Semi-Crystalline Polymer Morphologies and their Hierarchical - PowerPoint PPT Presentation

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies 1

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Semi-Crystalline Helical Structure Chain Folding Semi-Crystalline Fibrillar Growth Spherulitic, shish-kabob, epitaxial surface nucleation, Crystalline Orientation Lamellar Orientation Macroscopic Orientation 2

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Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Paul Phillips 1990 Review 9

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Kevlar Rigid, semi-Rigid, Flexible Polymer Chains On melting the entropy gain is small because the crystallizing units are chemically bound. The random coil state is seen classically as the highest entropy state. For rigid polymers the ground state may be a lower entropy state. Polythiophene Paul Phillips 1990 Review 11

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Tacticity Tacticity governs the helical structure Paul Phillips 1990 Review 12

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Chain Folding and Crystallization 18

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Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Melting (bottom) Point Boiling (top) or “n” n-alkane boiling and melting points 21

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies “Crystals act like crosslinks in rubber” P . Phillips 1990 22

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http://www.eng.uc.edu/~gbeaucag/Classes/MorphologyofComplexMaterials/Chapter2html/Chapter2.html 28

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies 29

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Solution Crystallization 30

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Why do Chains Fold? http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 32

Why do Chains Fold? For an infinite crystal V/S is very large and we can ignore the surface At the equilibrium melting point Δ G = 0 so: substituting in the first equation, 33

Why do Chains Fold? For a lamellar crystal S is 2R 2 and V is tR 2 At a pseudo-equilibrium point where the crystal has a finite thickness of t and a depressed melting point, T 34

Why do Chains Fold? or 35

Hoffman-Weeks Plot http://www.eng.uc.edu/~gbeaucag/Classes/MorphologyofComplexMaterials/Chapter2html/Chapter2.html 36

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies 37

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Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Diffusion of impurities versus growth rate of crystallization front J = -D dc/dx for flux of impurities G = linear growth rate of crystal D/G = δ , the Keith-Padden δ -parameter This determines the coarseness of the spherulite (lateral size) 43

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies 44

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 45

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 46

Hoffman-Lauritzen Secondary Nucleation Theory Add a first stem, then subsequent stems. First stem and subsequent stems add 2b 0 σ l and b 0 σ l To the free energy (cost to make a surface) http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 47

Hoffman-Lauritzen Secondary Nucleation Theory First stem: http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 48

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 49

http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 50

http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 51

http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 52

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 53

http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 54

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 55

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 56

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 57

Hoffman-Lauritzen Secondary Nucleation Theory http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 58

Primary Nucleation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 59

Primary Nucleation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 60

Spherulites http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 61

Primary Nucleation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 62

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies 63

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies http://www.eng.uc.edu/~gbeaucag/Classes/MorphologyofComplexMaterials/Chapter2html/Chapter2.html 64

Semi-Crystalline Polymer Morphologies and their Hierarchical Morphologies Non Crystallographic Branching 65

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Spherulitic Growth Rate 68

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 69

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 70

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 71

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 72

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 73

Avrami Equation http://scholar.lib.vt.edu/theses/available/etd-051799-162256/unrestricted/polyimide2.pdf 74