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The Power of Thermodynamics in the Characterization of Materials

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

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The Power of Thermodynamics in the Characterization of Materials

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  1. 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

  2. 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.

  3. Characterization 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

  4. 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

  5. Polymer Blends • A new class of materials is always needed to replace heavy metal alloys.

  6. Polymer Blends • 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)

  7. Polymer Blends • Solubility of Polymers is the key term in polymer characterization

  8. Polymer Blends • A pair of polymers may be: • Compatible (soluble) • Incompatible (insoluble) • Partially compatible FOR MORE INFO on IGC of polymer blends... Z.Y.Al-Saigh, Trends in Polymer Science, 5, 97 (1997)

  9. 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

  10. Unfortunately • Most of these techniques are beset by a number of technical difficulties

  11. For 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

  12. Gas 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).

  13. 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.

  14. Inverse 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.

  15. Thermodynamics of IGC

  16. Inverse Gas Chromatography IGC may provide data about: • Polymer-solvent interaction • Homopolymers • Blends • Diffusion • Glass Transition

  17. Current Use of IGC 1. 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

  18. 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

  19. Background: Thermodynamics of IGC

  20. Thermodynamics of IGC

  21. Heats of the Mixing Process

  22. Thermodynamics of Polymer Blends Miscibility

  23. Blend 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...

  24. Blend 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]

  25. 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

  26. Blends of semicrystalline diluent

  27. Blend of Semicrystalline Diluent

  28. 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.

  29. Dependence of Vg of Acetates-PANI-EB on Temperature (130 – 170 °C)

  30. Dependence of Vg of Alkanes-PANI-HEBSA on Temperature (80 – 130 °C)

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

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

  33. Table V : Molar Heat of Sorption, DH1s, of both PANI-EB and PANI-HEBSA

  34. Surface Energy

  35. Table VI : Dispersive Surface Energies of PANI-EB and PANI-HEBSA and gCH2

  36. Surface Energy (mJ/mA2) 11.04 26.47 200 41.50 40.00 28.90 20.30 33.10 61.00-106.00 Polymer PEO PVMK Hg PVC PMMA Polypropylene Polyurethane Polyethylene doped PPY Surface Energies of Polymers Comparative Data on Surface Energy of Several Polymers

  37. Inverse 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.

  38. 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

  39. 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.

  40. Amylopectin – Alkanes Syatems

  41. Amylopectin – Alcohols Syatem

  42. Effect of Temperature on the Interaction Parameters, χ12

  43. Effect of Number of Carbon on the Interaction Parameters, χ12

  44. Degree of Crystallinity of Amylopectin

  45. The dispersive Surface Energy, γsd, of Amylopectin

  46. Latest 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

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