Make your own bouncy ball!

Author: Maddie Van Beek


Have you ever bounced a rubber ball? Think about that experience--what makes a ball bounce? Bouncy balls bounce because of the highly pressurized rubber. Rubber is a highly elastic material, which makes it bouncy, but is also a polymer. We have learned about polymers in some of our previous blogs, such as when you created homemade slime (http://discoveryexpress.weebly.com/homeblog/two-times-the-slime-fun-with-polymers) or when you pierced a balloon without popping it (http://discoveryexpress.weebly.com/homeblog/balloon-science). Check them out to have more fun with polymers! 




Before you understand a polymer, you must know what a monomer is. See the visuals below.

http://www.brooklyn.cuny.edu/bc/ahp/SDPS/SD.PS.polymers.html

http://www.brooklyn.cuny.edu/bc/ahp/SDPS/SD.PS.polymers.html

A monomer is a small molecule that is able to bond with other monomers to form a larger molecule, or polymer.




Mono = one

Poly = many 




A polymer is created when monomers undergo a chemical reaction and form a chain. Think of a polymer as a necklace and the monomers as the beads on the necklace. 

Look at the visual below as an example. The paperclips form two separate chains. Each paperclip represents a monomer and each chain represents a polymer. Think of cross-linking as the two chains of paperclips being connected, just like the visual.

http://www2.lbl.gov/images/MicroWorlds/paperclip3.gif

In your activity today, you will be using glue, borax, and corn starch as your special ingredients to create a bouncy ball. Glue has polymer molecules in it already, but when you add the borax, it cross-links the polymer molecules in the glue to create polymer chains. 

https://www.teachengineering.org/collection/csu_/lessons/csu_polymer/csu_polymer_lesson01_figure5.gif

The corn starch that you mix in acts as a binding agent. Think of how the cornstarch helped you create your slime a few weeks ago. If you missed this blog, check it out here: http://discoveryexpress.weebly.com/homeblog/two-times-the-slime-fun-with-polymers. 



Now that you know a little bit about polymers and the ingredients’ purposes in your activity, let’s get started! 



YOU WILL NEED:

• Water
• Glue
• Borax
• Corn starch
• 2 small bowls or cups
• Spoons or stirring sticks
• Food coloring

Here’s what to do!

1. First, get organized. Label once cup ‘Borax Solution’ and one cup ‘Ball Mixture.’
2. Pour 4 ounces of warm water into the ‘Borax Solution’ cup and add 1 teaspoon of borax. Use a spoon to thoroughly stir the water and borax together until the borax dissolves. 
3. Pour one tablespoon of glue into the ‘Ball Mixture’ cup and add a few drops of food coloring. Use a second spoon or stick to stir the food coloring in. 
4. Add 1/2 teaspoon of the Borax Solution into the ‘Ball Mixture,’ then add 1 tablespoon of corn starch. DO NOT MIX. 
5. Wait about 15 seconds to let the ingredients interact. Observe. Can you see anything happening? 
6. Use a spoon to stir the ingredients in the ‘Ball Mixture’ cup together until the mixture becomes a solid substance that you can no longer stir. The ingredients should quickly form a ball. 
7. Remove the ball from the cup and use your hands to roll it into a sphere. It may start out a little messy and lopsided, but soon you’ll have a nice, round bouncy ball!

Extensions

1. Now that you’ve made the bouncy ball, test it out! What surface does it bounce best on? How high can you get it to bounce? 



2. Try changing the amount of borax, glue, or cornstarch. Test out several different combinations and test each ball to see what helps create the highest bounce. 



References

• https://sciencebob.com/make-your-own-bouncy-ball/
• http://www.theidearoom.net/2009/07/make-bouncy-ball.html
• http://www.pbs.org/parents/crafts-for-kids/super-bouncy-balls/
• http://www.brooklyn.cuny.edu/bc/ahp/SDPS/SD.PS.polymers.html