
Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)!
Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)! • Organic (Carboxylic) Acids • Neutralization Reactions
Readings for Today • 9.2 The “Big Six” • 9.3 Addition polymerization • 9.5 Condensation Polymers
Topics for Friday • Linking the PET(E) Chain
Readings for Friday • 9.5 Condensation Polymers
Announcements! Homework #4 due 1 week from today. Recommendation… Don’t start at the last minute!
Exam #3! Friday, April 20! Same format as always
Exam #3! Non-memory calculators OK. Please, no cell phones
Topics for Today • Where Do We Find Other Addition Polymers? • PETE (A Polyester)!
Polyethylene formation Review [ ]n H H R· –CH2–CH2– n C = C H H Monomer? Repeating Unit?
Addition Polymerization!! • Initiated by a free radical. • No by-products. Animation! http://chemincontext.eppg.com/chapter9/cic_interface9.swf
Types of Polyethylene Figure 9.7 (p. 409)
Different chemical structures = different chemical properties… Why does HDPE have a slightly higher density? Branched ~0.93 g / mL Linear ~0.96 g / mL
Does PE float or sink in water? • Density of Water = 1 g / mL
Will the PE float or sink? DEMO! Density = 0.94 Branched ~0.93 g / mL Linear ~0.96 g / mL
HDPE LDPE Figure 9.7 (p. 409)
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
HDPE • Most common plastic • White or semi-transparent
HDPE • Can add dyes for color or opaqueness
HDPE Some bases? • Inert towards acids and bases Some acids? NaOH (lab) NH4OH H2SO4 HNO3 HCl
HDPE • Inert towards acids and bases
HDPE • Inert towards acids and bases What is household ammonia?
HDPE Household cleaners are usually very basic • Inert towards acids and bases Under my sink…
HDPE • Very Robust!
HDPE • Drawbacks: softens with oils NOT HDPE!
HDPE • Major use = packaging • In comparison to LDPE • Stronger, more rigid • More opaque • Higher melting (~130 º C) (dishwasher safe)
Uses for LDPE? LDPE
LDPE • Major use = packaging • In comparison to HDPE • Lower strength • Semi-transparent to clear • Lower melting (~120 º C)
Dry Cleaner Bags Saran Wrap
Other monomers? • Polyethylene • Polypropylene • Polyvinyl Chloride • Polystyrene Other synthetic polymers
Name? H H C C H H Ethene (or ethylene), C2H4 CH3 H C C H H Propene (or propylene), C3H6
Isomers? H H C C H CH3 Any other monomers? CH3 H C C H H
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
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
Polyethylene • Polypropylene • Polyvinyl Chloride • Polystyrene Other synthetic polymers How do we make these?
Monomer – Propene (propylene) H H C = C H CH3
Polypropylene formation Compare to polyethylene H H H H R· — C – C— n C = C n H CH3 H CH3
Polyethylene formation [ ]n H H R· –CH2–CH2– n C = C H H
Resists oils and greases! Extremely tough and durable
Cheeses! Fresh Mozzarella