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:

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-C---C---C---C---C - n units
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