Page 28 - Plastics News December 2017

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Littering is fundamentally a problem of irresponsible So what are biodegradable plastics good for?
behaviour, which should be tackled by changing people’s In principle plastics are valued for their ability to make
attitudes rather than by changing the products they strong, durable products (for example in food storage,
are throwing away. Making products biodegradable
transport, building and construction). Biodegradability
should therefore be regarded as an additional functionality
when the application demands a cheap way to dispose of
the item after it has fulfilled its job (e.g. for packaging,
protect food and keep it fresh). Examples of useful
biodegradable products are:

may actually make the problem of littering worse, by
making people think that it is OK to throw away valuable Food packaging – packaging that can be composted
resources like plastics. For example, a biodegradable together with its contents when the product is past its
plastic bag that’s thrown into a hedge will still take years sell-by date or spoiled
to disappear, rather than days as some people believe.
Even a banana skin - when thrown away - needs 1-3 years Agriculture – plastic sheeting that can be ploughed-into
before it is biodegraded! biodegradable mulch and seed films
Medical – absorbable sutures; micro-devices containing
What’s more, biodegradable plastics require specific
conditions to biodegrade properly (micro-organisms, medicine, which break down inside the body
temperature, and humidity), and if not managed Biodegradability is a material property that depends
properly they may be worse for the environment than much on the circumstances of the biological environment
conventional plastics. When biodegradable plastics are (human body differs from soil). Given that this is the case,
put into landfill (which should always be avoided in any it could be said that making a product such as a plastic
case) they produce harmful greenhouse gases when bag compostable does not make much sense because this
breaking down. biodegradability performance will not resolve the litter
issue (different conditions in the compost and on soil).
What are biodegradable plastics?
To conclude, it is a mistake to focus on finding ways to
Biodegradable plastics are plastics that can be broken make products easier to throw away in the name of helping
down by microorganisms (bacteria or fungi) into water, the environment. Biodegradable plastics are exciting and
carbon dioxide (CO2) and some bio-material. It is important useful materials, but they should only be used when they
to note that biodegradable plastics are not necessarily have a concrete benefit for a specific product. The best
made from bio-material (i.e. plants). Several way to help save the planet is to save energy and improve
biodegradable plastics are made from oil in the same way ways of recycling and recovering all plastics.
as conventional plastics.

Plastics News December 2017 28