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Chemistry Open Book Paper
The development of polyethene and polypropene
Addition polymerisation is the creation of a polymer based upon straightforward monomer units. ...
In the polymerisation of ethene to polyethene, electrons are transferred from the carbon-carbon double bond of the ethene molecule, allowing the molecules to join together as a long chain of carbon-carbon single bonds. ... Because the branches on the chains cannot fit closely together so therefore the out come of the process has a low-density polyethene.
There are three main types of polyethene that is low-density polyethene, high-density polyethene and linear low-density polyethene.
High-density polyethene is formed when low pressures produce a harder and higher density polyethene consisting of united chains. High Density Polyethene (HDPE) is made at relatively low temperatures and pressures using special catalysts. These are called Ziegler-Natta catalysts after the two men who were awarded the Nobel Prize for their development and application to polymerisation of ethene and propene. This type of polyethene has no branching between the chains. These types of branches prevent the polyethene from packing closely together making it quite soft. This type of polyethene is strong and rigid and is easy to mould due to the lack of branching this product can often be used to replace metals, it is also used for domestic water tanks and pipes, car petrol tanks and fluid containers for hospitals.
Approximate Word count = 1028
Approximate Pages = 4.1
(250 words per page double spaced)
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