9.5 One way to differentiate between polymers is to look at their functional groups - distinctive arrangements of atoms that impart characteristic chemical properties to the molecules that contain them.

9.5 Condensation Polymers Examples Natural: starch, wool, silk, proteins Synthetic: nylon, kevlar, and ABS Formation of PET

9.7 Composition of municipal solid waste: 100 billion pounds of plastic is produced in the U.S. each year- much of this ends up in landfills.

Recycling 9.8 Example of closed loop recycling Ever heard of aluminum dross?

Recycling 9.8 Aluminum dross is a by-product of the primary and secondary aluminum industries White dross Black dross Salt cake None are on the EPAs Hazardous Materials List So in the U.S. it has been co-disposed along side of municipal solid waste for many years. Two Billion Tons are buried each year. Al skimming tool Scrap + white dross

Recycling: Al 9.8 Aluminum dross “Mount Rumke” before “Mount Rumke” after dross exposure to water

Recycling: Al 9.8 Aluminum dross Fe 2 O 3 (or sometimes Fe 3 O 4 ) + Al → Al 2 O 3 + molten iron (Fe) + A LOT OF HEAT 2 Al + 6 H 2 O → 2 Al(OH) H 2 + heat AlN + 3 H 2 O → Al(OH) 3 + NH 3 The chemistry behind the troubles