4 ms·

It's not clear to me, in general, how efficient recycling plastics like this actually is. Maybe someone on HN can enlighten me. As a thought experiment, if old

It's not clear to me, in general, how efficient recycling plastics like this actually is. Maybe someone on HN can enlighten me. As a thought experiment, if old plastic bottles needed to be heated until they melted, and then could be recast into something new, that would be great, but if that process generated a new round of toxic chemicals being emitted into the closest river, it might not be so attractive. In short, I'm ignorant of how useful and genuinely close to zero net new these sorts of efforts are.

selcuka 3y ago
According to the Wikipedia article [1] both methods are used: > 'basic' or 'physical' recycling. Bottle flake is melted into its new shape directly with basic changes in its physical properties. > 'chemical' or 'advanced' recycle. Bottle flake (or possibly a less pure feedstock) is partially or totally depolymerized then enabling purification. The resulting oligomers or monomers are repolymerized to PET polymer, which is then processed in the same way as virgin polymer. [1] https://en.wikipedia.org/wiki/PET_bottle_recycling https://en.wikipedia.org/wiki/PET_bottle_recycling
userbinator 3y ago
Depends on the plastic. Most plastics in common use are thermoplastics which can be remelted and recast.
hedora 3y ago
They are nowhere near zero net, and the actual recycling isn't the issue. To see the problem, go to your recycle bin, and grab all the plastic. Now, sort them by recycling code, then remove all the stuck on food for things with low-ish numbers. (High numbered stuff isn’t actually recycled anywhere.) Now, remove all the labels, lid tamper rings, etc. Now do that for 1 ton of plastic waste. Edit: actually, 1 ton is a lot more than I realized. 55lbs of ABS plastic costs $363. Start with that much, then figure out how to sort the plastic at a profit. https://www.mcmaster.com/product/4387N11 https://www.mcmaster.com/product/4387N11

selcuka 3y ago

According to the Wikipedia article [1] both methods are used: > 'basic' or 'physical' recycling. Bottle flake is melted into its new shape directly with basic changes in its physical properties. > 'chemical' or 'advanced' recycle. Bottle flake (or possibly a less pure feedstock) is partially or totally depolymerized then enabling purification. The resulting oligomers or monomers are repolymerized to PET polymer, which is then processed in the same way as virgin polymer. [1] https://en.wikipedia.org/wiki/PET_bottle_recycling https://en.wikipedia.org/wiki/PET_bottle_recycling

userbinator 3y ago

Depends on the plastic. Most plastics in common use are thermoplastics which can be remelted and recast.

hedora 3y ago

They are nowhere near zero net, and the actual recycling isn't the issue. To see the problem, go to your recycle bin, and grab all the plastic. Now, sort them by recycling code, then remove all the stuck on food for things with low-ish numbers. (High numbered stuff isn’t actually recycled anywhere.) Now, remove all the labels, lid tamper rings, etc. Now do that for 1 ton of plastic waste. Edit: actually, 1 ton is a lot more than I realized. 55lbs of ABS plastic costs $363. Start with that much, then figure out how to sort the plastic at a profit. https://www.mcmaster.com/product/4387N11 https://www.mcmaster.com/product/4387N11