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The Structure and Properties of Polymers

The Structure and Properties of Polymers. Also known as Bonding + Properties. What is a polymer?. A long molecule made up from lots of small molecules called monomers. Break it down…. Poly- Many Mono- One Meros - Part “ mer ” Macro- Many. Translate this….

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The Structure and Properties of Polymers

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  1. The Structure and Properties of Polymers Also known as Bonding + Properties

  2. What is a polymer? • A long molecule made up from lots of small molecules called monomers.

  3. Break it down… Poly- Many Mono- One Meros- Part “mer” Macro- Many

  4. Translate this… “I’m Hermann Staudinger. I say that rubber has a polymeric structure.”

  5. All the same monomer • Monomers all same type (A) • A + A + A + A  • -A-A-A-A- • eg poly(ethene) polychloroethene PVC

  6. Different monomers • Monomers of two different types A + B • A + B + A + B •  -A-B-A-B- • eg polyamides • polyesters

  7. http://www.umass.edu/molvis/tutorials/dna/dnapairs.htm

  8. So what does a synthetic polymer look like?

  9. Addition polymerisation • Monomers contain C=C bonds • Double bond opens to (link) bond to next monomer molecule • Chain forms when same basic unit is repeated over and over

  10. Copolymerisation • when more than one monomer is used. • An irregular chain structure will result egpropene/ethene/propene/propene/ethene • Why might polymers designers want to design a polymer in this way?

  11. Bellringer: Acid Plant Observations! Hwk: Finish Lab Template! Hwk: Finish Lab Template!

  12. Make Your Own Lab • Task: Design and Conduct (if time!) a lab that will examine “stress-strain behaviors of your “Original Recipe” polymer. • You will have tomorrow to conduct your experiment also • There are 3 types of “stress-strain” behaviors…

  13. Stress-Strain Behaviors • Tensile Strength • Amount of pulling force placed on a material before it breaks • Abrasion Resistance • Toughness of material against scraping, scuffing, or scarring • Puncture Strength • Ability of a material to keep moving objects from perforating a surface.

  14. What decides the properties of a polymer? • Stronger attractive forces between chains = stronger, less flexible polymer. • Chains able to slide past each other = flexible polymer . • Nylon has strong hydrogen bonds, why does this make it a strong fibre?

  15. Thermoplastics (~80%) • No cross links between chains. • Weak attractive forces between chains broken by warming. (erasers, gelatin) • Change shape - can be remoulded. • Weak forces reform in new shape when cold.

  16. Gelatin…no cross-linking

  17. PVC

  18. Polyethylene terephthalate (like in disposable water bottles)

  19. Sodium Polyacrylate – in diapers!

  20. Polystyrene (styrofoam)

  21. Teflon – nonstick coating on pans…also used to make Gor-Tex

  22. Thermosets • Extensive cross-linking formed by covalent bonds. • Bonds prevent chains moving relative to each other. • Best suited to high-temperature applications – can be brittle when very cold.

  23. Examples of thermosets: • Epoxy resins • Vulcanized rubber (car tires) • Injected molded items like • milk crates.

  24. Rubber (below is a monomer)

  25. Crystalline and amorphous polymers • Areas in polymer where chains packed in regular way. • Both amorphous and crystalline areas can be in the same polymer. • Crystalline - regular chain structure - no bulky side groups. • More crystalline polymer = stronger and less flexible.

  26. Examples of amorphous polymers:polyproplene

  27. Nylon

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