Did you know there is more than one way to make plastic? One fun way to make plastic uses just two ingredients: milk and vinegar. When vinegar is added to milk, curds are formed, which creates polymer chains in the casein proteins in milk. When this hardens, it looks and feels just like plastic! Kids will be fascinated by what they can make using just milk and milk plastic. 

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Milk Plastic Robots: Science for Kids

Have leftover milk that’s about to go bad? Transform into plastic for science! You’ll need a few things:

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

  • Milk
  • Vinegar
  • Food coloring (we used red)
  • Paper towels
  • Small plate
  • Robot accessories (if you want to make a robot)

Pour one cup of milk into a bowl. If you want to color it, add the dye now.

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Add two tablespoons of vinegar. Within seconds, the milk will curdle.

Remove the curds and place them on a paper towel.

Gently squeeze out as much water as you can. Don’t squeeze too hard or the paper towel will explode.

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Once the liquid is removed, shape the plastic into any shape you like. We did a square to make a robot.

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Let the plastic dry out for 48 hours.

Add robot accessories. We gave our robot googly eyes, pipe cleaner antennas, and drew on a mouth with a permanent marker.

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Isn’t science the coolest?

Milk Plastic Science Experiment Explained

Transform ordinary milk into plastic with just one ingredient! Mold the resulting plastic into anything, or make adorable robots!

Milk contains a protein called casein. This protein has polymer chains that can be molded and collected. When vinegar is added to milk, the casein protein molecules move from monomers to polymer chains, which forms it into a solid with properties similar to glue slime. However, when the mixture dries, it hardens, leaving a material that looks and feels like plastic. If you don’t want to mold the plastic, you can also use cookie cutters to make shapes instead.

 

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