26.4

Polymerization

Polymers from Monomers

                            

                   

Addition PolymersPolymers are giant molecules,

not small like the ones studied earlier in this chapterexamples are plastics

Polymer- large molecule formed by the covalent bonding of smaller molecules called monomers

Addition Polymers

An addition polymer forms when unsaturated monomers react to form a polymerethene will form polyethylene,

shown on page 795polyethylene is easy to clean,

chemically resistant- milk bottles, plastic wrap, refrigerator dishes

High Density Polyethylene

Addition PolymersPolypropylene is a stiffer polymer, used

in utensils and containersPolystyrene is formed from styrene

(phenylethene), and is a poor heat conductor (styrofoam ® Dow Chemical)molded coffee cups and picnic

coolers, insulates homesPolyvinyl chloride (PVC) used for pipes

in plumbing

Addition Polymers

Polytetrafluoroethene (PTFE, or teflon ® DuPont) is very resistant to heat and chemical corrosionfound on nonstick cookware; coating on bearings and bushings used in chemical reactors

Condensation Polymers

Condensation polymers are formed by the head-to-tail joining of monomer unitsusually accompanied by the loss of water from the reacting monomers, and forming water as a product

Condensation PolymersEx: 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

Condensation PolymersExamples:

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

Plastic container code system.

CODE MATERIALPERCENT 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

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...

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...

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...

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...

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...

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...

What Do the Numbers Mean?

7 -- Other•This is usually a mixture of various plastics, like squeeze ketchup bottles, "microwaveable" dishes...

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

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