Hi I have this rather old spool (4 years) of Polymide CoPA (yes back when there were clear PC spools) and for the past 2 years it's been giving me headaches and acting very brittle. Even when wet it acts brittle and I'm not too sure what happened. I've dried it many times, so I think that's part of the reason, but I don't think 10-20 thermal cycles at 100C should be enough, let alone this happening pretty early in those numbers of drying. I dried this in a toaster oven for most of those cycles. I would love to print with this again especially because of warp free technology, but it really sucks that it snaps in my reverse bowden setup or when I try to lock the filament in the spool holes.
#Brittle PolyMide CoPA
dawn cipher
That looks to be on par (maybe a tad more?) with how brittle certain pa filaments are.
fresh zinc
really? this is behaving more brittle than PLA in my experience or any other brittle filament
dawn cipher
My pa6-cf filament will snap like that easy
fresh zinc
and this wasnt like this before
fresh zinc
My pa6-cf filament will snap like that easy
funnily enough... my cf nylon is less brittle than this copa rn
different brand than polymaker so cant compare like that but its pretty interesting to say the least
dawn cipher
I mean it could just be that it’s an old roll and wasn’t stored properly. Between expanding and contracting from drying and getting wet again could’ve affected its molecular structure.
fresh zinc
mmm fair. didn't expect nylon to suffer as bad as my pla does sometimes
fresh zinc
I mean it could just be that it’s an old roll and wasn’t stored properly. Betwee...
i wonder actually if I perhaps crystallized it in the oven
dawn cipher
PA is an advanced filament (sorta). Pla is the most simple on the other hand
fresh zinc
which caused shrinkage and over time the internal stresses caused it to become brittle?
dawn cipher
i wonder actually if I perhaps crystallized it in the oven
I mean those are annealing temps
fresh zinc
yeaa... i just rechecked the drying settings on the website and theyre 80c :P
iirc Polymide PA6-cf used to be 100C and thats why i also did it (used PA6-CF first) but idk looks like my spool didnt like it :(
dawn cipher
Like I said before, between it being old, having unknown storage quality, cycling wet and dry, using an oven to dry it at 100°c (possibly more because ovens often tend to be inaccurate by 5-10°), it’s prob just gone bad. But yeah pa is brittle in filament form.
dawn cipher
iirc Polymide PA6-cf used to be 100C and thats why i also did it (used PA6-CF fi...
Pa6-cf is different than a CoPA
fresh zinc
well ues that is true
sterile laurel
All petroleum based filaments, and many bio-filaments, off-gas constantly. Drying cycles add to that off-gassing. The more it happens the less stable the filament will be. You wll notice too that as you go deeper into the remaining product that it will become more and more like it was originally. This is simply because it wasnt exposed at all, or very little, to the atmosphere. Unlike moisture that can wick deeper in, those gasses cant be reabsorbed by adjacent wraps of filament.
FAFO... remove the top layer or 2 of the spool to likely find usable product
quick geyser
whats the batch number?
i'm going to guess hydrolysis has permanently degraded the material.
or the heat from drying has also aeged the filament. Probably a combination of both. Maybe for a period the heat from drying speeds up hydrolysis.
it's better to constantly store in 10% RH if using for years at a time, otherwise the water molecule will damage the material and each drying cycle technically degrades the polymer to an extent.
interesting study that relates to Nylon used to make parachutes. Different storage conditions degrading the parachute
https://www.sciencedirect.com/science/article/abs/pii/S0141391004004124
fresh zinc
All petroleum based filaments, and many bio-filaments, off-gas constantly. Dryin...
oh cool i'll give that a shot
fresh zinc
i'm going to guess hydrolysis has permanently degraded the material.
that was my theory originally. if that truly affects the whole spool, then spool seems to be kinda hard to use. I've noticed lower down though it seems to be better similar to what AceMan mentioned, but its still brittle. It's also "contextually brittle" in the sense that bending it slowly stops it from breaking and suddenly even if I bend it fast again, it acts extremely ductile. I'm still not sure what causes this behavior. Perhaps the alignment of polymer chains from the bending? complete conjecture on my part
fresh zinc
it's better to constantly store in 10% RH if using for years at a time, otherwis...
yes i've kept it consistently in a polybox for all these years
although i think at certain points the rh rose to 30% at its peak when i neglected the dessicant 😅
fresh zinc
All petroleum based filaments, and many bio-filaments, off-gas constantly. Dryin...
i forgot where I saw something also about oils evaporating and PLA becoming brittle and having a limited shelf life as a result
quick geyser
that was my theory originally. if that truly affects the whole spool, then spool...
In the hydrolysis theory, I don't see a reason why the filament wouldn't all be affected. Maybe the outer layers will absorb moisture first but the layers closer to the centre of the spool are still exposed to moisture (and during drying the heat).
fresh zinc
hmm
long estuary
Depending on the nylon it might be semi annealed