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Not sure if that thing could be used as food packaging, since food has salt and water. Also that means this plastic probably has a very short lifespan.

by jokoon 2y ago

porphyra 2y ago
Also human hand sweat has both salt and water so anything that requires a human to carry them might not be suitable.
barbazoo 2y ago
> There’s one major hurdle with any degradable plastic material of course: what if it comes into contact with the catalyst for its destruction before you want it to? A plastic cup is no good if certain liquids can dissolve it, after all. > In this case, the team found that applying hydrophobic coatings prevented any early breaking down of the material. When you eventually want to dispose of it, a simple scratch on the surface was enough to let the saltwater back in, allowing the material to dissolve just as quickly as the non-coated sheets.
- Ancalagon 2y ago
  Is the coating made of PFAS, or wax?
  - 6177c40f 2y ago
    Parylene C, a chlorocarbon: [1] > Derivatives of parylene can be obtained by replacing hydrogen atoms on the phenyl ring or the aliphatic bridge by other functional groups. The most common of these variants is parylene C, which has one hydrogen atom in the aryl ring replaced by chlorine. [2] [1] https://www.science.org/doi/10.1126/science.ado1782 https://www.science.org/doi/10.1126/science.ado1782 [2] https://en.wikipedia.org/wiki/Parylene#Permeability https://en.wikipedia.org/wiki/Parylene#Permeability
    - pas 2y ago
      it seems there's even a biodegradable version https://www.kit-technology.de/en/technology-offers/details/705 https://www.kit-technology.de/en/technology-offers/details/7...
chongli 2y ago
Your remark hints at the fundamental problem with plastics: lifespan and chemical resistance. We worked so hard to develop plastics which have a long lifespan and high chemical resistance which makes them extremely versatile for containers and structures we don’t want to fall apart on their own. At the same time, it’s these exact same properties of plastics which make them non-biodegradable and resistant to being broken down by the human body’s immune system and waste removal processes. The advantages we developed them for are also the disadvantages we’re trying to replace them for. In the end, what we truly want is a product that lasts as long as we want and no longer. Something that’s indestructible while it’s in use but can be decomposed and recycled instantly with the push of a button. This is a paradox!
- permo-w 2y ago
  is it a paradox? how unlikely is it that there's a plastic substance out there that can be quickly dissolved to bio-degradable substances but only using a relatively cheap and non-toxic solvent not present in most use cases for plastic? that's not a paradox, it's an engineering problem.
- silisili 2y ago
  It's what makes sense. I don't think it's that hard given materials available, I think companies just forego putting thought into it because customers don't care and will claim their products are weak and not long lasting, while having to spend more money for the problem. Things like sandwich containers/wrappers shouldn't even be plastic to begin with. A salad container should probably not have a lifespan of much more than a week or so. A disposable cup should probably be designed to hold liquid for a period of something like 12-24h then rapidly degrade under liquid. I'd love to see more alternatives pop up in the short term, whether it's natural wax paper, banana leaves, hollowed out shells or gourds, some type of thin wood, etc. But plastic is just so cheap and ubiquitous it's a hard thing to convince a company to do.
  - c22 2y ago
    > A disposable cup should probably be designed to hold liquid for a period of something like 12-24h then rapidly degrade under liquid. As someone who once received a beverage in just such a disposable cup and then left it in my car overnight I have to say screw this idea.
Asooka 2y ago
It would at least be useful for food delivery, since the packaging on that doesn't need to last more than a few hours tops.
bgnn 2y ago
Plastic should not be used as food packaging.
- gitaarik 2y ago
  So what instead?
  - anticensor 2y ago
    Paper and glass.
ratg13 2y ago
The primary mechanism for this to work is similar to “paper” straws The product is coated in hydrophobic forever chemicals which protect the material ‘long enough’ before the core is compromised.
- pas 2y ago
  it seems there are biodegradable coatings, like this https://www.kit-technology.de/en/technology-offers/details/705 https://www.kit-technology.de/en/technology-offers/details/7...

Not sure if that thing could be used as food packaging, since food has salt and water. Also that means this plastic probably has a very short lifespan.

by jokoon 2y ago

Not sure if that thing could be used as food packaging, since food has salt and water. Also that means this plastic probably has a very short lifespan.

porphyra 2y ago

Also human hand sweat has both salt and water so anything that requires a human to carry them might not be suitable.

barbazoo 2y ago

> There’s one major hurdle with any degradable plastic material of course: what if it comes into contact with the catalyst for its destruction before you want it to? A plastic cup is no good if certain liquids can dissolve it, after all. > In this case, the team found that applying hydrophobic coatings prevented any early breaking down of the material. When you eventually want to dispose of it, a simple scratch on the surface was enough to let the saltwater back in, allowing the material to dissolve just as quickly as the non-coated sheets.

Ancalagon 2y ago
Is the coating made of PFAS, or wax?
- 6177c40f 2y ago
  Parylene C, a chlorocarbon: [1] > Derivatives of parylene can be obtained by replacing hydrogen atoms on the phenyl ring or the aliphatic bridge by other functional groups. The most common of these variants is parylene C, which has one hydrogen atom in the aryl ring replaced by chlorine. [2] [1] https://www.science.org/doi/10.1126/science.ado1782 https://www.science.org/doi/10.1126/science.ado1782 [2] https://en.wikipedia.org/wiki/Parylene#Permeability https://en.wikipedia.org/wiki/Parylene#Permeability
  - pas 2y ago
    it seems there's even a biodegradable version https://www.kit-technology.de/en/technology-offers/details/705 https://www.kit-technology.de/en/technology-offers/details/7...

chongli 2y ago

Your remark hints at the fundamental problem with plastics: lifespan and chemical resistance. We worked so hard to develop plastics which have a long lifespan and high chemical resistance which makes them extremely versatile for containers and structures we don’t want to fall apart on their own. At the same time, it’s these exact same properties of plastics which make them non-biodegradable and resistant to being broken down by the human body’s immune system and waste removal processes. The advantages we developed them for are also the disadvantages we’re trying to replace them for. In the end, what we truly want is a product that lasts as long as we want and no longer. Something that’s indestructible while it’s in use but can be decomposed and recycled instantly with the push of a button. This is a paradox!

permo-w 2y ago
is it a paradox? how unlikely is it that there's a plastic substance out there that can be quickly dissolved to bio-degradable substances but only using a relatively cheap and non-toxic solvent not present in most use cases for plastic? that's not a paradox, it's an engineering problem.
silisili 2y ago
It's what makes sense. I don't think it's that hard given materials available, I think companies just forego putting thought into it because customers don't care and will claim their products are weak and not long lasting, while having to spend more money for the problem. Things like sandwich containers/wrappers shouldn't even be plastic to begin with. A salad container should probably not have a lifespan of much more than a week or so. A disposable cup should probably be designed to hold liquid for a period of something like 12-24h then rapidly degrade under liquid. I'd love to see more alternatives pop up in the short term, whether it's natural wax paper, banana leaves, hollowed out shells or gourds, some type of thin wood, etc. But plastic is just so cheap and ubiquitous it's a hard thing to convince a company to do.
- c22 2y ago
  > A disposable cup should probably be designed to hold liquid for a period of something like 12-24h then rapidly degrade under liquid. As someone who once received a beverage in just such a disposable cup and then left it in my car overnight I have to say screw this idea.

Asooka 2y ago

It would at least be useful for food delivery, since the packaging on that doesn't need to last more than a few hours tops.

bgnn 2y ago

Plastic should not be used as food packaging.

gitaarik 2y ago
So what instead?
- anticensor 2y ago
  Paper and glass.

ratg13 2y ago

The primary mechanism for this to work is similar to “paper” straws The product is coated in hydrophobic forever chemicals which protect the material ‘long enough’ before the core is compromised.

pas 2y ago
it seems there are biodegradable coatings, like this https://www.kit-technology.de/en/technology-offers/details/705 https://www.kit-technology.de/en/technology-offers/details/7...