Experiment IV: MATERIALS ENGINEERING


Materials Engineering Laboratory
Processing and Properties of Materials

Note: This laboratory does not travel when the Chemical Engineering Laboratory travels.

I. Processing of Polymers

Objective
To introduce the girls to polymers and some of their applications

Materials
Polyurethane foam mixtures A and B. These can be obtained from Industrial Arts Supply Company (IASCO) 5724 West 26th St Minneapolis, MN 55416 Ask for Molding Foam (UrethaneA and B)

4 % aqueous solution of polyvinyl alcohol 4 % aqueous solution of borax These can be obtained from La-Mar-Ka 1-800-826-5959

safety glasses gloves cups stirring rods

Procedure

1) Discuss what a Materials Engineer does.

2) Follow the discussion from the chemical engineering lab on polymers and "polymerize the group" (see Chemical Engineering Microcapsules)

3) Explain the uses of polyurethane foam and how it is made. It is used as insulation, seat foam, packing foam, in couches.

Break the girls into groups of 2 or 3. Have each group make polyurethane foam. This is done by putting equal amounts of mixtures A and B in a foam cup and stirring rapidly.

Discuss the heat that is generated during the processing. Why does it form? Does this cause problems in a processing plant?

5) Slime is for fun.

Using the same small groups have them mix 20 ml of the polyvinyl alcohol solution with 5 ml of the borax solution and stir QUICKLY. SLIME will be the result.

Slime is a crosslinked structure, but the crosslinks are hydrogen bonds and thus can break and reform easily. This gives the mixture the flow properties and the bouncy properties that it exhibits. At short times, the bonds don't break and it bounces. At long times, the bonds break and the materials flows.....

II. Properties of Metal Alloys

Objective
To introduce the principle of shape memory alloys as an example of how engineers find interesting materials to solve problems (use the analogy with whale whiskers)

Materials

Ni-Ti shape memory wires Hot plate Beaker with water Tweezers

Procedure

1) Memorize the wires as straight wires. To do this, boil water ina hot pt and make sure the temperature stays above 80oC while holding the wires straight. VICKI???

2) Have each girl take a wire and bend it in any shape she wishes. Then have her hold the wire in boiling water. A phase transformation will occur and the wire will straighten out.

3) Discuss how this would be useful. Have them suggest the ideas.

Car Bumpers
Eye glasses
As filters for blood clots


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