Problems with PolymersOxford AQA IGCSE Chemistry: Revision notes
Section 1
Why are polymers difficult to dispose of?
Most polymers are made from crude oil and are not biodegradable - they are not broken down by microbes in the environment.
- Non-biodegradable polymers can remain in the environment for hundreds of years without rotting away
- This causes serious problems for waste disposal: polymer waste builds up in landfill sites, taking up valuable space that will not be reclaimed for a very long time
- Discarded plastic also causes problems as litter, harming wildlife on land and in the oceans
Key termsbiodegradablelandfill
Common mistake
Do not say plastics 'disappear' in landfill - most conventional polymers persist there for a very long time because they are not biodegradable.
Section 2
How are new polymers addressing this problem?
Chemists have developed alternative materials to reduce the environmental impact of polymer waste:
- Some plastic bags are now made from a mixture of conventional polymer and cornstarch, so they break down more easily than pure plastic
- Fully biodegradable plastics made from cornstarch have also been developed; because cornstarch comes from plants, microbes can break it down
- These materials are designed to reduce the amount of persistent waste sent to landfill or left as litter
Key termscornstarch
Example
A cornstarch-based plastic bag left in a compost heap will break down over time, unlike a conventional polyethene bag.
Must Know
- Most polymers are not biodegradable, so they are not broken down by microbes
- Non-biodegradable polymer waste causes problems in landfill sites and as litter
- Some plastic bags are made from a mixture of polymer and cornstarch to break down more easily
- Fully biodegradable plastics made from cornstarch have been developed as an alternative to conventional plastics
That's the notes covered.
Carry on to the next subtopic.