Polyurethane glue

[Richtee]

I am working on some stars with this as a base... promising stuff!

 

I find if you spread it out on the backing of say the foil type tape, or double sided tpe backing, it will detach pretty easily. Anything else sheesh! INCLUDING skin!

[Swede]

I am working on some stars with this as a base... promising stuff!

 

I find if you spread it out on the backing of say the foil type tape, or double sided tpe backing, it will detach pretty easily. Anything else sheesh! INCLUDING skin!

That's the problem... and the promise. As a "binder" I don't think there is an equal!

 

I'm still plugging away. A very small portion of Potassium Benzoate (whistle glue) speeds up the burn proportionally, and at least with the small % I've tried so far, exhibits no nasty sensitivities. With each new batch, I test tiny portions with abrasion and impact to be sure it isn't overly sensitive. So far it is no worse than any other perchlorate star mix I've tried, and better than most regarding impact.

[Pretty green flame]

I am working on some stars with this as a base... promising stuff!

 

I find if you spread it out on the backing of say the foil type tape, or double sided tpe backing, it will detach pretty easily. Anything else  sheesh! INCLUDING skin!

That's the problem... and the promise. As a "binder" I don't think there is an equal!

 

Every binder has it's uses, not willing to give up Dextrin for now . Though I am looking forward to some air testing, not that i'm going to use this stuff (I'll stick to the traditional, "natural" binders )

 

I do see some uses apart from star composition, for example, a torch, and seeing you clips this would light up a BIG area. Also, portfires anyone? Some slower composition might be well suited for this.

 

Swede, I'd really like to see a porfire made from this stuff, a thin walled tube, 3/8" ID and 6" long filled with a slower type composition.

[DeepOvertone]

 

Every binder has it's uses, not willing to give up Dextrin for now . Though I am looking forward to some air testing, not that i'm going to use this stuff (I'll stick to the traditional, "natural" binders )

 

I do see some uses apart from star composition, for example, a torch, and seeing you clips this would light up a BIG area. Also, portfires anyone? Some slower composition might be well suited for this.

 

Swede, I'd really like to see a porfire made from this stuff, a thin walled tube, 3/8" ID and 6" long filled with a slower type composition.

I had this same idea when I first read this post. On another note.. I made a little discovery. I found that this stuff doesnt burn as well untill its fully cured. Anyway, I mixed a bit of zinc in one of the batches. I half filled a small tube (5/16"). I put in a piece of fuse and let it cure. It foamed up while curing and puffed up over the top of the tube. Anyway, I just lit it and this stuff burned like crazy!! It burned the whole ammount in about a second. I had been testing the straight mix this way also and it usually took about 8 seconds to burn the whole ammount. It didnt make much smoke at all. Far less than the mix just burning out in the open. I'm asuming it burns faster/better under pressure. I'm curious what it will do with a nozzle. I think it would definitely take off.

[jacob]

Well wouldn't you know it, none of my local hardware stores have "elmers" brand glue, I'll have to keep looking.

 

Swede, anything huh? how about "great stuff" polyurethane foam?

[psyco_1322]

How about instead of using as the main fuel try it just as the binder to a basic comp. Like what you were saying about the whistle glue. If you could add some color to the whistle comp and then just binder it with say 10% glue to slow it down a bit. Thats my idea.

[Richtee]

How about instead of using as the main fuel try it just as the binder to a basic comp. Like what you were saying about the whistle glue. If you could add some color to the whistle comp and then just binder it with say 10% glue to slow it down a bit. Thats my idea.

Mine too..perfecting a Margarita green now :{)

[DeepOvertone]

Ok.... weird..... The rocket motor I tried to make didnt turn out very well. I pounded my nozzle then pulled it off the tooling. I inserted a fuse in the nozzle and plugged it up with some tissue. I turned the whole thing over and put the comp down the open end. I filled it about 1/3 of the way allowing for expansion. So I checked on it a few hours later. It still handn't cured in the middle. It was still wet like when you make the stuff. So I left it for a few more hours. Its still a bit tacky. and it made a big cavity in the middle. Its just not turning out well. I'm wondering why it didnt cure in the middle. Not enough exposure to air?

[Swede]

I think the expansion and creation of voids in a poured rocket motor with this stuff is going to limit its usefulness as a propellant, but perhaps there may be a means to limit the expansion.

 

I think psyco has the right idea, and I am leaning in that direction as well... that is, as a really good binder. As I've tried more varied and different compositions using perchlorate + glue, I've noticed that as the overall % of glue goes down, the ease of handling (and reduced foaming/expansion) is improved. Especially, compositions that use either sulfur or airfloat charcoal expand less, or do not expand at all, and if the thinning solvent is kept to a minimum, one can make a truly workable dough that handles like some of the other star comps I've attempted... yet when they cure in only a few hours, they still exhibit a rock hadness and imperviousness to water or other solvent attacks.

 

Right now I think it remains an interesting curiosity, though with some untapped potential. Knowing how imaginative most dedicated Pyros are, I'm sure something will come of it. For stars, the burn speed needs to be improved. I think the benzoate shows promise for this. I don't have any zinc to try, unfortunately.

 

I've been taking notes, and I've probably got 25 samples in various proportions yet to try. I am going to make a table showing the comp ingredients, and columns to indicate what special properties (if any) they exhibit... also, ease of ignition, burn speed, anything else useful. Rather than proceeding willy-nilly, I want to be more methodical with the experiments.

[TheSidewinder]

You might try vaccuum degassing, at pour time, to eliminate the voids.

 

It's commonly done with certain APCP formulas. And for a few, it's a necessity. This complicates the process, but it's still doable. There are a few threads here that discuss the needed equipment. The main thing it to use components that are immune to the chemical vapors released during degassing and cure. Something to consider, anyway.

[psyco_1322]

The shrinking and hole developed in the middle of the motor is from the evaporation of so much solvent and the overall amount of substance decreasing, it just tries to lower the level. Like water evaporating out of a glass. The paper tube soaks up the solvent like a sponge and causes the outside to dry faster, it cant fall down with the rest if its dry, so the inside that hasnt drying yet falls in. Its like a cake.

[DeepOvertone]

I understand how it normally happens but this stuff tends to foam up as it cures. It usually doubles in size but this time it didnt foam up. I think it didnt cure because it was not spread out and had no contact with air. I think the stuff is made to be spread thin like between two pieces of wood. But I'm still confused because I put it into tubes before and it cured fine. I did use a 1"ID tube this time vs a 5/8"ID. Regardless, it didnt work at all. I'm not too sure about the glue I have though. Swede said that the gorilla glue doesnt burn as well and foams up allot more than the elmers that he is using so I might try to find the elmers. I looked at Home Depot and they didnt have it so I'll check the smaller stores.

[FrankRizzo]

Don't some of those glues need a bit of moisture to begin the isocyanate catalyst process?

[lja]

Yes, they do need some moisture to cure. It's pretty common to wet the wood before gluing and clamping when using this type of glue.

 

There is probably plenty of atmospheric moisture present when making stars, the rocket grains might have to be made and allowed to cure outside the engine and inserted after curing. Might be tough for larger rockets.

[jacob]

Well I couldn't find "Elmers" brand glue so I got a small bottle of "PL Premium Polyurethane Wood Glue" it's advertised as 100% Polyurethane.

 

I made two batches of Swedes comp, sort of, I actually used,

KCLO4 8

Glue 3

Carbonate 2

I changed it a bit because the scale I used doesn't show fractions of a gram, and the extra gram of Perclorate was accidental

 

One was made with Strountium Carbonate and the other with Barium Carbonate, both thinned with Acetone, I'll let you know how they turn out.

[psyco_1322]

Might I suggest the addition of the same amount of parlon as cabonate. This I believe would make your color tones a bit better. Just an idea based off something Ive made before.

[Boomer]

Now, are these glues moisture-curing or true two-compound, one being the curing agent?

 

I did quite a few tests with PU compounds meant for potting electronics, and the mixes hardened without shrinking or swelling more than 2%, and without needing any air. IIRC the stuff needing air/moisture is cyanoacrylate based.

 

Those test were mainly for PBX'es, but also for delay plugs that DON'T short-circuit in a cardboard tube because of shrinking leading to internal voids.

 

I HATE COMMERCIAL MATCHHEAD DELAYS as some of you may remember.

[psyco_1322]

Well im not sure if this helps but I used to just put water right on to super glue to get it to cure faster. Its majorly isocyanate based I believe. Not sure what that is but it sounds good.

[bmarley5780]

Wondering if the polyurethane wood surfacer would do anything?

 

Did Lowes / HD carry the Elmers?

 

-Joe

[jacob]

My lowes didn't, I didn't try HD, don't have one locally.

[bmarley5780]

Any star gun tests yet?

[Richtee]

Any star gun tests yet?

I have fired a few. They DON'T break for sure! Using a .25 inch walled .375 tube, went all the way to Benzo to lift 'em. The tube went..with a nice yellow-green star lofted WAAY up. Colored end plugs? Tough stuff

[jacob]

Well my results with this stuff weren't good, instead of Green I got white and my Red wasn't near as good as Swedes, my only thoughts as to why are,

 

Wasn't mixed well enough,

Something to do with the glue I used,

And/or it wasn't fully cured, it never got really hard like Swede mentions, but it did sit overnight, maybe their was water in the Acetone

I used? don't know.

 

I may experiment with this more in the future but one thing to remember is, WEAR GLOVES when working with this glue, I did use them when mixing these comps but didn't later that day when actually glueing something, it took days for the stuff to come off (aong with some skin)

[Photon_Junkie]

Going to answer some of the previous questions.

 

All of the "urethane type wood glues" use urethanes are initiated by water. Again, as someone said, its a one-part system.

 

Isocyanates form urethanes when mixed with any type of hydroxl group (alcohols). What makes Gorilla glue and its analogs so good as adhesives is that the pre-react the isocyanate with a long chain alcohol such as 1,4 butanediol or a carboxylic acid. They do this in an off-ratio manner with a massive excess of isocyanate. This creates a stable homopolymer that then can react with water to form polyurethane. So you essentially have a two-part urethane in a one-part system.

 

Oh...and an excess of water will make any isocyanate foam like crazy. In fact, the spray insulation Great Stuff, is just a can of isocyanate and water (plus some surfactants).

 

Traditional "super-glue" is a methyl methylacrylate system. It also uses water to start the reaction but its a completely different chemistry and product.

 

Jacob, in my humble opinion your stars are seriously lacking any chlorine donors. The symptom of this is washed out or "white light" stars. Also with carbonates, I generally have to use metals to get the temperature higher...but that could just be me.

Oh yes...this adhesive loves skin...it will pull moisture from anything. One of the reason you wet your wood pieces before gluing is so that it doesn't actually "rip" water from the lower levels of wood and create a form of dry rot. Wood needs some water to maintain strength and flexibility.

 

Hope this info helps.

[Richtee]

Any star gun tests yet?

I have fired a few. They DON'T break for sure! Using a .25 inch walled .375 tube, went all the way to Benzo to lift 'em. The tube went..with a nice yellow-green star lofted WAAY up. Colored end plugs? Tough stuff

Also, am planning some rising comet applications...self-adhering! Just roll a fat ring around the time fuse and press into place I figger. Any comments / ideas?