polymers

• Polymers can be separated into two types: addition and condensation polymers.
• Polymers are large molecules made of thousands of smaller identical molecules called monomers.
• When forming addition polymers, monomers are alkenes.
• Polymerisation requires a high temperature, a high pressure and the presence of a catalyst.
• When addition polymers form, the double bond in the alkene monomers opens up and joins one monomer to another.
• Polymerising ethene makes poly(ethene)
• Poly(ethene) is used to make plastic bags and bottles.
• Addition polymers have no carbon to carbon double bonds so in reality, are very large alkanes.
• Addition polymers contain many C-C and C-H bonds which are non-polar and relatively strong, giving these polymers their unreactive nature.
• Their lack ofr reactivity means addition polymers can exist in the environment for a very long time.
• The repeating unit shows the arrangement of atoms that are repeated in the polymer chain.
• Poly(chloroethene) is also known as PVC and is used to make pipes and cables.
• Poly(propene) is used to make carpets.
• Poly(phenylethene) is commonly known as polystyrene and is used to make foam containers and cups. Poly(phenylethene) contains a benzene ring in its monomers.
• Plasticisers insert between polymer chains, weakening the intermolecular forces between them, allowing them to get further from one another which makes the polymer more flexible.
• The unreactivity of many addition polymers makes them very useful, but also very difficult to dispose of, and harmful to the environment.
• Addition polymers are non-biodegradable, meaning they aren't broken down by microorganisms in the environment. This means they can stay in the environment for decades.
• Some organisms may get wrapped around some polymers, or even mistake them for food.
• To produce addition polymers, we require crude oil which must be transported and refined, both requiring energy.
• Because addition polymers are so mass produced, they can occupy alto of space in land fills.
• Rather than sending waste polymers to landfill, we can combust them to generate energy. However this combustion can release harmful chemicals such as hydrogen chloride gas which is produced from poly(chloroethene).
• We can also recycle waste polymers, by sorting them into different polymers and melting them into substances which can then be solidified to produce new products.
• Recycling waste polymers reduces the use of crude oil and also reduces the amount of waste going to land fills.
• Another type is feedstock recycling where waste polymers are converted back to simpler hydrocarbons which can then be cracked, and then converted into different polymers.
• Feedstock is the raw materials which are used by the chemical industry.
• In feedstock recycling, waste polymers do not need sorting.
• Scientists are working on new biodegradable polymers based on biological material such as plants which would be renewable and able to be broken down by microorganisms.
• Scientists are also working on oil-based polymers which will slowly break down in sunlight. These are called photo degradable polymers.