Transcript Making Plastic - South Dakota School of Mines and Technology

Making Plastic from Protein
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A plastic is made from casein, the
protein in milk.
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Purpose
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Using common household items such as
milk and vinegar a complex polymer
such as plastic can be made.
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Demonstration
Milk was heated to almost boiling and
vinegar was added.
 Rubbery material(casein) was drawn off
and pressed into mold.
 The casein hardened over time and
formed a plastic.
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Concepts
 1.
Biological Molecules
 2. Denaturation
 3. Polymers
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1. Biological Molecules
(Carbohydrates, Fats and Proteins)
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Carbohydrates consist of carbon, hydrogen and oxygen.
– often sugars and starches
Milk sugar - Lactose
Fats consist of carbon, hydrogen and oxygen.
– built up in plants and animals
Milk fats - stearic acid - oleic acid
Proteins contain carbon, hydrogen, oxygen and nitrogen.
– occur in all living matter
– building blocks of life
Milk protein - casein - albumin
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2. Denaturation
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Proteins have definite shapes and structures
Altered shape  Denaturation  Loss of biological activity
High temperature
– Cooking an egg
Strong acids and bases
– Vinegar + Milk
The vinegar caused the protein (casein) in the milk to coagulate.
The casein changed shape from a liquid to a rubbery solid.
Altered shape  Denaturation  Loss of biological activity
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3. Polymers
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Some polymers occur naturally, but the vast majority of polymers
are man made.
Polymers are long chains of the same small molecule repeated
over and over.
A=B  A-B-A-B-A-B-A-B-A-B...........
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These long chains get tangled up like spaghetti.
It is the way they get tangled up that gives plastic its strength.
– If the strands are held rigidly together, the result is a stiff
plastic like casein.
 ornaments
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Conclusion
The casein was denatured by the
vinegar.
 The casein was extracted from the milk.
 The rubbery casein’s protein molecules
bound tightly together.
 A hard plastic was made.
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Comments
There are now thousands of
plastics and polymers and new
ones are being made for
everything from sports clothes
to spacecraft.
Plastics are so strong, light
and unaffected by corrosion
that they are used in virtually
everything from light aircraft
to artificial hips.
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