Chemical compatibility test: Formlab resins vs. KOHaq

[programlich]

Long term compatibility test of clear v4 at room temperature

Solution	T (°C)	t (h)	$m_{v4}$ (g)
KOH 29.9 w%	~20	0	1.206
KOH 29.9 w%	~20	23	1.2043
KOH 29.9 w%	~20	51	1.2045
KOH 29.9 w%	~20	140	1.2049
KOH 29.9 w%	~20	308	1.2063

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Compatibility test of resin v4 and rigid 10k at 80°C

Solution	T (°C)	t (h)	$m_{v4}$ (g)	$m_{10k}$ (g)
KOH 29.9 w%	80	0	1.2092	1.7293

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First quick compatibility test of clear v4

Sample	Resin	Solution	Temperature (°C)	$m_{t_0}$ (g)	$m_{t=23h}$ (g)	$m_{51h}$ (g)	$\Delta_{m, t=23h}$ / %
1	clear v4	KOH 29.9 w%	~20	1.206	1.2043	1.2045	-0.141
2	clear v4	KOH 29.9 w%	~45	1.2112	1.2085	1.2090 (@~20°C)	-0.223

[sgbaird]

I'm planning to print the Rigid 10k cubes.

1. Should we do larger cubes? (before was 1 cm^3, should we do 2 cm x 2 cm x 2 cm?)
2. Keep the numbering label? (I'm guessing yes)
3. OK to print directly on the platform, or should we have the mix of direct platform and ones with bases?
4. Which ones did you use? (i.e., which were samples 1 and 2)
5. These samples were manually washed and then cured, correct?

[programlich]

1. Lets to the 10k rigid cubes with the same dimension, as these fit perfectly into the round neck flasks -> 1cm^3
2. Numbering is perfect
3. Please print directly on the platform -> results in more homogeneous shape
4. Sorry, I don´t get the question
5. Yes, exactly

[sgbaird]

4. sorry, were samples 1 and 2 printed directly on the platform, or were they ones with a base?

[sgbaird]

[programlich]

Ah, I think they were both not printed on the base, if I remember correctly

[sgbaird]

All good - probably shouldn't matter, just wanted to double check.

[programlich]

Chemical compatibility after 51 hours still seems to be reasonable good. No clear degradation could be observed. However, I think it will be a lot more interesting, investigating at 70 or 80°C. Haven't done that so far, because the hotplate did not get the water bath warm enough. Will do that next week for a couple of hours with a flask directly placed on the hotplate.

[sgbaird]

Sounds good! If it stabilizes, that would be ideal. (EDIT: if the mass stabilizes)

[programlich]

Definitely.
I just figured out that the safety temperature of these hotplates controlles the temperature of the hotplate itself, not the one measured by the thermocouple (it works that way with the ones I use back home). This is why I did not get to the desired 70°C in the water bath. Will repeat the high temperature experiments next week with both, v4 and rigid 10k resin.

[programlich]

I added a last value of the compatibility test at room temperature. As you can see, over time the mass is slightly increasing, which might either be due to not perfectly washed cubes with remaining KOH on the surface or to some kind of swelling mechanism. Either way, the mass remains more or less constant over time at room temperature. The more interesting tests will start when I do electrochemical tests at elevated temperatures. For now, I think we are good to proceed this way