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Topics for Today

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  1. Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)!

  2. Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)! • Organic (Carboxylic) Acids • Neutralization Reactions

  3. Readings for Today • 9.2 The “Big Six” • 9.3 Addition polymerization • 9.5 Condensation Polymers

  4. Topics for Friday • Linking the PET(E) Chain

  5. Readings for Friday • 9.5 Condensation Polymers

  6. Announcements! Homework #4 due 1 week from today. Recommendation… Don’t start at the last minute!

  7. Exam #3! Friday, April 20! Same format as always

  8. Exam #3! Non-memory calculators OK. Please, no cell phones

  9. Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)!

  10. Polyethylene formation Review [ ]n H H R· –CH2–CH2– n C = C H H Monomer? Repeating Unit?

  11. Addition Polymerization!! • Initiated by a free radical. • No by-products. Animation! http://chemincontext.eppg.com/chapter9/cic_interface9.swf

  12. PE comes in more than 1 form!

  13. Types of Polyethylene Figure 9.7 (p. 409)

  14. Different chemical structures = different chemical properties… Why does HDPE have a slightly higher density? Branched ~0.93 g / mL Linear ~0.96 g / mL

  15. Does PE float or sink in water? • Density of Water = 1 g / mL

  16. Will the PE float or sink? DEMO! Density = 0.94 Branched ~0.93 g / mL Linear ~0.96 g / mL

  17. HDPE LDPE Figure 9.7 (p. 409)

  18. HDPE and LDPE are primarily used for packaging…

  19. Why?

  20. Need 27 pounds of glass… Lightweight!!! Need 8 pounds of steel… To package 8 gallons of liquid… Need 2 pounds of plastic… http://www.americanchemistry.com/s_plastics/sec_content.asp?CID=1078&DID=4232

  21. Other properties of PE?

  22. HDPE

  23. HDPE • Most common plastic • White or semi-transparent

  24. HDPE • Can add dyes for color or opaqueness

  25. HDPE Some bases? • Inert towards acids and bases Some acids? NaOH (lab) NH4OH H2SO4 HNO3 HCl

  26. HDPE • Inert towards acids and bases

  27. HDPE • Inert towards acids and bases What is household ammonia?

  28. HDPE Household cleaners are usually very basic • Inert towards acids and bases Under my sink…

  29. HDPE • Very Robust!

  30. HDPE • Drawbacks: softens with oils NOT HDPE!

  31. HDPE • Major use = packaging • In comparison to LDPE • Stronger, more rigid • More opaque • Higher melting (~130 º C) (dishwasher safe)

  32. Uses for LDPE? LDPE

  33. LDPE • Major use = packaging • In comparison to HDPE • Lower strength • Semi-transparent to clear • Lower melting (~120 º C)

  34. Dry Cleaner Bags Saran Wrap

  35. Used for squeezables!

  36. Other monomers? • Polyethylene • Polypropylene • Polyvinyl Chloride • Polystyrene Other synthetic polymers

  37. Name? H H C C H H Ethene (or ethylene), C2H4 CH3 H C C H H Propene (or propylene), C3H6

  38. Isomers? H H C C H CH3 Any other monomers? CH3 H C C H H

  39. Monomers!!! Cl H H H C C C C H H H vinyl chloride H ethylene What do these all have in common? H CH3 H C C C C H H styrene H H propylene

  40. Monomers!!! 1) They all have C-C double bonds. Cl H H H C C C C H H H vinyl chloride H ethylene 2) They all form addition polymers! H CH3 H C C C C H H styrene H H propylene

  41. Polyethylene • Polypropylene • Polyvinyl Chloride • Polystyrene Other synthetic polymers How do we make these?

  42. Polypropylene

  43. Monomer – Propene (propylene) H H C = C H CH3

  44. Polypropylene formation Compare to polyethylene H H H H R· — C – C— n C = C n H CH3 H CH3

  45. Polyethylene formation [ ]n H H R· –CH2–CH2– n C = C H H

  46. Resists oils and greases! Extremely tough and durable

  47. Plastic storage containers

  48. Cheeses! Fresh Mozzarella

  49. What else has lots of grease or oil?