Temperature analysis of PVA and Bridge Nylon

[Anders Olsson]

I will continue testing this new forum with some hardcore polymer stuff
(The nerd level of this post is probably a bit too high for the average user, even I realize that)

A polymer chemist at out lab ran some tests on "Torwell" PVA and on Taulman Bridge Nylon.
This technique is totally new to me, but the results were very interesting, so I will try to explain them.

To start with, the results confirms is that both PVA and Bridge Nylon are hygroscopic.
It also confirms that the the horror stories about PVA degrading rapidly at temperatures higher than 210 C are certainly true!

The first curve shows how much heat is needed to increase the temperature of PVA, the slope that starts above 210C means PVA uses heat to degrade.

This curve shows the weight of the PVA sample as you heat it. Drying temperature, water content and catastrophic degradation can be seen here.

Here is the same kind of "heat needed to increase the temperature"-measurement for Bridge Nylon. The completely horizontal line above the melting point means Bridge can take heating far beyond the melting point without degrading.

In this graph we see the temperature when drying starts and the water content of Bridge Nylon. We can also see that Bridge can take a lot of overheating before it starts degrading.

I should add that PVA prints perfectly fine at 190 C, 0.15 mm layers and 40 mm/s. No problem whatsoever as long as it is kept dry.
When subjected to humidity it slowly transformed into something sticky/rubbery like half boiled pasta.

[LePaul]

Well it looks like the attachments are working well!

[Neotko]

:O wow, not that's what I call science at work.

[Meduza]

Very interesting, i would love to hear a lot more of what a polymer chemist has to say about other 3d printing filaments!

[Anders Olsson]

Yes, indeed, they know a lot of stuff that I had no idea about.
The problem is that even the most basic thing for a polymer chemist is black magic for me right now, but I am slowly learning

We had funny discussions lately, like:
Chemist: Why did you select to mix boron carbide in ABS and how did you manage to get it dispersed? (expecting scientific explanation)
Engineer: I had ABS pellets and there was acetone in the lab.
Chemist: Okay, but did the particles really disperse well, ABS is polar-whatever something- ....... there should be other polymers......... ? (engineer does not understand a thing)
Engineer: The smallest particle size was difficult to mix with the ABS, so I used the larger size particles instead.
Chemist: Yes, but I am surprised how it dispersed that well, how did you do that?
Engineer: I just added acetone while stirring until it looked well dispersed.
Chemist: Ohh, and that worked, interesting.

A slight barrier to overcome as you can imagine

Maybe one should do the DSC/TGA more often, that thing was relatively easy to understand and provides a lot of interesting information.
The first filament that came up in my mind when I got these results was the infamous Ultimaker blue vs. normal PLA.
It would be interesting to know what that evil thing really consists of.

[Meduza]

Do you have any of the infamous blue PLA to try with? We just unpacked a UMO+ kit the other day, so i have a new-in-bag roll of the old crappy Ultimaker Blue

[Anders Olsson]

Yes, I have half a spool that came with the printer left.
I have given it a new chance several times, always ending up with me concluding that something is horribly wrong with that filament

[Meduza]

Haha, i finally used up my old spool by printing a lot of my UM2 power supply holders (https://www.youmagine.com/designs/a-bet ... ply-holder) for Stockholm Makerspace with a 0.6mm nozzle, thick layers and not caring about the surface finish :p

[LePaul]

That blue PLA is horrible stuff...I still have 3/4 a roll sitting in an airtight bag.

[reibuehl]

I am puzzled to hear that so many people complain about the blue PLA from UM. The one that came with my UM2 has produced some of the best prints I did with PLA.

[LePaul]

When's your birthday? I have a gift for you

[Anders Olsson]

I have a half a spool too, but I giving it way would be a very ugly thing to do. Instead I will store it in a safe place where it is guaranteed not to come close to a 3D-printer

Honestly though, I actually got some nice prints from the Ultimaker blue too. It is extremely unpredictable to print though in particular if you have lots of retractions, it just starts underextruding and causing problems without a warning.

From what I understood Ultimaker got a reasonably large batch of faulty blue PLA at some point, which they then (unaware of the problem) started shipping. So I am sure that there are lots of spools out there that are good too, but the spool that came with my machine is the most unreliable unfilled filament I ever come across, by far.

[LePaul]

It prints out so glossy so to the human eye, you get a nice print. If you try to photograph it, forget it!

The MatterHacker Black PLA Pro is similar, but prints really well at a cooler temp. But if you try taking a picture, people will think you tried to print with wax!

[Izzy]

That was interesting, I think I am going to look at recalibration get the temperature for PLAs, I think I'm between 190 and 205 for the ColorFabb and Faberdashery ones I have.
My roll of UM Blue PLA has gone terminal towards the end, I now have lots of short lengths.

[LePaul]

I start ColorFabb at 210 to feta good first layer then back it down to 200c. Of course every printer is a little different on temp.