Thursday, November 01, 2007


Furfuryl Alcohol and blocked catalyzers

Hi all!

Today I made some progress on the blocked catalyzer for Furfuryl resin mixes.
As a reminder, the catalyzer is para-Toluene Sulfonic Acid (pTSA), wich is a strong organic acid, in solid form. I have dissolved it in Isopropanol alcohol (a solvent quite similar to Ethanol).

This catalyzer, if added in this solved form to Furfuryl Alcohol (FAlc, the actual polymer resin) will cause it to polymerize extremely fast and under the release of heat. This should not be done, take my word! ;)

The trick here is to reversibly block the catalyzer just enough, so that you can mix it with the FAlc and the mix stays stable, for at least a day. The reversible word here means that with the application of heat, the catalyzer gets released again and the resin starts polymerizing on demand.

So this is what I have been testing today: I have tried different degrees of blocking and the temperatures necessary for unblocking the catalyzer.

The blocker I used is a strong organic amine base (N-Methyldiethanolamine, short MDEA).
This amine will react with the organic acid and form an organic salt, but that is reversibly bound. The fact that it's a base makes it possible to use the pH level (acidity level) to measure on how much it has been blocked.

I have tried pH 7 (neutralized), 6, 5, 4, 2 and 1 (strong acid).
What I have discovered is that MDEA blocks pTSA quite a lot and that the pH 7 down to pH4 samples were only marginally active catalyzers, even at heats up to 100ºC.
The pH 2 and 1 samples were catalyzers that reacted very nicely at 85ºC.

The method used to apply heat was a water bath. I used a small flat dish with 10g of resin and blocked catalyzer, wich I deposited on top of said waterbath. I couldn't use light-spot because i haven't been able to focus a light beam from a halogen bulb enough to produce a heat spot warm enough.

In future tests I will procede to try out the effect of filler materials such as Titanium Oxide (TiO2 probably replaceable with cheaper Zinc Oxide) and Starch (thanx for the idea Viktor!).
I will also have to fix myself a decent laser diode from an old CD burner I have or from a laser pointer. This will serve as a better proof of concept for the whole experiment than a water bath.

Cheers and keep posted!

Very cool. Glad to see that someone with some materials foo is tackling this sort of stuff.
While you're doing filler tests, give some graphite a whirl and if you've got an ohm meter you can do a quick check for conductivity too.
I'll be over that one too.
Don't have graphite but i do have plenty of copper powder to spare. It wouldn't be hard to fill one of these batches with it and see what happens... I'll be informing of that one too
Graphite is easy to come by. You can buy a squeeze bottle of the stuff in any hardware store.

I know my dad has a largish bottle of the stuff from back when we were playing around with pinewood derby and balsa CO^2 drag racing cars. We used it as an axle lubricant. The bottle, if memory serves, is about 3" diameter, by about 6" height. (approx 7cm dia. x 15cm height)
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