22 replies to this topic

[seymour]

I have. It burns well, but the main reason it is used in rocketry is because a two part liquid monomer system can be used, so that the grain cures as a solid block. Solvent activated binders leave a porous structure that is fine for most firework uses, but causes havoc inside a high power rocketry motor. Think expensive catos.

As Pyrotrev said the two part polyurethanes are readily available. Some work much better than others, and some cause gas to be evolved, especially if your Ammonium perchlorate is not BONE DRY, which makes them unusable for high power rocketry uses. One of these is the one I have used for stars, as I received it from a rocketry friend who needed a material that did not create any bubbles, and thus passed it on to me!

Be aware that the monomers are not human friendly, particularly isocyanate.

[al93535]

The incompatibility of magnesium and AP was lightly addressed. I would like to add that mg/al and AP are also incompatible. Stick to aluminum and AP and use something else to lower the activation energy required.

I am also currently working on some AP/aluminum fueled rockets. I had one burning so hot the thing catoed quite spectacularly. I should have a working formula here within a few months. This is on standard BP cored rocket tooling and is pressed.

Heptane is what you want to dissolve latex.

[pyrotrev]

As Pyrotrev said the two part polyurethanes are readily available. Some work much better than others, and some cause gas to be evolved, especially if your Ammonium perchlorate is not BONE DRY, which makes them unusable for high power rocketry uses. One of these is the one I have used for stars, as I received it from a rocketry friend who needed a material that did not create any bubbles, and thus passed it on to me!

Are you able to let on the variety that works please? - I happen to know an arty-crafty place that imports some PU components from Australia, I wonder if it's one of those. At £30ish for the MOQ of isocyanate/polyol it would be kind of expensive to go through their complete catalogue to find whch is best

Edited by pyrotrev, 20 February 2009 - 01:35 PM.

[knackers]

thanks do you mean celluose 'thinners' ? re compatible with nh4clo4 any i should defietly avoid?
ffs

g'day steve,
i'm sorry, off the top of my head i can't advise you on which solvents to avoid, i would have to research that, and i'm sure you can do that,
as in al93535 s' post he says to use heptane for the solvent, reaserch that

regards phill

[seymour]

Are you able to let on the variety that works please? - I happen to know an arty-crafty place that imports some PU components from Australia, I wonder if it's one of those. At £30ish for the MOQ of isocyanate/polyol it would be kind of expensive to go through their complete catalogue to find whch is best

I'm afraid I do not. I'm not the one who bought them, and right now I'm not in NZ so I cannot check. I'm in Boston, but in a few weeks when I'm back I'll try to remember to post the details. Remember though, the one I have is one that does cause bubbles to be formed.

The way my friend sourced the best stuff was informed trial and error. I believe he was looking for stuff where the basic monomers had already been linked into short chains, therefore reducing the number of active functional groups that can cause problems.

You really need to mix the separate parts of the binder into the dry chemicals very thoroughly and evenly, and they are fairly viscous. Plus they start to cure, giving you a limited working time. Are you sure you know what you are getting into??

Out of curiosity, what do you plan to make with the AP/Polyurethane?? Stars, Rockets, Go-getters???

PS, anyone in Massachusetts ??

[pyrotrev]

I'm afraid I do not. I'm not the one who bought them, and right now I'm not in NZ so I cannot check. I'm in Boston, but in a few weeks when I'm back I'll try to remember to post the details. Remember though, the one I have is one that does cause bubbles to be formed.

Well, it would be interesting to know. I'm interested mainly to see whether it's a viable binder/fuel for stars, though it would be fun to make the odd mental rocket

[whoof]

I know this is an old thread but i was wondering if any American based pyros have experimented with this
http://aeroconsystem...ubber-92-0.html

[Vic]

A bit of info from APC forum.

HTPB (CH2-CH=CH-CH2)n(OH)2. See Polybutadiene R45 Resin.
Elastomeric resin used in composite rocket fuel. Hydroxy-Terminater Polybutadine, more commonly referred to as HTPB, is a yellowish flammable liquid most commonly used as a polymer binder in AP/AN solid rocket propellants. RT-45M or the non mil-spec R45HTLO type resin are often used, which requires a seperate curing component.
HTPB is also used commercialy to make adhesives, modify rubbers, sealants and other types of coatings.

Polybutadiene R45-M Resin (HTPB)
Used in some composite rocket motor fuels. Room temp cures with Isonate 143-L or at 140° F with IPDI (Isocyanates).

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