2a.3 - New materials and Polymers Flashcards
Why do smart materials have weird properties?
They behave differently depending on the condtions
What is nitinol?
A memory shape alloy
How does nitinol work? (2)
- When it’s cool you can bend it but if you bend it too far it will stay like that.
- If it is heated above a certain temperature it goes back to a remembered shape
How big are nanoparticles?
1 - 100 nanometres across
What is a fullerene? (3)
- Molecules of carbon, shaped like hollow balls or closed tubes
- They are arranged in hexagonal rings
- Different fullerenes contain different numbers of carbon atoms
What can fullerenes be joined together to make?
Nanotubes
What is a nanotube?
Fullerenes joined together
How strong are Carbon nanotubes?
Very Strong
What can nanomaterials be used to make? (4)
- Catalysts - huge surface are to volume ratio
- Sensors - To detect one type of molecule
- Building materials - Stronger and lighter
- New cosmetics - Don’t leave white marks
What are weak polymers called?
Thermosoftening polymers
What are the features of a thermosoftening polymer? (4)
- No cross-links
- Easily melted
- When cools hardens into a new shape
- Can be melted and remoulded many times
What are strong polymers called?
Thermosetting polymers
What are the features of thermosetting polymers? (4)
- Cross-links
- Solid structure
- Doesn’t soften when heated
- Strong,hard and ridgid
What will affect the properties of polymers?
Starting materials and reacting conditions
How is low density polyethene made?
Heating ethene to about 200C under high pressure
How is high density polyethene made?
Made with a lower temperature and pressure (with a catalyst)
