
Reycling Plastic from the Inside Out - chmaynard
https://newscenter.lbl.gov/2019/05/06/recycling-plastic-from-the-inside-out/
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maliker
This is probably a dumb question, but what essential products use plastics and
for which no other material is an adequate substitute for the plastic
components?

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TehCorwiz
Lots of medical and lab supplies, such as tubing, tools, and stents. For some
applications glass is too fragile, metal can be too reactive. Even "inert"
metals like titanium or nickel eventually develop bio-films.

Various plastics' combination of temperature stability at both high and low
temps (cryo / autoclave), non-bio-reactivity (body doesn't attack or reject
over short spans), and corrosion resistance makes plastics perfect for these
situations. Especially wet situations. And since plastics can be fine tuned
for application specific needs they can be iterated on quickly with a
materials but not manufacturing process change in some cases.

My wife and I had this conversation a couple weeks ago asking this very
question which ultimately boils down to: "Are plastics worth it at all ever?"
And the answer we found, surprisingly, was yes.

edit: a typo.

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phkahler
Aren't plastics usually reasonable to burn as well? As in burning mostly
produces CO2 and water? Or do common plastics contain some nasty atoms we dont
want in the air in any way?

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code_duck
They can be burned safely in an incinerator. Ad hoc burning can produce very
toxic chemicals, though, including dioxins, hydrogen cyanide, vinyl chloride
and furans. It could release lead. It depends on the type of plastic (PVC?
Polyethylene? Polypropylene?). This is why it’s troubling to see people
burning bags of trash and tossing in plastic bags and soda bottles as if they
magically disappear.

This is a good rundown:
[https://www.directplastics.co.uk/about_plastics/post/whats-i...](https://www.directplastics.co.uk/about_plastics/post/whats-
in-those-fumes)

MIT says... [https://engineering.mit.edu/engage/ask-an-engineer/can-we-
sa...](https://engineering.mit.edu/engage/ask-an-engineer/can-we-safely-burn-
used-plastic-objects-in-a-domestic-fireplace/)

“When plastic is burned, it releases dangerous chemicals such as hydrochloric
acid, sulfur dioxide, dioxins, furans and heavy metals, as well as
particulate.”

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jacobush
To be fair, aren't soda bottles and plastic usually PET, which should not
release nasty stuff? Or am I just misinformed?

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grenoire
See TehCorwiz' response below. It seems it never is JUST plastic.

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jagger27
"Unlike conventional plastics, the monomers of PDK plastic could be recovered
and freed from any compounded additives simply by dunking the material in a
highly acidic solution. The acid helps to break the bonds between the monomers
and separate them from the chemical additives that give plastic its look and
feel."

Anyone know if any acid will work or if the solution is somehow special?
Sounds like a big downside to lose acid resistance.

~~~
HillRat
Looks like they use sulfuric acid at 0.5 to 5 M over a 24-hour period to
depolymerize the plastics. So highly acidic, but probably better to keep your
acids in polyethylene containers!

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inflatableDodo
Look as though the polydiketoenamines themselves are also quite easy to make;

>"Surprisingly, polydiketoenamines could be made simply by mixing ketones and
amines. ‘It’s a click reaction that works at room temperature, without needing
catalysts, additives or even a solvent,’ says Helms. ‘They just require a few
minutes in a ball mill.’"

[https://www.chemistryworld.com/news/new-family-of-
polymers-c...](https://www.chemistryworld.com/news/new-family-of-polymers-can-
be-easily-recycled-and-even-upcycled/3010439.article)

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cr0sh
I'm kinda curious if this "new" plastic is going to be flexible enough in the
number of applications to replace most common plastics in common applications,
or if it's going to have the same issues (ie, needing fillers or other things
to make it work for certain applications).

What is it's heat resistance? How well does it work in extreme cold? How
flexible is it? Impact resistance? Can it be made clear?

Maybe any fillers, etc can also easily separate out?

If it can replace most uses of PP/PE/ABS/PVC - it would be huge on the
consumer market (also, providing it doesn't have a similar BPA-like issue).

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stevespang
Hmmm, last I checked concentrated sulfuric acid is not commonly available to
or advised to be used by the public . . . so forget about the common man
recycling this stuff, just another development of "big corporate" to keep this
product and the system surrounding it all within their clutches. On the other
hand, my son and I just filed a patent for a low melt temp polymer system that
is flexible, recyclable merely with low heat, biodegradeable (without acids),
repurposeable, NON TOXIC, and all processes can be done at home safely by the
public, no corporate involvement necessary.

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cr0sh
> Hmmm, last I checked concentrated sulfuric acid is not commonly available to
> or advised to be used by the public

IIRC, lead-acid batteries, common in automobiles, contain a somewhat
concentrated form of sulfuric acid; they are also made of plastic, so assuming
they continue to be available, I doubt that such batteries will use this new
plastic.

