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One with Nature, Nearly

Is PLA Biodegradable? – All You Need to Know

Picture of Amir M. Bohlooli
by Amir M. Bohlooli
Feb 20, 2019
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PLA is one of the most popular filaments in 3D printing. One of its main selling points is that it's biodegradable, but is that really the case? Is PLA biodegradable? Keep reading to find out the truth!

Is PLA Biodegradable? What Is PLA and What Is It Made Of?

A roll of the popular PLA filament
A roll of the popular PLA filament Source: Amir Bohlooli / All3DP

Polylactic acid, or PLA, is the most utilized filament in the FDM 3D printing industry. It prints easily, extrudes at 180°C and has a wide variety of blends. All these make it the standard choice for beginners and professionals alike, but there’s also this other less-cited and rather unique feature: PLA is biodegradable and nature-friendly. The reason, of course, is that PLA is from nature.

PLA is a polymer made up of small lactic acid units. Lactic acid is an organic acid that plays an important role in our daily lives. The pain in your muscles when you overwork yourself and the taste of sour milk are some familiar examples of lactic acid’s role. Anything with glucose can be turned into lactic acid and the favorite source of glucose in this industry is corn. Your 3D printed model might be literally corny.

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Is PLA Biodegradable? Where and How Fast Does It Happen?

Metamorphosis of frogs is quite different in the 3D printing world.
Metamorphosis of frogs is quite different in the 3D printing world. Source: Amir Bohlooli / All3DP

The process of biodegradation and its duration is highly dependent on the environment. In short, heat, humidity, and microbes are the three necessary elements for visible degradation in the span of one year.

PLA decays best in high-temperature environments with rich microorganism presence. Soil could be one, but to reach the required heat (around 60°C, the PLA glass transition temperature) you’ll have to bury your print deep in the dirt. It takes roughly six months for visible cracks and signs of decay but that too profoundly depends on your soil sample.

PLA takes much longer to degrade in room temperature and pressure. In a regular room, PLA will endure for many long years. Sunlight doesn’t speed the biodegradation (apart from the heat) and UV light only causes the material to lose its color and go pale, the same effect it has on most plastics. 

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Is PLA Biodegradable? Good or Bad?

PLA biodegradation in landfill conditions
PLA biodegradation in landfill conditions Source: Journal of Metals, Materials and Minerals

Whether this slow process of biodegradation is good or bad depends highly on your perspective and the use you have in mind for your object. According to sustainable development principals, biodegradable materials are ideal because they eventually return to nature. This is beneficial, for example, in situations where the object is intended to disappear after a certain time, like in bone surgeries, for instance. 

On the other hand, most printed objects are meant to stay unchanged. And fortunately, most will stay that way. As mentioned above, biodegradation of PLA requires conditions that are not present in the everyday environment that we live in, and your PLA prints will endure much longer if you counter the biodegradation requirements. In other words, keep them in cool, dry places. 

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Is PLA Biodegradable? Recap

PLA is naturally transparent, though it looks white when layers stack up.
PLA is naturally transparent, though it looks white when layers stack up. Source: Amir Bohlooli / All3DP
  • PLA biodegrades because its origins are natural and microorganisms can feed on it to turn it into compost.
  • Humidity, 60°C temperature, and microorganisms are required, which can be found in garden soil.
  • In good conditions, PLA will show signs of biodegradation in 6 months.
  • In ordinary room-conditions, PLA will endure for hundreds of years.

See also: Is PLA Food Safe? – What You Really Need to Know

License: The text of "Is PLA Biodegradable? – All You Need to Know" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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