Summary

In this lesson students will learn about polymerization, specifically as it pertains to rubber tires and other materials in a vehicle. Students will take on the role of an engineer, and will investigate physical properties of different polymers and/or elastomers to determine the best material to use for an assigned product.

Grade Level

High school

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
• HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability and aesthetics as well as possible social, cultural and environmental impacts.
• Scientific and Engineering Practices:
  • Analyzing and Interpreting Data
  • Planning and Carrying Out Investigations
  • Engaging in Argument from Evidence

Objectives

By the end of this lesson, students should be able to

• Plan and conduct an investigation.
• Gather evidence to infer which product would be best to be used as materials for a tire
• Explain the relationship between cross-linking and the properties of a polymer.
• Identify patterns various properties of polymers and the classifications of polymers.
• Make a claim supported by scientific evidence.

Chemistry Topics

This lesson supports students’ understanding of

• Polymers
• Physical Properties
• Organic chemistry
• Intermolecular Forces

Time

Teacher Preparation: 60 minutes

Lesson: 7-8.5 hours/class periods

Materials

Engage Section:

• 1 – 12 sets of happy and sad balls
• Meter sticks
• Beakers
• Thermometers
• Heat gun
• Preform
• Sodium alginate

• Calcium chloride
• Water
• Cups
• Glue
• Borax
• Empty two liter bottle

Explore Section:

• Chalk
• Talcum powder
• Sodium alginate
• Plaster of Paris
• Citric acid
• Vinegar
• Oil
• Cream of tartar
• Mortar & pestle
• Cornstarch
• Microwave
• Hot plate
• Calcium chloride
• squeeze bottle for the sodium alginate solution
• Gorilla glue
• Elmer’s Nanoglue®

• Newspapers or tarps
• Cups for mixing
• Plastic bags
• Stir sticks
• Plastic cups
• Plastic medicine cups
• Glue - various types
• Liquid starch
• 4% Borax solution
• Flour
• Salt
• Water
• Food coloring
• Epsom salt
• Guar gum
• 4% polyvinyl alcohol solution
• Latex
• Sodium polyacrylamide - water gel crystals (ghost crystals)

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• If anyone is allergic to Latex then omit the Latex station
• If students have skin sensitivities, use nitrile gloves.
• Solids to be disposed in the trash
• Liquids can be flushed down the sink.

Teacher Notes

• This resource could be used as a post-AP Chemistry exam activity.
• This lesson can serve as an extension/application to an organic chemistry unit, intermolecular forces, properties of materials and mixtures, or bonding. Topics include but not limited to:
  • Factors that affect intermolecular forces
  • Relative bond strengths
  • Atoms bond to form compounds - types of hydrocarbons
  • Mixtures and pure substances - the difference between composites and other materials
  • Different types of chemical bonds.
• Essential Questions for this lesson:
  • What is the difference between the varieties of polymers?
  • How are polymers made?
  • How can we alter the properties of a polymer?
  • How is a tire made?
  • How does chemical structure affect physical properties?
• This lesson was designed to be implemented over a time frame of 7-8.5 hours, or class periods. However, a teacher could break this into several smaller activities instead.
  
  
• Engage: The students will be given two spheres (happy and sad balls) that look alike. They will be asked to observe what happens to them when they are thrown to the ground. One ball will bounce and the other will not. They will also place the two spheres in warm water and try to bounce them again. Finally student will repeat the experiment in cold water. The students will then have to determine the densities of each sphere to see if they are made out of the same material. More Information about this Happy and Sad Ball activity adapted from the Polymer Ambassadors: Happy and Sad Ball Activity
  
  Students will participate in a class discussion regarding their findings from the happy and sad balls. The teacher should also lead the class in a discussion about: What is a polymer? What are examples of polymers? What are different ways to classify polymers? Also, teachers could ask students which they might think is the best ball to represent a tire. They can relate prior knowledge of the behavior of matter and their own experiences to make predictions. If students are not sure, ask them if when they are in their parent’s car do they feel every bump or is it more of a smooth ride? Follow up by asking them to explain why? This should help them make a connection.
  
  Examples of polymers that students might suggest include: DNA, starch, proteins, lipids, rubber, tires, plastics, rope, bottles, and fleece for possible examples.
  
  Use this resource to find information about polymer classification: Various Polymer Structures
  
  Several videos can be used to enhance the discussion:
  • The Story of Rubber: This website contains information about the history of rubber, where we find latex, how it is made and properties of rubber.
  • History of Rubber: University of Akron has a 7 ½ minute video on the history of rubber.
    

The teacher should plan time for a lecture after the class discussion.
Sample Polymer Notes
Example of Monomers and Polymers (Chart)

• Other resource suggestions:
  • Website - everything about polymers: information about what a polymer is and how things are made.
  • Polymer Ambassadors: information about polymers and activities to do for any grade level.
  • Pop bead Demo: use a demo to show an analogy of the length of one molecule.
  • Milk Jug Demo: thermoplastic demo and other information about polymers.
  • Slime activity
  • Forming rubber: How rubber is crosslinked
  • Nylon 6-10 demo
  • Mystery of Nylon Flinn demo
    
• The Engage section of the lesson should take 1.5 to 2 hours/classes total: one hour/one class for the activity, and analyzing the results, and an additional 30 minutes to 1 hour for the discussion and notes.
  
  
• Explore: Students will do miniature lab experiments and write reports about the various polymers they made. They will analyze the properties of the polymers that they made, and think about how they might alter the polymer to make it appropriate for a specific product. Students will also complete a cost analysis.
  
  Students will be placed in groups of 4 and work as a team to determine a material that would be best suited for their assigned product to be used in a car. Each group will roll the die to determine their polymer assignment:
  • First group to roll a 1 – polymer for new seat cushions
  • First group to roll a 2 – polymer for new material for a dash board
  • First group to roll a 3 – polymer for new tire material
  • First group to roll a 4 – polymer for new seat belt material
  • First group to roll a 5 – polymer for a new bumper material
  • First group to roll a 6 – polymer for a new material for the body of the car
    
    Once assigned a product focus, students will brainstorm about characteristics necessary for the assigned product and its function of the car. Students will have a couple of lab days to synthesize various polymers to determine which polymer is best for their product. The team will have a meeting after the first round of polymer synthesis is done to discuss which option might be the best choice to pursue. Cost analysis and physical properties will all be address in the group discussion.
    
    Approximately 2.5 hours/classes are needed: 30 minutes for the group to work on the planning stage; 2 hours for the research/lab portion.

Download the Teacher's Guide to view the rest of this lesson.