Furfuryl Alcohol resins (and Waterglass stuff too it seems )

Hey all!

I'm happy to inaugurate this sub-forum and I will do it with this matter which is what I'm working on.

To start, i'll explain what Furfury Alcohol (FA) is and why I chose to investigate it. FA is a brownish flammable liquid, of the similar viscosity as water. It is produced from plant waste through chemical reaction with sulfuric acid and is quite a cheap and readily available product. The cost of 1 liter of the stuff cost me around 20

Edited 1 time(s). Last edit at 12/12/2007 02:32PM by Fernando.

ohiomike Wrote (General forum):
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> Try mixing the catalyzer into the flour first,
> partially fill a pan with the resultant mixture,
> and then using a syringe write a pattern in the
> pan with FA, add another layer and repeat. I would
> be very interested to see if you have any
> interlayer adhesion issues and what your surface
> finish is like on the finished piece.

Hey Mike!

I will try this out once i figure out how to make it happen. i'm concerned about the catalyzer and filler not diffusing through the whole width of the FA thread, so that it will only mix and harden on the surface. I guess the filler would be better mixed with the FA. I would only add filler to the catalyzer to match the density of the FA so as that the deposited thread floats on the surface of the catalyzer. As for interlayer adhesion, that's really unwalked territory....

Brian Dolge Wrote (General forum):
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> Have you considered using powdered fibre-based or
> "volume enhancing" laxatives like musilex or any
> psylium based product? As Mike pointed out it
> won't enhance flexibility but it might increase
> toughness by as part of a composite material.

Hey Brian!

I tried this recently. I went to a nutritionist shop and bought myself one of those off-the shelve fiber mixes. The result was similar but less effective than regular flour. I'm waiting for the pure cellulose fiber powder I have ordered at amazon to settle this issue once and for good.

ohiomike Wrote (General forum):
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> A major issue with fibers is that they are resin
> hungry materials. If you want flex in the material
> add polyurathanes. Most two part polyurathene
> casting resins sold at craft stores are straight
> chain polyols so they have relatively high
> molecular weights to hydroxide values. The
> furfural with react with the polyol so you wont
> even have to use the isocyanate.
>
> Also detergents or soaps are going to add a great
> deal of flex to the system with relatively small
> additions, they will also stabilize an emulsion if
> you want to add heavier oils for even more flex,
> or if you want to try some water based additives.
> And since most commerical detergents are weakly
> basic they should further stablize the blocking
> agent on the cataylst. The water will tend to
> slow the dehydration reaction of the furfural but
> that can likley be formulated around.
>
> Soaps and detergents are also heavily ionic in
> nature and so should assit in lowering the
> resistance of the end traces.
>
> Mike
>
> The thoughts expressed in this post are my own and
> do not reflect those of my employer. Any attempt
> at implementation is at your own risk.

Hey Mike!

The fact that fiber soak up the FA resin is actually good in my case, as it adds some interesting viscosity to the mix. Depositing would be a lot more accurate this way, as it would cause less sagging.

I have been checking what your interesting comment about polyurethanes and have come to the conclusion that the other components of the comercial urethane resins could interfere with our FA in random ways (isocyanates would interfere with the blocking amines). I need more control over the components and comercial mixes are just to obscure on that side.

So what I did is to see what souces of cheap and readily available polyols there were around that we could use easely in our mix.
I tried with Glycerin, wich didn't add any interesting properties to the resin. It actualy degraded the hardness of the final polymer and made it crumble somewhat. I am now testing with something different: Castor oil, also called Ricinus oil. This is the only cheap and readily available hidroxylated oil that occurs in nature. I have made a test batch yesterday and this morning i had a slab of rubbery, flexible plastic on my work-bench. I was pleasently surprised!
I don't know if soaps and detergents could do the same trick, but I fear that the water soluble properties of soaps will not be ideal for this case. Also adding more water or any other small volatile molecule in the end polymer will degrade its properties i guess, unless you heat it above 100

Edited 1 time(s). Last edit at 12/12/2007 11:58AM by Fernando.

Hi Fernando,

... i experimented with Natron-waterglass for ceramic-like solids - it's a longer way then planned, as i didn't get the wished materials in time ...

Today i experimented with materials i found in my basement and found some, that can work as support for extruding overhangs - all products stay brittle with a not so strong contact to the surface, so easy to remove ...

1. waterglass with lanolinum and panasonic dry toner FP-1300 (pure toner didn't mix with waterglass):
- not so easy to mix, as the toner is very 'dusty' - should find a better intermixer then lanolinum
- extruded with a syringe ...
- forms stable trays, surface dries in some minutes, body stays semiliquid ...

2. waterglass with gelatine-powder:
- when pouring waterglass in the powder, then it forms at once coarse granules, better put the powder with continuous mixing in waterglass.
- stiffens on air after some minutes to a brittle mass, as the water dries and the silicate solidify between the gelatine-particles
- output as paste with a syringe, stays stable when heating to over 500

Hey Viktor!

This Waterglass investigation is really cool!
And it has a LOT of possibilities i see. I have been reading up a little on this Sodium Silicate. It really is the ideal sintering composite! Do you have pictures of a final glass sintered with this stuff? Does it look like regular glass or is it more like aerogel?

Now that we have a separate forum for our gooey threads, don't you think it would be better to post this issues on a separate thread, so as to keep everything neat and searchable and organized? Or maybe i'm just an order freak.. (although my apartment doesn't look that way!)

Hi Fernando,

... i'll land here with the next posts

The basic-structure of the waterglass-mixtures is dependant of the powder - with glass-powder i have a white paste, which dries to solid with the finish of the powder-granulity.

When heating the paste with H2O2-flame to melt the glass, it behaves as normal - went black, then brown, then yellow and at over 800

... update:

I tried with solving and melting gelatine befor mixing with waterglass - it's more gelatine (elastic) then silicate and stays a bit brittle, but i used some gelatine with citric acid inside, so the reaction was at sudden (yes, acidic additives force the silicate to fall out).

Then i tried with mixing plaster and other powders with sometimes interesting effects - some powders (pure ceramic and glass) could be mixed to a paste and stay stable in the box some time, others as plaster react at once to a brittle solid.

So it's an interesting play to put powder on a bed (as in the ink-jet-3D-printers) and spray or ink-jet the waterglass on the surface - it stiffens in 0-time!

The solid isn't very hard and remains brittle, so it's more for one-run-moulds or as support for the main body, but maybe with additives or heat-curing there could be better material-selecting ...

Viktor

Viktor, did you use limestone plaster or plaster of paris (gypsum plaster)?
[en.wikipedia.org]

I'm assuming the latter. I seem to recall my sculpture teacher told me the latter is acidic, which is why it rusts your tools if you don't clean it off. I am not sure if this is true: I should get some pH test strips and verify for my own sake.

I know when you're mixing up plaster, if you don't clean the old plaster out of your cup or if you use plaster-bearing water to mix it up the plaster-water mixture hardens very quickly. (As it does with hot water) I figured the old plaster serves as nucleating centers for the gypsum crystal formation.

Lime plaster is calcium hydroxide and sand, and is basic.

I'll create a inkjet-head forum, Adrian says there will be some students working on it.

Edited 1 time(s). Last edit at 12/13/2007 07:27AM by SebastienBailard.

Hi Sebastien,

... yes, it was a sort plaster of paris with some additives for better volume-control ...

Ink-head-forum sounds good, i have the schematics, background and some code to control an HP-ink-head - with time i'll go in ILS-fabbing or so ...

Viktor

Viktor, I've created an inkjet forum here, and threw in a couple links to start a thread of inkjet-fabrication resources.
[forums.reprap.org]