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
