Blog

Fact: PLA is biodegradable
Fact: Nature cannot decompose pla without human help

You will probably say that these 2 facts are very contradictory, but they are equally true.

So is PLA really biodegradable or is it just marketing?

"PLA (Polylactic acid) is made from natural corn starch, biodegradable and BIO! "

In this manner PLA sounds (and smells) so good that we can slowly start 3D printing gnocchi at home and eat them.
This is how PLA is sold to us, this is how we will sell it to you because it is in fact true, PLA will be biodegradable at some point.

However, marketing will not specify when and how the PLA will be this perfect.
Let's start with a very important definition: What does "Biodegradable" mean?

– That I throw it into nature and in 2 months it's gone
– A substance or object capable of being decomposed by bacteria or living organisms without polluting the environment.

Reality:

PLA will still be just plastic, and if we don't treat it responsibly, nature won't cope, despite all its amazing BIO properties. PLA will take thousands of years to decompose in our normal climate, and our print will be just another piece of plastic in nature. PLA is not as weak material as it seems to be.

So how to decompose PLA? (Recipe)

PLA = Industrial composter + 60°C constant temperature + 2/3 organic substrate cocktail + 80% humidity + lots of oxygen + minimum 5 days.

These conditions may be available to 0.1% of us, and thus in the other 99.9% of cases, a PLA printout can be considered an ordinary piece of plastic that will lie next to other plastics for the same amount of time.

Which PLA is the least harmful?

The least modified PLA is transparent (uncolored), as this is its initial form after production. Transparent can be considered as "Real unmodified raw PLA". By the way, it is also the best printable. Black, blue, red, and all colored plates are already modified by adding color pigments, manufacturers have different pigments, so it is not possible to determine an exact rule about which color is the most harmful. In general, black filaments are the most modified (it is necessary to put more pigment into them than others) and therefore filaments of the same material but of a different color may be printed slightly differently.

However, Pla will still have an advantage over other plastics, namely that when it decomposes after those x years, it will not leave behind anything harmful (according to the definition: it decomposes without polluting the environment)

What do we propose? – Conclusion

The most ideal general solution that currently exists for plastics is to preserve them in their final form and reuse them.

We ask you to work with our filaments as responsibly as possible, and in any case, whether it is PLA, ABS, PET-G, never throw away the remnants after printing in the yellow container. This is because the surpluses after printing are not marked and only cause problems in the sorting lines. Unfortunately.

The least modified (and best printable) is transparent PLA. It is still better to use PLA than for example ABS, as when PLA finally decomposes, it leaves no traces behind.

For almost every material, you can find information about its "heat resistance". However, this term is very broad and does not have a clear definition across websites. If the heat resistance of the material is key for your application, a deeper understanding of the individual terms on the technical sheets is necessary. Let's start with what we encounter most often:

Glass Transition Temperature (Tg)

Tg is the temperature at which the crystalline or semi-crystalline part of the polymer begins to melt and changes from an ordered structure to an amorphous structure.

Simply put, it is the temperature at which the internal structure of the material begins to change and the material "begins to lose" its mechanical properties. At first glance, it may seem that if we exceed Tg, we can no longer rely on the print from the given material. However, Tg is treacherous in that it doesn't say anything specific about the mechanical properties, only that they change, but by how much, Tg won't tell us. Tg is not a mechanical stress test but a chemical property.

So if Tg doesn't tell me much about mechanical properties, what should I be looking at?

The second term we will introduce is:

Heat Deflection Temperature (HDT)

"HDT is a measure of the polymer's resistance to deformation under a given load at elevated temperature." In practice, it is the temperature at which a given polymer sample will be bent by 0.25 mm under a given load. 2 the most commonly used loads are: - 1.8 MPa (264 psi) ISO 75 -A– 0.46 MPa (67 psi) ISO 75-B

HDT represents the degree of stiffness of the material when the temperature increases, for mechanical applications it is much more relevant than Tg!

The difference between Tg and HDT can best be illustrated in the example of two materials directly from our e-shop: PLA Filament-PM:

• Tg: 55°C, HDT (method unknown, we will assume 0.46MPA): 55°C
• PolyMide™ PA6-CF PolyMaker: Tg: 56.6°C , HDT 0.46MPa: 215°C!
  

Fun fact: We deliberately use some materials above their Tg (TPE, TPU) because then they have more useful properties for us (flexibility).

Sources:
https://www.toppr.com/guides/chemistry/the-solid-state/crystalline-and-amorphous-solids/
https://omnexus.specialchem.com/polymer-properties/properties/glass-transition- temperature
https://omnexus.specialchem.com/polymer-properties/properties/heat-deflection-temperature-of-plastics
https://www.iso.org/standard/55653.html

We asked AI how it could help 3D printing