Polymers: The Discovery
M. Elaine Granger Beethoven Elementary
25 West 47th Street
Chicago IL 60609
(312) 535-1480
Objectives:
This lesson(s) can be adapted and made appropriate for grade levels K - 8.
Students will be able to:
1. Understand what a polymer is.
2. Observe and compare the properties of a polymer.
3. Describe the relationship between the cross-linking of molecules
to make a polymer.
4. Explore common uses of a polymer.
Materials needed:
Divide class into groups of three (3). Prior to lesson, set up materials for
each group and activity.
Activity A: Activity B: Activity C:
2-polystyrene cups 1-graduated cylinder 1-50mL beaker
plastic petri dish 1-container 1-250mL beaker
paper towels 1-stirring rod 1-spatula
1/4" to 1/2" acetone newspaper 50mL vinegar
ruler liquid latex
water
3.1g table salt
105mL liquid starch
50mL white glue
Strategies:
Activity A
A styrofoam coffee cup is really a combination of many materials. In this
experiment only two (2) of the materials (polymer and air) will be separated.
1. Take a good look at the cup. Describe the cup, its appearance and
properties.
2. Fill the petri dish with 1/4" to 1/2" of acetone.
3. Place the polystyrene cup into the petri dish. What happens?
4. Remove the clump of material from the dish with your fingers.
5. Examine and describe what you see and feel, its appearance and properties.
6. Form this polymer into a shape and let it dry.
7. Why do you think the cup was made with the air trapped inside of the plastic
in the first place?
Activity B
In this experiment, we will be making a substance called GLURCH. Glurch is a
mixture of (2) two colloids. A colloid is a substance that has another
substance suspended within it. Colloids may be gases, liquids, or solids inside
or outside as part of the suspension.
1. Cover desk with newspaper.
2. Pour 105mL of liquid starch into the container. Add the salt slowly. Stir.
3. Add glue and stir 30-40 more beats.
4. Remove the material from the container and roll/knead it, squeezing out the
excess liquid until the substance becomes doughy.
If the glurch becomes runny, add more salt sparingly until it firms up.
Be patient!
Activity C
Natural rubber latex is found in the inner bark of many trees grown in the Far
East and Brazil. Latex is an emulsion that is a mixture of a solid polymer and
water. Latex will turn into a rubbery mass within 12 hours after it is exposed
to air. When this happens the tiny particles come together to form larger
particles making a solid mass.
1. Pour 50mL of liquid latex into a beaker.
2. Put a drop or (2) two into the palm of your hand. Spread it around with your
finger. How does it feel? What do you see?
3. Dip the spatula into the vinegar, then into the latex on your hand, then back
into the vinegar again, and so on until the latex becomes solidified.
Describe your observations.
4. Pour 10mL of liquid latex into the 250mL beaker.
5. Add 50mL of water to the beaker of latex and stir the mixture.
6. Add 50mL of vinegar into this beaker and stir the mixture.
7. Remove this mass from the beaker. What do you have? Carefully squeeze the
mass while washing it under running water. Drop the mass on the floor.
What happens? WOW!
Performance Assessment:
Have each student build a polymer model using gum drops or raisins and tooth-
picks or straws. Display their works.
Have students complete a worksheet identifying every polymer item they have in
their homes. Graph this information. Write a short news report about the
recent development of a polymeric tool being used in the aerospace program by
you, the astronaut.
Conclusion:
When nonmetal elements combine together, they form molecules. Some of these
molecules are small, like water (H2O) or carbon dioxide (CO2). Other
molecules are made up of larger combinations such as C20H42. Polymers are
created by the chemical bonding of many identical or related molecules, and/or
the crosslinking of two or more monomers into long, linear chains like:
H H H H H
| | | | |
-C---C---C---C---C - n units
| | | | |
H H H H H
Polystyrene
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