surface energy of various liquids
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7/27/2019 Surface Energy of Various Liquids
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Mallikarjunachari.G Date: 15/02/2013 1/3
Work of Adhesion
Where , Surface energy per unit area of surface 1 and 2
1
1
= 2
1
3
=
1
2
1
2
2
1
12
1
12
= 2
4
1
23
3 1
23
3 = 33 3 3
Definition: The work of adhesion is the separation to create two new surfaces from one interface
or The free energy change, or reversible work done, to separate unit areas of two media 1 and 2 from
contact to infinite in vacuum. Jacob.N. Israelachvili
Ceramic Polymer Interface Development
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Adsorption Effect
= = v v
differs from v
by the “spreading pressure” which represents the lowering of the surface energy of material in vacuum by adsorption of the vapour
1= - v
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Neumann Van Oss – Chaudhury -Good OWRK
+ −
(mJ/m2)
Diiodomethane 50.8 50.8 0.0 0.0 50.8 0.0
Ethylene Glycol 48.0 29.0 1.9 47.0 29.0 19.0
Formamide 58.0 39.0 2.3 39.6 39.0 19.0
Water 72.8 21.8 25.5 25.5 21.8 51.0
Surface tensions of various solvents
Ref: Thesis
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The work of adhesion &
practical adhesion
G = W A x
G = Fracture Energy W A = Work of adhesion = temperature and
rate dependent viscoelastic term
Fowkes’ Theory:
Assumptions:
Additivity
= . . . d = dispersion forcep = polar forceh = hydrogen bonding forcei = induction force(Debye)ab= acid/base force
Dispersion
Geometric Mean
= 2
= 2
Polar…
The work of adhesion
= 1 = . . .
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Method of OW (Owens-Wendt)
. . = 0.5(1cos
. . = 0.5(1cos =
Where = surface free energy of solid
= Dispersion component
= Polar component
Method of vOCG (van Oss-Chaudhury-Good)
Solid surface free energy
Dispersion
(London dispersion Van der Waals)
Polar
(Polar + hydrogen +Inductive + Acid Base)
Solid surface free energy
Van der Waals
Dipole –dipole, dipole –induced dipole and London
Acid Base
. +− . −+ . = 0.5 1
.
+
− .
−
+ .
= 0.5 1
. +− . −+ . = 0.5 1
= 2 +− .
=
+, − =Acid , Base interactions
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Liquid Contact Angles required
2 3
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Ceramic Polymer Interface Development
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Volume(microliters) Drop radius(mm) Contact Angle(0)
1 1.0 54.3
3 1.5 54.5
5 1.75 53.9
10 2.3 53.8
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Hysteresis
1. Mechanical Hysteresis surface roughness
2. Chemical Hysteresis
Parameters affect the contact angle
1. Temperature
2. Material TransitionsEg: glass and crystalline transitions,
contaminants and adsorbed materials polar and apolar interactions,drop dimension,surface crystallinity,molecular weight and conformation of chains.
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Substrate Diiodomethane Distilled Water Glycerol
Glass 34.7( ±2.2) 49.5( ±3.1) 48.5( ±3.5)
Epoxy 26.6( ±1.8) 70.6( ±3.9) 62.5( ±2.6)
Contact Angle Measurements (degrees)
Surface Energies of Glass and Epoxy (mJ/m2 )
Substrate + −
Glass 42.2 0.43 27.4 6.9 49.1
Epoxy 45.6 0.02 10.39 0.9 46.5
Silica 78.0 - - 209.0 287.0
Epoxy 41.2 - - 5.0 46.2
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Surface Force Apparatus
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Sources of Thermodynamic Contact Angle Hysteresis
General
Assumption
Specific
AssumptionEffect on Hysteresis
Time
Dependent
Surface I smoothSurface must be smooth at
the 0.1 to 0.5 μm level
∆θ increase with increasing roughness( θadv. increases and θ rec decreases with
increasing roughness)No
Surface ishomogeneous
Surface must behomogeneous at the 0.1
μm level and above
θadv. dependent on low energy phase:θ rec dependent on high energy phase
No
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Sources of Kinetic Contact Angle Hysteresis
General Assumption
Specific Assumption Effect on Hysteresis Time Dependent
Surface is nondeformableModulus of elasticity in
surface > 3x105dyne/cm
Not known Yes due to surface
deformation/relaxationeffects
Wetting liquid does
not penetratesurface
Liquid molecular
volume > 60-70 cc-mole
Increased liquid penetrationlends to increased hysteresis
Yes due manly to
diffusion
Surface does notreorient
Reorientation time attime of measurement
Increased tendency to orientlends to increased hysteresis
Yes
Surface immobile,therefore, surface
entropy is constant
Configurationalentropy independentof local environment
Unknown but probably increase in hysteresis as
surface mobility increases Yes
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Literature
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EFFECTS OF STOICHIOMETRY AND EPOXY MOLECULAR MASS ON WETTABILITY AND INTERFACIALMICROSTRUCTURES OF AMINE-CURED EPOXIES
Epoxy Equiv.Mass (g/mol)
degree degree
Surface free energy components
(mJ/m2)
190 63.1±0.7 40.6±1.3 36.88 16.97 53.85
255 59.3±1.6 32.1±4.2 40.40 18.05 58.45
500 65.7±1.4 41.9±1.8 36.32 15.80 52.13
900 58.5±1.5 44.1±1.3 35.28 19.74 55.03
2250 61.7±1.9 44.1±1.1 35.30 18.08 53.39
3050 62.3±1.6 44.4±1.2 35.17 17.81 52.98
, water and methylene iodine contact angle respectively, , , : Nonpolar, polar and total surface free energy,
respectively. Values after the ± sign indicate one standard deviation.
Conclusion: Epoxy molecular mass does not seem to affect wettability of amine – cured epoxies
i l f l
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Literature: The contact angle of thin-uncured epoxy films: thickness effect
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Liquid Time (min)
1 5 10 15 20 25
MI 43.1 40.5 32.8 30.4 26.8 25.4
EG 46.1 46.7 45 47.1 45.2 46.9
Contact Angle of EG and and MI on a thin film
Adhesion and debonding of multi-layer thin ®lmstructures
C i P l I f D l
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Interface Delamination
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Critical Energy Release Rate: (Gc)
1. Physical Interaction:
4. Heat Dissipation:ℎ 3. Mechanical Interaction:
2. Chemical Bongs:
Irreversible material deformation
Gc = ( + )(1+ ) +
C i P l I t f D l t
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Thermodynamic Work of Adhesion
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(1 cos) = 2( +− −+ )
∗ = ( +− −+
= ∗ ∗ 2 ( +− −+
= ( +− −+
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