3.3 Plastics
Write the learning objectives into your notebooks:
On your mini white board…
Can you name any plastics??
What do you already know about plastic?
What is plastic made from?
Oil is used widely for the production of plastics
as it is composed of carbon and hydrogen.
This is why oil is called a hydrocarbon. Oil and
natural gas are the most important raw
materials for plastics manufacture.
What are plastics?
Plastics are versatile and flexible materials, and they may be very
suitable for use in your project. This may be an area of materials
research that you need to investigate in detail.
All plastics are based on polymers, and they are created by bonding
molecules together.
The terms monomer and polymer are very important in the plastics
industry.
A monomer is a relatively small molecule that can chemically bond to
other monomers, forming a polymer. Remember, all plastics are
polymers.
Thermosetting plastics
Once 'set' these plastics cannot be reheated to soften,
shape and mould.
The molecules of these plastics are cross linked in three
dimensions, and this is why they cannot be reshaped or recycled.
The bond between the molecules is very strong.
Thermosetting plastics
Name always end in resin or formaldehyde
• The one you are probably most familiar with is epoxy resin, which we use as
an adhesive for joining plastics together
• Epoxy resin in larger amounts can be used for varnishing and sealing and
also creating aesthetically pleasing furniture
• Polyester resins can also be used to cast boat hulls
• Melamine formaldehyde is used for electrical plugs and switches
Thermoforming plastics
These plastics can be re-heated and therefore shaped in
various ways.
They become mouldable after reheating as they do not undergo
significant chemical change.
Reheating and shaping can be repeated. The bond between the
molecules is weak and become weaker when reheated,
allowing reshaping.
Thermoplastics tend to be composed of 'long chain
monomers'. These types of plastics can be recycled.
Thermosetting plastics
Material
name
Description
Application
Find 5 thermosetting
plastics, write a
description and an
application. Use the e
textbook unit 3.3 and the
internet to help you.
Produce a table like this
in your books…I want
you to write it out so
there’s no temptation to
copy and paste!! 
Thermo plastics
Material
name
Description
Application
Find 5 thermoplastics,
write a description and
an application. Use the e
textbook unit 3.3 and the
internet.
Produce a table like this
in your books…I want
you to write it out so
there’s no temptation to
copy and paste!! 
Plastic numbers for recycling
These symbols help
companies identify
plastics and sort
them into the
correct types for
recycling
Find between 5-10
plastic items, do they
have a recycling symbol
and code/number?
Select a product and
evaluate the
recyclability of the
product, including how
easy it is to disassemble,
is there more than more
material used?
What are the disadvantages of
plastic?
What are the disadvantages of
plastic?
Plastic takes tons of years to decompose. Some plastics may even take 400 years
or more to completely decompose.
Producing plastic is done using a variety of toxic chemicals and colours. This can
cause harm to the environment.
The recycling process for plastic can be very expensive.
Heavy use of plastic increases the pollution in the environment. Since most of the
waste lands up in the oceans, it is harmful to aquatic life as well.
It is also said eating from plastic boxes could be dangerous
The burning of plastic releases toxic materials into the environment.
Plastic degrades the quality of the soil.
If it’s bad for the environment,
why do we still use plastic?
If it’s bad for the environment,
why do we still use plastic?
Plastic is durable
Plastic is versatile
Plastic protects from contaminants and the elements
Plastic reduces food waste by preserving food and increasing its
shelf life
Plastic is readily available
Plastic is cost effective
Plastic is corrosion resistant and waterproof
Plastic is available in different colours, thicknesses and strengths
Knowledge check
1. Explain the advantages of plastic when designing and
making everyday products (5)
2. Explain the disadvantages of plastics when designing
and making everyday products (5)
3. Explain why plastics are commonly used in everyday
products (3)
Write the key terms into your books. Test each other
and see if you can define these terms without
looking