AQA A Level Chemistry

Revision Notes

3.4.6 Solution to Plastic Pollution

Disposing of Polymers

  • Though poly(alkenes)s are extremely important in everyday such as their use as plastics, the disposal of these polymers is problematic
  • Poly(alkenes) are very large alkane molecules which are unreactive and therefore do not undergo any chemical reactions; they are resistant to chemical attack
  • Due to their unreactivity, polymers are non-biodegradable and take up to hundreds of years to decompose when dumped in landfill sites
    • Throwing away poly(alkenes) therefore cause the long-term pollution of the environment
  • Burning the polymers results in harmful combustion products which again cause the pollution of the environment

Exam Tip

The disposal of polymers is a challenge due to their unreactivity, their non-biodegradability, and the formation of harmful combustion products when burnt.

Solutions to Plastic Pollution

  • Possibly the easiest method to reduce the amount of plastic, is to reuse it rather than throwing it away
  • Since polymers have a long chain full of saturated, non polar C-C bonds
  • This makes them very unreactive molecules, which is why they are said to be non-biodegradable
    • They cannot be attacked and broken down by biological agents, such as enzymes
  • This is what makes throwing plastic away to end up on a landfill such a problem
  • Instead of throwing it away or reusing the plastic, you could recycle it

Feedstock Recycling

  • This is one possible solution to deal with the excess pollution that is caused by plastic
  • This process involves
    • Heating the plastic to a high enough temperature that the polymer bonds break, and monomers are formed
    • The monomers formed are then used to produce new plastics

Mechanical Recycling

  • This is a more straight forward type of recycling
  • The different types of plastic are separated and washed thoroughly
  • Then, they are ground up into small pellets
  • The pellets are heated up until they melt, and then remoulded so that they can be used again

Some Issues

  • These types of recycling are not perfect solutions
  • Some plastics, like poly(propene), can only be heated and reused a number of times
  • Each time the plastic is heated, some of the key chains break
  • This means that over time, the properties of the plastic are degraded
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