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“The World We Create” NATS 101 Section 6. Next Homework Posted in D2L!. 04/01. Polymer Transformations. How we change the materials that have changed society and beyond. These Transformations…. ?. Transforming Polymers. Natural Polymers of Glucose (or modified glucose).

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04/01

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  1. “The World We Create”NATS 101Section 6 Next Homework Posted in D2L! 04/01

  2. Polymer Transformations How we change the materials that have changed society and beyond...

  3. These Transformations… ?

  4. TransformingPolymers Natural Polymers of Glucose (or modified glucose) Muscle Fuel:GLYCOGEN Wood:CELLULOSE All made from the monomerGlucose Arthropod Exoskeletons:CHITIN Plant Food:STARCH

  5. Made by Transforming a Single Polymer TransformingPolymers TranslucentFlexibleStable StrongDenseRigid DuctileFlexibleDegradable? All made from the monomerEthylene High Tensile StrengthElastic Degrade ResistantFlexible OpaqueNon-Permeable

  6. TransformingPolymers We Can Not Duplicate Nature Why? 400 Vs. 4,000,000,000 4 Hundred Years of Chemistry Vs. 4 Billion Years of Evolution Nature inspires us, but is much too complex and subtle to mimic. Scientist have had to develop methods that differ from nature.

  7. A Simple Demonstration: TransformingPolymers • We start with a clear liquid polymer • We combine with an additive • We get a slimy goo(yes, “goo” is a technical term) • What happened in the beaker?

  8. TransformingPolymers A simple demonstration: What Happened? n Polymer: Polyvinyl Alcohol (PVA)Small Section of Two Chains Shown n

  9. TransformingPolymers A simple demonstration: Weak Crosslinks Formed n Additive: Borax(Sodium tetraborate decahydrate)Forms bonds, linking chains Notice the dashed lines: ||||||||These represent a weaker interaction than Covalent Bonding. n

  10. Vulcanization: TiresTransformedSociety When sulfur and heat is added to rubber, the sulfur bonds to the polymer forming covalent crosslinks...

  11. Vulcanization: When sulfur and heat is added to rubber, the sulfur bonds to the polymer forming covalent crosslinks. • How would this change the properties of the rubber? • Sulfur chain length can differ – what part of a tire should get the longer and shorter chains? • Tread? • Sidewalls?

  12. Bouncing Balls: • Two balls are composed of the same polymer • One is much more elastic • How is this achieved? • A different additive perhaps? • Now it’s your turn with the balls…

  13. TransformingPolymers Bouncing Balls: • Part I: • Follow the directions on your worksheet to transform a liquid polymer into an elastic ball. • Add the Borax slowly to the glue and observe the changes. • Part II: • Perform a bounce test by dropping your ball from the top of a meter stick and observing the height of the bounce. • Report your results to your TA.

  14. TransformingPolymers Bouncing Balls: Crosslinker: Borax What Happened? Polymer: Polyvinyl Acetate (PVAc)

  15. A Few Additives Used to Change Polymer Properties: TransformingPolymers Plasticizers: Used to soften polymers e.g. Phthalates Fillers: Used to strengthen a polymer e.g. Inert materials like cellulose and asbestos Stabilizers: Used to reduce polymer degradatione.g. Antioxidants, UV absorbers Flame Retardants: Used to reduce combustibility e.g. Halogens (Cl and F atoms) Colorants: Used to provide color e.g. Pigments (insoluble/opaque) and Dyes (soluble/transparent)

  16. Polymer Structure Review: Linear chains: Crosslinked chains: Branched chains: NEW: Copolymers: …form when different “mers” are used to form a polymer. Can be linear, branched, etc… e.g.: Nylon

  17. Transformingthe Environment BPA: What’s the Deal? Water bottles were being made using copolymers of carbonate and BPA… BPA (Bisphenol A) is not an additive here – it combines with carbonate monomers to form a copolymer. This adds strength and chemical stability to carbonate alone. Next Week: Why this may be a problem...

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