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Slide 1

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Polymers
Polymers and plastics were first
discovered/manufactured in the 1930's.
Some polymers, such as bakelite were
widely used as electrical insulators, e.g.
in car electrics, such as battery casings.
In the early 1930's, PVC was used in the
manufacture of car shock absorber seals.
The range of polymers available today
include many more, such as polythene,
polypropene, and polystyrene.
They are commonly called plastics and
can be turned into a whole range of
useful products.…read more

Slide 2

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Using Alkenes to Make Polymers
Polymers are very large molecules formed by a combination of
many identical smaller molecules (the monomer).
Example:
Monomers called alkenes are widely employed in the production
of polymers. They contain a double bond which is `opened up' so
the alkene molecules repeatedly combine to form a long polymer
chain.
heat, pressure
Monomer Polymer
catalyst (initiator)…read more

Slide 3

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Polythene
Polythene is short for poly(ethene). The prefix `poly' means many,
so `polyethene' literally means `many ethenes' joined together.
Polythene is made by heating ethene at high pressure along with
special substances called `initiators'. The word initiate means `to
start' and these initiators start the process of opening up the
double bonds in the ethene molecules.
Once this has happened, the carbon atoms from separate ethene
molecules can join together making polythene.
Initiators function in a similar way to catalysts in this reaction.
heat, pressure
catalyst (initiator)
Ethene (monomer) Polythene (polymer)…read more

Slide 4

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Polythene
Discovered in 1933, polythene consists of very long chains of up to
5000 carbon atoms. When we write a chemical formula that has
repeating units, we use the letter `n' to show the unit is multiplied.
In polythene `n' is usually 500 - 2500.
high temp, high pressure
+ initiator
As monomers are continually being added to the chain, this kind of
polymerisation reaction is also known as addition polymerisation.
Polythene can be put to a wide range of uses and owes its
versatility to its chemical properties.…read more

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