Sciencemadness Discussion Board - Geopolymeres

Geopolymeres

Organikum - 6-5-2005 at 07:22

I got recently interested into geopolymeres:

http://www.geopolymer.org/

The prices they charge are insane though. Has anybody an idea how to prepare such polymeres, in special the high-temperature resistant kind?

/ORG

12AX7 - 6-5-2005 at 08:18

Wow, that could be... very useful! Rocks molded from aqueous instead of molten solution!

But what to use... can't be as simple as sodium aluminate + sodium silicate, can it?

Tim

solo - 6-5-2005 at 09:26

Here is some information.....solo
-------------------------------------------
http://www.geopolymer.org/library_papers/publications_refere...

Info on geopolymers....

solo - 6-5-2005 at 10:16

Property controlling influences on the generationof geopolymeric binders based on clay
Ch.Kaps, A. Buchwald

[url= http://rapidshare.de/files/1609911/Bu-Ka-Geopolymer2002.pdf.html]pdf[/url]

Organikum - 6-5-2005 at 13:22

I get only advertisement with this link?

This works:
http://rapidshare.de/files/1609911/Bu-Ka-Geopolymer2002.pdf....

Very good! Thanks!

[Edited on 6-5-2005 by Organikum]

Cyrus - 10-5-2005 at 18:05

That is a very interesting link...

I added 3 g of fine grog (prefired clay, hey they said to activate it somehow, I don't know how long or how hot this was fired because I just bought it as grog) to about 120 mL of about 1.5 M NaOH.

The site was pretty vague about some stuff, but I guess I'll just let it sit there at room temp. for a few days... and then what? At that point it will be (in all probability) a liquid with some solid grog power at the bottom, but where are the silica and alumina monomers we want for polymerization located? In the clay at the bottom or the liquid? Colloidal silica is a clear liquid, but then again the site showed an aluminum ladle being formed from ceramic matting and a binder that looked like clay.

I guess I'll just have to do some experimenting- I'm interested in low sodium/ potassium/ etc mixes because those metals are fluxes at high temperatures, and would cause the geopolymer to melt. I wonder what NH4OH does....

Madandcrazy - 5-6-2005 at 06:43

I checked out the site, the link seems to be interested.

I wonder about the post of easy fine grog

in the thread.
Try the usage of sodium amide (NaNH2) in your experiments.

Cyrus - 5-6-2005 at 13:41

Well, the grog is still just sitting there at the bottom of the NaOH solution. Hmm. I guess I'll have to do some tests on it. It seems to have turned more of a pure white color than it was originally, but that could just be my perception.

I tried putting a little of the solution on a paper towel and let it dry. It didn't seem to strengthen the towel very much.

Madandcrazy, why and how do you suggest I use sodium amide? Are you talking about geopolymers? Or are you just being mad and crazy?

Tacho - 6-6-2005 at 08:33

This sounds interesting. Isn't there a recipe somewhere? I presume it's made of aluminum-based clay, alkali hydroxide and sodium silicate. Somewhere on my google search someone mentioned that the mix must have very little water, however, in the www.geopolimer.org site (I could only open this link) they show ceramic fiber being impregnated with what seems to be a rather liquid mix.

Cyrus - 6-6-2005 at 16:08

I decanted all of the liquid and let the solid dry on a paper towel. It shows no strength whatsoever.

Madandcrazy - 7-6-2005 at 06:22

It seems interesting for strength fine grog recipes within the alkalamin group

Organikum - 7-6-2005 at 09:45

Roman cement is told to be a geopolymere. There seems to be a variation of the Mayas to, made with some plantextract.

Whilst the Roman making is wellknown - volcanic ash + CaOH, the Mayan recipe is not known to me.

Jome - 8-6-2005 at 04:30

The chinese added a small ammount of rice starch to their cement, this made the cement more resistant, perhaps this has something to do with enhancing the polymerisation process?

http://www.china.org.cn/english/culture/121291.htm

12AX7 - 8-6-2005 at 05:07

No, I think that's just organic reinforcement. Roman cement was also just that, cement. Geopolymers appear to be something similar but completely different, polymerized rather than crystallized bonding agents.

The Mayan stuff might've been along the same lines, maybe lime and such mixed with latex instead?

Tim

sparkgap - 8-6-2005 at 05:15

I seem to remember reading somewhere that the Maya used wet clay soil mixed with dried grass (the cellulose probably for stiffening) as cement. Quite far-off from modern-day designer ceramics.

sparky (~_~)

Jome - 8-6-2005 at 07:25

They have a bunch of chemical formulas on the site, here:
http://www.geopolymer.org/what_is_a_geopolymer/chemical_anal...
and here: http://www.geopolymer.org/what_is_a_geopolymer/geopolymeriza...

Seems like it's all about polymerizing different ratios of alumina and silica using a NaOH or KOH catalyst. The conditions however is mentioned as being "at room temperature", and their casting of "limestone" suggests this too, though that's chemically different. from silicic minerals.

It could probably be tested quite fast with chemically produced Al(OH)3 (this should dehydrate in the process) and SiO2, "colloidal silicia" from Na2SiO3 ("water glass"

and HCl. Just add NaOH/KOH and see what happens.

EDIT - add:
Polymerisation probably occurs because of temporary formation of soluble sodium silicates and aluminates, which then together forms chains and 3D-matrixes that will not get attacked by the sodium ions....

[Edited on 8-6-2005 by Jome]

Organikum - 8-6-2005 at 18:58

Quote:

No, I think that's just organic reinforcement. Roman cement was also just that, cement.

Bullshit. Don´t post statements like this when you don´t have a clue.

12AX7 - 8-6-2005 at 21:28

Quote:

Originally posted by Organikum
Bullshit. Don´t post statements like this when you don´t have a clue.

Well, I can just as well say fuck you too, but I will stick to the gracious side and ask, please provide cites on roman cement chemistry? For that matter I'm curious what exactly is in it, too.

Tim

Jome - 9-6-2005 at 06:31

It would not work as reinforcement, glutionous rice is not at all stronger than concrete, in itself it's more like porridge/glue. So it must work in another way than simpy reinforcing the cement like glass fiber is used today.

Just got home from buying 5L of hydrochloric, im going to start making Al(OH)3 soon.

12AX7 - 9-6-2005 at 09:17

Quote:

Originally posted by 12AX7
For that matter I'm curious what exactly is in it, too.

Interesting:
http://www.geopolymer.org/science_archaeology/roman_cement_c...

Quote:

Civil infrastructures, especially works related to water storage (cisterns, aqueducts) required a high-performance material and a special technology. The technology of this first Roman cement analogue was known under the generic technical term of Opus Signinum obtained by blending crushed and sieved ceramic, in Latin testa, with lime. According to the Roman author Plinius (Natural History, Book 35, 165), this technology was recognized as: "..one of the most spectacular inventions of mankind.." The ingredient testa is a special ceramic powder from calcined kaolinitic clay (alumino-silicate oxide) and therefore identical to the KANDOXI ingredient in modern geopolymeric cements. We performed 29 Si and 27 Al NMR Spectroscopy on Opus Signinum samples, dating to the 2nd Century A.D. There spectra are identical to those of modern GEOCISTEM Geopolymeric cements.

Appears to be calcined clay required, then...

So does that mean, besides plain quicklime, portland was the first "cement" as such discovered?

Tim

Nerro - 1-7-2005 at 01:28

Why do they call these polymers "geo"-polymers? "lithopolymers" makes much more sense.

Such a material might be extremely usefull for creating our own furnaces or other interesting things.

How about making a block of this material with a certain percentage of some alkali resistant material that readily dissolves in acids. If carefully mixed and not to fine (the metal powder that is) the metal powder might be removed with hydrochloric acid after polymerisation so as to create a superporous structure that may be used as a catalyst-holder for things such as H2SO4 production or other contact catalysations.

Just a thought. (probably noobish but hell).

PS. Just thought of this. Sn becomes brittle at low temperatures. Maybe that property can be used too...

12AX7 - 1-7-2005 at 02:02

You could add say, CaCO3 chips. Wax or styrofoam bits if it doesn't need/make too much curing heat. No idea how you prevent them from being encapsulated though.

Tim

Nerro - 1-7-2005 at 02:31

Using big particles and lots of them i guess.

Jome - 2-7-2005 at 02:15

I'm having a hell trying to remove water from the SiO2 and Al(OH)3 I've made just for this experiment. I used Na2SiO3+2HCl for the silicia and Al+KOH---> KAl(OH)4+HCl-->Al(OH)3 for the aluminium hydroxide.

They´re just that partickle size that gets STUCK in the filter paper and nothing happens, no fluid is dripping out. Ever! What could I do?
Sadly I dont have any fancy-vacuum filtration device.

Im planning to use Al(OH)3 and SiO2 to bind together fine clay-particles to make artificial rock, with the aid of a little KOH or NaOH.

Nerro - 2-7-2005 at 07:40

Would waterglass dehydrate Al(OH)3 maybe? Because if it does that would be an ideal solution. Just make Al(OH)3 and dry it and add it to waterglass, hopefully...

Jome - 2-7-2005 at 09:50

That would result in a precipation, not a slow polymerisation...The idéa of adding just a small ammount of NaOH/KOH is to dissolve SiO2 and Al(OH)3 a little at a time and allow for polymerisation. Thats how I interprete whats said on the pages.

Now the water (~800ml) with about 48 grams of colloidal SiO2 in it has turned into a gel. Looks kind of funny

Guess I'll have to fry it in the oven at about 100 degrees to get rid of the water (as done with silicia dessicant), but how in hell do I remove the NaCl that was formed in the precipation of silicia from waterglass + hydrochlorid acid... Im worried that the salt might mess with the final products stability.

[Edited on 2-7-2005 by Jome]

geopolymers

Pyridinium - 2-7-2005 at 20:38

This geopolymer stuff has tremendous madscience potential. It has the association with ancient Egypt, lost technology, a touch of academic controversy, verifiable results that can (theoretically) be duplicated by amateur chemists, and best of all, association with Imhotep (aka The Mummy).

I didn't have time to read many papers on it yet, but was there a specific one that mentioned sodium amide?

The thing that really intrigues me is that they could make geopolymers of basaltic composition (?). I am going to lose sleep tonight over this one. I now foresee many nights of working at 3 AM with the neighbours wondering whether I'm up to something shady, when in fact I'm just trying to cast a basaltic urn. "A 5000-year old mummy commanded me to do it."

Jome - 9-7-2005 at 11:32

Well, Im only 200ml of water and a few grams of salt away from testing my geopolymer mix.

How do I remove water from a sludge that "stops" the filtration? (the Al(OH)3) and how do I remove salt from salt mixed with silicia gel?

12AX7 - 9-7-2005 at 12:54

Last time I made some Al(OH)3 (same method as a matter of fact), it settled just fine. You must've precipitated it too quick.

Can always boil the water out (vacuum or heat), but that doesn't remove the salts stuck in it.

AFAIK, acid + silicate solution always causes a gel. I would think it would be possible to grow quartz crystals of any size with a solution and slow enough acidification, but...who knows.

Heh, can always get some 325 mesh flint from a pottery supply, if that's fine enough. I have a 50 pound bag of such concentrated silicosis in the basement.

Tim

Tacho - 11-7-2005 at 03:58

I used to think that the solid I got from mixing sodium silicate with common mineral acids was silica gel.

Recently I mixed dilute boric acid with dilute neutral sodium silicate. Initially there was just a haze in the liquid solution but, after a couple of days, there was a true gel formed. Gelatin like. After completelly dry it shrank to and insoluble mass.

I'm testing this as a silicate based binding for graphite powder. Since it remains liquid for a long time, it can be mixed with fillers to obtain all kinds of solid, insoluble materials.

Hey pyro people, maybe it could be used to bind lead oxide in electrodes.

Cyrus - 11-7-2005 at 17:10

What would the reaction be?

I'm guessing sodium borate would be formed (NaB4O7 IIRC).

Sounds interesting enough, I'll try it on a test tube scale. But I don't know if it would make a good binder for PbO2 if it shrinks a lot.

Tacho - 12-7-2005 at 03:36

I think it's just the classic silica gel formation. That's why it was called gel. I tried boric acid because I read somewhere that a (true) gel would be formed using weak organic acids in dilute solutions. Boric is not organic but it's weak and I was interested in it's insect killing properties.

The fact that is shrinks doesn't mean much. The filler should make a paste with the silicate-acid solution, so, just enough gel should be left to bind the dry particules, keeping electric contact between them.

EDIT: in fact, the shrinking may compress the particles, improving electrical conductivity.

I had a reasonable sucess with powdered graphite after 24h. The resulting solid conducts VERY well, just a few ohms p/ cm. After immersion in water it broke in larger pieces, but didn't dissolve completely. Not bad for a first try. I believe I should use more concentrate solutions and prevent drying for a couple of days, so that the gel has time to form.

I know i'm a bit off-topic, but not much if you think about it.

[Edited on 12-7-2005 by Tacho]

Cyrus - 16-7-2005 at 11:43

I tried this reaction with very dilute boric acid and very dilute sodium silicate. It does make a wierd gel after a day or so. I think my solution was too dilute because the gel is weak and watery. Nothing like Jello. What was the consistency of your gel, Tacho?

I'll see how it changes over the next few days.

Tacho - 18-7-2005 at 04:20

I think you can get all sorts of consistencies, depending on concentrations.

I made a "standart" solution of 2g of boric acid in 40 ml of water.

My sodium silicate bottle does not state it's concentration, but I guess is a industry standard, viscous like thick oil.

A mix of 1 ml SS, 2 ml water and 3 ml of the standart solution of boric acid yiels a gel in a few minutes. The gel is like jello, but more fragile.

As you add more water to this mix, the gellification takes longer to happen. At about 7ml water, it takes many hours.

Gellification also happen with borax solution and ascorbic acid (vitamin C)solution. It takes days though. Sorry, but I can't give you numbers. Did those in a hush, with chemicals at hand.

I made a solid graphite piece, mixing the powder with the liquids before gellification, keeping it humid for a couple of days, and letting it dry. I have dismolded it, but I'm waiting one more day to let it dry more completelly. Maybe some reaction with air CO2 will also happen. I'll break it in two pieces, one goes in an acid solution that, hopefully, will make it more water resistant. The other will be tested "as is" in water.

Cyrus - 18-7-2005 at 06:39

I used, perhaps, 0.3 g of borax to 8 ml H2O. The gel wasn't displaying much activity or potential, so I threw it away. Perhaps I'll try a more concentrated one.

[Edited on 18-7-2005 by Cyrus]

Tacho - 18-7-2005 at 07:32

My borax experiment took about 4 days to gellify. Maybe it gellified because part of the water evaporated. I'll try more concentrated solutions. Anyway, the borax rendered a milky gel, much less transparent than the boric acid one, although the latter was not transparent at all when was a gel, becoming more transparent as it dryied.

Tacho - 22-7-2005 at 05:34

Just for the record: I meant "borax solution + sodium silicate solution" and "ascorbic acid solution + sodium silicate solution".

I don't think there is easy method of making silica gel without sodium silicate.

trilobite - 31-7-2005 at 05:22

In case you guys missed one of the original patents, US4349386, I think answers some of your questions. The reference was found in http://www.geopolymer.org/davidovits/milestones_geopolymer.h....

Maybe FR2512805 holds the key to refractory materials. It apparently describes expansion of these materials to foams with sodium perborate.

[Edited on 31-7-2005 by trilobite]

trilobite - 2-8-2005 at 12:59

Here's some information on refractory geopolymer materials. It seems metakaolinite is the typical mineral used in making geopolymers but the patents tell us that kaolin aka china clay could be used as well. Metakaolinite can be made by heating kaolin at 700°C for 6 hours but then you need a furnace anyway, kinda defeats the advantage of curing at low temperatures. It would be awesome if worked with kaolin.

Synthesis and thermal behaviour of potassium sialate geopolymers
Materials Letters, 57, 1477-1482 (2003)

http://www.geocities.com/tatssnart/Materials_Letters_57_1477...

Fire-resistant Aluminosilicate Composites
Fire and Materials, 21, 67-73 (1997)

http://www.geocities.com/tatssnart/Fire_and_Materials_21_67-...

Baluuuu - 7-3-2007 at 12:58

Hi

I'd like to ask for any subject-matters, technical literature, references, recepts or any help from you to my diploma work.
My theme is the Industrial use for Geopolymers and one of concrete geopolymer's research.

abaluuuu@gmail.com

franklyn - 9-3-2007 at 07:49

I must be missing something , for how does this differ from a zeolite ?
Also the Al - O - Si cross bonding is found in a machinable sintered ceramic
made of silicon nitride and alumina trade name Sialon. What appears new
here is that this is formed without firing. I'm reminded too of a mention
some years ago of a discovery called Beer stone. It was a mix of pearlites
and other minerals that when wetted with beer ( apparently serving as a
blowing agent does for expanded polymers ) foamed and quite rapidly
solidified into a light porous pumice like material with superior strength.

This is the most comprehensive explaination I found on Geopolymer _
http://composite.about.com/library/weekly/aa030529.htm

All I could find on Beer stone _
http://en.wikiquote.org/wiki/Talk:Beer
Perhaps it's related to this ?
http://www.birkocorp.com/brewing/beerstone.asp
burp !

ShadowWarrior4444 - 6-5-2008 at 15:39

Rise up, ancient thread! And carry with you a slight request--someone change the title of the thread so that it is spelled correctly. *sigh*

Geopolymers have captivated my interest lately for their potential to create high-quality crucibles for aluminum casting, as well as their superiority to concrete in most if not all applications. They have interesting ties to ancient times, specifically the theories that Roman fortifications were constructed from geopolymers, as well as the limestone in Egyptian pyramids.

Video by a French university showing the formula, process, and construction of Egyptian limestone: http://youtube.com/watch?v=znQk_yBHre4
Do try to ignore the comments on it, the sheer amount of fanaticism and religious raving began to wear on me, and I read alchemical texts for fun.

I believe the more professional way of creating geopolymers is to simply mix a white aluminosilicate clay (usually simply Kaolin, occasionally metakaolin,) a bit of sodium or potassium silicate, then add KOH as the catalyst. Any home/lab formulations would be appreciated--I would very much like to create molds and crucibles for the casting of aluminum.

[Edited on 5-6-2008 by ShadowWarrior4444]