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MSEASUSlides: Muddiest Points: Polymers I - Introduction

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This slide set was used to create the MaterialsConcepts YouTube Video "Muddiest Points: Polymers I - Introduction". Here is the link to that video:

This slide set was used to create the MaterialsConcepts YouTube Video "Muddiest Points: Polymers I - Introduction". Here is the link to that video:
https://www.youtube.com/watch?v=D0I7ukw18FE

To study the vocab used in this video, visit this site:
http://quizlet.com/21161469/61-polymers-ia-concepts-terms-flash-cards/

This work was supported by NSF Grants #0836041 and #1226325

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    MSEASUSlides: Muddiest Points:  Polymers I - Introduction MSEASUSlides: Muddiest Points: Polymers I - Introduction Presentation Transcript

    • Muddiest Points Muddiest Points: • “I don’t get the difference between a monomer, a mer, and a polymer?” • “How do I calculate degree of polymerization?” • “How does degree of polymerization affect polymer properties?” • “I don’t get polymer microstructures and how they affect properties?” • “I don’t get the different techniques for processing polymers.” Polymers I: Introduction to Polymers
    • What is a Polymer? Poly mer Many Units repeat unit repeat unit repeat unit What is a Polymer? Definition: PE Milk Container PVC Pipe PP Rope
    • •C-C rotations along the chain give the polymer molecule a loosely-coiled, string-like shape Polymer Chain Geometry Carbon Hydrogen
    • What are Important Polymer Concepts & Terminology?Monomers, Mers, Polymers, and Degree of Polymerization Degree of Polymerization: Concept and Definition • Monomer - small, unreacted single molecule for polymer. Ethylene Monomer: • Mer – single repeat unit of a polymer Polyethylene Mer: 2 C-C chain bonds / mer • Polymer – entire polymer chain Polyethylene Molecule: n mers / chain molecule n = degree of polymerization (DP) = n mers / chain molecule n= DP = n = DP = • n is typically 100  10,000 but may go higher than 100,000 number of mer units polymer molecule molecular weight of polymer molecule molecular weight of mer Hydrogen Carbon Ethylene Monomers
    • Candle (Paraffin) Container (HDPE) n (DP) 10 10,000 MW Chain (g/mol) (28 g/mol )(10) = 280 g/mol (28 g/mol)(10000) = 280,000 g/mol Tm (°C) MW of Molecule = n * MW Mer 2.Why does the Tm increase with more C atoms in chain? 1. What are the similarities and differences of candles and plastic milk containers? How Degree of Polymerization Affects Properties: Melting Point n= Degree of Polymerization (DP) Molecular Weight= MW Temperature(°C) Number of carbons= 2n = 2* DP
    • What are the Four Different Types of Polymer Structure and Morphology? • Polymer – a long chain molecule of 1-D covalently bonded repeat units or a network of 3-D covalently bonded repeat units • Length of molecule varies from 1,000s to 100,000s of atoms long. • Four main classes of polymer solids we will consider are: –Thermoplastic AMORPHOUS polymers are 1-D covalently-bonded chains. They are randomly-oriented and form a glassy solid. When heated, they melt; when cooled, they solidify; and they can be remelted (melt recyclable). - Thermoplastic SEMICRYSTALLINE polymers also have 1-D covalently-bonded chains. They form layers of thin, chain-folded crystalline lamellae separated by amorphous regions and are connected with tie molecules. When heated, they melt. When cooled, they solidify and can be remelted (melt recyclable). – Heat Set ELASTOMERS are 3-D LIGHTLY to MODERATELY crosslinked networks of long chain molecules that are covalently crosslinked during a curing chemical reaction. After the cure, the 3-D network maintains its structural integrity when heated (not melt recyclable). –Heat Set THERMOSETS are 3-D HIGHLY crosslinked networks of covalently- bonded molecules. The thermoset reaction forms a rigid amorphous solid with very good thermal resistance (not melt recyclable). PS Glass PE Trash Bag Rubber Shoe Sole Bakelite Billiard Balls
    • How can Polymers be Classified?
    • What is the Effect of Structure & Morphology on Mechanical Properties? Polymer E (MPa) TS (MPa) %EL Natural Rubber 2.5 20 600- 1000% HDPE 830 28 300- 600% Polystyrene 3100 40 1.2- 2.5% Bakelite 6900 55 0.1% A B C PS Glass PE Trash Bag Rubber Shoe Sole D Bakelite Billiard Balls
    • Morphology and Thermal & Mechanical Properties Lightly X-linked Elastomer Heavily X-linked Thermoset Semicrystalline Polymer Amorphous Polymer Thermoplastic Polymers Heat Set Polymers Tg = 100C T25 < Tg Glassy Tg = -103C Tg < T25 Elastic Tg = -90C; Tm = 130C Tg < T25 < Tm Flexible Tg = 163C T25 < Tg Rigid Tg = Glass Transition Temperature, below which a polymer is rigid and brittle PS Glass PE Trash Bag Rubber Shoe Sole Bakelite Billiard Balls
    • 1010 What is the Effect of Structure on Processing of Plastics? • Thermoplastics – Amorphous & Semicrystalline • Processing can be continuous – only cooling required • Heat to melt, shape & cool below Tg or Tm • Can be reversibly melted and solidfied, i.e. recyclable • Ex: PE, PP, PS. • Heat Sets – Thermosets and Elastomers – Processing not continuous – one part at a time – Heating & crosslink reaction require time in fixed shape mold – Permanent 3-D crosslinked network – not recyclable – Shape is permanent – does not change with heat; will only degrade – Elastomer + crosslink agent (S, O) mixed, shaped, reacted – Ex. polybutadiene, polyisoprene – Thermoset prepolymer pressed into a shape & reacted – Ex: Bakelite, urethane, epoxy For additional information on polymer processing terminology go to: GOOGLE “matsciasu” and get Quizlet.com vocabulary e-flash cards for 6.2 Polymers II – Processing PS Glass PE Trash Bag Rubber Shoe Sole Bakelite Billiard Balls
    • Processing for Thermoplastic and Crosslinked Polymers PS Glass PE Trash Bag Rubber Shoe Sole Bakelite Billiard Balls Thermoplastic Amorphous Thermoplastic Semicrystalline Heat Set Elastomers Heat Set Thermosets Processing: Film Blowing Processing: Injection Molding Processing: Transfer Molding Processing: Compression Molding
    • Effect of Molecular Weight and Bonding on Properties Metals Ceramics Polymers 0.2 8 0.6 1 Wood( gr AFRE( fib CFRE* GFRE* Glass fibers Carbon fiber Aramid fiber Epoxy only 0.4 0.8 2 4 6 10 20 40 60 80 100 200 600 800 1000 1200 400 CFRE( fib GFRE( fib GFRE(|| fib AFRE(|| fib CFRE(|| fib Why is elastic modulus of polymers two orders of magnitude less than metals or ceramics? How do Polymer Properties Compare to Metals and Ceramics? Property Polymer Metal Ceramic E (GPa) 0.2-4 40-400 10-1200 Tensile Strength (Mpa) 26-60 (Fibers~700) 200-3400 70-140 Ductility (% elongation) 2-500 1-8 1< Tm (°C) 100-250 200-2800 500-4000 Coefficient of Thermal Expansion (m/m-K) 15 x10-6 - 100 x10-6 5x10-6 - 12x10-6 1x10-6 - 5x10-6 E(GPa)
    • Wrap-Up • “What is a polymer?” • “I don’t get the difference between a mer and a monomer.” • “How do I calculate degree of polymerization?” • “How does degree of polymerization affect polymer properties?” • “I don’t get polymer microstructures and how they affect properties.” • “I don’t get the different techniques for processing polymers.” Polymers I: Introduction to Polymers