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Polymer Parameters

Polymer Parameters. Chemical structure Chemical composition and distribution Sequence length and distribution Molecular weight and distribution Chain isomerism Morphology Topology Additives Cost. Hierarchical Fiber Morphology. “skin”. “core”. macrofibril (~1 µ m diameter).

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Polymer Parameters

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  1. Polymer Parameters • Chemical structure • Chemical composition and distribution • Sequence length and distribution • Molecular weight and distribution • Chain isomerism • Morphology • Topology • Additives • Cost

  2. Hierarchical Fiber Morphology “skin” “core” macrofibril (~1 µm diameter) microfibril (50 nm)

  3. Folded Chain Crystal Habit polymer melt crystallization

  4. Polytehylene

  5. Polyethylene

  6. Fiber Drawing semicrystalline lamellae microfibril

  7. Mechanical Properties microfibril amorphous 6 GPa 320 GPa crystalline

  8. Mesogens (liquid crystals)

  9. Crystal & Isotropic Liquid Long-range order - orientational - translational

  10. Polyphenyls

  11. Crystal  Mesophase  Isotropic

  12. Nematic LC Long-range order - orientational

  13. Polyphenyls

  14. NversusSA

  15. N, SA, SC

  16. Typical Calamitic Mesogen n = 6

  17. Mesogens

  18. Calamitic vs. Discotic Nematics

  19. Polymer Liquid Crystals

  20. PLCs Thermodynamics

  21. Liquid Crystalline Polymers (LCPs) • 1970’s: lyotropic LCPs (Kevlar) - ultra-high strength fibers • 1980’s: thermotropic Polyesters - stronger, low CTE, low viscosity,

  22. Ultra-high Strength Polymers react diamines with diacids Poly(p-benzamide)s 1967 Stephanie Kwolek & Paul Morgan (DuPont)

  23. “Stronger than steel?”

  24. Origin of Strength? “skin” “core” macrofibril (~1 mm diameter) extended-chain crystal habit microfibril (50 nm)

  25. I to N Transition

  26. Liquid Crystalline Polymers (LCPs) • 1970’s: lyotropic LCPs (Kevlar) - ultra-high strength fibers • 1980’s: thermotropic Polyesters - stronger, low CTE, low viscosity, Key: Inexpensive monomers.

  27. Liquid Crystalline Polymers (LCPs) • Some introductory literature • E. T. Samulski “The Mesomorphic State”, Chapter 5 in Physical Properties of Polymers, 3rd Edt, Cambridge University Press (2004) • D. Acierno and A. A. Collyer, Rheology and Processing of Liquid Crystal Polymers, Chapman & Hall (1996) • N. A. Plate, Editor. Liquid Crystalline Polymers, Plenum Press, NY (1993). • A. A. Collyer, Edt. Liquid Crystal Polymers: From Structures to Applications, Elsevier Applied Science Publishers, London (1992). • A. M. Donald and A. H. Windle, Liquid Crystalline Polymers, Cambridge University Press (1991)

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