Are materials still hygroscopic after printing?  

RE: Are materials still hygroscopic after printing?

Simple answer is yes.  Its still the same underlying material.

RE: Are materials still hygroscopic after printing?

Neophyl gave you correct answer.

However...
Posted by: @kev-3

If using  prints to use as a tool organizer, like a wrench holder or socket organizer, is there a chance of the print could absorb enough moisture to cause corrosion? At points of contact of the metal tools, over a period of time.

No, printed objects won't cause corrosion of your tools. If that would be the case, then no tools would be saved in plastic boxes or holders. Being hygroscopic means, material tends to absorb (not release) humidity from environment (air). Amount of humidity filaments can absorb, is much lower than surrounding humidity. When we talk about "wet filament", it just means it absorbed certain amount of water... but is never really wet, of course. In short, if tools start to corrode then that's because of surrounding air.

RE:

Yes.  The moisture is bound though so although it will eventually contribute to corrosion the reactions will be greatly slowed.  Whilst damp cardboard may allow contents to rust in days hydrated thermoplastics will need months, probably years before equivalent damage - most of your non printed plastic containers have similar chemistry and you can expect similar performance.

Cheerio,

RE: Are materials still hygroscopic after printing?

I printed several tool organizers for my basement work bench a few years ago and have not had any issues with rust on the hand tools stored in them. Some are printed in PETg and a few are PLA.

The main reason we care about moisture in the filament is that it boils when the filament is melting. The increased pressure from the vaporizing water causes mechanical issues like voids and such. If I remember correctly the high temperature water vapor also reacts with the molten plastic terminating the polymer chains resulting in a weaker end product.

RE: Are materials still hygroscopic after printing?

PLA will get brittle though when it absorbs moisture and that changes mechanical properties a lot. I learned the hard way when it happened to some PLA parts in a ceiling lamp I made. The parts that attached the whole thing to the ceiling were printed in PLA (and most likely not too well designed either) simply disintegrated around the bolt holes that held them in place and the whole thing dropped down 🙁

So probably no heavy wrenches stored on PLA hooks over fragile items...

RE: Are materials still hygroscopic after printing?

I've had a PLA printed gear sitting in a toilet tank (above the water line), part of an automatic flush actuator, for about two years now, and the humidity level in there from the evaporation has to be high, and it has not degraded at all, at least so far.

RE: Are materials still hygroscopic after printing?

I'm too lazy to test my hypothesis but I'll just throw it around anyway:

I have the suspicion that some brands do freely change the suppliers of their base polymers as well as the colorings. Thus generating rather different products from batch to batch. I don't say everybody does it, neither am I implying it is only cheap brands but (hehe, everybody knew this was going to be sentence with a but) so far I had batches from a small local supplier that varied differently between batches (the first tentative buy was absolutely brilliant, the second round about a year later and much bigger prints awful and is basically splintering when you look at it the wrong way three days after printing (freshly dried spool).

Sorry, shouldn't have hijacked the thread for my rant.

disintegrated around the bolt holes

PLA does evade continuous stress, especially when warmed a little so it may have been a poor choice for this task.  When given a chance to recover it lasts a long time so does well with projects like @jsw's where the stresses are intermittent.

Cheerio,

RE: Are materials still hygroscopic after printing?

Posted by: @hawai

PLA will get brittle though when it absorbs moisture and that changes mechanical properties a lot. I learned the hard way when it happened to some PLA parts in a ceiling lamp I made. The parts that attached the whole thing to the ceiling were printed in PLA (and most likely not too well designed either) simply disintegrated around the bolt holes that held them in place and the whole thing dropped down 🙁

 

So probably no heavy wrenches stored on PLA hooks over fragile items...

I wouldn't use PLA for that kind of application--it's not suited as you found out. I'd print in ABS for that.

RE: Are materials still hygroscopic after printing?

If I ever give this project another go I'll most likely use PC for it Prints so much nicer than ABS/ASA.