Plastics play an important role in our lives. Plastics are used to manufacture many everyday items and have significantly reduced the use of glass. Some plastics are very durable and make things like furniture and appliances. Other plastics make items such as diapers, trash bags, cups, utensils and medical devices. The largest amount of plastic is used to make containers and packaging for items such as soft drink bottles, lids, shampoo bottles, etc. Common plastic is made from petroleum, a fossil fuel which is nonrenewable.
Nonrenewable resources are made naturally by the earth, but do not renew themselves fast enough to be able to count on having the resource for an indefinite period time. Some resources are considered non-renewable because our access to the resource is limited. For example, glass and metal are non-renewable resources. The elements and minerals used to make glass and metal are found in the structure of the earth’s crust, however we are limited to what we can access through mining.
Renewable resources are either naturally reproduced at a sustainable rate or they can be produced in agriculture at a rate equivalent to the demand or need. For example, corn can be used for ethanol fuel and to produce corn oil. Corn is a renewable resource.
Bioplastics are a type of plastic made from renewable, biological materials like starches, cellulose, oils or proteins. They generally contain little to no petroleum and therefore are usually biodegradable. When bioplastics are exposed to the environment (sunlight, heat, water, microorganisms) they breakdown into non-toxic compounds like carbon dioxide and water. Additionally, unlike petroleum-based plastics, bioplastics are made from renewable resources. These resources are typically agricultural byproducts, like cornstarch and potato starch, tapioca starch and casein (milk protein).
Biodegradable: refers to material capable of breaking down into harmless products through the action of living organisms or natural processes
Byproducts: in agriculture refers to secondary products created from a crop. For example, corn starch is a byproduct of corn
Make Your Own BioPlastics
- Plant based oils (Corn Oil, Sesame Oil, Vegetable Oil)
- Food coloring
- Measuring spoons
- Eyedropper (optional)
- 1 Ziploc bag per student
- Access to a microwave oven
- Place the following ingredients in a plastic bag: 1 tablespoon of cornstarch, 2 drops of oil, 1 tablespoon of water, and 2 drops of food coloring.
- Seal the bag and gently mix the cornstarch mixture by rubbing the outside of the bag with your fingers until combined.
- Open the bag slightly, making sure it can vent. Place the bag in a microwave oven on high for 20-25 seconds.
- Carefully remove the bag from the microwave and let it cool for a few minutes. While it is still warm, students can try to form their plastic into a ball. Observe what it does.
- Ask them to describe their plastic; did it turn out differently than others? Does the type of oil you used affect the bioplastic? Have the students name three things they could make with bioplastic.
Take it Further
I’m committed to sharing activities and resources for teaching science in your homeschool. I believe it is helpful to see that science isn’t scary and it doesn’t require special curriculum. Here are a few resources that you can use to further your study of plastics and renewable vs. nonrenewable resources.
Watch the 3-minute How Stuff Works video clip about Corn Plastic.
In this hands-on, inquiry based Plastics Lab Activity, students investigate whether all plastics the same? How are they different?
Polymers Are Cool ~ Experiment with different polymers, large molecules composed of many repeated subunits, with these 3 great recipes.
As plastics are not biodegradable, learn how you can make a difference in encouraging others to reduce our use of plastics. The volunteers at Washed Ashore inspired us to create a Bottle Cap Mural to help spread the word of the harm done to our oceans by plastics.