Creating New Materials - Mrs. Temple's Science Classes



Creating New Materials

Key Words: Chemical Reaction, Cross-Link, Monomer, Polymer, Product of a Chemical Reaction, Reactant

Getting Started:

1. Look at the molecule below. It is made up of 4 hydrogen atoms, 2 carbon atoms, 1 oxygen atom, and 7 bonds. This molecule is called vinyl alcohol.

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2. These single molecules of vinyl alcohol can be used to build a chain that looks like the molecule below.

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3. The building of this chain models a chemical reaction of vinyl alcohol into polyvinyl alcohol. The beginning part of this reaction is called a monomer, and the resulting chain of many parts is called a polymer, which means “many parts.” Polyvinyl alcohol will be used in this activity.

4. In the last activity you investigated four plastics. What did each of their names have in common? (Polypropylene, High-density Polyvinyl Chloride, High-density Polyethylene, Polystyrene)

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5. All plastics are polymers. Like the polyvinyl alcohol, they are made of long chains of chemically bonded smaller molecules called monomers. A molecule is a group of chemically bonded atoms that forms a compound with specific chemical and physical properties.

The process of bonding monomers (one-part molecules) together is called polymerization, and typically 1,000-10,000 monomers are linked to form a polymer. While many polymers are made by linking monomers together, other polymers are made by changing the structure of existing polymers.

In this activity, you will start with the polymer known as polyvinyl alcohol (PVA) and see how its properties change when it is mixed and reacts chemically with another compound, to change its molecular composition. Read the introduction and Challenge to Activity 19, “Creating New Materials,” in your Student Book.

Procedure:

1. In the space provided, create a table to record your observations of the reactants before the reaction and the results after the reaction is completed. Hint: Read through the entire procedure before making your table so you know what you will need to record.

2. You will not be able to see the properties of the two materials used in the lab, yet you need them for your data. Therefore, you must talk to a lab partner or your teacher about the properties of each of the two liquids (reactants) used in the Procedure.

3. Watch the LABsent video (found here: ). Be sure to record the appropriate data on the table you created.

Follow-Up:

1. It is the number of cross-links that determines the properties of the polymer. Which do you think is a harder substance, a polymer with more cross-links or a polymer with fewer cross-links?

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2. What do you think would happen to the final polymer if you continued to add sodium borate?

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Analysis Questions:

1. How do the physical properties of the final product compare to the physical properties of:

a. polyvinyl alcohol (PVA), one of the reactants?

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b. sodium borate, the second reactant, which was added to the PVA?

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2. What evidence can you provide that a new substance formed?

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3. Plastics are a category of materials. Compare the plastics that you worked with in this activity to the properties of the plastics you tested in Activity 18, “Properties of Plastics.” From these two investigations, what can you say about the properties of plastics?

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