the power of thermodynamics in the characterization of materials zeki y. al-saigh department of...

The Power of Thermodynamics in the The Power of Thermodynamics in the Characterization of MaterialsCharacterization of Materials

Zeki Y. Al-Saigh

Department of Chemistry

Buffalo State, State University of New York

1300 Elmwood Avenue

Buffalo, N.Y., USA

OutlineOutline

Background about MaterialsTechniques used in the CharacterizationThe Physics of CharacterizationResults Derived from the Speaker’s

Research: Polymers, Polymer Blends, Conducting Polymers, Biodegradable Polymers.

Characterization of MaterialsCharacterization of Materials

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:Materials:

Can be anything which exists in nature:Plastics (polymers), synthetic and naturalRubbersAlloy and CeramicsOil, Coal and carbon fibersPowders and clayFood

Polymer BlendsPolymer Blends

– A new class of materials is always needed to replace heavy metal alloys.

Polymer BlendsPolymer Blends

Blending of polymers is a fast and inexpensive route to obtaining a new class of materials

Z.Y.Al-Saigh, International J. of Polymer Analysis and Characterization, 3, 249-291 (1997)

FOR MORE INFO on IGC of polymer blends...

Polymer BlendsPolymer Blends

Solubility of Polymers is the key term in polymer characterization

Polymer BlendsPolymer Blends

A pair of polymers may be:Compatible (soluble)Incompatible (insoluble)Partially compatible

Z.Y.Al-Saigh, Trends in Polymer Science, 5, 97 (1997)

FOR MORE INFO on IGC of polymer blends...

Present Techniques AvailablePresent Techniques AvailableGlass transition temperatureThermal & mechanical NMR Electron spin resonanceSolvent vapor sorptionheat of mixingSmall angle light & X-ray scatteringSmall angle neutron scatteringInverse gas chromatography

UnfortunatelyUnfortunately

Most of these techniques are beset by a number of technical difficulties

For ExampleFor Example

Vapor sorption method takes a long time for the establishment of equilibrium between the vapor and the polymer

Neutron scattering uses modified dueterated polymers which are chemically different from the parent polymer

Gas ChromatographyGas Chromatography

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:Gas Chromatography is:

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 ChromatographyInverse Gas Chromatography

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 IGCThermodynamics of IGC

Inverse Gas ChromatographyInverse Gas Chromatography

IGC may provide data about: Polymer-solvent interaction

• Homopolymers

• Blends Diffusion Glass Transition

Current Use of IGCCurrent Use of IGC1. Interaction parameters of polymer-solvent systems

2. Interaction parameters of polymer-polymer 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 polymers7. Diffusion of gases and liquids into the polymer layer8. Glass transition and melting temperatures9. Surface energy of solids10.Detection of melting point depression of a polymer blend as an indicator of miscibility

BackgroundBackground: Thermodynamics of IGC: Thermodynamics of IGC

Thermodynamics of IGCThermodynamics of IGC

Heats of the Mixing ProcessHeats of the Mixing Process

Thermodynamics of Polymer Blends MiscibilityThermodynamics of Polymer Blends Miscibility

Blend of semicrystalline diluentBlend of semicrystalline diluent

Are interesting systems for the characterization by inverse gas chromatography

C.T.Chen and Z.Y.Al-Saigh, Macromolecules, 24, 3788 (19910

FOR MORE INFO...

Blend of semicrystalline diluentBlend of semicrystalline diluent

Two blend systems were studied:

Poly(vinylidene fluoride)-poly(ethyl methacrylate) [PVF2-PEMA]

Poly(vinylidene fluoride)-poly(vinyl methyl ketone) [PVF2-PVMK]

Blend of semicrystalline diluentBlend 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 surfacesAbsorption of solutes by the amorphous

layer

Blends of semicrystalline diluentBlends of semicrystalline diluent

Blend of Semicrystalline DiluentBlend 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 VDependence of Vgg of Acetates-PANI-EB of Acetates-PANI-EB on Temperature (130 – 170 on Temperature (130 – 170 °°C)C)

Dependence of VDependence of Vgg of Alkanes-PANI-HEBSA of Alkanes-PANI-HEBSA on Temperature (80 – 130 on Temperature (80 – 130 °°C)C)

Table III : Interaction Parameters of Alkanes at a Table III : Interaction Parameters of Alkanes at a Temperature Range 140-170Temperature Range 140-170°°C for 7% PANI-EBC for 7% PANI-EB

Table IV : Interaction Parameters of Alkanes at a Table IV : Interaction Parameters of Alkanes at a Temperature Range 80-130Temperature Range 80-130°°C for 7% PANI-HEBSAC for 7% PANI-HEBSA

Table V : Molar Heat of Sorption, Table V : Molar Heat of Sorption, ss, ,

of both PANI-EB and PANI-HEBSAof both PANI-EB and PANI-HEBSA

Surface EnergySurface Energy

Table VI : Dispersive Surface Energies of PANI-EB and Table VI : Dispersive Surface Energies of PANI-EB and PANI-HEBSA and PANI-HEBSA and CH2CH2

Surface Energy (mJ/mA2)11.0426.4720041.5040.0028.9020.3033.1061.00-106.00

Surface Energies of PolymersSurface Energies of Polymers

Polymer PEO PVMK Hg PVC PMMA Polypropylene Polyurethane Polyethylene doped PPY

Comparative Data on Surface Energy of Several Polymers

Inverse Gas Chromatography of PolyanilineInverse Gas Chromatography of Polyaniline

REFERENCES:By Ali Al-Ghamdi & Zeki Y. Al-

Saigh, 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 potentialWettability test (determination of water

sorption isotherm)Surface adsorption characterizationThermodynamic studieswood-polymer interface studies

Current ResearchCurrent 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.

Amylopectin – Alkanes SyatemsAmylopectin – Alkanes Syatems

Amylopectin – Alcohols SyatemAmylopectin – Alcohols Syatem

Effect of Temperature on the Interaction Effect of Temperature on the Interaction Parameters, Parameters, χχ1212

Effect of Number of Carbon on the Effect of Number of Carbon on the Interaction Parameters, Interaction Parameters, χχ1212

Degree of Crystallinity of AmylopectinDegree of Crystallinity of Amylopectin

The dispersive Surface Energy, γThe dispersive Surface Energy, γssdd, of , of

AmylopectinAmylopectin

Temperature, oC γCH2, mJ/m2 γs

d, mJ/m2

80 32.16 0.24

100 31.00 0.075

200 25.20 0.028

Latest Applications of IGCLatest Applications of IGC

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