Transcript Current Use of IGC - PhysicsEd.BuffaloState.edu

The Power of Thermodynamics in the
Characterization of Materials
Zeki Y. Al-Saigh
Department of Chemistry
Buffalo State, State University of New York
1300 Elmwood Avenue
Buffalo, N.Y., USA
Outline
Background about Materials
 Techniques used in the Characterization
 The Physics of Characterization
 Results Derived from the Speaker’s
Research: Polymers, Polymer Blends,
Conducting Polymers, Biodegradable
Polymers.
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Characterization of Materials
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Obtaining information on the physical and
chemical properties of materials, such as:
Mechanical Properties
Thermal Properties
Interaction Forces Among Molecules
Crystallinity
Molecular Weight
Diffusion of Gases into Layers
Materials:
Can be anything which exists in nature:
 Plastics (polymers), synthetic and natural
 Rubbers
 Alloy and Ceramics
 Oil, Coal and carbon fibers
 Powders and clay
 Food
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Polymer Blends
– A new class of materials is always needed to
replace heavy metal alloys.
Polymer Blends
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Blending of polymers is a fast and
inexpensive route to obtaining a new
class of materials
FOR MORE INFO on IGC of polymer blends...
Z.Y.Al-Saigh, International J. of Polymer Analysis and
Characterization, 3, 249-291 (1997)
Polymer Blends
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Solubility of Polymers is the key term in
polymer characterization
Polymer Blends
A pair of polymers may be:
 Compatible (soluble)
 Incompatible (insoluble)
 Partially compatible
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FOR MORE INFO on IGC of polymer blends...
Z.Y.Al-Saigh, Trends in Polymer Science, 5, 97 (1997)
Present Techniques Available
Glass transition temperature
 Thermal & mechanical
 NMR
 Electron spin resonance
 Solvent vapor sorption
 heat of mixing
 Small angle light & X-ray scattering
 Small angle neutron scattering
 Inverse gas chromatography
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Unfortunately
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Most of these techniques are beset by a
number of technical difficulties
For Example
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Vapor sorption method takes a long time
for the establishment of equilibrium
between the vapor and the polymer
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Neutron scattering uses modified
dueterated polymers which are chemically
different from the parent polymer
Gas Chromatography
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As an alternative method for polymer analysis
and characterization
Al-Saigh, Z.Y. and Guillet, J., in “Inverse Gas
Chromatography in Analysis of Polymers and Rubbers”,
Invited Chapter. Encyclopedia of Analytical Chemistry:
Instrumentation and Applications, R. Meyers, Editor, PP.
7759-7792, John Wiley & Sons Ltd, Chichester, (2000).
Gas Chromatography is:
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A technique by which a mixture of components
can be separated, analyzed and quantified.
 It works on the principle of interactions of two
phases; stationary and mobile.
 The stationary phase contains material with
active interaction sites, such as sand.
 The mobile phase is the vapor of the mixture to
be analyzed.
Inverse Gas Chromatography
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The method is called inverse gas
chromatography because the stationary
phase (polymers or polymer blends) is of
interest, unlike the traditional GC method.
Thermodynamics of IGC
Inverse Gas Chromatography
IGC may provide data about:
 Polymer-solvent interaction
• Homopolymers
• Blends
 Diffusion
 Glass Transition
Current Use of IGC
1. Interaction parameters of polymersolvent systems
2. Interaction parameters of polymerpolymer systems
3. Solubility parameters and weight
fraction coefficients
4. Molar heat, free energy, and entropy
of mixing
5. Molar heat, free energy, and entropy
of sorption
6. Degree of crystallinity of
semicrystalline polymers
7. Diffusion of gases and liquids into the
polymer layer
8. Glass transition and melting
temperatures
9. Surface energy of solids
10.Detection of melting point depression
of a polymer blend as an indicator of
miscibility
Background: Thermodynamics of IGC
Thermodynamics of IGC
Heats of the Mixing Process
Thermodynamics of Polymer Blends Miscibility
Blend of semicrystalline diluent
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Are interesting systems for the characterization
by inverse gas chromatography
FOR MORE INFO...
C.T.Chen and Z.Y.Al-Saigh, Macromolecules, 24,
3788 (19910
Blend of semicrystalline diluent
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Two blend systems were studied:
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Poly(vinylidene fluoride)-poly(ethyl
methacrylate) [PVF2-PEMA]
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Poly(vinylidene fluoride)-poly(vinyl methyl
ketone) [PVF2-PVMK]
Blend of semicrystalline diluent
Above PVF2 m.p., both polymers are at
melt
 Below PVF2 m.p., two retention
mechanisms are expected:
 Adsorption of solutes on crystal surfaces
 Absorption of solutes by the amorphous
layer
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Blends of semicrystalline diluent
Blend of Semicrystalline Diluent
Conducting Polymers: The unique
properties have lead to an interest in the
potential use of PANI as a new class of
conductors. This interest was generated
due to the relative ease of synthesis, low
cost, and the stability of PANI in the air.
However, the insulating form a PANI,
polyaniline emeraldine base (PANI-EB)
suffers from the limited solubility in
organic solvents.
Dependence of Vg of Acetates-PANI-EB
on Temperature (130 – 170 °C)
Dependence of Vg of Alkanes-PANI-HEBSA
on Temperature (80 – 130 °C)
Table III : Interaction Parameters of Alkanes at a
Temperature Range 140-170°C for 7% PANI-EB
Table IV : Interaction Parameters of Alkanes at a
Temperature Range 80-130°C for 7% PANI-HEBSA
Table V : Molar Heat of Sorption, DH1s,
of both PANI-EB and PANI-HEBSA
Surface Energy
Table VI : Dispersive Surface Energies of PANI-EB and
PANI-HEBSA and gCH2
Surface Energies of Polymers
Comparative Data on Surface Energy of Several Polymers
Polymer
Surface Energy (mJ/mA2)
 PEO
11.04
 PVMK
26.47
 Hg
200
 PVC
41.50
 PMMA
40.00
 Polypropylene
28.90
 Polyurethane
20.30
 Polyethylene
33.10
 doped PPY
61.00-106.00
Inverse Gas Chromatography of Polyaniline
REFERENCES:
 By Ali Al-Ghamdi & Zeki Y. AlSaigh, Journal of
Chromatography, A, 969, (2002)
229.
 Al-Saigh & Guillet, Encyclopedia
of Analytical Chemistry, Volume
9, Page 7759 (2000), Wiley.
Application of IGC to Biodegradable
Polymers
 ----------------------------------------------------------- Fibers acid/base interaction potential
 Wettability test (determination of water
sorption isotherm)
 Surface adsorption characterization
 Thermodynamic studies
 wood-polymer interface studies
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Current Research
Characterization of Starch-Based
Polymers such as Amylopectin
 Amylopectin is known to be mechanically
weak.
 Blending Amylopectin with another
biodegradable polymer may improve the
mechanical properties.
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Amylopectin – Alkanes Syatems
Amylopectin – Alcohols Syatem
Effect of Temperature on the Interaction
Parameters, χ12
Effect of Number of Carbon on the
Interaction Parameters, χ12
Degree of Crystallinity of Amylopectin
The dispersive Surface Energy, γsd, of
Amylopectin
Temperature, oC
γCH2, mJ/m2
γsd, mJ/m2
80
32.16
0.24
100
31.00
0.075
200
25.20
0.028
Latest Applications of IGC
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Amorphous, co-polymer and blends
Semicrystalline polymers and blends
Inorganic polymers
Amorphous-plasticizer blend
Conducting polymers
Rubbers
Coal and carbon fibers
Powders and clay
Food