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Is PLA recyclable?

By Our Lovely Earth
Page last updated: 03/05/2022 | Next review date: 03/05/2024
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Our Lovely Earth
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This article discusses how PLA gets recycled. We first discuss what is PLA and how it is made, also what organisations help to recycle PLA-containing substances.

Is PLA recyclable?

Yes, PLA is recyclable, but it cannot be recycled by the curbside recycling program. 

Despite the fact that PLA is a recyclable and biodegradable material, it cannot be recycled with other forms of plastic due to its lower melting temperature, which will cause complications at recycling facilities.

What is PLA and where is it used

PLA stands for Polylactic Acid. It is a form of polyester manufactured from corn, cassava, maize, sugarcane, or sugar beet pulp that has been fermented. 

These renewable resources’ sugar is fermented and converted to lactic acid, which is subsequently converted to polylactic acid, or PLA.

Its qualities make it appropriate for the production of plastic film, bottles, and biodegradable medical equipment (such as screws, pins, plates, and rods that biodegrade in 6 to 12 months).

Because PLA constricts when heated, it can be utilised as a shrink-wrapping material. Polylactic acid is also suited for 3D printing due to its ease of melting.

Many varieties of PLA, on the other hand, have a low glass transition temperature, rendering them unsuitable for creating hot liquid-holding plastic cups.

Is PLA environmental- friendly?

PLA manufacture consumes 65 percent less energy than traditional polymers, emits 68 percent fewer greenhouse gases, and is toxin-free. If the proper end-of-life scenario is followed, it can also remain environmentally friendly.

In ambient conditions, however, the rate of degradation is exceedingly slow, with a 2017 study revealing that the material did not degrade after being submerged in seawater at 25°C for nearly a year.

Hydrolysis, thermal degradation, and photodegradation can all be used to break down PLA:

  • Hydrolysis: By cleaving the ester groups of the main chain, the molecular weight is decreased.
  • Thermal degradation: Varying substances, such as linear and cyclic oligomers or lighter molecules with different lactide and Mw, arise as a result of this process.
  • Photodegradation: UV radiation degrades PLA, especially when it is exposed to sunshine.

PLA recycling

Despite the fact that PLA is a recyclable and biodegradable material, it cannot be recycled with other forms of plastic due to its lower melting temperature, which will cause complications at recycling facilities.

The two most common ways to recycle PLA are to send it to a facility that can process it or to grind it up and extrude it into new filament.

While this may appear to be a simple and clear response, recycling PLA is not as straightforward as it appears.

Because Polylactic Acid Plastic (PLA) is a plant-based material, one may assume that it is both biodegradable and recyclable.

Both assertions are correct, but they necessitate a more sophisticated method because PLA cannot just be thrown into the plastics bin and expect it to be recycled.

One would need to take a deeper look at how PLA is recycled, as well as what you should do with your PLA prints that came out to be so unattractive that you wanted to toss them away.

PLA is a thermoplastic, which means it melts and becomes pliable once it reaches a particular temperature. This means that almost any thermoplastic may be recycled.

The problem emerges during the sorting process at the recycling plant, because PLA is nearly indistinguishable from PET plastic, and if they are recycled together, the recycled plastic’s overall strength and resale value are reduced.

Ways to recycle PLA

There are three distinct methods one can use in order to recycle PLA, which are:

  • Sort it along with other plastics
  • Send it to a Material Recovery Facility
  • Recycle PLA using a Filament Extruder

We shall discuss these methods in more detail.

Sort it along with other plastics

PLA is a recyclable thermoplastic that may be separated from other polymers and recycled. The issue is that there are now no effective ways for distinguishing PLA from other polymers.

Mixed PLA and PET plastic streams are difficult to sort at municipal solid trash transfer facilities since they are both transparent. 

If PLA contaminates waste streams including other polymers, purchasers will give lower prices or refuse to acquire the recycled material altogether. 

PLA is a relatively new polymer on the market, thus the accompanying volumes haven’t yet achieved the critical mass needed to separate PLA from post-consumer trash. 

Many classic polymers, such as PS, ABS, PC, and PVC, have yet to reach critical mass.

Recycling along with organic waste

There is some misunderstanding about PLA’s compostability and biodegradability. PLA is biodegradable since it is created from renewable resources including starch (corn, potatoes, etc.), soy protein, cellulose, and lactic acid. 

However, this technique is only deemed “composted” if three criteria are met:

  • Carbon dioxide, water, and biomass are released when the item decomposes.
  • The PLA completely decomposes.
  • There are no harmful leftovers, and the compost promotes plant growth.

Biodegradable plastic is plastic that degrades over time due to the action of naturally occurring microorganisms such as bacteria and fungi. 

It’s worth noting that there are no requirements for leaving “no harmful residue” or for the amount of time it takes to biodegrade.

Depending on (quite high) temperature conditions and material type, the entire composting process takes 1 to 6 months in an industrial composting facility. 

In comparison to the rate of PLA composting at home, the rate of PLA composting in industrial facilities is substantially higher. 

Composting used PLA containers and cups, for example, can take anywhere from 1 to 3 months in an industrial setting and up to 6 months at home.

Furthermore, composters must follow municipal restrictions when producing compost. If PLA residues are still present in the compost, it does not comply with the regulations. 

As a result, PLA is regarded as a “contaminant” by many composters.

Send it to a Material Recovery Facility

Material Recovery Facilities (MRFs) collect and sell possibly recyclable materials to manufacturers for future manufacturing as an intermediate processing destination.

You can call your local MRF and request that they pick up your PLA, which will prevent it from ending up in a landfill. A simple Google search for “Material Recovery Facility Near Me” should get the desired results.

If you’re a cheapskate, though, you might be surprised to learn that PLA can be recycled and used to make filament again.

Recycle PLA using a Filament Extruder

Remember how PLA-based materials are thermoplastics and their ability to melt down? You may re-extrude all of your failed pieces by melting them down and re-extruding them without losing any material.

This does come at a cost, as you must either buy a filament extruder, such as the Filastruder, or create one yourself, which I must tell is not an easy feat.

However, it’s worth mentioning that the filament extruder pays for itself over time because you’ll save a significant amount of money on filament.

Disadvantages of PLA

There are certain disadvantages of PLA that can cause complications for the end-user. Some of these are:

  • Complex Process
  • Significant Investment
  • Poor Performance

We shall discuss these in more detail.

Complex Process

Unfortunately, recycling PLA isn’t as simple as cleaning it and tossing it in with your other recyclables. 

Because of its molecular makeup, it has a lower melting point than other recyclable plastics, so if it’s mixed in with them, it’ll stay solid while the rest is processed around it, causing problems at the recycling facility.

As a result, PLA is classified as a “other” plastic. And, unless you include a Resin Identification Code in each of your PLA prints, they won’t be identifiable as such, which means you won’t be able to recycle unlabeled plastics in most areas.

Before you recycle your PLA filament, check with your local materials recovery centre to discover what types of plastics they take and if you can meet all of their requirements.

Significant Investment

If your local recycling facility doesn’t accept PLA, you’ll have to look for a specialty business that can. You might have to pay a fee in that situation.

As previously noted, filament recycling equipment isn’t cheap when it comes to DIY projects. And it may never be worth it unless you’re ready to put in the effort (to perfect the process) and time (to offset the initial cost).

Poor Performance

Re-extruded filament suffers from a considerable decrease of performance unless done precisely. 

Its tensile strength is reduced from roughly 40 to 35 MPa, which means it’s more likely to break when being extruded by your 3D printer. 

It also entails a greater risk of warpage, which can cause your entire product to deform.

If you’re concerned about the quality of your home-made recycled PLA, send your scraps to a professional PLA recycler and get professionally-recycled filament (hopefully from the same organisation).

Conclusion

Despite the fact that PLA is a recyclable and biodegradable material, it cannot be recycled with other forms of plastic due to its lower melting temperature, which will cause complications at recycling facilities.

There are three distinct methods one can use in order to recycle PLA, which are: i.)Sort it along with other plastics, ii.) Send it to a Material Recovery Facility, and; iii.) Recycle PLA using a Filament Extruder.

There are certain disadvantages of PLA that can cause complications for the end-user. Some of these are: i.)Complex Process, ii.) Significant Investment and lastly; iii.) Poor Performance.

FAQs

How do you reuse old PLA filaments?

Using a 3D printer filament recycling, you may turn your 3D printed trash into fresh spools. A typical recycler will break down unsuccessful prints into smaller pieces, melt them down, and force the liquid plastic through a hole. After cooling, the heated plastic is coiled onto a reel.

Is PLA actually biodegradable?

PLA, contrary to popular notion about biodegradable polymers, can take hundreds of years to break down in a compost or landfill. Indeed, simply keeping a PLA component outside for years will have no impact on its plastic composition.

PLA plastic is a renewable bioplastic in theory since it is made from renewable plant lactic acids. These facilities, however, are only the beginning of the process of creating PLA plastic; various added chemicals and intensive procedures are also employed. 

As a result, while the PLA in a PLA product may be biodegradable, additives like impact modifiers may be less biodegradable or even non-biodegradable. 

The time it takes for a material to deteriorate is determined by its crystallinity, and the two have a direct relationship. 

The smaller the crystallinity of a substance, the easier it is for microorganisms involved in biodegradation to chemically break it down. 

Lastly, PLA has a low crystallinity when compared to other polymers, particularly those that are petroleum-based.

References