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Museum at Home: DIY Corn Plastic
Science Educator Don Riefler shows how to make a basic, plant-based plastic using three ingredients from your kitchen and your microwave oven!
- Corn starch
- Vegetable oil
- Food coloring (optional)
- Microwave save bowl
- Eyedropper or pipette
- Fun shaped cookie cutters
- Place two tablespoons of corn starch into a microwave safe bowl.
- Add three tablespoons of water to the cornstarch.
- Use the eyedropper or pipette to add six drops of oil to the cornstarch and water.
- Stir the ingredients together until the mixture is smooth and shows no lumps.
- Place the bowl in the center of your microwave oven and heat the mixture using the high setting for 45 seconds.
- Let the bowl sit and cool for a few minutes.
- When you open the microwave door, be aware that steam may have built up inside, so stand away from the door when you open it to retrieve the corn plastic.
- Turn the bowl upside down and tap on its base to release the layer of newly formed corn plastic from the bottom. You may also need a plastic spoon to scrape the plastic out.
- Give the plastic a few minutes to cool.
- Cut fun shapes out of the plastic with your cookie cutters!
When you are done with the plastic, you may wish to add it to a compost pile rather than throw it away. This way you can be sure the plastic will be broken down into something useful—plant fertilizer!
What's going on?
We all know plastic! We think we do, anyway. Everyone knows what it is, but does everyone know what it’s made of? All plastics are something we call polymers, made of long chains of molecules. The polymer chains are made of smaller pieces called monomers. Depending on the exact chemistry of a polymer, it might be bendy and flexible, hard and tough, or even soft and squishy. We tend to think of polymers as being made by humans, but there are naturally occurring polymers as well, like rubber, cellulose, and even DNA.
Most synthetic plastics these days are made from petroleum: fossil fuel. But it doesn’t have to be that way! Scientists have figured out ways to make plastic out of plant products like algae or corn, and some companies use those methods to make bioplastic products. Such plastics are much closer to carbon-neutral than petroleum-based plastics. The plastic you made in this experiment is very quick and basic, which means it will start to break down before too long. On the upside, it is completely biodegradable! How it is made is simple: cornstarch is actually already a polymer! But the chains of monomers are pretty short when it’s in its powdered form. Heating it up allows those short polymers to connect to each other to make much longer polymers, and with the right amount of water and heat you get a simple plastic!
Share your plastic creations by using the hashtag #TCMatHome on social media!