Polymers, Composites and Other Materials
Metals are just the start. Explore polymers, composites, ceramics and timbers, learn the key difference between a thermoplastic and a thermoset, and choose the right material for the job.
Get the method right under pressure
Free interactive practice on the steps that lose marks under exam pressure.
Start revising freeWhat you'll cover
Choosing the right material
An engineer chooses a material to match the job. Metals are one family, but there are many others. Polymers can be moulded into complex shapes, composites combine materials for the best of both, and ceramics and timbers each bring their own properties. Pick well and the product is strong, light, cheap or long-lasting, whatever the design needs.
Four material words
Beyond metals, four ideas cover most engineering materials. Learn them.
Thermoplastic or thermoset?
This is the classic exam trap. The difference is whether heat can reshape the plastic a second time.
Reshape it again
Acrylic can be heated and reshaped many times over. What type of material is it?
- A thermoplastic
- A thermoset
- A composite
- A ceramic
Match the material
- Acrylic
- Epoxy resin
- CFRP
- Porcelain
- A thermoplastic used for signs and displays, can be reshaped
- A thermoset resin used as a strong glue, sets permanently
- A composite of carbon fibres in resin, very strong and light
- A hard, brittle ceramic that resists heat and insulates
Complete the materials
A _____ plastic can be heated and reshaped many times, but a _____ plastic sets permanently and cannot be remoulded. A _____ combines two or more materials for better properties. Carbon fibre reinforced polymer is known as _____. A hard, brittle material like porcelain is a _____.
What is a composite?
A composite is made by combining two or more materials so the result beats either one alone. Carbon fibre reinforced polymer, or CFRP, sets carbon fibres in resin to be stiff and light. Glass reinforced plastic, or GRP, does the same with glass fibres. Reinforced concrete adds steel bars to concrete so it can resist bending as well as squashing.
Match the composite
- CFRP
- GRP
- Plywood
- Reinforced concrete
- Carbon fibres set in resin, stiff and very light
- Glass fibres in resin, light and corrosion-resistant
- Thin wood veneers glued with the grain at right angles
- Concrete with steel bars added to resist bending
Pick the composites
Which of these are composite materials? Choose all that apply.
- Carbon fibre reinforced polymer
- Plywood
- Reinforced concrete
- Aluminium
- Acrylic
True about thermosets
Tap the two statements that are true about thermosetting plastics.
- A thermoset sets hard and cannot be remoulded.
- Epoxy resin is a thermoset.
- A thermoset can be reheated and reshaped many times.
- Polystyrene is a thermoset.
Hardwood or softwood?
Pine comes from a fast-growing coniferous tree. What type of timber is it?
- A softwood
- A hardwood
- A composite
- A thermoset
Choosing a material
Put the steps of choosing a material for a part in the correct order.
- Identify what the part must do and the properties it needs
- List the candidate materials that could work
- Compare their properties against the requirements
- Consider the cost, supply and availability
- Choose the material that best fits the design
Match the material to the job
Choose the best material for each job.
- A racing bike frame must be very strong but as light as possible.
- A part must resist high heat and insulate against electricity.
- A moulded casing should be cheap to shape and easy to recycle.
Explain the difference
Explain the difference between a thermoplastic and a thermoset. Give an example of each and say when an engineer might choose each one.
- Say what happens to each type when it is heated
- Give one example of a thermoplastic and one of a thermoset
- Say why the difference matters when choosing a material