Re: What would be a good lab experiment with polymers?

This was a tough one.  The 3rd grade portion of the request was easy to 
find.  Making it in depth enough for college freshmen made it much more 
difficult.  I hope this will fill the bill.  It is very easy to produce 
this polymer with ingredients found in any kitchen.  The items you need to 
perform this process are as follows:

muslim
jars
milk
vinegar
spoon
saucepan(large beaker)
rubber band
heat source

1. Warm 0.3 liters (10 FL OZ) of milk in a pan or beaker, but do not boil.  
Add a tablespoon of vinegar and stir in.

2. A white , rubbery material, the casein, forms in the milk.  Strain it 
off through muslim held over a container(jar or beaker).

3. Squeeze the milk through the muslim until  you have recovered all the 
solid, rubbery casein.

4. Push the casein into a suitable mold, such as a cookie cutter, or shape 
it by hand.  Then leave it to sit and cure.  After several days, the 
casein will gradually dry out and harden as the protein molecules bond 
tightly together.  You can speed the process by leaving it near a radiator 
or other heat source.  The shape can be painted after it is solid.

This is a simple experiment to make a natural plastic(polymer), casein 
with very common ingredients.  I hope it works for both groups.