how to deal with old filament
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@arhi I don't know about mythbusters, but I lived in Phoenix for a few years and the plastic parts of my car, primarily ABS (maybe a different formulation than we print with), never melted, and neither did the bracket for holding my GPS unit or the GPS unit's housing. OK, no boiling water in printed plastic cups, that's easily avoided, since prints are usually not watertight anyway. I'd worry more about boiling water leaking on my hands and burning me more than I'd worry about the cup melting. I have put ABS prints in my dishwasher for a few cycles and they came out unscathed.
I'm not sure how well PETG holds up in a hot car. Maybe not much different than PLA. I'll go put a print out in my car now and see how it goes.
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@mrehorstdmd I lived in LA for a year, ABS holder for a nokia phone (not printed but injection m.) was bent beyond recognition. HDPE cup colder too (not the factory one). Here in Belgrade we have 43-45C days during summer, never measured temperature inside the car but have PLA parts that survived years (I did not expect them to), I often mention my PLA holder for external thermometer sitting outside for 7th year now, direct sunlight, easily over 60C during summer, easily -20 during winter (not every winter, not every day but) and is still going strong like day1, it is not colored any more, color is gone, but the part itself changed less than the plastic casing of the wireless sensor itself. You need 180+ for PLA to really make a mess, it will lose strength and bend at high temps but so will most other thermoplastics, that's why most of the stuff in your car is made from PC or better; pet, abs, hips... not that much
Anyhow PLA is not that "pure" material, there is PLA and there is PLA so...
What's much more important than temperature resistance of thermoplasts is this difference in aging of filament vs printed parts. It's different - A LOT different and I don't see a reason why
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@mrehorstdmd I am not printing printer parts in PLA -- sorry if I was being unclear. I am reasonably fine with PETG parts, but I'm gravitating towards ASA more and more.
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I also have problems with the PLA becoming brittle inside a PTFE tube. It's different between different brands. EasyPrint from 3D Prima is worst I have, It's enough for it to be left half a day inside PTFE and it's broken in several places.
Generally all materials get brittle when they absorb moisture and I dry even my PLA for better end results. -
problems again, opened 7+ year old box of ABS ... behaves like crap .. does not crumble like PLA but it's rather unprintable ... 24h in dehumidifier at 70C, did not help, still unprintable.... I don't get it, was never exposed to UV, in original vacuum bag with desicant, no water... also does not print like wet filament it just behaves weird - poor layer adhesion, mega warping, curling out of the nozzle...
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At the start of the covid-19 pandemic I used several old rolls of eSun ABS that were never stored properly to print faceshields. I did dry them before using as insurance policy, and had no single issue with them. Printed like new.
The advantage of ABS was that I was able to heat all the faceshields I printed to 80C, making sure that no virus was alive on the shipped parts.
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@DaBit this was also eSUN and also ABS ... only around 8 years old I think and it was in the pile with PC and PA so that's why it was unnoticed for a while
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This looks similar to a problem experienced in the UV ink print industry when printing older new media vs fresh new media ( both never used and in sealed bags) plastizers in the older media migrate to the print surface causing unexpected print results .
Turns out PLA uses all kinds of plastizers as well and they also can change wildly over time depending on what plastizer is actually used , which may explain what your experiencing
I went down a rabbit hole of info , this one was an interesting read
Printability, Mechanical and Thermal Properties of Poly(3-Hydroxybutyrate)-Poly(Lactic Acid)-Plasticizer Blends for Three-Dimensional (3D) Printing
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@DigiD said in how to deal with old filament:
Printability, Mechanical and Thermal Properties of Poly(3-Hydroxybutyrate)-Poly(Lactic Acid)-Plasticizer Blends for Three-Dimensional (3D) Printing
The article you point to seems to indicate the plasticizers were needed in the PHB/PLA mixes, which are extra-biodegradable mixes. In those mixes, they behaved badly without plasticizers. I didn't see anything in there saying pure PLA has plasticizers. As far as I know it doesn't. Anyone an expert on this?
On the other had, I have had a few spools of PLA go completely brittle. It's been more a problem with 3mm diameter filament, which is already very stiff, and I think a bit of differential embrittlement of the outer shell makes it useless.
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@mendenmh I would bet the PLA+ blends have more plasticizer.
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I have some 11 year old natural PLA from bitsfrombytes, 3mm dia, that you can't unspool
.. it does not crack as easy as some modern old PLA but is hardened so much you can't uncoil and straighten it .. I did manage to print with it using a heat gun to heat it up while unspooling but is a manual process acceptable for test only, not for actual printing; it's only total of maybe 500g so not really a big deal (when I remember how much I paid for it it hurts) ... but this last issue was with ABS. Not sure why this happens. I seen few times in videos of ppl like Tomas or Joel that they mention "these are old spools of filament that is unprintable" so they too have the issue of - after some time on the shell filament is unusable, but why ?!Also, what's weird, as I already mentioned, I have pieces printed out of PLA that are 10 years old and still are totally ok, never became brittle?! Why does filament becomes extra brittle and week while printed part does not ?!
