Sometimes you see an FDM filament pop up that makes you do a triple-take because it doesn’t seem to make a lot of sense. This is the case with a hybrid PLA/PETG filament by Stronghero 3D that features a PETG core. This filament also intrigued [Dr. Igor Gaspar] who imported a spool from the US to have a poke at it to see why you’d want to combine these two filament materials.
According to the manufacturer, the PLA outside makes up 60% of the filament, with the rest being the PETG core. The PLA is supposed to shield the PETG from moisture, while adding more strength and weather resistance to the PLA after printing. Another interesting aspect is the multi-color look that this creates, and which [Igor]’s prints totally show. Finding the right temperatures for the bed and extruder was a challenge and took multiple tries with the Bambu Lab P1P including bed adhesion troubles.
As for the actual properties of this filament, the layer adhesion test showed it to be significantly worse than plain PLA or PETG when printed at extruder temperatures from 225 °C to 245 °C. When the shear stress is put on the material instead of the layer adhesion, the results are much better, while torque resistance is better than plain PETG. This is a pattern that repeats across impact and other tests, with PETG more brittle. Thermal deformation temperature is, unsurprisingly, between both materials, making this filament mostly a curiosity unless its properties work much better for your use case than a non-hybrid filament.
Very thorough and informative video. I really like his test setup. It would be wonderful if the community could agree on a set of standardized tests which reputable manufacturers could perform and publish.
WUT. PETG is more moisture-resistant than PLA. It’s resists with sun UV. PLA is a bit more rigid than PETG and it may be some reasonable to put PLA core inside PETG, but why they made vice versa.
WTF are you talking about. PETG absorbs MORE moisture than PLA. Maybe you should do a simple google before commenting
It absorb moisture ok, but then what? Leave a PLA pool open for 3 months and a PETG pool in the same situation, you can’t print with PLA anymore (the filament becomes brittle and breaks for any reason), while you’ll (only) get strings with PETG. Putting PETG inside the PLA core prevents the PLA from breaking (the PETG doesn’t break and likely prevent moisture from creeping into the PETG. If you do the other way around, you won’t gain much, but again, I’m not convinced there are any gains at all.
PETG doesn’t adhere to PLA (or vice versa), so the combination is obvious that layer adhesion will suffer. All in all, it’s a bad idea, IMHO.
Yeah, the PLA+PETG combination seems weird to me too.
But the idea seems good, there might be some other material which would be better suitable for moisture protection.
Petg and pla are only a good combination when one is the print, and the other is support. While it creates a lot of “poop”, on intricate prints with tons of support, nothing beats the combination. (Although finding the right “middle ground” nozzle temp is dependent on which pla and which petg are available.
Disagree about PLA vs PETG – PETG is universally considered to be very hygroscopic, while a lot of PLA options are famously resilient as far as storage and forgiving printing goes. Having said that, a filament being hygroscopic isn’t necessarily a problem in a finished part – nylon in infamous for being horrible to keep dry enough to print but no one sweats leaving nylon parts out in the air.
As for this, I’m guessing the idea was that the PETG could provide a slightly higher temperature resistance to the parts by acting as a skeleton while being easier to store and therefore print than pure PETG, plus the layer adhesion issue isn’t obvious since it should be PLA adhering to PLA anyway (there’s been other dual filaments like this before and the core doesn’t meaningfully mix with the outer sleeve material) – of course, when it was tested and found to still exhibit layer adhesion issues in the real world they should have probably stopped there rather than bringing it to market, but maybe they found some sort of niche use case that doesn’t rely so much on layer adhesion? Not a filament I could think of a use for personally but I appreciate the experimentation if nothing else
To clarify on PLA, there’s definitely some options that become brittle very rapidly but it seems to be an issue with specific blends rather than intrinsic to PLA, I’ve got some PLA spools that work just fine after no attempt at all to store them dry for some time – they’re a bit more brittle than brand new but not enough to matter, and it’s not even close to the degree of stringiness you get from leaving PETG out for even a week in some places
It’s a 2 part answer. Unprinted PETG in filament form is of course affected by moisture during the printing process. However, a printed part from PETG is more moisture resistant than PLA. That means, contact with moisture does not degrade the material as much as it would with PLA.
PETG absorbs more moisture than PLA which makes it ooze and bubble during printing, but PLA becomes brittle when it hydrolyzes as anyone who’s tried to use a roll that’s been open for a few years can confirm.
PLA isn’t moisture impervious, so I doubt it shields the PETG well. If that weren’t the case then an embrittled PLA coating wouldn’t be a big deal. With all the above and the poor bonding between the two, I don’t know why this is a product and didn’t stop at being a fun experiment.
Idk man I don’t see a lot of PLA water bottles out there
I don’t see a lot of PETG bottles either though (PET is a very different and much tougher beast than PETG), although I would still pick PETG over PLA for a print intended to get wet/hold water
It’s about absorbing less moisture prior to printing. Absorbed moisture is not an issue with an end-use product but it makes the printing process less reliable, i.e. stringing, blobs, poor layer adhesion, etc.
what about pla with an abs core so the pla holds the fumes in and sticks to the bed
Or ASA?
Or tpu!
Low durometer TPU with a thin PETG core to add rigidity during printing might work
That is what carbon fiber TPU is for :)
I’m kinda old school tech/engineer and I find myself asking only one question: what urgent need is being addressed by this material?
Show me the problem that this stuff ‘fixes’, and maybe I’ll have a more open mind.
The urgent need is called some guy at the factory messed up and we need to sell five pallets of this stuff.
The reviews on it aren’t kind either. I don’t know if Strong Hero is a real company in China or just some lazy person in an apartment here in the United States, but this couldn’t have been intentional.
I can’t think of a way to do this by accident though unless it’s being made on a line that already produces multiple different hybrid filament options – the extruders used to make hybrid filaments like this are far more expensive than basic single material options
I suspect it’s people just throwing random sh*t at the wall to see what sticks / what sells – you can make almost any bizarre and awful filament and you know you’ll sell at least 100 rolls to the various youtubers out there who want to talk about it.
Hmmm…. Thinking that wrapping a bunch of this around an old primary wire spool and leaving it at a workplace could be fun!
Evil. You are evil.
I think this was a mistake, and there’s just enough suckers who would be willing to buy it because it has a sale price and is available on Amazon.
Stop giving bad companies money like this.
I’ve been watching Igor since he had about 40 subscribers and he has gotten better and better at testing methodology and presence, I really enjoy his content.
Stronghero3D has always been my favorite petg supplier, I don’t have any experience with their PLA but the petg is excellent every time.