4mo ago

PLA Print Degraded Over Time

This was an ornament I printed roughly 6 years ago. Being a Christmas ornament it spent most of those 6 years stored in my roof space.

Being in Australia this would have been subject to average temperatures of 30 to 35 degrees c but also peaks across summer approaching 70 degrees c. Also in high humidity.

The PLA crumbles into tiny pieces at the softest touch.

I thought it was interesting that PLA would start to break down in these conditions.

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60C is when PLA starts to warp, but even lower is when it starts to degrade. 6 years is more than enough for this level of degradation even in a less volatile environment.
- It’s interesting to me the reported natural feature of PLA to be biodegradable. The state it ends up in these conditions almost seems worse for the environment like micro plastics.
  
  PLA is widely used as a medical plastic and its normal decomposition is into lactic acid.
  Even if it is just being atomized down into smaller and smaller particles it's safer for you than any other common plastic.
  The colorants added are the only risk
  
  After reading a bit, it seems that you are correct. Under natural conditions PLA wont actually turn into non toxic compounds at all. Biodegradable just means that it can be theoretically done. The conditions necessary for it are however only available in industrial, heated and controlled composting systems. Without those conditions it will break apart but it will stay bad for the environment on a chemical level.
  Just look up "PLA biodegradable test" on a search engine or youtube and you will find plenty of people that tested this.
  
  It will decompose, but only it a hot compost pile.
  To some extent, this means large scale composting, but you could theoretically do it at home if you live somewhere with four seasons (specifically fall) and have trees that drop leaves on your property or nearby. Let your grass get a bit taller as the trees start turning and mulch/bag the grass and leaf mixture. Bonus points if you have a ratio of 30 carbon (brown stuff) to 1 nitrogen (green stuff) by weight. "Normal" composting into. This is why big piles of fresh mulch get pretty warm and stream in the middle.
  I don't know what it would take to break down PLA in compost, but suspect it would take more time than a typical home pile if you manage to get it hot. It would probably be benefit from shredding to speed things up, as would the rest of the stuff in a typical compost pile. Amusingly, your PLA is probably ripe for getting whacked with a hammer, or a hammer mill.

average temperatures of 30 to 35 degrees c but also peaks across summer approaching 70 degrees c. Also in high humidity.
Oh Australia... 🫠
- You'd get those kinds of attic temps in many places in the US.
  Attics are no place to store stuff, keeping them under 140f in the summer is a challenge
- Tis fucking hot and fucking humid, well here in bris anyhow.

My boss printed me three LEGO bricks when he got his 3D printer (everyone here knows I am an AFOL = Adult Fan Of Lego). I have no idea what kind of printer that was, but the bricks were very detailed. Now they have totally warped out of shape. I kept them on my desk in the electronics lab, so heat or sunlight are no major issues here.
- Resin printer probably
- Maybe fumes from solvents in the room?
  
  No solvents, thank goodness. It's a lab, but it's an electronics lab. And no, anything with soldering or cleaning boards is done far elsewhere.

70 Celsius degree and humid? Bro where it is in Australia? Since i see that even in Dubai it peaks around mid 50s and not humid

Heat and humidity. Humidity more than the heat in my experience. Spools of pla get brittle if left in a humid environment.

Humidity ruins PLA. It turns brittle AF once it has absorbed any major amount of moisture, and that is significantly sped up with temperature.

It hatched.

it's a starch-based polymer, isn't it? it will be readily metabolized by the various ubiquitous species populating our biosphere. i suppose it's a good thing. possibly the only microplastic that doesn't suck
- it will be readily metabolized by the various ubiquitous species populating our biosphere. i suppose it's a good thing. possibly the only microplastic that doesn't suck
  Not really, it is considered compostable in industrial composting conditions. It will not degrade at a reasonable timeframe in natural conditions and will basically just remain micro plastic.
  
  yep sadly PLA being ok for the environment is a big ol myth unless it is either turned back into filament or properly recycled / industrially composted

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