The Misleading Biodegradability of PLA

Biodegradable PLA

 

The vast majority of FDM (fused deposition modeling) 3D printers primarily consume ABS or PLA filament. ABS, a petroleum based thermoplastic, is a little tougher and bit more flexible than PLA, but also a little more finicky to print with. ABS generally requires a heated bed to reduce warpage, and also emits a potentially troublesome scent as it is extruded. PLA on the other hand, or poly lactic acid, is derived from starchy sources - most often sugarcane or corn starch and has a far more palatable (some note a breakfast waffle-like) scent when extruded.

The marketing writes itself. PLA is a natural, bio based alternative to petroleum laden ABS!  Sounds (and smells) like you could eat it! I'm a hands on guy so I tried a nib, tastes like plastic. The baked out, boiled down, unsweetened truth is that it is indeed, plastic. Marketeers love to tout the biodegradability of the material, and its true, that at some point it will biodegrade. The reality however, is that this process will take several hundred years in a typical landfill. To biodegrade, PLA requires a laundry list of conditions to effectively break down. Specifically - oxygen, a temperature of 140+ degrees, and a 2/3 cocktail of organic substrate. Collectively, these are absent in any scenario outside of industrial composting facilities. This means that PLA plastic will sit in that landfill right alongside ABS and other plastics for a very long time.

When considering the environmental friendliness of a particular product, it is essential to consider the amount of energy used to create that product. For all plastics, the energy required is particularly significant. This dictates that the ultimate waste of that energy is to literally discard it. For this reason, keeping the material in its intended physical form is far more responsible. 

What do we propose? Print responsibly and recycle accordingly. The Filabot, for lack of a better engineered example, is capable of turning your old PLA or ABS prints into fresh filament again so you can indefinitely extend the practical life of the material. Plastic, once it has been industrially produced, is categorically best staying plastic. Giving this plastic renewed purpose is the key, and is ultimately a far more productive future than an impractically slow death in the ground. 

 

 

 


13 comments

  • Filabot Team

    Paul, thank you for your comments. Referring to PLA as degrading instead of biodegradable is a neat way to think about this. Thank you for sharing your link.

  • paul

    No:
    "
    1) PLA is not biodegradable it is degradable.
    2)Enzymes which hydrolyze PLA are not available in the environment except on very rare occasions.
    3) Proteinase K catalyze the hydrolytic degradation of PLA

    Williams in 1981 and Tsuji and Miyauchi in 2001 had the same question ” is PLA is biodegradable” . They have written white papers around the subject and are featured in the book Biomaterials Science: An Introduction to Materials in Medicine. In the book and discussed at the conference of the European Society for Biomaterials PLA is controlled by hydrolysis and the hydrolysis is independent of all biological agents.

    So while many people believe PLA to be biodegradable, it simply is not, PLA is degradable and should be considered as such, in the Biomaterials Science book, they actually go on to say that the situation where Proteinase K hydrolyze PLA is so rare it is not worth discussing further."

    -http://www.biosphereplastic.com/biodegradableplastic/uncategorized/is-pla-compostable/

  • Filabot Team

    Betty, we totally see your point and frustration close loop systems are the way to go. We have different customers trying new ways to repurpose their old plastics by turning it into 3D filament. Currently, we are working with a school that is sourcing recycled PETG and additives for the use of experimental large format prints and filament uses.

  • Betty

    As someone who cares deeply about the environment and will go to great lengths to do the right thing I find it utterly impossible to understand how to deal with “biodegradable” “recyclable” “compostable” materials and where to put them. Organic farms are not allowed to accept soil that contains PLA. There is no special commercial composting facility in the San Francisco area to compost PLA. it all goes to landfill and takes up to 1000 years to “decompose”, whatever that means. I read that that ALL plant fiber “compostable” carry out boxes contain either pfas (no thanks!) or are lined with PLA. I read that Chinet plates are the only disposable plated made of 100% recycled PAPER that readily break down in back yard compost piles suitable for organic gardens. Why not make a 100% paper carry out container? I get that 100% paper containers aren’t as durable. Can’t we handle a tad less perfection and convenience for the sake of the environment? Obviously “circular” and “closed loop” (reusable glass, stainless steel….) is the ultimate answer to saving our environment.

  • Karel Lootens

    So the message to all your readers should rather be – dispose of your PLA in the compost bin, so it gets industrially composted and becomes a fully eco-friendly alternative to ABS, no?

    It shouldn’t land on a landfill – it should end in the compost facility.

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