Ward's World Activity Guides

Polyurethane Foam Demonstration + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com Recommended Grade Level(s): Appropriate for: 5th Grade–12th Grade Time Requirements: Prep Time: 10 minutes Activity Time: 30 minutes Teaching Topics & Concepts: In this demonstration, two viscous liquids are mixed, and the ensuing reaction creates polyurethane foam. The foam rapidly expands to a much larger volume than the original liquids. Materials: • Part A, mixed isocyanates, 500 mL • Part B, dichlorofluoroethane, 500 mL • Plastic cups, 30 • Blue food coloring, 30 mL • Instructions including answer key and worksheet Safety • Wear gloves, lab apron or lab coat, and safety goggles throughout this demonstration. • Review the safety data sheets (SDS) for the substances used in the demonstration before starting the demonstration. • Both reactants used in this demonstration are skin and eye irritants. Care should be taken to avoid any spillage. • The reaction is exothermic and generates a small amount of heat. Caution should be exercised. • The chemicals used in this demonstration can ruin the finish on lab counters. Protect the lab counter by placing a mat or large tray under the beaker. ! Procedure: 1. Using a medicine cup or disposable cylinder, measure 25 mL of Part A (mixed isocyanates) and add it to the large plastic cup. If colored foam is desired, add several drops of food coloring to Part A. Place the container on a lab mat, paper towel, or newspaper to absorb any overflow. 2. Using a medicine cup or disposable cylinder, measure 25 mL of Part B (dichlorofluoroethane) and add it to Part A in the large plastic cup. Stir until foam starts to form. 3. The ensuing reaction should produce a large amount of foam within a few minutes. 4. As the foam begins to grow, feel the outside of the plastic container—it should feel warm. Have a student feel the outside of the plastic container and describe it to the class. CAUTION: Do not touch the foam until it hardens. This may take 10–15 minutes to occur. Assessment: 1. The prefix "poly–" is used in the starting materials (polyol) and the product, polyurethane. What does "poly–" mean? 2. If the contents of the reaction container were stirred rapidly to allow the carbon dioxide to escape readily, how would the results differ? 3. Polymers are everywhere. Identify three products made from synthetic (man-made) polymers and three products made from natural polymers that you might use today. 4. Why did the plastic container get warm when the polymer was forming? Teacher Tips: • The foam will be difficult to remove from any surface that it touches. Take care not to let it touch tabletops or other surfaces. • After the foam hardens, you may loosen it from the cup with a small amount of acetone. • If the foam accidentally comes into contact with the table or floor, a small amount of acetone may help remove the foam. Find materials for this activity at wardsci.com. Discover more free activities at wardsworld.wardsci.com

• Cover