Gluep - Experiment 19
Many of the materials we use every day, like starch, are made up of molecules called POLYMERS. POLY means “many” and MER means “unit”. Because the units of chains are so long, the movement of polymers is restricted. Viscosity is a physical property of liquids that describes their rate of flow. Honey and corn syrup are described as having high viscosity because they flow more slowly than water.
|2 400 mL beakers||2 jars or 2 styrofoam cups|
|Elmer’s Glue All|
|25 mL graduated cylinder||measuring spoons|
- Mix 30 mL (2 Tbsp) of glue with 20 mL water (4 tsp) in a beaker.
- Add 2 or 3 drops of your choice of food coloring.
- To the second beaker, add 200 mL (3/4 cup) of water. Add 2.6 grams (1/2 tsp.) of powdered borax and stir until the borax dissolves.
- Add 15 mL (1 Tbsp) of the borax solution into the beaker containing glue and water.
- Stir gently and allow it to sit momentarily.
- Take the Gluep out of the beaker and stretch it. Will it bounce? Does its consistency change? Can you break it?
Try making one of the other non-Newtonian fluids in this lab manual. See Experiments 18 and 20.
- Gluep is a non-Newtonian fluid. A non-Newtonian fluid has properties of both a solid and a liquid and reacts to stress with increased viscosity.
- Gluep can make a mess!! Be prepared for your students to have some “play” time. Towels and water should be on hand.
- Do not eat Glue or Gluep.
- Alternative procedure: Replace the 400-mL beaker in step 1 with a Styrofoam™ cup. Then in step 4, pour the 15-mL of the borax solution into the cup containing the glue/water mixture. This procedure reduces cleanup time.
- The Elmer’s glue is a solution of a polymer. With the addition of borax, the polymer chains become cross-linked. In this type of reaction, the chains are bonded together to create a larger, stronger polymer.
If you have Ziploc™ bags, you could allow the students to take their Gluep home with them. Solutions of borax may be poured into the sinks. Unused mixtures of the borax and glue should be placed into a solid waste container.