PLA parts exposed to the outside environment

[xrunner]

I designed a custom dipole antenna insulator as a test about 5 years ago because I couldn't find anything that really fit what I want in an insulator (my own personal desires). I originally just wanted to see how bad they would end up after one year if subjected to a full year of seasonal temps and weather if printed in PLA. PLA is not recommended for this type of application (UV exposure etc.), but I just wanted to see what would happen. If you don't know what they are for, they connect the end of an antenna wire to a support line. This support line is held at the far end by something which puts tension on the wire, thus keeping it straight. This is installed at both ends of the dipole antenna.

Regarding PLA and the environment -

PLA isn’t UV resistant and will be negatively affected by sunlight over a long period of time. ABS has better UV resistant qualities, but one of the most UV resistant filament is ASA, which is an alternative from ABS. Not only is it easier to print with than ABS, but it is more durable overall.
PLA is a biodegradable plastic that is made from renewable resources such as sugar cane or starch of corn.

Just because it is biodegradable, doesn’t necessarily mean it won’t fair well outside in the sun. It may start to become more brittle and lose its rigidity, but for the most part it will keep its main form and strength as long as it’s not functional. Basically meaning you can leave PLA out in the sun for visual, aesthetic pieces, but not for let’s say a handle or mount.

PLA is more prone to weathering compared to other plastics used for 3D printing as it is biodegradable. It is found that exposure of PLA towards UVC for 30 to 90 minutes can shorten it’s time of degradation.

https://3dprinterly.com/is-pla-uv-resistant-including-abs-petg-more/

The first set I installed for a year didn't suffer any significant damage, so I took them down and re-installed a new set for a longer test. That was four years ago. I printed them in white PLA so they wouldn't get so hot in the sun. I used up the rest of the white PLA for other projects and ordered a new roll from Atomic filament. Due to other maintenance on the antennas, I decided to make a new set of insulators for the dipole antenna and take down the ones I put up four years ago; having the same tension applied for four years. Truthfully, I really forgot about them because they were holding up so well.

After examining the insulators, having been in the environment year-round for four years, I was really pleased with the performance of PLA. In the pic you can see the new one I printed yesterday, and the old one I just took down after four years. It exhibits a slight bending at the middle bar where the force of the pull was felt. I re-designed the insulator to have a wider center bar. But other than that, they performed extremely well, far better than I would have guessed. What is your experience with PLA in the outside environment?

[MarkF]

I have about the same experience as you.
I have a pole light in the front yard with a short horizontal bar that had plastic balls on the ends.  The plastic eventually broke and came off.  I printed new ones in white PLA in 2020.  So far, except for being dirty, they are holding up and look like new.  They aren't under any strain as what you did.  Good to know.  I mostly use Hatchbox PLA for my prints.

[Brumby]

With a possible question in regards shading, I would suggest your success up to this point is due to:

1. The choice of white filament - because white reflects
2. The aerial location - with plenty of air flow and away from the immediate proximity of heat radiating bodies, such as concrete paths and brick walls.

I'd be tempted to add latitude and normal weather patterns as factors as well.  For example, would the outcome be the same in Texas or Australia (say, Sydney)?


Either way, it's always interesting to hear of the experience of others.

[CatalinaWOW]

I have used PLA in a number of outdoor applications and have had no issues to date.  Longest application is an adapter to route water from a gutter downspout into underground drainage.  About four years, in direct sunlight, against a concrete block wall and adjacent to the ground.  Environment is Southern Oregon with hot sunny summers and cold wet winters.  Another application is a finial on top of a flagpole.  This gets the most sun exposure, but also is also painted with a metallic paint for decorative reasons.  The paint eliminates all UV concerns and may reduce temperature because of reflectivity.  Most of my applications are not structurally challenging, but I don't see any crazing, shrinkage or color changes which would indicate incipient problems.

With proper structural design I don't see any issue with using PLA outdoors.  Your antenna application is as close as I can think of as an exception, simply because of the difficulty of replacement.  For most things, even if it does degrade and become unusable after a few years it is cheap, quick and easy to replace.

[xrunner]

With a possible question in regards shading, I would suggest your success up to this point is due to:

1. The choice of white filament - because white reflects
2. The aerial location - with plenty of air flow and away from the immediate proximity of heat radiating bodies, such as concrete paths and brick walls.

Correct, I chose white to avoid extra heating with a dark color. The airflow doesn't hurt, but it also means the part is hung out to get maximum sun exposure also. There is little shading except for very late in the afternoon say 5 PM.

I'd be tempted to add latitude and normal weather patterns as factors as well.  For example, would the outcome be the same in Texas or Australia (say, Sydney)?

Would it be the same in Texas? I know exactly what the results would be because ... that's where I live - North Texas. 

I attached a screenshot of historical temp data from July of 2023 (just one of the four years it was outside in the same place). Last year's temps were brutal July through September.

[TheSteve]

I've had thinner black PLA prints warp in the sun within an hour. I'm sure using white is key. Myself I'll still stick with petg whenever possible.

[thm_w]

I had a black PLA bike mount crumble after a years use, maybe 1hr of sun exposure every day. Others have had PLA crumble even when stored inside.
Depends on the quality, color, and additives in the PLA probably.

As Steve said, I'll stick to PETG for anything outside.

[xrunner]

As Steve said, I'll stick to PETG for anything outside.

So would I. As I said I'm just experimenting and I wouldn't sell them for outside use or recommend it to anyone else. I'm simply showing what happened when I experimented using PLA for an outside project. 

[thm_w]

No eye roll is needed here

[CatalinaWOW]

I actually use PETG for almost everything now.  The extra degrees of temperature usability gets me away from all problems I have had.  None solar driven for me, all artificial heat sources.

[Whales]

Black plastics tend to be UV resistant because of the use of carbon black.  (I only wish this were true of white)

[Brumby]

Would it be the same in Texas? I know exactly what the results would be because ... that's where I live - North Texas. 

OK .... I walked into that one.   

[diminddl]

From my experience it really depends on the brand and composition of the PLA filament. I had some cheap Chinese stuff melt in the sun within hours, and other higher quality PLA holding up to 60C temps in my enclosed ABS 3D printer for months. I think generally if you use white name brand filament with a large number of perimeters then you can get away with it being outside for a long while. You can improve it quite a bit by annealing the printed part as described https://blog.prusa3d.com/how-to-improve-your-3d-prints-with-annealing_31088/. But if you want truly weather proof stuff there is no competitor to PETG/ABS/ASA.

[kosine]

Perhaps worth pointing out that PLA is NOT regarded as biodegradable in the environment and requires hot composting to break it down. Even then, it's only certified up to a couple of mm in thickness. (You only get 6 months in an industrial compost heap, larger items take too long.)

As far as I'm aware, there are no PLA compounds currently certified for soil biodegradation, although BASF do have a couple of PBAT/PLA materials that are TUV listed (part of their Ecovia range, M2351 and M2361). However, these seem to contain no more than 10% PLA, possibly because the test standard only requires 90% biodegradation over 2 years. I don't know if anyone makes printer filament from PBAT, but it's a fairly easy plastic to work with.