One of PLA's main selling points is its biodegradability, but is PLA really biodegradable? Keep reading to find out the truth.
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.
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.
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.
License: The text of "Is PLA Biodegradable? – The Truth" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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