Lecture26 - EMA 6165 - Polymer Physics Crystallinity...

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Unformatted text preview: EMA 6165 - Polymer Physics Crystallinity Lecture 26 Professor Anthony Brennan Department of Materials Science & Department Engineering Engineering University of Florida University of Florida: EMA 6165 Polymer Physics - A. Brennan 1 Crystalline State Crystalline Definition: Crystalline state diffracts Definition: x-rays and exhibits first order thermodynamic transitions. thermodynamic This is too specific since DSC, FTIR, This NMR can measure crystalline behavior not measureable with xbehavior rays. rays. Polymers are Semi-Crystalline NO polymer is 100% crystalline . University of Florida: EMA 6165 Polymer Physics - A. Brennan 2 Outline General Features Crystal Architecture Single Crystal Morphology Spherulites Growth Processes Properties University of Florida: EMA 6165 Polymer Physics - A. Brennan 3 Key Characteristics Cryst alline State State Degree of crystallinity Number of crystalline unities emanating from nuclei Average diameter or size of crystallite Average distance between crystallites University of Florida: EMA 6165 Polymer Physics - A. Brennan 4 Three key factors that lead to crystallization lead Crysta lline State State q Minimization of bond rotation energy i.e. P.E. ~1 to 5 kcal/mol. q Interchain interactions: dipole, H- bonding ~0.5 to 8 kcal/mol q Close packing: For PE, from 0.1 to 0.5 kcal/mol. University of Florida: EMA 6165 Polymer Physics - A. Brennan 5 Crystal line State Unit Cell: Repeat fundamental structureState along any of three primary axes composed of atoms, molecules or ions. Same geometric form as macroscopic crystal University of Florida: EMA 6165 Polymer Physics - A. Brennan 6 Crystalline State State Motif: Atoms or molecules that occupy a unit cell or actually define its dimensions and geometry Miller Indices c b Intercepts 111 Intercepts-1 111 hkl a University of Florida: EMA 6165 Polymer Physics - A. Brennan 7 Crystalline State c abc 1 ∞∞ 2 b a 1 intercept 200 University of Florida: EMA 6165 Polymer Physics - A. Brennan 8 Lattices There are 7 different lattices... Cubic α = β = γ = 900a = b = c Tetragonal α = β = γ = 900a = b ≠ c Orthorhombic a≠ b≠ α = β = γ = 90 0 c Trigonal α6165 Polymer = - A. Brennan a = b =9 c University of Florida: EMA = β Physics Lattices a=b≠ c α = β = 900 γ = 1200 Monoclinic a≠ b≠ c α=γ =900 ≠ β Triclinic a≠ b≠ c Hexagonal α≠β≠γ University of Florida: EMA 6165 Polymer Physics - A. Brennan 10 Lattices WAXS q Electron Braggs Law (XRays) Braggs Law Diffraction q Calorimetry Thermodynamics q Density Archimedes Principle (assume 2 phases) University of Florida: EMA 6165 Polymer Physics - A. Brennan 11 Lattices q NMR Line width q FTIR Crystalline bands q Dilatometry Volumetric discontinuity q Raman Longitudinal acoustic modes q Other methods: LALS, R.I., DES, DMS, Ebullometry University of Florida: EMA 6165 Polymer Physics - A. Brennan 12 Crystalline Morphology Of Crystalline Polymers Polymers Fringed Micelle Staudinger - PET, Nylon 10 nm University of Florida: EMA 6165 Polymer Physics - A. Brennan 13 Crystalline Morphology Of Crystalline Folded Chain Model Polymers Polymers Keller 1957 P.E. 10-20 nm Single Crystal Contour length of PE chains were 200 nm, thus they must have been folded University of Florida: EMA 6165 Polymer Physics - A. Brennan 14 PE - Single Crystal PE PE single crystal University of Florida: EMA 6165 Polymer Physics - A. Brennan 15 Switchboard Morphology University of Florida: EMA 6165 Polymer Physics - A. Brennan 16 Adjacent Reentry Morphology University of Florida: EMA 6165 Polymer Physics - A. Brennan 17 Non-adjacent Reentry Morphology University of Florida: EMA 6165 Polymer Physics - A. Brennan 18 PE Lattice Structure University of Florida: EMA 6165 Polymer Physics - A. Brennan 19 PE Unit Cell University of Florida: EMA 6165 Polymer Physics - A. Brennan 20 Unit Cell Structural Dimensions Unit PE PE PE Orthorhombic cell a = 7.417 angstroms b = 4.945 angstroms c = 2.547 angstroms Planar zig-zag (2/1) helix ρ crystal=1.00 g/ m3 University of Florida: EMA 6165 Polymer Physics - A. Brennan 21 Spherulite Morphology http://spm.phy.bris.ac.uk/research/polymers/spherulites/ University of Florida: EMA 6165 Polymer Physics - A. Brennan 22 AFM Image of Spherulite Growth http://spm.phy.bris.ac.uk/research/polymers/spherulites/ University of Florida: EMA 6165 Polymer Physics - A. Brennan 23 Rate of growth Edge view Top view University of Florida: EMA 6165 Polymer Physics - A. Brennan 24 Rate of growth University of Florida: EMA 6165 Polymer Physics - A. Brennan 25 Rate of Rate Growth Rate of growth Avrami Keith and Padden Hoffman Measure by: Optical Microscopy Synchroton Radiation Dilatometry Calorimetry University of Florida: EMA 6165 Polymer Physics - A. Brennan 26 Summary Unit cells basic structure of crystals Numerous Motiffs defined by unit Numerous cell dimensions cell Single crystals are the result of chain Single folding folding Three basic morphologies, Three switchboard, adjacent reentry and non adjacent reentry non University of Florida: EMA 6165 Polymer Physics - A. Brennan 27 ...
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