Polyurethane glue

[Swede]

I have no idea if this is old news, but I am excited by the possibilities this presents.

 

I was experimenting with black match. Maybe it's my technique, but I'm not thrilled with my BM. I decided to try "binding" meal to the string with a slurry of meal powder and polyurethane glue, thinned with MEK. It dried in an hour, but sucked as BM. The shiny glue coating seemed to quench any burning. On a whim, I decided to try BM made with both KNO3 and KClO4 as oxidizers to the polyurethane glue.

 

http://www.5bears.com/firew/pug001.jpg

 

Before I executed any batch larger than a couple of grams, I tested the sensitivity of the mixtures in their liquid state. Both were safe to handle, using the unscientific test of scraping the goo hard with a metal blade on concrete, and also beating balls with a hammer.

 

I guessed at a 75:25 ratio of oxidizer to glue, mixed thoroughly, and made some "Yellow Match." The KNO3 match burned, but only stubbornly, and did not perform.

 

http://www.5bears.com/firew/pug002.jpg

 

The perchlorate + glue in a 75:25 not only burned, it burned fiercely, with a brilliant white flame. The ratio seemed close, as almost no ash was left behind. The ONLY problem I saw was that it did not take fire easily... it took some moments with a torch before it caught, but once lit, it sustained itself.

 

A test of three small "dough balls" of this material, 75:25 was a total success:

 

http://www.5bears.com/firew/pug003.jpg

 

http://www.5bears.com/firew/pug004.jpg

 

The burn time of those samples was about 3 to 4 seconds.

 

Right now, I have about six each ten gram samples in various ratios, to try and find the best stoichiometry of this mixture. I have 2 others, with additions of airfloat charcoal, and sulfur, to see what their behavior is like. I am especially hoping with the sulfur to see a reduced ignition temp. 2 more samples have been "cast" into 4 ounce rocket tubes.

 

Some thoughts - This could possibly make a castable rocket propellant. Unthinned, a 75:25 mix forms a thick paste, like spackling compound. It can be thinned to syrup with MEK. The mixture could make an extremely potent black match. Finally, it can form the basis for stars, acting both as binder and as fuel. The mixture burns so brightly, it left spots in my eyes. I would suspect a respectable star could be made solely from glue + perchlorate, if ignition is not a problem.

 

As with any other unknown mixture, especially when dealing with perchlorate, caution is indicated. On about 1 out of 4 tries, samples of the dried material about the size of a pea was ignited with a strong hammer blow. It took some real effort, but it can be done. One other issue - this glue expands as it dries, and tends to overflow tubes, etc unless the expansion is accounted for. When manipulated and allowed to dry as a dough, however, it handles pretty easily and the expansion doesn't seem to present a problem.

[ULTRABUF]

Interesting. This is new to me. Have you tried quickmatch with it or anything?

[TheSidewinder]

Now this is an interesting thread.

 

Swede, in your tests, did you try adding some Sulfur (or maybe Iron Oxide) to lower ignition temp?

 

Your formula (vagely) reminds me of an APCP formula. The Polyurethane glue is at least close to "Epoxy", and nearly all of them will work for that purpose.

 

Keep experimenting, and please keep us posted!

[Swede]

Ultrabuf, I have not tried QM yet. I am in the very early stages of experimenting with this mixture. I did want to post because if this is old hat, I'd like to know, rather than try and reinvent the wheel. I am going to let the current samples dry a bit more before I continue testing. I will try and get some video as well.

 

Sidewinder, I have two samples with added fuels. One is 75:15:10 with 15 glue and 10 charcoal, the other is about 75:20:5 with 5 sulfur. I will try iron oxide as well.

 

The charcoal batch was interesting. It seemed to dry very quickly, much moreso than the others; the batch became rock hard blobs in just 2 hours, and an initial burn test showed promise. You could possibly pump or even cast stars (a silicone mold would work) that would be incredibly strong and ready to go in a very short time.

 

And as expected, the sulfur batch seemed easier to ignite. I want to be sure both of these additive mixtures are reasonably stable before continuing... I will compare burn rate, color, sensitivity, and ignitability. Once a particular mixture is established as a good one, then I can vary the proportions and try to optimize it. I'd be especially excited if this could be turned into a pourable rocket fuel.

[DeepOvertone]

I'm so excited!!! This seems to have promise!!! What brand of glue are you using? Isnt gorilla glue poly? Please let us know how the sensetivity tests go. How about some other fules? Put a little zinc in there. Maybe a bit of mgal or straight mg. It would have to be a small ammount of the pure mg I would think. Wouldn't want it to explode. Does poly heat upon curing or just foam up? You might also try kclo3 as the oxidiser. IIRC Kclo3 contains less oxygen so you might have to use a higher ratio but it gives up its oxygen easier so it might make an easier to ignite material but also may make it more sensetive. I'm no chemist so please shoot me down if I've suggested something totally stupid.

[DeepOvertone]

I was also thinking. How fiercely does it burn? Is it fast or just produce allot of gas? Reason I'm asking... could it be used as a handheld flare if put into an open ended tube?

[BPinthemorning]

I'm genuinely interested. What kind of glue are you using?

[DIYMark]

I'm genuinely interested...

Same here, however good luck with KClO4 in Australia KNO3 is bad enough

[Photon_Junkie]

Guys, I don't mean to be a wet blanket, but polyurethane glues (like Gorilla Glue) are an isocyanate and usually a carboxylic acid or alcohol as the homopolymer. Burning the isocyante will give you fair amounts of cyanide gas.

 

I work for an adhesives company and we get Mondur MRS-4 from Bayer in tote and drums. The totes we return but we have to dispose of the drums ourselves. We have to insure the state that those drums are crushed because if they get into the normal wastestream and some yocal makes a BBQ grill out of it....well...its bad news.

 

Again, sorry to be a downer, I just want you all to be safe. The first link below is a FAQ about isocyanates and does mention what happens when you burn them.

 

 

http://www.baycareonline.com/cgi-bin/inq_d...files/10273.pdf

 

http://www.bayermaterialsciencenafta.com/p...187008D&o_num=5

 

http://en.wikipedia.org/wiki/Polyurethane#Adhesives

[WarezWally]

HCN is something you really really don't want to make

[BPinthemorning]

Dam. Not worth it. It would have to be one hell of a star...

[50AE]

That's too bad. I was hoping that this fuse gets useful.

[Swede]

Guys, I don't mean to be a wet blanket, but polyurethane glues (like Gorilla Glue) are an isocyanate and usually a carboxylic acid or alcohol as the homopolymer. Burning the isocyante will give you fair amounts of cyanide gas.

You're not being a wet blanket (well a little bit! ) but I want to thank you for bringing this to our attention. I burned quite a bit of this stuff yesterday... didn't smell any almonds, but it would be insane to continue given this information.

 

It's a shame, I was kind of revved up over the possibilities, mainly because the straight 75:25 mix was genuinely brilliant, and would have been eye-popping, I think, with some metallic constituents.

 

Epoxies plus oxidizers are used in rockets, true? Do you have any of the same issues with cyanide generation in those cases?

 

I wanted to put these videos up, now unfortunately only for curiosity value. I am going to cease experimenting with this mixture. Unfortunately I've got a bit of unburned material. I tried dissolving it in acetone - no dice. I need to figure out a way to safely dispose of it.

 

As expected, both iron oxide and sulfur accelerated the burn. Charcoal lengthened the burn, was easy to ignite, and if anything showed promise for star material. Each piece is about the size of a lima bean. All are less than 1 megabyte and pretty low quality.

 

Added Sulfur MPEG video

 

Added charcoal MPEG video

 

Added iron MPEG video

[Swede]

I was using Elmer's Probond Ultimate polyurethane glue. From their web site:

 

 

The ingredients listed below have been associated with one or more

immediate and/or delayed(*) health hazards. Risk of damage and effects

depends upon duration and level of exposure. BEFORE USING, HANDLING, OR

EXPOSURE TO THESE INGREDIENTS, READ AND UNDERSTAND THE MSDS.

% by weight

101-68-8 *Diphenylmethane 4,4'-Diisocyanate 10-30

9016-87-9 *Polymeric Diphenylmethane Diisocyanate 30-50

*Modified Polymeric MDI 50-70

 

Here is the link to the MSDS for this glue:

 

http://www.elmers.com/products/msds/mP9411_c.htm

[RocketNut]

AWW Nuts. Swede I thought you were really on to something there. Anyhow keep experimenting I really enjoy reading your post! Thanks and keep up the good work.

[TheSidewinder]

Well, THAT throws a wrench into the gears.

 

One of the two most common epoxies used in APCP has an isocyanite curative, and you can smell the "super glue" odor when it's mixed. It's the R-45 (HTPB), and uses Isophorone Diisocyanate as a curative. There are a couple other curatives available which allow for faster cures at room temperature, but they all have "xxx isocyanate" as an ingredient.

 

It's available from Firefox as is the other common one, PBAN (CTPB), which uses DER-331 Resin as a curative. The latter one has almost no odor at all.

 

Here's some general info I harvested from the Firefox site. (NOTE: I take no credit for its authorship, nor have specific knowledge of any hazards, not can vouch for its accuracy. It's just cut and paste.)

 

Anyway... they carry a fair number of "epoxy curatives". Those include HX-878 Tepanol, Isonate 143L, Isophorone Diisocyanate as above, "Hysol Curative, surplus from 934 Kits" (whatever the hell that is), DER-331 as above, DDI 1410 Aliphatic Isocyanate, Versamid 140 Polyamide Resin, and Fomrez Sul-4 Dibutlytin Dilaurate.

 

That information may be useful to Swede and others who experiment.

 

 

The first time I used the R-45 HTPB, I got one faint whiff of it as I was mixing in the curative, and immediately realized what that meant. Needless to say, I put on my respirator mask. I was already mixing outdoors (foolish not to, regardless of the formula) so it wasn't a big deal. Once this batch had cured fully, I cut apart the grains and sniffed them. No residual odor at that point, so I think it was "cooked off" during the cure. When I burned some openly, I didn't stick my face in it but I did walk downwind and got a very faint whiff of the byproduct smoke. No "superglue" odor then, either. But I realize that isn't a "scientific" test, it's just an observation.

 

Maybe Photon Junkie has some more info on those, their relative toxicity pre- and post-cure, and what they will do when burned?

 

Firefox also published a nice book on "composite color stars" which I purchased. I think once launched and burned high in the air, they won't be any more of a problem than the other chemicals we use.

 

Of course that's assuming the tree-huggers, who went after Perchlorates with some rigged information about actual pollution hazards, don't focus their attention on them.

[fizeau]

I don´t want to strain anybody, but we all use PVC and so far as I know burning PVC produce dioxine and maybe furane, better known as Seveso poisson. Who cares?

It wasn´t nice too hear bad news about my lovely Diphenylmethane-

Diisocyanate glue. Some month ago I build some rockets with a PU/NaClO3/ Mg grit solid and was happy...but now.

Ah, yes, the rocket:

http://www.youtube.com/watch?v=VnL0xPAfnTY

[Swede]

I will say this - during testing, I ran around and basically sniffed the smoke, because I'm curious and kind of dumb, and got no ill effects. I read a bit more after posting today, and the Bayer documents themselves say pretty much any Nitrogen/carbon compound can generate HCN. I guess the question is, how much? Is it an issue? We burn Barium mixtures all day long... I can't imagine the byproducts there are really too good for you.

 

TheSidewinder mentioned some fairly complex polymer fuels used by the high-powered rocket types, among others, using isocyanates. Grrr, I just don't know. Today I burned a string heavily coated with this mixture (I stood upwind) and it was like looking at a magnesium flare, it was so bright.

 

I'm going to poke around and learn a bit more. I'm loathe to discontinue, because even in my newbieness, I recognize the utility, especially when I consider how brightly it burns, at what must be an ungodly temperature. Added metal fuels could only improve it. The cured nuggets are rock hard, too, and could probably withstand a powerful burst without physical failure.

 

I can't in good conscience encourage anyone to take chances, but given the data so far, if anyone wanted to test a small amount, especially someone well-experienced with star formulation, I'd love to hear what you think. Here's a simple test formulation:

 

20 grams KClO4, milled

6 Grams Elmers "Ultimate Glue", Polyurethane

0.5 grams Red iron oxide or sulfur

 

Eliminate lumps from KClO4, combine glue, KClO4, and a few drops of MEK or Acetone to thin. Add iron oxide or sulfur. Stir/mash mixture thoroughly with a wooden stick (popsicle stick) until uniform. Add further drops of MEK as the mixture stiffens during manipulation. When completely uniform and any/all lumps of KClO4 are dispursed, spoon onto waxed paper in small pieces or segments. One big blob is hard to cut or break when fully cured, although it can be cut while still doughy, so it's best to create smaller lumps while still soft.

 

When cured, it is ready to test. It might be worthwhile to prime while still damp... sprinkle some granulated BP and press lightly to embed the grains in the glue dough skin.

 

Given what we know, please be safe. Moderators, if you think any of this doesn't belong, trash it.

[Photon_Junkie]

I did some asking around at work today, and pretty much everyone agrees that 2,4 diisocyantes (Mondur MRS2) and 1,4 diisocyantes (Mondur MRS-4) produce a free radical version of cyanide (.CN). Now with any moisture you will usually get HCN.

Absolutely no one will comment on how much...so much depends on temperature, competing species, etc.

I have a bomb calorimeter, I might try to make up a batch and see how much CN is produced. Basically...if its less than 20ppm per gram...there are far more toxic things we play with already.

 

Swede, man...those mixtures rock! I had no idea. Now I REALLY feel like a wet blanket.

 

This topic interested me cause someone mentioned Gorilla Glue. I have been bringing home waste isocyanates and making my own Gorilla Glue. Its also used in the spray foam "Great Stuff"...insulation in a can. This is also the primary ingredient in Rhino Truck bed linings. Its incredibly useful stuff.

 

I will keep digging...don't give up hope just yet. Hell, I am thinking of all the possibilities too!

[Swede]

Photon Junkie, ANY light you can shed in terms of toxicity, PPM, or other hazards, will be hugely appreciated. My gut feel is that unless you are burning pounds of this stuff in a closed area, it'll be OK. But I have been wrong many times before. I added some flake aluminum to a small batch and it was brilliant... from an upwind perspective. THANKS!!

[psyco_1322]

Ya I was going to say we burn things that are toxic and/or produce toxic fumes all the time but no one every tends to taket that into consideration. Like lead based dragon eggs.

[DeepOvertone]

Oh im so happy... I was so bummed when the potential high toxicity burst my bubble. I'm glad to hear that it "might" not be that bad. I will be trying some of this out in small portions just as a novelty for now. Thanks swede for your contribution.

[psyco_1322]

Just dont go running into the smoke taking deep long breaths and you should be ok. Its kinda like SO2.

 

You could also try using resorcinol glue in the place of polyurathane.

[Swede]

I've slept on this project, pondered a bit, and decided to continue on a limited basis based upon a couple of thoughts... first thought, the odor of the smoke itself. I am aware that toxic gasses don't have to smell at all, but GENERALLY when polymers burn, the stench is truly awful. When you burn plastic at a low temperature, that is when it generates more complex, toxic compounds. I wish I had a way to measure the temperature of this mixture's burn, but given the brilliance, I'm thinking it is very high.

 

High temps = simpler combustion products. The Bayer PDF file recommends incineration for disposal. I am thinking incineration in the industrial sense means extreme temps. I do understand that HCN IS a very simple compound, though, but isn't it, in this case, a partial decomposition product? Complete combustion hopefully would destroy this, producing oxides of nitrogen and carbon. The smell of the smoke - "simple" for lack of a better term. I am not smelling anything I would describe as unpleasant. There is no overpowering single odor, and definitely no fruity or almond-like smell.

 

I've got 4 additional samples to try today, for fun.

 

10:3.2 + 0.9 = 70% oxidizer, added iron powder, 325 mesh

 

7:2.5 + 1.6 = 63% oxidizer, + Strontium Carbonate, the only strontium compound I have; probably will burn slowly, which might be a good thing.

 

7:2 + 1 = 70% oxidizer, + Flake aluminum, 200 to 350 mesh

 

7:1.4 = 83% oxidizer, a straight mix, to see what that ratio will do.

 

All of these experiments since day one have used only acetone or MEK, no water. We'll see what happens, again from an upwind location. And I am going to continue online study. Thanks for the cautions, encouragement, and support.

[Sylar]

Let me be the first to tell you that breathing ANY type of smoke or airborne particles will kill you in the end.

 

That said, HCN is the least of your worries as long as you don't heavily overfuel the mix.

HCN is VERY flamable and will combust to H2O, CO/CO2 and N2 at the first sign of flame and available oxygen. Ofcourse hardly any combustion is perfect and trace amounts of HCN can definately be produced.

 

Be more worried about:

CO

SO2

ZnO dust suspended in air

Ba2O3 dust suspended in air

Lead oxides and vapor

...

 

Ullmann's encyclopedia of industrial chemistry:

In the presence of oxygen or air, hydrogen cyanide burns with a very hot flame. For the reaction

2 HCN + 1.5 O2  ¾®  N2 + 2 CO + H2O

the heat of formation is calculated to be –723.8 kJ/mol and the adiabatic flame temperature is 2780 °C.

 

The high heat of formation would be the main cause of the white hot flame I think.