The Misleading Biodegradability of PLA

2015 Filabot NYC World Maker Faire Recap Reading The Misleading Biodegradability of PLA 3 minutes Next Unboxing the Filabot EX2

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 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. 

 

 

 

17 comments

William mace

William mace

So does this also mean that pla with water and warm conditions isn’t avaliable for microorganisms to consume. Biodegradable is not only chemical is it? Bioconsumable?

So does this also mean that pla with water and warm conditions isn’t avaliable for microorganisms to consume. Biodegradable is not only chemical is it? Bioconsumable?

Filabot Team

Filabot Team

Mitch, we aren’t entirely qualified to say- but would certainly love to see you give a shot and report back to us! We’ve got some similar experiments going on right now at our own homes and are waiting to see the results. We would say that the “best” thing to do would still be to recycle failed prints into filament, but we might be biased!

Mitch, we aren’t entirely qualified to say- but would certainly love to see you give a shot and report back to us! We’ve got some similar experiments going on right now at our own homes and are waiting to see the results. We would say that the “best” thing to do would still be to recycle failed prints into filament, but we might be biased!

Tim Dunn

Tim Dunn

Earthnurture.com offers an additive that can make PLA biodegradable at ordinary ambient temperatures. The additive takes the place of the requirement of high temperature hydrolysis.

Earthnurture.com offers an additive that can make PLA biodegradable at ordinary ambient temperatures. The additive takes the place of the requirement of high temperature hydrolysis.

Mitch

Mitch

Does this mean it would be best to put it in my home compost since it has oxygen, at least is 2/3 organic material and in summer can get around the 140 degrees?

Does this mean it would be best to put it in my home compost since it has oxygen, at least is 2/3 organic material and in summer can get around the 140 degrees?

Filabot Team

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, 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

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/

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

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, 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

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.

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

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.

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.

Jim

Jim

> The EU standard EN 13432 mandates: Disintegration [..] composted with biowaste for
3 months. After this time, the mass [..]

What is this a mandate for? For being able to say something is “compost-able”, rather than “recyclable”? Surely it wouldn’t mean that you couldn’t say (presumably in fewer words), “is recyclable into biomatter in a proper waste processing facility that uses appropriate shredding technology, pre-treatment, filtering, and long-duration microbial bio-processing”

> The EU standard EN 13432 mandates: Disintegration [..] composted with biowaste for
3 months. After this time, the mass [..]

What is this a mandate for? For being able to say something is “compost-able”, rather than “recyclable”? Surely it wouldn’t mean that you couldn’t say (presumably in fewer words), “is recyclable into biomatter in a proper waste processing facility that uses appropriate shredding technology, pre-treatment, filtering, and long-duration microbial bio-processing”

iksea

iksea

I have investigated PLA compostability for work projects in the past and dug into understanding what BPI and Cedar Grove (PNW compost facility) are looking for to certify a polymer or fiber based product to be compostable. The reality is that you may want your PLA 3D prints to compost, but they will not in the commercial facilities because they have too thick of wall sections to degrade in the batch time of the process. Most systems use 12 weeks or so to break down and if the wall sections are too thick, this will not happen. This is what made it hard to come up with compostable forks/spoons initially since you need some thicker sections for strength. Because most 3D prints are much larger/thicker than utensil wall thicknesses, they most likely will not compost in the time allowed and will be screened out with the rest of the contaminates and sent to the landfill. The only way to ensure that composting could happen would be to shred your parts into fine shavings (<.06") before sending to the compost. Another issue would be that the colors and additives are most likely not food safe and would most likely contribute to chemical contamination unless specifically formulated for this purpose. Look up PFAS and BPA chemical contamination of compost from migration from treated paper products. Another toxic mess building up.

The EU standard EN 13432 mandates:
Disintegration, namely fragmentation and loss of visibility in the final
compost – this is measured in a pilot composting test (EN 14045) in
which specimens of the test material are composted with biowaste for
3 months. After this time, the mass of test material residues has to
amount to less than 10% of the original mass.

https://docs.european-bioplastics.org/publications/bp/EUBP_BP_En_13432.pdf

I have investigated PLA compostability for work projects in the past and dug into understanding what BPI and Cedar Grove (PNW compost facility) are looking for to certify a polymer or fiber based product to be compostable. The reality is that you may want your PLA 3D prints to compost, but they will not in the commercial facilities because they have too thick of wall sections to degrade in the batch time of the process. Most systems use 12 weeks or so to break down and if the wall sections are too thick, this will not happen. This is what made it hard to come up with compostable forks/spoons initially since you need some thicker sections for strength. Because most 3D prints are much larger/thicker than utensil wall thicknesses, they most likely will not compost in the time allowed and will be screened out with the rest of the contaminates and sent to the landfill. The only way to ensure that composting could happen would be to shred your parts into fine shavings (<.06") before sending to the compost. Another issue would be that the colors and additives are most likely not food safe and would most likely contribute to chemical contamination unless specifically formulated for this purpose. Look up PFAS and BPA chemical contamination of compost from migration from treated paper products. Another toxic mess building up.

The EU standard EN 13432 mandates:
Disintegration, namely fragmentation and loss of visibility in the final
compost – this is measured in a pilot composting test (EN 14045) in
which specimens of the test material are composted with biowaste for
3 months. After this time, the mass of test material residues has to
amount to less than 10% of the original mass.

https://docs.european-bioplastics.org/publications/bp/EUBP_BP_En_13432.pdf

Adam

Adam

PLA can be composted in commercial composting facilities. It is a much more renewable plastic for 3D printing than ABS.

PLA can be composted in commercial composting facilities. It is a much more renewable plastic for 3D printing than ABS.

Me

Me

Compare hundreds of years for decomposition of PLA to effectively “never” for ABS. True, PLA may take a while, but it’s still a vast improvement over ABS. And less toxic than ABS if ingested by marine organisms. It’s not perfect, but it’s a step in the right direction.

Compare hundreds of years for decomposition of PLA to effectively “never” for ABS. True, PLA may take a while, but it’s still a vast improvement over ABS. And less toxic than ABS if ingested by marine organisms. It’s not perfect, but it’s a step in the right direction.

Mihaela

Mihaela

I’ve also been looking at the biodegradability of PLA for printing art for my home, and came across this research study commissioned by the California Department of Resources Recycling and Recovery and produced by California State University in Chico: http://www.calrecycle.ca.gov/publications/Documents/1435%5C20121435.pdf

Long story short: PLA doesn’t degrade under any measurable criteria in 365 days in a simulated marine environment, complete with sand, microbiota, 30 deg. C, etc.

For PLA degradation in landfill environments:
http://www.material.chula.ac.th/Journal/v18-2-2/83-87%20RUDEEKIT.pdf
Not much degradation there either.

A generic biodegradable polymer review article that includes a short paragraph about PLA and acknowledges (somewhat by omission) that it is only biodegradable in industrial composting facilities (by and large missing in any major US city I’ve lived in):

http://homepages.rpi.edu/~grossr/_doc/publication/SCIENCE%202002%20297%20803.pdf

and another, highly cited one:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769161/pdf/ijms-10-03722.pdf (skip to this one first if you are a science geek and want to have a bit of perspective on plastics; not all plastics are equally bad, and PLA is by far NOT the most biodegradable one.)

Scientific American thinks that a PLA bottle will biodegrade, yes, but it will take between one hundred to one thousand years, in a landfill environment:
https://www.scientificamerican.com/article/environmental-impact-of-corn-based-plastics/

The plastics of choice for good biodegradability in landfill conditions, seem to be PHB, poly(hydroxybutyrate), which is bio-based, and PCL, poly(caprolactone), which is (surprise !) petroleum-based. From here on I ran out of breath, but the next logical step would be to investigate where we can access 3D printers that use these two friendlier plastics for home projects. Please write to me at the address above if you have the answer. I wish you happy and thoughtful printing :)
M

I’ve also been looking at the biodegradability of PLA for printing art for my home, and came across this research study commissioned by the California Department of Resources Recycling and Recovery and produced by California State University in Chico: http://www.calrecycle.ca.gov/publications/Documents/1435%5C20121435.pdf

Long story short: PLA doesn’t degrade under any measurable criteria in 365 days in a simulated marine environment, complete with sand, microbiota, 30 deg. C, etc.

For PLA degradation in landfill environments:
http://www.material.chula.ac.th/Journal/v18-2-2/83-87%20RUDEEKIT.pdf
Not much degradation there either.

A generic biodegradable polymer review article that includes a short paragraph about PLA and acknowledges (somewhat by omission) that it is only biodegradable in industrial composting facilities (by and large missing in any major US city I’ve lived in):

http://homepages.rpi.edu/~grossr/_doc/publication/SCIENCE%202002%20297%20803.pdf

and another, highly cited one:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769161/pdf/ijms-10-03722.pdf (skip to this one first if you are a science geek and want to have a bit of perspective on plastics; not all plastics are equally bad, and PLA is by far NOT the most biodegradable one.)

Scientific American thinks that a PLA bottle will biodegrade, yes, but it will take between one hundred to one thousand years, in a landfill environment:
https://www.scientificamerican.com/article/environmental-impact-of-corn-based-plastics/

The plastics of choice for good biodegradability in landfill conditions, seem to be PHB, poly(hydroxybutyrate), which is bio-based, and PCL, poly(caprolactone), which is (surprise !) petroleum-based. From here on I ran out of breath, but the next logical step would be to investigate where we can access 3D printers that use these two friendlier plastics for home projects. Please write to me at the address above if you have the answer. I wish you happy and thoughtful printing :)
M

Soumyakant

Soumyakant

Being able to degrade into innocuous lactic acid, PLA is used as medical implants in the form of anchors, screws, plates, pins, rods, and as a mesh.23 Depending on the exact type used, it breaks down inside the body within 6 months to 2 years. This gradual degradation is desirable for a support structure, because it gradually transfers the load to the body (e.g. the bone) as that area heals. The strength characteristics of PLA and PLLA implants are well documented.
Source: https://en.wikipedia.org/wiki/Polylactic_acid

Being able to degrade into innocuous lactic acid, PLA is used as medical implants in the form of anchors, screws, plates, pins, rods, and as a mesh.23 Depending on the exact type used, it breaks down inside the body within 6 months to 2 years. This gradual degradation is desirable for a support structure, because it gradually transfers the load to the body (e.g. the bone) as that area heals. The strength characteristics of PLA and PLLA implants are well documented.
Source: https://en.wikipedia.org/wiki/Polylactic_acid

Meredith

Meredith

I would note that it is compostable in commercial composting facilities, like we have in Seattle. This makes it a much greener material than ABS.

I would note that it is compostable in commercial composting facilities, like we have in Seattle. This makes it a much greener material than ABS.

Steve

Steve

I didn’t realize it took so long to decompose and how misleading the claims were. I’m wondering if the pla prints degrade with absorption of water faster than abs. Thanks for enlightening me.

I didn’t realize it took so long to decompose and how misleading the claims were. I’m wondering if the pla prints degrade with absorption of water faster than abs. Thanks for enlightening me.

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