Download TEXTILES NANO EXPERIMENT 1 MAKING AND INVESTIGATING CASEIN PLASTIC

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NANO
EXPERIMENT 1
MAKING AND INVESTIGATING CASEIN PLASTIC
Experiment 1: Making and Investigating Casein Plastic
Part A: Making Casein Plastic
Introduction
Casein is a phosphoprotein found in fresh milk. It is also used in the manufacture of
adhesives, binders, protective coatings, plastics (e.g. knife handles and knitting needles),
fabrics, food additives and many other products. Bodybuilders use powdered casein as a
slow-digesting source of amino acids.
Aim
To make casein plastic.
Materials

full cream milk

vinegar

Bunsen burner

heat-proof mat

tripod

gauze mat

100mL measuring cylinder

two 250mL beakers

thermometer

stirring rod

elastic band

coarse cloth for straining

paper towel

assorted moulds (bottle tops, chocolate trays)

fine sandpaper

tongs
Method:
1.
Place 100ml of milk in a 250mL beaker and heat gently to 50°C. Do not overheat.
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Experiment 1: Making and Investigating Casein Plastic
2.
Add 10mL vinegar and stir with a stirring rod. The milk should curdle forming white
lumps of curds (casein) and a yellowish liquid called whey.
3.
Place the coarse cloth in a funnel and strain the curds and whey into another
beaker.
4.
Squeeze the cloth to remove as much liquid as you can
5.
Empty the curd onto paper towel and pat dry.
6.
Press casein into a mould and leave to dry in the sun.
7.
After 1 to 2 days, remove from mould and polish with sandpaper.
Discussion:
1.
Describe your casein plastic.
2.
Casein is a protein. What is a protein? Are there any other proteins found in milk?
3.
When the casein was allowed to dry it forms a polymer. What is a polymer? Give at
least 5 examples of other polymers (2 must be biological molecules).
4.
Research the toothpaste product ‘Recaldent’. How do Nanotechnologists use casein
to create the active ingredient in this product?
Part B: Investigating the Properties of Plastics
Aim
To test a variety of plastics and look at their properties.
Introduction
Plastics are made up of polymers, which are very large molecules made from repeating
units called monomers. Chemists describe polymers according to their plastic properties.
Polymers can be either thermoplastic or thermosetting polymers. Thermoplastic polymers
are soft, stretchy and they soften and melt when heated. Thermosetting polymers are
hard and rigid. They char when heated leaving a black carbon residue.
Materials and Equipment

Labelled samples of plastics (casein - prepared in Part A, polythene, polystyrene,
PVC, Perspex, nylon,

fireproof mat
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Experiment 1: Making and Investigating Casein Plastic

scissors

turpentine

nail polish remover

dilute HCl

250mL beaker

Tongs

Bunsen burner in fume hood (teacher demonstration only).
Method
1.
Observe and record the results of the flame test carried out by your teacher.
2.
Carry out each remaining test as demonstrated by your teacher
Discussion
1.
What is the difference between thermoplastic and thermosetting plastic?
2.
Classify your plastics as thermoplastic or thermosetting polymers.
3.
Do any plastics sink in water? What does this indicate about their density?
4.
Why must the burning of plastics be done in the fume hood? What does PVC
produce when burnt?
Conclusion
Briefly summarise Part A and Part B and write some concluding comments.
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Experiment 1: Making and Investigating Casein Plastic
Results:
Casein
Polythene
Polystyren
e
PVC
Perspex
Nylon
Appearance
Transparent,
translucent,
opaque?
Flexibility
Bendable or
stiff?
Feel
Does it feel
waxy?
Ease of
scratching
Fingernail or
scissors?
Ease of
cutting
Does it cut
with scissors?
Description
of cut edges
Smooth or
jagged?
Density
Does it float in
water + 2
drops
detergent?
Dissolvability
Does it
dissolve in
turpentine,
HCl, nail
polish?
Effect of
flame
Does it melt or
char?
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Experiment 1: Making and Investigating Casein Plastic
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