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					Polymers
 By: Si Man Lam
  Date: June 7, 2005
          What is a Polymer?
• Polymers are commonly known as plastics
• Long chain of carbon molecules with repeating
  units joined by covalent bonds
• Each repeating unit known as a monomer
• Polymer is Greek for “many parts”
• Imagine a bowl spaghetti – that is how the
  molecular arrangement of polymers looks


                                                  2
      Two Groups of Polymers
• Thermoplastic
   – Soften with heat and harden with cooling
   – Examples: HDPE, LDPE, PET
• Thermosets
   – Cured or Hardened with heating
   – Examples: Bakelite, Epoxy, Polyurethane



                                                3
            Natural Polymers
• Existed since the beginning of time
• Examples include shellac, turtle shells and horns,
  latex, silk
• Chemically modified natural polymers include
  rubber and gun cotton




                                                       4
       World War II: Revenge of the Synth
• Reduced supply of natural sources of latex, wool,
  silk and other materials
• Emergence of synthetic polymers
• Increased usage and development of nylons,
  acrylics, neoprene, polyethylene




                                                      5
                    Bakelite
• Developed in 1907 by Leo Baekeland
• First synthetic polymer and first widely
  manufactured plastic
• At that time used to make everything from
  telephones and radios to auto parts, furniture, and
  jewelry




                                                        6
       Polyethylene
• Simplest and most basic polymer chain
• Made up of a long chain of Ethane molecules
  (CH3-CH3)
• Monomer form is Ethylene (CH2=CH2)
• Available in Low Density and High Density
  Variations
• Commonly used for milk bottles, medicine bottles,
  bags, Toys

                                                  7
             PET
• Polyethylene Terephthalate
• Derivative of polyethylene with terephthalate
  molecule included in the chain
• Durable and clear properties with oxygen and
  water barrier
• Great for soda bottles and drink containers



                                                  8
                     Teflon
• PolyTetraFluoroEthylene
• Discovered by Accident by Roy Plunkett at
  Dupont in 1938
• Secret Weapon of WWII - used to coat bearings
  and metal surfaces to reduce friction and wear and
  tear
• Now used for non stick pots and pans and dental
  floss

                                                       9
Other Commonly Used Polymers
•   Polypropylene (Microwavable Containers)
•   Polyvinylchloride (Water pipes)
•   Polystyrene (Foam Cups, Packing Peanuts)
•   Polycarbonate (aka Lexan, Bulletproof Glass)
•   Polyamide (Nylon)




                                                   10
What Is Used to Make Plastic Stuff?
•   Injection Molding
•   Injection Blow Molding
•   Injection Stretch Blow Molding
•   Extrusion Molding
•   Extrusion Blow Molding
•   Rotational Molding



                                     11
             Why Use Plastic?
•   Looks Good
•   Durable
•   Flexible
•   Light Weight
•   Easy to shape and color
•   Cheap



                                12
             The Plastic Age
• Stuff made out of plastic is everywhere
• Cell phones, computer parts, car parts, tables,
  chairs, etc.
• New uses for plastic being discovered everyday
• What used to be glass is now made in plastic
• What used to be metal is now made in plastic
• What used to be wood is now made in plastic
• Plastic has revolutionized the world
                                                    13
                    References
• http://web.umr.edu/~wlf/CHEM381/chap11.html

• http://www.calibre.co.nz/plastics.htm

• http://www.packagingtoday.com/intronaturalpolymers.htm

• http://www.packagingtoday.com/introplasticexplosion.htm

• http://www.teachingplastics.org/hands_on_plastics/intro_t
  o_plastics/teachers.html

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