Disposal of Addition Polymers — Synthetic Polymers | IGCSE Chemistry

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 5% of your exam marks.

stable

Rare

Stable5%

Addition polymerisation (drawing repeat units, identifying monomers, common polymers + uses) and disposal / environmental impact regularly tested.

The chains in an addition polymer are held together by strong C−C single bonds and they contain no chemically reactive functional groups
This makes the polymers chemically inert and non-biodegradable: bacteria and other decomposers in soil cannot break the chains down
Once thrown away, the polymer persists in the environment for centuries — a serious downside of one of the chemistry industry's most useful product families

Most household plastic waste ends up in landfill sites
Landfill takes up large amounts of land and the polymer waste does not degrade, so each site fills up quickly and a new one has to be excavated
Plastic in landfill can leach additives (plasticisers, pigments) into groundwater over time

Burning waste polymers in an incinerator is an alternative, and it can recover energy for heating or power
Drawbacks:
- Burning hydrocarbons releases large amounts of carbon dioxide, a greenhouse gas, contributing to climate change
- Burning polymers that contain chlorine (PVC) releases toxic hydrogen chloride (HCl) gas, which is corrosive and contributes to acid rain
- Incomplete combustion in a poorly run incinerator releases carbon monoxide, the toxic gas that cuts the blood's ability to transport oxygen around the body (see topic 22 section 2)

Many addition polymers can be sorted, melted and re-moulded into new products — the most environmentally friendly disposal route for those polymers that can be recycled
Drawbacks: sorting different plastics is labour-intensive; mixed-polymer waste reduces the quality of the recycled product; thermosetting polymers cannot be melted and re-formed