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Polymerization

Polymerization. K Minhas. Polymers Polymers are: Long-chain molecules. Found in nature, including cellulose in plants, starches in food, proteins and DNA in the body. Also synthetic such as polyethylene and polystyrene, Teflon , and nylon. Common Synthetic Polymers.

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Polymerization

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  1. Polymerization K Minhas

  2. Polymers Polymers are: • Long-chain molecules. • Found in nature, including cellulose in plants, starches in food, proteins and DNA in the body. • Also synthetic such as polyethylene and polystyrene, Teflon, and nylon.

  3. Common Synthetic Polymers

  4. A Look at Polymers Look at the term: polymerPoly- means "many." Polytechnic: many technical subjects Polygon: many-sided figure Polyunsaturated:many double bonds So what does polymer mean? Polymer means many monomers. Sometimes polymers are also known as macromolecules or large-sized molecules. Usually, polymers are organic (but not necessarily).

  5. What is a monomer?A monomer is a molecule that is able to bond in long chains.Here is a monomer: Ethene CH2=CH2 Here is a polymer : Polyethylene CH3(CH2CH2)2000CH3 A polymer can be made up of thousands of monomer. This linking up of monomers is called polymerization.

  6. Types of Polymerization • Addition Polymerization • For example: Polyethelyne • 2. Condensation Polymerization • Example : Nylon

  7. Examples of Monomers The highlighted areas show the side groups on these monomer molecules. These groups give the polymer chain some of its properties.

  8. The second group of monomers With two functional groups each that is, they are difunctional. R-NH2

  9. Polymerization In polymerization, small repeating units called monomers are bonded to form a long chain polymer

  10. Addition Polymerization. 1. Chain Initiation(Formation of free Radical) Below is an example of how a free radical forms (this one starts with peroxide, ROOR):The peroxide molecule has an easy-to-break O-O single bond. Heat or light energy can break this O-O single bond The RO· fragments are the free radicals, and they are very unstable and reactive.

  11. Step 2 Chain Propagation Free radicals are very reactive. When a free radical gets close to a double bond, one of the bonds is disrupted. One of the electrons in the double bond is attracted to the free radical. The double bond breaks, and a new single bond is formed

  12. Once again, we can write an equation for this Addition Polymerization Propagation reaction: Chain Propagation

  13. STEP III. TERMINATION--- How the reaction stops --- • A growing polymer chain joins with another free radical. • two free radicals could join to make a stable bond.

  14. Polymers from Addition Reactions

  15. Properties of PolymerThe physical properties of a polymer chain depend on the polymer's average length, the amount of branching, and the constituent monomers.

  16. Condensation PolymerizationThe Amide Linkage When a carboxylic acid and an amine react, a water molecule is removed, and an amidemolecule is formed.  

  17. The Ester Linkage:When a carboxylic acid and an alcohol react, a water molecule is removed, and an ester molecule is formed.

  18. The Mechanism of Condensation PolymerizationFormation Of Nylon

  19. Formation of Ester

  20. Condensation Polymers • Condensation polymers are formed by the head-to-tail joining of monomer units • usually accompanied by the lossof water from the reacting monomers, and forming water as a product

  21. Condensation Polymers • Ex: polyethylene terephthalate (PET) • Dacron (® DuPont), Fortrel (® Wellman), Polyesters: permanent press clothing, tire cords • Sheets of polyester called Mylar (® DuPont), used as magnetic tape in tape recorders and computers, as well as balloons • Nylon: carpet, fishing line, hosiery

  22. Condensation Polymers • Examples: • aromatic rings form Nomex (® DuPont), which is a poor electrical conductor; makes parts for electrical fixtures; flame resistant clothing for race car drivers; flame resistant building materials • Kevlar (® DuPont): strong and flame resistant

  23. CODE MATERIAL PERCENT OF TOTAL Polyethylene Terephthalate (PET) 20-30 percent High Density Polyethylene 50-60 percent Polyvinyl Chloride (PVC) 5-10 percent Low Density Polyethylene 5-10 percent Polypropylene 5-10 percent Polystyrene 5-10 percent All other resins 5-10 percent Plastic container code system.

  24. What Do the Numbers Mean? • 1 -- PETE (Polyethylene terephthalate) • PET (or PETE) is used in the production of soft drink bottles, peanut butter jars... • PET can be recycled into fiberfill for sleeping bags, carpet fibers, rope, pillows...

  25. What Do the Numbers Mean? • 2 -- HDPE (High-density polyethylene) • HDPE is found in milk jugs, butter tubs, detergent bottles, motor oil bottles... • HDPE can be recycled into flower pots, trash cans, traffic barrier cones, detergent bottles...

  26. What Do the Numbers Mean? • 3 -- V (Polyvinyl chloride) • PVC is used in shampoo bottles, cooking oil bottles, fast food service items... • PVC can be recycled into drainage and irrigation pipes...

  27. What Do the Numbers Mean? • 4 -- LDPE (Low-density polyethylene) • LDPE is found in grocery bags, bread bags, shrink wrap, margarine tub tops... • LDPE can be recycled into new grocery bags...

  28. What Do the Numbers Mean? • 5 -- PP (Polypropylene) • PP is used in most yogurt containers, straws, pancake syrup bottles, bottle caps.... • PP can be recycled into plastic lumber, car battery cases, manhole steps...

  29. What Do the Numbers Mean? • 6 -- PS (Polystyrene) • PS is found in disposable hot cups, packaging materials (peanuts), and meat trays... • PS can be recycled into plastic lumber, cassette tape boxes, flower pots...

  30. What Do the Numbers Mean? • 7 -- Other • This is usually a mixture of various plastics, like squeeze ketchup bottles, "microwaveable" dishes...

  31. Timeline of Plastics 1862 – First man-made plastic 1866 – Celluloid makes it’s debut 1891 – Rayon is discovered 1907 – Bakelite is invented 1913 – Cellophane causes the plastics craze

  32. Timeline of Plastics 1926 – PVC is invented 1933 – Polyethylene is discovered 1933 – Saran makes it’s debut 1938 – Teflon is discovered 1939 – Nylon stockings hit market 1957 – Here comes velcro

  33. End of Chapter 3

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