Science U
Plastic Milk
Season 4 Episode 3 | 2mVideo has Closed Captions
Can you turn milk into plastic?
Can you turn milk into plastic? Milk is full of a protein called casein. When you add an acid like vinegar, it lowers the milk’s pH and causes the casein molecules to unfold and link together into long, repeating chains — a process called polymerization. Those chains clump into solid curds you can lift out, dry, and knead into a moldable, all-natural plastic called casein plastic.
Problems playing video? | Closed Captioning Feedback
Problems playing video? | Closed Captioning Feedback
Science U is a local public television program presented by WPSU
Science U
Plastic Milk
Season 4 Episode 3 | 2mVideo has Closed Captions
Can you turn milk into plastic? Milk is full of a protein called casein. When you add an acid like vinegar, it lowers the milk’s pH and causes the casein molecules to unfold and link together into long, repeating chains — a process called polymerization. Those chains clump into solid curds you can lift out, dry, and knead into a moldable, all-natural plastic called casein plastic.
Problems playing video? | Closed Captioning Feedback
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Learn Moreabout PBS online sponsorshipCAMP INSTRUCTOR: When I say Science, you say U. Science.
CHILDREN: U!
CAMP INSTRUCTOR: Science.
CHILDREN: U!
NARRATOR: Plastic is everywhere nowadays, and just about all of it is made from fossil fuels.
CHILD: But guess how we used to make it.
[cows mooing] NARRATOR: For a long time, starting in the 1800s, people made what's known as casein plastic out of milk.
They made everything, from coat buttons to hair combs to fountain pens to jewelry, specifically from the casein protein found in milk.
Can you turn milk into plastic?
Yeah!
You can make your own!
NARRATOR: Today, campers are making their own casein plastic using hot milk and vinegar.
We are going to be making some plastic today out of milk.
We got a big pot of milk sitting up here.
CHILD: First, our camp instructor heats up milk for us to make our own plastic.
We each get 1 cup of milk.
We're going to take the protein that's in here, and you are going to get it to come out of the liquid.
NARRATOR: When you add about 4 teaspoons of vinegar, it denatures the milk.
CHILD: It's forming clumps!
NARRATOR: It's a chemical process called polymerization.
Small molecules of casein protein combine to form larger molecules called polymers.
The campers slowly, gently stir the mixture for a few seconds.
CHILD: We put a piece of cheesecloth over an empty cup and pour the milk mixture through the cheesecloth.
INSTRUCTOR: You're making a strainer.
CHILD: Using a spoon, we gently push the clumps against the side of the cloth and try to squeeze out any excess liquid.
Squishing the clumps between paper towels gets out more of the liquid.
NARRATOR: Then you gather up the plastic into a ball and knead it well.
You can make it fancy by adding food coloring or glitter and start to create your own shapes.
CHILD: I'm making friendship necklaces out of the plastic.
Can you make your own plastic?
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