Polymerisation (T5 Flashcards
What is ‘addition polymerisation’?
Under the right conditions, molecules containing carbon-carbon double bonds can join together to produce very long chains.
Pat of the double bond is broken and the electrons in it are used to join neighbouring molecules.
This is called ‘addition polymerisation’
What is polymerisation?
Give a common example.
Polymerisation is the joining up of lots of little molecules (monomers) to make one big molecule (the polymer)
Eg: lots of ethene molecule often join together to make poly(ethene), usually called polythene.
Heat, high pressure and an initiator is used to get the process of polymerisation started. What is an initiator?
It is used to get the process started but is NOT a catalyst as it gets used up in the reaction.
What is produced in the polymerisation of ethene?
Poly(ethene)
Usually called polythene
The chain length can vary from between 4000-40000 carbon atoms
What are the two types of poly(ethene) / polythene and what are its uses?
- low density poly(ethene) (LDPE)
Mainly used as a thin film to make polythene bags. It is very flexible and not that strong. - high density poly(ethene) (HDPE)
Used where greater strength and rigidity is needed like plastic milk bottles.
What is produced in the polymerisation of propene?
Poly(propene)
Name some uses of poly(propene)..
Used to make ropes and crates etc.
If an item has a recycling mark ‘PP’ it is made of poly(propene).
What is chloroethene and what do you get when it is polymerised?
It is an ethene molecule where one of the hydrogen atoms is replaced by a chlorine atom.
When polymerised you get poly(chloroethene) - usually known by its old name polyvinyl chloride (PVC)
What are some used of poly(chloroethene) / polyvinyl chloride (PVC)?
Strong and rigid so used for drainpipes or replacement windows.
Can be made flexible by adding plasticisers, making it good for sheet floor coverings and even clothing.
Electrical insulation.
How do you work out the monomer from a given addition polymer?
Find the repeating unit.
Put back the carbon carbon double bond.
