If plastic was made in 1907 how do they know it may take up to 1000 years to decompose?
In: Chemistry
The real tragedy here is the fact that we have destroyed our oceans with plastic in just over 100 years..
I think the worlds plastic is more likely to end up on that trash floating island than it is to actually decompose.
They don’t. It’s bullshit. A small piece of plastic exposed to harsh sunlight might decompose in a few months. A large block at the bottom of a lake might last a million years. Any scientific statement that includes the phrase “may take up to” isn’t scientific at all.
Chemical Engineer here. General rule of thumb is that for every 10 deg C increase in temperature it doubles the reaction rate. Raise temperature and everything starts moving around faster and we can extrapolate times that are longer than our observable lifetimes. Subject plastic to high temperatures = higher degradation rates. Compute that back to normal temps for actual decomposition time
Like pouring a cup of water in the sink. You don’t have to pour the entire cup to estimate when it’s going to run out.
PhD in plastics engineering here. There’s a technique known as time-temperature superposition, which allows us to predict how long it will take to degrade plastics by subjecting the plastics to high temperatures (keeping most details out of it) and seeing how long it takes to degrade at this high temperature. Then we use this information to compute how long it will take the plastic to decompose at ambient (room) temperatures. This method gives a very precise number much more accurate that a qualitative 1000s of years. The most stable plastics would probably survive for 100s of years, not 1000s.
Maybe by then it will turn back to oil! So we really dont have an oil shortage! We just have to wait 1000 years lol.
The same way you can figure out how long it will take to fill a 5 gallon bucket by figuring out how long it takes to fill a 1 gallon bucket. The rate doesn’t change, just the time.
If it takes 1 minute to fill 1 gallon, then it’s going to take 5 minutes to fill 5 gallons.
The conceptual study design to determine something like this is modified and used in many other endeavors on weathering predictions. Engineers want to know how long steel might take to corrode in different environments, so they might design purposefully stressful conditions and add a piece of steel to it. The conditions might not reflect actual ambient conditions but by doing this they make room for a margin of safety in their predictions (i.e., if high humidity, salty air, and high temperatures corrode steel X fast, it’s safe to set a floor on how soon we ought to expect corrosion in less harsh conditions). This is also a common practice in running stability test son pharmaceutical or food products – accelerating degrading conditions to estimate the expected shelf life of consumer-goods. In the case of plastic, it’s possible to design chambers or experiments where a piece of plastic decomposes in only, say, 2 years and design a model which might predict how that plastic would decomopose under less harsh (“ambient”) conditions.
Well it doesn’t.
There is not material called “THE PLASTIC”, just like how there is no such thing as “THE METAL”.
There are gazillion kinds of plastics, some of them are very resistant to the elements, some of them decompose when hit by a stiff breeze.
The “plastics take 1000 years to decompose” is a very nice and illustrative argument against littering. Without much insight on whats going to happen to said stuff.
As that depends on what kind of plastic we are talking about, how thick the thing you want to see disappear, where do you leave it (buried in earth, most plastics can last extreme long)… etc.
And ofc, there are unknown factors, like “will anyone create GMO organisms with the enzimes to eat the stuff”.
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