martinzoo

This experiment from Home Science Tools was really fun, too. And GB like the fact that he has a new toy to play with. I’m sure it won’t last very long. And before you know it, I’ll be chucking it into the trash can. But for now, it’s PURE entertainment!

Science Project: Make a Colorful Bouncy Ball

Polymers are used to make numerous things, including clothing, plastic containers, nonstick cookware, and bulletproof vests. Try this experiment to see how polymers can make a toy.

Materials:

• 1 tablespoon white glue

• 1/2 teaspoon borax

• 1 tablespoon cornstarch

• 2 tablespoons warm water

• 2 plastic cups

• 2 wooden craft sticks

• Food coloring

What To Do:

1. Pour the glue into one of the plastic cups. Add a few drops of food coloring to the glue and mix with one of the craft sticks until it’s the color you want.





2. In the second cup, combine the water and borax together and mix with the second craft stick. Stir until dissolved.

3. Add the cornstarch and 1/2 teaspoon of the borax solution to the glue and let stand for 15 seconds.



4. Stir with a craft stick until fully mixed together and it becomes very difficult to stir.

5. Mold the ball in your hands. It will be sticky at first but will become more solid as you roll it in your hands.

6. You now have a bouncy ball. Try bouncing it. How high does it go? Store your ball in an airtight container or Ziploc bag so it doesn’t dry out and crumble.

What’s Happening?

The white glue contains polyvinyl acetate, a strong and flexible polymer that gives the ball strength. Cornstarch contains amylopectin, a polymer whose shape is best described as “branched” - it sticks out like the branches of a tree - and gives the ball the property of elasticity. Elasticity allows the ball to return to its original shape after being compressed or stretched, such as when it hits the floor. So instead of splattering everywhere, the ball bounces back up. The borax is needed to help the glue and the starch stick together. This connects the two polymers into a netlike formation, keeping the ball from crumbling or becoming slime when it is bounced.

***Edited by me on Sunday evening: I wanted to let you all know that GB and I did this three more times today, trying to get a ball that bounces even better. Our conclusions….. We had a huge difference just by substituting the blue glue gel that Elmer’s makes, in place of the white school glue. And I do mean a huge difference. On our last try, we put the cornstarch into the cup AFTER we had added the water/borax mixture to the glue mixture. It made for a much more condensed ball, which I think also helped with the bounce. I suspect, but we haven’t tried this, that the cornstarch is unnecessary. If someone tries it without the cornstarch, let me know.