Polymers Flashcards
What is plastic always?
A polymer.
In plastics what holds the atoms together?
Strong covalent bonds in long chains.
What determines the properties a plastic?
The bonds between the different molecule chains.
What are the two different types of plastics?
- Plastics with weak intermolecular forces.
- Plastics with strong intermolecular forces.
What is an example of a plastic with weak intermolecular forces?
Thermosoftening polymer.
What are the properties of thermosoftening polymers?
- Arranged with individual tangled chains of polymers, held together by weak intermolecular forces.
- The tangled chains are free to slide over each other.
- It is easy to melt.
- When it cools it hardens into a new shape.
Why are thermosoftening polymers easy to melt?
As the forces between the chains are really easy to overcome.
What does thermosoftening polymers hardening into a new shape when it cools mean?
That you can melt and remould these plastics as many times as you want.
What is an example of a plastic with strong intermolecular forces?
Thermoetting polymers.
What are the properties of thermosetting polymers?
- Arranged with crosslinks between the polymer chains that hold them together in a solid structure.
- This means that they have strong intermolecular forces between the chains.
- The polymer doesn’t soften when its heated.
- They are strong, hard and rigid.
How are the properties of a polymer affected?
With the way you make them.
What are the two types of polythene?
- Low density (LD) polythene.
- High density (HD) polythene.
How is Low density polythene made?
By heating ethene to about 200’c under pressure.
What are the properties of low density polythene?
It is flexible.
What is low density polythene used for?
Bags and bottles.
How is high density polythene made?
At a lower temperature and a pressure (with a catalyst).
What are the properties of high density polythene?
It is more rigid.
What is high density polythene used for?
Water tanks and drainpipes.
What does the use of a plastic depend on?
Its properties.
