Polymerisation Mechanisms Compared
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The following two tables compare some of the aspects of addition polymerisation (e.g. the free radical polymerisation of ethene) with condensation polymerisation (e.g. the formation of Nylon-6,6 or PET).
The first table compares the properties of the reaction types, while the second table shows the differences over the course of the reaction.
| Condensation | Addition |
|---|---|
| any two molecular species can react | molecular species can react only with active centres |
| chains start short and steadily grow | chains are long at all times |
| most monomer gone early in reaction | some monomer remains until end of reaction |
| reactions relatively slow, generate little heat | reactions relatively fast, generate lots of heat |
| Early in the reaction | Midway through the reaction | Late in the reaction | |
|---|---|---|---|
| Addition | Lots of monomer, a few long chains, (a few smaller chains) |
Less monomer, more long chains, (more smaller chains) |
Little bit of monomer, lots of long chains, some middle-sized chains |
| Condensation | Some monomer, lots of short chains |
Some short chains, lots of middle-sized chains |
Some middle-sized chains, lots of long chains |
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