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Open book paper (4th April 2001)-2852/01
An addition polymer is a long chain molecule with a high molecular mass, made by joining many together many small molecules called monomers:
Many monomers à Single polymer
n molecules à 1 single molecule
· The monomer used is an unsaturated alkene containing a double C=C bond. ... During the polymerisation of ethene, thousands of ethene molecules join together to make poly(ethene) - commonly called polythene. ...
The mechanism for the polymerisation of ethene is by a free radical addition reaction. ...
Serendipity has played a part in giving chemists more control of the process of polymerisation as when ethane was heated with benzaldehyde at 1400 atmospheres pressure, the pressure inside the reaction was much lower than expected. ...
Chemists did not have total control of the processes of polymerisation in the high pressure, high temperature polymerisation of ethene and of propene because when ethene was heated with benzaldehyde at 1400 atmospheres their attempts to repeat this procedure were often spoiled by explosions in the reaction vessel due to the exothermic decomposition of the ethene (see equation below).
The study of polymerisation of propene in the presence of an activated zirconocene catalyst showed that the growth of the polymer molecules is similar to that which occurs with a traditional trialkylanium Ziegler-Natta catalyst.
Approximate Word count = 1169
Approximate Pages = 4.7
(250 words per page double spaced)
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