Polymers- Casein Plastic
Polymers are chemicals that are widely
used in society. Some polymers are
naturally occurring such as silk and cotton,
while others are man-made or synthetic.
Polymers are made up of small repeating
units called monomers chemically joined up
together to form a chain. It is a bit like linking
individual paperclips together to form a long string.
Aim To……………………………………….
Materials
150 mL milk (full cream)
25ml measuring cylinder
250 mL beaker
Glass thermometer
Chux Cloth and Sieve
Bunsen Burner
Gauze
15mL vinegar
100 ml measuring cylinder
500 ml beaker
Stirring rod
Paper towels
Tripod
Heat Proof Mat
Method
1. Set up Bunsen burner, tripod, gauze, heat proof mat
2. Place 150mL of milk in the 250mL beaker with one (1) drop of dye
3. Add 125 mls water to the 500ml beaker and place on the gauze (the
Water Bath)
4. Place the beaker with the milk inside the water bath
5. Place the thermometer in the milk
6. Heat the water bath until the milk reaches 50-55 °C
7. Use a paper towel to remove the beaker of milk from the water bath
8. Stir 15 ml vinegar into the holt milk.
9. Place the CHUX cloth at bottom of sieve place pour the coagulated
milk though the cloth in the sink
10. Twist and squeeze the CHUX to remove as much liquid as you can
11. Lay the CHUX cloth on the bench scrape any excess with the flat end
of the stirring rod
12. Gently knead the polymer together, place on a dry paper towel, gently
roll back and forwards to remove excess liquid. Repeat with a dry part
of the towel until it stays together without falling apart
13. Press firmly into the mould tray.
Questions for you to do in your Science Book
1. Draw a scientific diagram of your apparatus
2. Write a risk assessment
Discussion and conclusion (for homework)
3. Why was the water bath used to heat the milk?
4. What is the monomer in the casein plastic
5. What caused the monomer to form long chains to form the polymer
casein?
6. Use page 363 of your text book
• name 3 synthetic polymers
• name 4 natural polymers
7. Write a conclusion for your experiment
Extension
8. Note down at least 3 facts you find interesting about Casein from your
reading (the history, its uses, the chemistry etc.).
9. Write the chemical formula for Casein
Resources:
https://www.artistsnetwork.com/art-mediums/oil-painting/krieger-casein/
https://www.chemistryworld.com/podcasts/casein/3007625.article