Nylon, a thermoplastic,
is one of the most important synthetic polymers. About four million tonnes per year
is produced worldwide. Much of the nylon is made into fibres for
ropes, clothing and for reinforcing tyres.
Nylon is made from two monomers.
Adipic acid, more properly called hexanedioic acid,
has a chain of six carbon atoms. Just concentrate on the ends of the chain
Hexamethylene diamine,
more properly called 1,6-diaminohexane, also has a chain of six carbon atoms.
Again, just concentrate on the ends of the chain.
When the two monomers react together
a molecule of water is produced as each link is formed.
These two monomers continue to link together to form long chains called nylon.
The raw materials used to make the two monomers are cyclohexane and adiponitrile.
These are both derived from crude oil.
Cyclohexane is oxidised,
first by air and then by nitric acid, to give adipic acid.
Adiponitrile is hydrogenated
to give hexamethylene diamine.
The two monomers first react to form a salt. Heating the salt
to drive out water produces nylon.
On this site, cyclohexane arives by pipeline and is stored here.
It is first oxidised here
and then further oxidised, with nitric acid made from ammonia, in this plant.
The product is adipic acid.
The hydrogenation of the
adiponitrile to produce hexamethylene diamine takes place here
and the two monomers are mixed in this building.
Polymerisation is carried out in this plant and nylon stored for delivery to customers.
Cyclohexane is oxidised to form adipic acid
in two stages, first with air and then nitric acid.
This is what happens in these reactions.
Adipic acid,
one of the two monomers, is a white powder.
Adiponitrile is reacted with hydrogen to give hexamethylene diamine,
the second of the two monomers.
The two monomers are mixed together and react to give nylon salt.
This, and all other processes, are monitored and
controlled remotely.
Nylon is produced from nylon salt
by driving out the water.
These are the tops of the autoclaves in which the salt,
at a pressure of 18 atmospheres, is heated to a temperature
of 280 degrees Celsius.
At this stage additives and pigments are added and the conditions can be changed
to produce polymers with different properties.
When the white nylon is produced it's molten and is forced through holes
to form laces of nylon
The laces are cooled in water and chopped into short lengths
about three to four millimetres long called granules.
Nylon leaves the site in lorries as granules.
The granules which are
thermoplastic will be remelted and moulded, or forced through fine holes
to make nylon fibres.