Polymers Flashcards
What do forces between molecules determine?
The properties of plastics.
What do strong covalent bonds hold?
The atoms together in long chains.
Describe weak forces?
Individual tangled chains of polymers.
Held together by weak inermolecular forces.
In weak forces individual tangled chains are free to do what?
Slide over each other.
Name a weak polymer?
Thermosoftening polymer.
Thermosoftening don’t have what?
Cross-linking between chains.
In thermosoftening the chains are really easy to overcome this means?
Its really easy to melt the plastic.
When the thermosoftening cools what happens?
Polymer hardens into new shape.
Describe strong forces?
Some plastics have stronger intermoleular forces between polymer chains called crosslinks.
What do crosslinks do?
Hold the chains firmly together.
In solid structures.
Name a hard polymer?
Thermosetting polymers.
Thermosetting polymers have what?
Crosslinks
Thermosetting polymers don’t do what?
Soften when heated.
Describe thermosetting polymers in 3 word.
Strong.
Hard.
Rigid.
How you make a polymer affects its…
Properties.
What 2 things affect the properties of a polymer?
Starting materials.
Reaction conditions.
What two types of polythene can be made using different conditions?
Low density.
High density.
How is low density polythene made?
Heating ethene to about 200dc under high pressure.
Characteristics of low density polythene?
Flexible.
Used for bags and bottles.
How is high density polythene made?
Lower temp and pressure (with a catalyst)
Characteristics of high polythene?
Rigid.
Used for water tanks and drainpipes.
The use of the plastic depends on what?
Its properties.
A disposable hot drink would need what properties?
Low cost - disposable.
High melting point - hot drinks.
Clothing needs what properties?
Flexible.
Made into fibres - clothing usually woven.
