4 ms·

Maybe we'll have a chance to get off oil-based plastics after-all.

by dottjt 3y ago

nomel 3y ago
I know little of chemistry, but I would assume this wouldn't work where longevity was needed, especially in moist environments, since there are plenty of bacteria that will happily break down the types of bonds in carbohydrates.
- froggit 3y ago
  That isn't an issue here. Structural polysaccharides, such as the cellulose used in this case, can be engineered to be extremely durable while remaining biodegradable. In cases where extreme longetivity is required (i.e. decades, centuries, universal heat death, etc.), biodegradable materials were never an option to begin with.
  - nomel 3y ago
    I'm not sure I understand. You seem to be restating what I said. These are not appropriate for longevity, and will biodegrade. Could you help me understand what I'm missing here?
- deleted 3y ago
  [deleted]
- floatrock 3y ago
  What if that’s exactly the point — it’s a material not designed for longevity? I mean I hate disposal plastic as much as anyone who’s seen a turtle with a straw stuck up its nose, but paper straws really don’t work more than 3 min. To keep conveniences like my iced caramel frappalattechino we need a fast biodegradable, but like 3 hours degradable not 3 min degradable. No idea if this is that, but “artificial shapes made of sugars like cellulose but not quite cellulose” sounds like you might be able to design something good that isn’t a forever chemical. Remember SunChips? They made a “this multi-layer plastic snack bag can actually biodegrade AND keep our snack grease from leaking out on the shelf” chip bag. But they killed it because every crinkle sounded like a gun so people hated it. We still haven’t figured out those kinds of materials that work well.
  - LegitShady 3y ago
    3 hour biodegradable is too fast. The material has to go somewhere. If it breaks up before it can be collected it's going to make a mess and cause buildups of whatever can feed off the carbs you're spreading everywhere.
  - nomel 3y ago
    Only around 36% of plastic is used for packaging. My comment was a direct response to the grandparent comment. If “for packaging” were included, I would have agreed. Replacing only plastic used for packaging will leave us dependent on oil.
- themitigating 3y ago
  Could it work in a situation where it provided the structural support and was coated in plastic?
  - nomel 3y ago
    Probably unrelated, but here's a neat video about the problems with resin coated rebar: https://youtu.be/xVDy84rR5Z8 https://youtu.be/xVDy84rR5Z8 TLDW: in practice, it's worse than leaving it bare! Probably unrelated because it's rebar degradation is ionic, so it can concentrate, where decomposition from microorganisms is surely related to the actual surface area.
  - toss1 3y ago
    Protective coating could be a good approach for some things, typically of intermediate lifespan. Protective coatings are becoming used more and more extensively in many fields, and they can produce astonishing results. That said, with applications for sugar-based structures, the slightest flaw, scratch, cut, or perforation becomes a barn door through which bacteria can drive their metaphorical horses and carriage. But for temporary applications such as packaging, a sugar-based material with a thin coating (maybe plastic, maybe another material) to preserve it for a short life, but allow it to biodegrade or compost could be excellent. For example, I find it particularly ironic that when the garden is out of season, I go to the grocery store only to find "organic triple washed" greens packaged in permanent plastic clamshells that will last for years. Sure, it does the job of getting the greens to us, but then it is making the problem worse.
    - themitigating 3y ago
      That actually makes sense for produce because if it goes bad the container and product can be composted. What I was thinking of is similar to wax coated paper cups.
- drycobbler 3y ago
  Bacteria famously can’t break down cellulose—wet or dry—, a structure made of glucose monomers. It took fungus hundreds of millions of years of evolution to develop the ability to break down cellulose.
  - nomel 3y ago
    > Bacteria famously can’t See firmicutes [1] and bacteroidetes: cellulomonas, thermobifida, clostridium. Bacteria also experienced those hundreds of millions of years. In fact, there's some cellulose melting bacteria in your gut right now! ;) But, you are right that it's not just bacteria [2]. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143619 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143619 [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277587 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277587
  - mistercow 3y ago
    I think you're thinking of lignin, not cellulose.

Maybe we'll have a chance to get off oil-based plastics after-all.

by dottjt 3y ago

Maybe we'll have a chance to get off oil-based plastics after-all.

I know little of chemistry, but I would assume this wouldn't work where longevity was needed, especially in moist environments, since there are plenty of bacteria that will happily break down the types of bonds in carbohydrates.

froggit 3y ago
That isn't an issue here. Structural polysaccharides, such as the cellulose used in this case, can be engineered to be extremely durable while remaining biodegradable. In cases where extreme longetivity is required (i.e. decades, centuries, universal heat death, etc.), biodegradable materials were never an option to begin with.
- nomel 3y ago
  I'm not sure I understand. You seem to be restating what I said. These are not appropriate for longevity, and will biodegrade. Could you help me understand what I'm missing here?
deleted 3y ago
[deleted]
floatrock 3y ago
What if that’s exactly the point — it’s a material not designed for longevity? I mean I hate disposal plastic as much as anyone who’s seen a turtle with a straw stuck up its nose, but paper straws really don’t work more than 3 min. To keep conveniences like my iced caramel frappalattechino we need a fast biodegradable, but like 3 hours degradable not 3 min degradable. No idea if this is that, but “artificial shapes made of sugars like cellulose but not quite cellulose” sounds like you might be able to design something good that isn’t a forever chemical. Remember SunChips? They made a “this multi-layer plastic snack bag can actually biodegrade AND keep our snack grease from leaking out on the shelf” chip bag. But they killed it because every crinkle sounded like a gun so people hated it. We still haven’t figured out those kinds of materials that work well.
- LegitShady 3y ago
  3 hour biodegradable is too fast. The material has to go somewhere. If it breaks up before it can be collected it's going to make a mess and cause buildups of whatever can feed off the carbs you're spreading everywhere.
- nomel 3y ago
  Only around 36% of plastic is used for packaging. My comment was a direct response to the grandparent comment. If “for packaging” were included, I would have agreed. Replacing only plastic used for packaging will leave us dependent on oil.
themitigating 3y ago
Could it work in a situation where it provided the structural support and was coated in plastic?
- nomel 3y ago
  Probably unrelated, but here's a neat video about the problems with resin coated rebar: https://youtu.be/xVDy84rR5Z8 https://youtu.be/xVDy84rR5Z8 TLDW: in practice, it's worse than leaving it bare! Probably unrelated because it's rebar degradation is ionic, so it can concentrate, where decomposition from microorganisms is surely related to the actual surface area.
- toss1 3y ago
  Protective coating could be a good approach for some things, typically of intermediate lifespan. Protective coatings are becoming used more and more extensively in many fields, and they can produce astonishing results. That said, with applications for sugar-based structures, the slightest flaw, scratch, cut, or perforation becomes a barn door through which bacteria can drive their metaphorical horses and carriage. But for temporary applications such as packaging, a sugar-based material with a thin coating (maybe plastic, maybe another material) to preserve it for a short life, but allow it to biodegrade or compost could be excellent. For example, I find it particularly ironic that when the garden is out of season, I go to the grocery store only to find "organic triple washed" greens packaged in permanent plastic clamshells that will last for years. Sure, it does the job of getting the greens to us, but then it is making the problem worse.
  - themitigating 3y ago
    That actually makes sense for produce because if it goes bad the container and product can be composted. What I was thinking of is similar to wax coated paper cups.
drycobbler 3y ago
Bacteria famously can’t break down cellulose—wet or dry—, a structure made of glucose monomers. It took fungus hundreds of millions of years of evolution to develop the ability to break down cellulose.
- nomel 3y ago
  > Bacteria famously can’t See firmicutes [1] and bacteroidetes: cellulomonas, thermobifida, clostridium. Bacteria also experienced those hundreds of millions of years. In fact, there's some cellulose melting bacteria in your gut right now! ;) But, you are right that it's not just bacteria [2]. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143619 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4143619 [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277587 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277587
- mistercow 3y ago
  I think you're thinking of lignin, not cellulose.