Polymers: Sources, Origins & Properties
Design & Technology: AQA GCSE, topic 5.1.3
Sources, Origins, and Properties
Plastics can be made from different resources and methods. Chemicals and compounds can be added to polymers to change the properties of plastic.
What is plastic made from?
- Plastics can be made from petrochemical resources such as oil.
- Some plastics are made from natural materials such as rubber.
- Newer bioplastics such as corn can be grown.
- Grown bioplastics are better for the environment because they biodegrade relatively quickly.
Refining
- Refining is the process of turning crude oil into a usable material.
- This is where the oil is heated up so the different materials separate out in a tank.
- Refining produces petrol, gases, oil, and polymers.
Cracking
- Cracking turns large hydrocarbon molecules into smaller ones.
- Large hydrocarbon molecules aren’t good for plastics so making them smaller makes them usable.
- Heat and pressure break the large molecule down.
- A catalyst can also be used to break the molecule down.
Additives
- Chemicals and compounds can be added to the polymers to change their properties.
- Pigments allow the plastic to be different colours.
- Plasticisers make the plastic more flexible and bendy.
- Fragrances can be added to make the polymers smell nicer.
- Stabilisers can be added to make the plastic resistant to UV rays which makes the plastic fade.
Biodegradable plastic
- Biodegradable plastics are newer plastics that are better for the environment.
- Examples of biodegradable plastics include PLA for 3D printing and PHB used in water bottles.
- Biodegradable plastics come from corn and starch-based plants.
- Biodegradable plastics fully biodegrade if composted which means they can't be recycled.
Test yourself on Polymers: Sources, Origins & Properties
What can be added to polymers to make the plastic more flexible and bendy?