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The differences between thermosetting, thermosoftening and partially biodegradable plastics, and how they can be recycled.Key facts
- We throw away a lot of plastic and most is non-biodegradable.
- It can be recycled using mechanical and chemical methods.
- Scientists are now making biodegradable plastic.
- They add non-oils to monomer chains like sugar, silk, even bamboo.
Transcript
Modern plastics, or polymers, are extremely unreactive, and extremely durable.
We throw away 100 million tonnes of this finite product every year.
However, these sturdy, durable plastics are not normally biodegradable – they are not broken down naturally by microorganisms and may remain in the environment for hundreds, or even thousands, of years.
One way to limit the amount of plastics we throw away is to recycle them.
There are two key types of plastics, with different properties that affect the recycling process
Thermosoftening Plastics
Thermosoftening plastics can be recycled simply by adding heat, the weak intermolecular forces that hold the polymer chains together are readily overcome and the plastic melts.
So it can be remoulded into new products.
This is called mechanical recycling.
Thermosetting Plastics
Thermosetting plastics, on the other hand, only melt at very high temperatures and their chemical structure makes them much harder to recycle and remould.
This is because during the initial moulding process, strong cross-links are formed in thermosets that give them a stable structure.
These require chemical recycling to break them apart, using high temperatures and strong chemicals.
However, separating the two different types of plastics, and the different plastics within these groups, is very difficult. They can have similar properties and look the same.
So scientists have been working on other ways to make the disposal of plastics safer.
So scientists have been working on other ways to make the disposal of plastics safer.
They have now developed methods to make some plastics biodegradable, by adding a small percentage of non-oil based materials into the polymer chains, including sugar, corn starch, silk, and even bamboo.
These cause the plastic to biodegrade over time or when exposed to sunlight.
Although this means the plastic is broken down further, the small petrochemicals can still persist in the environment.
So the best solution of all is to reduce plastic production in the first place.
It uses far less energy and fewer resources.
