r/science • u/mvea Professor | Medicine • Feb 20 '21

Chemistry Chemists developed two sustainable plastic alternatives to polyethylene, derived from plants, that can be recycled with a recovery rate of more than 96%, as low-waste, environmentally friendly replacements to conventional fossil fuel-based plastics. (Nature, 17 Feb)

https://academictimes.com/new-plant-based-plastics-can-be-chemically-recycled-with-near-perfect-efficiency/
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u/[deleted] Feb 20 '21

My reply takes that factor into consideration. Just do a bit of digging to see that hardly any plastic is recycled currently. Most of it goes to landfills. Of what isn't usually get "repurposed", not recycled. This is not widely known.

The recycle symbol many people think indicates that a material can be recycled is not what it seems to be. It used to be a symbol for recycling, but is now a resin identification code.

If you want to assert that significant amounts of HDPE, PET, or PP are recycled (in the true sense of the word) then feel free to post the source. As far as I'm aware, the best that can be done with the overwhelming majority of plastics is repurposing into secondary products, not reclaiming the material for it's original purpose.

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u/Brookenium Feb 20 '21

That's a problem of recycling, not plastic. Glass is the same way hell we barely recycle anything, unfortunately. But that's an entirely separate problem.

If you want to assert that significant amounts of HDPE, PET, or PP are recycled

I said they're recyclable, not heavily recycled at the moment. A simple google search is enough to corroborate that. We're not talking about what is currently done though, we're talking about feasible plans for the future. Those plastics can be melted down and reformed. Some plastics by their nature cannot be recycled although this is the same for plenty of other things we use. For those, it can be acceptable to use them depending on how long the product is supposed to last. If it can be reused that's even better than recycling. If it lasts a few decades and ends up in a landfill that's not any worse than what we do with steel.

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u/[deleted] Feb 20 '21 edited Feb 21 '21

They aren't recyclable. Only a small amount of plastics are. You are welcome to prove that wrong. I'm basing my statement on chemistry and facts about long-chain polymers. HDPE is generally pelletized and REPURPOSED. It cannot be recycled in the sense you are suggesting. HDPE milk jugs are not recycled back into milk jugs, for instance.

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u/Brookenium Feb 21 '21 edited Feb 21 '21

Literally just google "are HDPE, PET, or PP" recyclable. Those ones are.

I'm a chemical engineer I know the science I've literally studied it. I know HDPE can be recycled because I've literally done so in college using an injection molder and remelting down the HDPE over and over again.

https://www.azocleantech.com/article.aspx?ArticleID=255#:~:text=HDPE%20is%20accepted%20at%20most,large%20facilities%20to%20be%20processed.

HDPE is accepted at most recycling centers in the world, as it is one of the easiest plastic polymers to recycle

HDPE is then shredded and melted down to further refine the polymer. The plastic is then cooled into pellets which can be used in manufacturing.

HDPE isn't a thermoset, it can be melted back down. Thermosets tend to be plastics that are designed for many many uses. They would be reused instead of recycled.