Chapter 14.6

Chapter 14.6 - solidification from a melted state and are...

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26 MSE 2090: Introduction to Materials Science Chapter 14, Polymer Structures Polymer Crystallinity (III) Crystalline polymers are denser than amorphous polymers, so the degree of crystallinity can be obtained from the measurement of density: ρ c : Density of perfect crystalline polymer ρ a : Density of completely amorphous polymer ρ s : Density of partially crystalline polymer that we are analyzing 100 ) ( ) ( ity crystallin % a c s a s c × ρ ρ ρ ρ ρ ρ =
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27 MSE 2090: Introduction to Materials Science Chapter 14, Polymer Structures Polymer Crystals (I) Thin crystalline platelets grown from solution - chains fold back and forth: chain-folded model Polyethylene The average chain length can be much greater than the thickness of the crystallite
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28 MSE 2090: Introduction to Materials Science Chapter 14, Polymer Structures Polymer Crystals (II) Spherulites: Aggregates of lamellar crystallites ~ 10 nm thick, separated by amorphous material. Aggregates are formed upon
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Unformatted text preview: solidification from a melted state and are approximately spherical in shape. Photomicrograph of spherulite structure of polyethylene 29 MSE 2090: Introduction to Materials Science Chapter 14, Polymer Structures Summary Alternating copolymer Atactic configuration Bifunctional mer Block copolymer Branched polymer Chain-folded model Cis (structure) Copolymer Crosslinked polymer Degree of polymerization Graft copolymer Homopolymer Isomerism Isotactic configuration Linear polymer Macromolecule Mer, monomer Molecular chemistry Molecular structure Make sure you understand language and concepts: Molecular weight Network polymer Polymer Polymer crystallinity Random copolymer Saturated Spherulite Stereoisomerism Trans (structure) Trifunctional mer Five Bakers Dancing...
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Chapter 14.6 - solidification from a melted state and are...

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