SURFACE FORCES DERIVED FROM SURFACE ENERGIES

2007 ◽  
pp. 113-136
Author(s):  
C. Mathew Mate
Keyword(s):  
Surface Forces ◽  
Surface Energies

Paper 5: Preparation and Properties of Molecularly Flat Surfaces

1967 ◽  
Vol 182 (11) ◽  
pp. 65-69
Author(s):  
R. H. S. Winterton
Keyword(s):  
Shear Strength ◽  
Surface Damage ◽  
Surface Forces ◽  
Calcium Stearate ◽  
Smooth Surfaces ◽  
Flat Surfaces ◽  
Surface Energies ◽  
Multiple Beam ◽  
Strong Adhesion

Very smooth surfaces may be prepared by cleaving suitable crystals of mica and other lamellar solids. Large areas of these surfaces are free from steps, even 1 molecule high, as may be shown by multiple beam interference techniques. In this paper the nature of contact between mica surfaces has been investigated and strong adhesion has been found. The application of tangential loads to cause sliding results in severe surface damage—Amonton's law is not obeyed. If a monolayer of calcium stearate is spread on the surfaces, damage is eliminated and the shear strength of the interface falls to one-fortieth of its previous value. Surface energies of mica, and mica coated with monolayers, have been measured and, in addition, these very well-defined surfaces are suitable for measuring the range of action of surface forces.

Surface Forces Derived from Surface Energies

2019 ◽  
pp. 140-180
Author(s):  
C. Mathew Mate ◽  
Robert W. Carpick
Keyword(s):  
Surface Roughness ◽  
Rough Surfaces ◽  
Surface Forces ◽  
Adhesion Forces ◽  
Flat Surfaces ◽  
Surface Energies ◽  
Contact Points ◽  
Starting Point ◽  
Jkr Theory ◽  
Flat Geometry

As it more practical to measure the forces acting between two contacting surfaces then the energies of surfaces, this chapter covers those surface forces that are derived from surface energies. The starting point is Derjaguin’s approximation, which relates the energy between two flat surfaces to the force in other geometries: sphere/flat, sphere/sphere, and crossed cylinders. Next is a discussion of the surface forces in dry contacts with no liquid menisci around the contact points. This discussion covers the cases where adhesion causes significant deformation (JKR theory), where deformation is insignificant (DMT theory), and the cases in between. How surface roughness impacts adhesion is also discussed. The second half of this chapter deals with how liquid menisci around contacts contribute to adhesion forces, both for the sphere-on-flat geometry and for contacting rough surfaces.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Surface Energies of Nonionic Surfactants Adsorbed onto Nylon Fiber and a Correlation with Their Solubility Parameters

1992 ◽  
Vol 62 (9) ◽  
pp. 535-546 ◽  
Author(s):  
Philip E. Slade ◽  
Debra N. Hild
Keyword(s):  
Homologous Series ◽  
Nonionic Surfactants ◽  
Solubility Parameters ◽  
Nylon 66 ◽  
Synthetic Fibers ◽  
Surface Energies ◽  
Nylon Fiber

The surface energies of spin finishes adsorbed onto synthetic fibers are a major factor in determining the processing capabilities of these fibers. They also play a key role in determining how wettable the fibers are by other materials that may be applied to yarn or fabrics in later stages of processing, such as dyes, sizes, or anti-soiling agents. We have applied several homologous series of nonionic surfactants, which can be used as spin finish emulsifiers, to nylon 66 fibers and determined the polar, dispersion, and total surface energies of these adsorbed materials. We also propose a relationship between the measured surface energies and the calculated Hansen fractional solubility parameters.

Imaging the condensation and evaporation of molecularly thin ethanol films with surface forces apparatus

2014 ◽  
Vol 85 (1) ◽  
pp. 013702 ◽  
Author(s):  
Gutian Zhao ◽  
Qiyan Tan ◽  
Li Xiang ◽  
Di Zhang ◽  
Zhonghua Ni ◽  
...  
Keyword(s):  
Surface Forces ◽  
Surface Forces Apparatus

scholarly journals Vertical Orientation of Liquid Crystal on 4-n-Alkyloxyphenoxymethyl-Substituted Polystyrene Containing Liquid Crystal Precursor

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 736
Author(s):  
Kyutae Seo ◽  
Hyo Kang
Keyword(s):  
Molecular Structure ◽  
Liquid Crystal ◽  
Surface Energy ◽  
Polymer Films ◽  
Ultraviolet Irradiation ◽  
Molar Fraction ◽  
Side Chain ◽  
Polymer Modification ◽  
Vertical Orientation ◽  
Surface Energies

We synthesized a series of polystyrene derivatives that were modified with precursors of liquid crystal (LC) molecules, such as 4-ethyloxyphenol (homopolymer PEOP and copolymer PEOP#; # = 20, 40, 60, and 80, where # indicates the molar fraction of 4-ethyloxyphenoxymethyl in the side chain), 4-n-butyloxyphenol (PBOP), 4-n-hexyloxyphenol (PHOP), and 4-n-octyloxyphenol (POOP), via polymer modification reaction to investigate the orientation of LC molecules on polymer films, exhibiting part of the LC molecular structure. LC molecules showed a stable and uniform vertical orientation in LC cells fabricated with polymers that have 4-ethyloxyphenoxymethyl in the range of 40–100 mol%. In addition, similar results were obtained in LC cells fabricated with homopolymers of PEOP, PBOP, PHOP, and POOP. The vertical orientation of LC molecules in LC cells fabricated with polymer films correlated to the surface energy of polymer films. For example, vertical LC orientation was observed when the total surface energies of the polymer films were lower than approximately 43.2 mJ/m2. Good alignment stabilities were observed at 150 °C and 20 J/cm2 of ultraviolet irradiation for LC cells fabricated with PEOP film.

Cleavage and surface energies of LiNbO3

2020 ◽  
Vol 193 ◽  
pp. 338-349
Author(s):  
Yotam Hirsh ◽  
Semën Gorfman ◽  
Dov Sherman
Keyword(s):  
Surface Energies

scholarly journals Thermodynamic Stabilities of U(VI) Minerals: Estimated and Observed Relationships

1996 ◽  
Vol 465 ◽  
Author(s):  
Robert J. Finch
Keyword(s):  
Gibbs Energy ◽  
Reaction Pathways ◽  
Free Energies ◽  
Fine Grained ◽  
Surface Energies ◽  
Stability Diagrams ◽  
Activity Diagrams ◽  
Mineral Stability ◽  
Mineral Compositions

ABSTRACTGibbs free energies of formation (ΔG°ƒ) for several structurally related U(VI) minerals are estimated by summing the Gibbs energy contributions from component oxides. The estimated ΔG°f values are used to construct activity-activity (stability) diagrams, and the predicted stability fields are compared with observed mineral occurrences and reaction pathways. With some exceptions, natural occurrences agree well with the mineral stability fields estimated for the systems Sio2-Cao-Uo3-UOH2O and Co2-caO-UO3-H2O providing confidence in the estimated thermodynamic values. Activity-activity diagrams are sensitive to small differences in ΔG°f values, and mineral compositions must be known accurately, including structurally bound H2O. The estimated ΔG°f values are not considered reliable for a few minerals for two major reasons: (1) the structures of the minerals in question are not closely similar to those used to estimate the ΔG°f* values of the component oxides, and/or (2) the minerals in question are exceptionally fine grained, leading to large surface energies that increase the effective mineral solubilities.

Sign in / Sign up

Export Citation Format

Share Document