Materials & manufacture · Higher
Plastics, composites & elastomers
10 cards · 6 quiz · 2 exam
Design & Manufacture · Higher · mrkellydt.co.uk
What you're learning in this topic
Learning intention WALT
We are learning about plastics, composites & elastomers, specifically to understand:
- the difference between thermoplastics and thermosetting plastics
- the properties and uses of ABS, acrylic, polypropylene and polystyrene
- the properties and uses of urea formaldehyde and melamine formaldehyde
- nylon, polythene and PVC
- elastomers and composites (GRP, carbon fibre)
- methods to identify materials, including what each result tells you
- how materials influence design and manufacture
- developments in new materials and their impact
Success criteria WILF
- I can explain the difference between thermoplastics and thermosetting plastics
- I can describe the properties and uses of ABS, acrylic, polypropylene and polystyrene
- I can describe the properties and uses of urea formaldehyde and melamine formaldehyde
- I can describe nylon, polythene and PVC
- I can describe elastomers and composites (GRP, carbon fibre)
- I can describe methods to identify materials, including what each result tells you
- I can explain how materials influence design and manufacture
- I can describe developments in new materials and their impact
Two groups of plastic
- Thermoplastics: soften when heated and can be reshaped repeatedly ("plastic memory"). Recyclable.
- Thermosetting plastics: set permanently when first heated and shaped; can't be softened again. Heat resistant.
Plastics are lightweight, corrosion resistant, insulate heat and electricity, come in any colour, and suit mass production.
Plastics you need to know
| Plastic | Properties | Uses |
|---|---|---|
| ABS (thermo) | Tough, impact and scratch resistant, light, high surface finish | Toys (Lego), phone cases, helmets, 3D printing |
| Acrylic (thermo) | Rigid, clear or coloured, polishes well, scratches, brittle | Glass substitute, light covers, signs |
| Polypropylene (thermo) | Tough, chemical resistant, resists fatigue (living hinges), light | Bottle caps, crates, chairs, medical equipment, kayaks |
| Polystyrene (thermo) | Stiff, light, buoyant, insulates | Food packaging, disposable cups |
| Nylon (H) | Tough, self-lubricating, wear resistant | Gears, bearings, bristles |
| Polythene (H) | HDPE rigid and tough; LDPE soft and flexible | Buckets, bottles; carrier bags, film |
| PVC (H) | uPVC rigid, weatherproof; plasticised PVC flexible, insulates | Window frames, pipes; cable insulation, hoses |
| Urea formaldehyde (set) | Rigid, hard, heat resistant, electrical insulator | Plugs, sockets, switches |
| Melamine formaldehyde (set) | Hard, scratch and heat resistant, food safe | Worktop laminates, picnic plates |
Composites and elastomers HIGHER
- Composite: two or more materials combined (a matrix, usually resin, holding a reinforcer such as fibres) to give improved properties.
- GRP (glass-reinforced plastic): light, strong, easily formed. Boat hulls, car panels, surfboards.
- Carbon-fibre plastic: very high stiffness and strength-to-weight, but expensive. Bikes, F1, aerospace.
- Elastomers (rubber, silicone): flexible, non-slip, water and impact resistant. Seals, grips, wheels, utensils.
- Identifying materials: look and feel, recycling symbols and labels, tests (float, magnet, flexibility), comparison with known samples.
- New materials (e.g. bio-composites, graphene) change what products can do, how they're made and their environmental impact.
Key terms
| Thermoplastic | Softens when heated; can be reshaped and recycled. |
|---|---|
| Thermosetting plastic | Sets permanently once heated; heat resistant; cannot be reshaped. |
| ABS | Tough, impact resistant, high gloss. Toys, casings, helmets. |
| Acrylic | Rigid, clear, polishes well. Glass substitute, signs. |
| Polypropylene | Fatigue resistant (living hinges), chemical resistant. Caps, crates. |
| Urea formaldehyde | Thermoset electrical insulator. Plugs and sockets. |
| Melamine formaldehyde | Hard, scratch and heat resistant. Laminates, picnic ware. |
| Nylon | Self-lubricating and wear resistant. Gears, bearings. |
| Composite | Matrix + reinforcer combined for better properties, e.g. GRP, carbon fibre. |
| Elastomer | Flexible, grippy material like rubber or silicone. |
Quick check
1. Which plastic is used for electrical plugs?
- Polystyrene
- Polypropylene
- Acrylic
- Urea formaldehyde
Show answer
D: Urea formaldehyde. Thermoset that insulates and resists heat.
2. A flip-top shampoo lid with a living hinge is made from…
- Polypropylene
- Acrylic
- Melamine
- Polystyrene
Show answer
A: Polypropylene. Polypropylene resists fatigue.
3. Which can be reheated and reshaped?
- Melamine formaldehyde
- Acrylic
- Urea formaldehyde
- Bakelite
Show answer
B: Acrylic. Acrylic is a thermoplastic.
4. Which is the best substitute for glass in a light cover?
- ABS
- MDF
- Acrylic
- Polystyrene foam
Show answer
C: Acrylic. Transparent and shatter resistant compared to glass.
5. Why is nylon used for small gears?
- It is transparent, so the teeth can be checked
- It is the cheapest plastic to injection mould
- It is a thermoset, so it can't soften with heat
- It is self-lubricating and wear resistant
Show answer
D: It is self-lubricating and wear resistant. Low friction and hard wearing.
6. Carbon-fibre plastic is chosen for racing bikes mainly because of its…
- High strength-to-weight ratio
- Low cost compared with steel
- Flexibility to absorb bumps
- Transparency, so the frame looks clean
Show answer
A: High strength-to-weight ratio. Very strong and stiff but light.
Exam-style questions
1. Describe two advantages of plastics over wood and metal for a product such as a kettle. (2 marks)
Show marking guidance
- Can be moulded into complex forms in one piece (1)
- Electrical/heat insulator so safe to hold (1)
- Range of colours with no finishing needed (1)
- Water/corrosion resistant (1)
2. Describe two methods used to identify the materials in commercially manufactured products. (2 marks)
Show marking guidance
- Identification symbols/recycling codes on the part (1)
- Tests: magnet test, float test, flexibility (1)
- Look and feel / comparison with known samples (1)
Printable worksheet
An I do, we do, you do worksheet for this topic, with a separate answer sheet.