Monday, Sept 28, 2009 - 3A

HW: Check Quia for review questions
Test next time on Material Science

Reviewed previous class results
Quiz on previous class

Powerpoint on polymers

Recognizing patterns and making connections.

What is a polymer - many parts
polymer is a long chained molecule made of many repeating parts
Had students recite this until they could do it with gusto

Classifying polymers - natural vs synthetic
Went around room asking for examples of natural polymers

Told Nydam's joke about silk worms having race to see who could produce the most silk - ended in a tie

Examples of synthetic polymers - come from petroleum

Thermoplastics - recyclable (recycle numbers on products)
Thermosets - non-recyclable

Packing peanuts - how many peanuts can I fit in film canister?
Starch vs polystyrene peanuts. Do you thing that the different properties in what dissolves what could tell you something about the microscopic structure of the polymers? Would it be wise to pour gasoline in a styrofoam cup?

Synthetic polymers come from petroleum. Slides showed that as number of carbons increased, so did density, melting point temperature, and boiling point temperature.

Hand hold model of polymerization. Did in hall. Hands represent chemical bonds, bodies represent carbon atoms.

Chain model of polymer. Chain was 2500 beads long; a normal polyethylene molecule has 10,000 carbons. Had students visualize entanglement. Showed with steel wool.

HDPE vs LDPE. Story of trucks with trees. Used heat gun to separate HDPE and make more transparent. As it cools, it goes back to being tighter packed with fewer spaces and less transparent. Heated again and blew bubble.

Back to slide of chemical structures of various polymers. PVC replaces H with Cl.
Identified monomer units.

Finished with using torch on light bulb forming dimple (low pressure inside) and then pimple (high pressure inside from heating up atoms and molecules). Temperature is random wiggling and jiggling of particles. In some classes, plugged bulb in and it lit.