AQA A Level Chemistry复习笔记3.4.6 Solution to Plastic Pollution

• 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

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