Good Science Victorian Curriculum Year 7

INVESTIGATIONS
Investigation 7.3B
Making bioplastic
KEY SKILL
IDENTIFYING AND MANAGING
RELEVANT RISKS
Brainstorm with a partner to identify three possible
hazards or risks that may be involved in this
investigation. Suggest one way that each hazard
or risk could be reduced.
AIM
To investigate how plastic is made using cornflour
MATERIALS
• cornflour
• vinegar
• vegetable glycerine
• water
• aluminium foil
• 250 mL beaker
• hotplate
• stirring rod
• tablespoon
• teaspoon
• spatula
• selection of commercially produced plastics
METHOD
1 Copy the results table into your notebook, adding a
title and rows as needed.
2 Set up the hotplate.
3 Add 1 tablespoon of cornflour, 1 teaspoon each of
vinegar and glycerine and 4 tablespoons of water to
the beaker. Stir with the stirring rod until combined.
30 min
Level 2
4 Place the beaker onto the hotplate and switch on
to low heat.
5 Continue stirring the solution until it thickens and
starts to become translucent. This will not take long!
6 Carefully pour the plastic onto a sheet of aluminium
foil and spread using the spatula.
7 Allow the plastic to completely cool. This will take
several hours. If you wish to form the plastic into
another shape, leave it spread out on the foil to cool
for approximately 1 hour. It can then be carefully
moulded into shape before it sets completely.
8 Compare the flexibility of your plastic with the
samples provided. Record your observations.
9 Take a piece of your plastic and add it to water.
Record your observations.
10 Take a piece of your plastic and heat it in a beaker
over the hotplate. Record your observations.
QUESTIONS
1 Describe the properties of the bioplastic you created.
2 Compare these properties to the properties of some
conventional plastics.
3 What happened when you added your bioplastic
to water?
4 What happened when you reheated your bioplastic?
5 Explain the benefit of using a bioplastic, such as the
one you have made, compared to a conventional
plastic.
CONCLUSION
Copy and complete:
‘The results show that: (respond to the aim)’.
RESULTS
TABLE I7.3B
Material Flexibility Behaviour
in water
Behaviour
when heated
TAKE CAUTION USING THE HOTPLATE.
IF YOU BURN YOURSELF, TELL YOUR
TEACHER IMMEDIATELY AND PLACE THE
BURNT AREA UNDER COLD RUNNING
WATER FOR 20 MINUTES.
172 GOOD SCIENCE VICTORIAN CURRICULUM 7