Polymers Experiment

Here’s an interesting experiment you can do at home. All you need are a leak proof zipper-top bag, some sharpened pencils, water and a sink. This experiment demonstrates something that is sure to arouse your curiosity about plastics. Parents: Your child may need an extra hand conducting this experiment.

Step 1

Find a quart size zipper bag, plus four or five finely sharpened pencils.

Step 2

Fill the zipper bag 2/3 to 3/4 full of water.

Step 3

Hold the water-filled bag over a sink using your non-dominant hand (the one you don't use to write)

Step 4

Using your dominant hand, take a single sharpened pencil and carefully jab the pencil completely through the bag. Leave in place.

Step 5

Continue stabbing the bag in different places using the other pencils

Is your bag leaking?

What’s going on? The bag generally does not leak. The plastic bag is made of molecules called polymers. Polymers are made up of long chains of repeating molecules. When you put a hole in the bag the polymer chains close in tightly around the pencil, preventing the bag from leaking.

Were you a little too forceful? Here’s what happens when you go through the other side of the bag accidentally. Thanks for being a young scientist with the Evansville Museum!