cylindrical Droplets on Rough Solid Surface

2015 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Xiao-Song Wang
Keyword(s):  
Surface Tension ◽  
Thermodynamic Equilibrium ◽  
Solid Surface ◽  
Line Tension ◽  
Contact Angles ◽  
Radius Of Curvature ◽  
Equilibrium Conditions ◽  
Vapor Interface ◽  
Curvature Effects ◽  
Young's Equation

<p class="1Body">The surface tension depends on the radius of curvature of the liquid-vapor interface. For nano-scale wetting phenomena of cylindrical droplets, we should consider the curvature effects of the surface tension and the line tension. However, previous works have not analyzed the influence of the curvature effects of the surface tension. In this paper, we discuss the influence of the curvature effects of the surface tension on the contact angles based the Kim-Lee-Han-Park equation. The hydrophilic wetting of cylindrical droplets on rough and chemically homogeneous non-deformable substrates were studied by methods of thermodynamics. A generalized Young’s equation for wetting of cylindrical droplets on chemically homogeneous and rough non-deformable substrates was derived based on the thermodynamic equilibrium conditions. This equation reduces to the Wenzel equation if we ignore the influence of line tension. For contact angles of cylindrical droplets with sufficiently large radii, a generalized Young’s equations were derived considering the curvature effects of the surface tension.</p>

scholarly journals Some problems of characterization of a solid surface via the surface free energy changes

2017 ◽  
Vol 35 (7-8) ◽  
pp. 647-659 ◽  
Author(s):  
Emil Chibowski
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Experimental Determination ◽  
Surface Free Energy ◽  
Solid Surface ◽  
Contact Angles ◽  
Absolute Value ◽  
Receding Contact

During the processes occurring at a solid surface, the changes in the surface free energy take place. The knowledge about surface free energy is very helpful for understanding the processes taking place on the surface. However, experimental determination of solid surface free energy is still not a fully solved problem. In this paper, some problems dealing with calculation of solid surface free energy from contact angle are discussed based on literature values of advancing and receding contact angles measured on four different fluoropolymers surface. The four approaches most often used for the calculation are described and especial focus on the approach in which both the advancing and receding contact angles is paid. It is concluded that using probing liquids the absolute value of solid surface free energy cannot be determined. However, the determined apparent values of the energy are very helpful to understand the conditions necessary for a given process to occur.

Wetting

Surfactants ◽  
2019 ◽  
pp. 427-464
Author(s):  
Bob Aveyard
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Surface Forces ◽  
Solid Surfaces ◽  
Surface Topology ◽  
Spreading Coefficient ◽  
Surfactant Solutions ◽  
Receding Contact ◽  
Solid Liquid

Wetting of one liquid by another can be understood in terms of the spreading coefficient; the relevance of surface forces to wetting is also explained. If a small liquid drop does not spread, it forms a lens whose shape is determined by the various interfacial tensions. The wetting of solids is characterized by the contact angle θ‎ of the liquid with the solid surface; θ‎ usually depends on how a configuration is reached and advancing and receding contact angles are defined. It is often useful notionally to split solid/liquid tensions into polar and nonpolar contributions in the treatment of wetting. Effects of surfactant on the wetting of both hydrophobic and hydrophilic solids by water are explored. Surface topology can greatly influence wettability, and superhydrophobic solid surfaces exist widely in nature. Finally some dynamic aspects of wetting of solid surfaces by surfactant solutions are described briefly.

scholarly journals Free Energy Balance of Polyamide, Polyester and Polypropylene Surfaces

2012 ◽  
Vol 7 (4) ◽  
pp. 155892501200700 ◽  
Author(s):  
Marcela Bachurová ◽  
Jakub Wiener
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Energy Balance ◽  
Surface Energy ◽  
Solid Surface ◽  
Contact Angles ◽  
Surface Energies ◽  
Receding Contact ◽  
Smooth Plate

The wettability of a solid surface is often characterized by the contact angle of liquid on the solid surface. The wettability is pertinent to surface energy, which is an important parameter. The wettability can be affected, for example, by the roughness of the solid surface. In our work textiles are used as macroscopic roughness surfaces, and smooth plate surfaces are used as well to determine surface energies. For the calculation of surface energies it is fundamental to know the contact angle. The advancing and receding contact angles are measured, and the relation between the hysteresis and surface energy is monitored.

Numerical Analysis of Microdroplet Impact and Evaporation on a Solid Surface

2011 ◽  
Author(s):  
Gihun Son
Keyword(s):  
Solid Surface ◽  
Inkjet Printing ◽  
Mass Fraction ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Droplet Motion ◽  
Droplet Shape ◽  
Gas Phases ◽  
Receding Contact

Microdroplet impact and evaporation on a solid surface, which is an integral part of an inkjet printing process, is studied numerically by solving the equations governing the conservation of mass, momentum, energy and mass fraction in the liquid and gas phases. The deformed droplet shape is tracked by a sharp-interface level-set method which is modified to include the effects of evaporation at the liquid-gas interface and dynamic contact angle at the liquid-gas-solid interline. The numerical results show that the droplet impact and evaporation pattern depends significantly on the advancing and receding contact angles. Also, the effect of cavity sidewall on the droplet motion is investigated.

Numerical Simulation of Microdroplet Impact and Evaporation on a Solid Surface

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Gihun Son
Keyword(s):  
Solid Surface ◽  
Inkjet Printing ◽  
Mass Fraction ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Droplet Motion ◽  
Droplet Shape ◽  
Gas Phases ◽  
Receding Contact

Microdroplet impact and evaporation on a solid surface, which is an integral part of an inkjet printing process, is studied numerically by solving the equations governing the conservation of mass, momentum, energy, and mass fraction in the liquid and gas phases. The deformed droplet shape is tracked by a sharp-interface level-set method, which is extended to include the effects of evaporation at the liquid–gas interface and dynamic contact angle at the liquid–gas–solid interline. The numerical results show that the droplet impact and evaporation pattern depends significantly on the advancing and receding contact angles. Also, the effect of cavity sidewall on the droplet motion is investigated.

Contact Angle Hysteresis – Advantages and Disadvantages: A Critical Review

2020 ◽  
Vol 8 (1) ◽  
pp. 47-67
Author(s):  
Andrew Terhemen Tyowua ◽  
Stephen Gbaoron Yiase
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Theoretical Models ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Advantages And Disadvantages ◽  
Volatile Liquid ◽  
Receding Contact ◽  
Rain Drops ◽  
The Difference

The existence of contact angle hysteresis – the difference between the values of the advancing and receding contact angles – is evident in nature (e.g. sticking of rain drops to car windscreens and window panes) and many industrial processes (e.g. surface coating, spraying, and dyeing of fabrics). This phenomenon is often viewed as a nuisance, but it is advantageous in many processes including dip and spin coating, spraying, and painting. With the early theoretical framework of Thomas Young, Robert Wenzel, and A. B. D. Cassie and S. Baxter, describing the wettability of solid surfaces and by extension contact angle, contact angle hysteresis has been deeply investigated. We review here the various ways of measuring contact angle and, consequently, contact angle hysteresis as well as related theoretical models. The successes and limitations of these models are highlighted. We conclude with the advantages and disadvantages of contact angle hysteresis whose presence in many processes is often considered as a nuisance, especially when "coffee stain" forms from the evaporation of a volatile liquid drop containing nonvolatile components.

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