Polymer: a large molecule made up of many repeating units or monomers
Addition polymers can be formed by repeated addition reactions between unsaturated hydrocarbons, such as alkenes
Unlike in condensation polymerisation, the polymer itself is the only product formed during addition polymerisation
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Uses of Addition Polymers
Monomer Polymer Repeating Unit Uses
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Condensation Polymers
Condensation polymers are formed by a condensation reaction between two different functional groups.
For example, polypeptides are formed from amino acids, which each contain an amine group and a carboxylic acid group
Polyesters are fromed from a dicarboxylic acid and a diol: a compound containing two hydroxyl groups
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Biodegradability
Poly(alkenes) are chemically inert and are therefore non-biodegradable
Poly(alkenes) can become more biodegradable if, for example, starch is incorporated into poly(ethene) used for carrier bags. Starch is hydrolysed by microorganisms, which breaks down the carrier bag
Polyesters and polyamides are biodegradable. Methyl ethanoate can be hydrolysed to produce methanol and ethanoic acid, for example
Polyesters are readily hydrolysed by strong alkalis, and polyamides are readily hydrolysed by strong acids. Certain enzymes can also be used for hydrolysis
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Recycling Polymers
Advantages
Protection of useful hydrocarbons for the future
Reduces landfill
Disadvantages
Difficult and expensive; polymers are often mixed with paints or dyes and must be separated
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Disposing of Polymers
Landfill
Limited amount of land available
Landfill sites fill up very quickly, especially when non-biodegradable polymers are disposed of
Incineration
Carbon dioxide, a greenhouse gas, is produced
Toxic gases can be produced unless polymers are incinerated at very high temperatures
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