Science Questions

Why aren't plastics biodegradeable?

Sun, 26th Jul 2009

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Ken Ellingson asked:

Why are plastics not biodegradable? Why won’t they breakdown when we chuck them in the ground?


We put this to John Williams, Polymers and Materials Manager, at the National Non-Food Crops Centre:

John -   Well, I mean, traditionally, if you look at the materials we’ve produced from petrochemicals then the majority of plastics need to actually be durable. That’s what they’ve been developed for - maximum functionality.  And there are one or two pressure of petro-derived plastics that are biodegradable very used in speciality sort of type situations like medical applications and so on.  What’s happened recently, of course, is that the drive toward some aspect of biodegradabilities as a function is quite useful if you look into co-disposal of things which are also biodegradable like food waste, for example.  So, the answer is you actually you – the important thing is you pick the material for its functionality in terms of what its use is going to be rather what its disposal route is going to be.  But now, at the same time you say, actually if we did say, develop a biodegradable version of that, is that useful way to go or not?


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Ellingson, Kenneth L asked the Naked Scientists: Chris Why are most plastics not biodegradable? What makes some greener plastics biodegradable? Knute Ellingson, Chicago What do you think? Ellingson, Kenneth L , Thu, 16th Oct 2008

Thats a great question. i dont know how to answer it but i have had a similar question roaming my brain. Ok so , everything we make has had to start out from natural resources right? So shouldnt plastic or foam and such be able to go through some sort of cycle back through the earth if the components of the plastic or object came from the earth at some point. chrissylynn, Wed, 22nd Oct 2008

For most applications, it would be very inconvenient for them to biodegrade.
Tools, pipes, insulation, cups, etc. mustn't degrade. Plastics are very economical for these applications.
Plastic bags, even, could be problematical unless you know how long they will last.
Their chemistry makes them  rather uninviting as an energy source for animals or fungi so they tend to just stay there.
If only we could find a suitable bug to eat the stuff and produce foold/ oil from it. lyner, Sun, 9th Nov 2008

And now imagine this bug getting out into the environment. Better be a bug that can be controlled. Similar to the "other" controllable environmental experiments.

OOps, the synthetic thread holding together my clothes just got eaten! Karsten, Fri, 31st Jul 2009

I object and move to strike as non-responsive. btchoutex, Mon, 20th Oct 2014

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