24 replies to this topic

[Arthur Brown]

Is it possible to make a solid compound (star/comet etc) using an adhesive like an epoxy or polyester resin. The resin forming bothe the binder and part of the fuel requirement (and possibly a lacquer for aluminium particles too).

[lavenatti]

I believe the Chinese use phenolic resins in a number of their stars. 'DAP' makes a readily available phenolic resin, I picked some up but have yet to try it. I'm not sure if epoxy would work (color contamination) but it's fine for rocket fuels.

[pyrotrev]

It most certainly is, but since the technique isn't suited for rolling stars in the normal way, it's better for pumped comets and microstars. Brocks were the first people I heard of doing it, in their last years before ceasing UK manufacture, certainly their resin/perc. hummers were the best I've ever seen.

Edited by pyrotrev, 02 March 2008 - 06:25 PM.

[Arthur Brown]

I was tempted by the thought of some comets made with oxidiser resin colour and flitter poured into moulds in something like vinamould or...

Trouble is getting enough solids mixed in with the resin.

[cooperman435]

I did a little bit of experimenting in my early days using a formula I found on the net that used epoxy two-part glue as a binder for e-match pyrogen, but found it simply didn't work, which I put down to an under-oxidised composition. Even when I added an excess of pot perc, I could still hardly get it to sustain a flame and definatly wasn't of use for a pyrogen.

For the life of me I can't remember the webpage nor another I was reading about AP based cast rocket propellant.

I do think that the type of resin is very important, but I have no idea what types there are or which would be suitable. If anybody does know, then make yourself known as my comets are taking months to dry and a resin based one would be far better.

[Richard H]

Brocks did many experiments with phenolic (phenol resorcinol) resin. Humbrol sell it under the trade name 'Cascophen'. A few years ago I tracked down the patents filed by Brocks and other companies like Astra, if you are interested I will find the reference numbers so you can track them down online.

[rr22]

Hardt mentions resorcinol-formaldehyde resins,
then goes on to say that phenol-formaldehyde thermoplastics called "novolacs"
are widely used in the Chinese and Brazilian Pyro. industry due to low price and a wider variety of
forms (powder etc..).
Hardt says Shidlovskii goes into detail in "principles of pyrotechnics" using the name "Iditol"
for the resins,but I don't have that book.
I have found a company that does "sample" sizes of just about every resin /solvent I have ever heard of,
I don't want to publish it here,but PM if anyone wants details.

Edited by rr22, 05 January 2008 - 06:39 PM.

[Bonny]

I've heard of others using it for comets,
See this link on APC forum.
http://www.apcforum....?showtopic=1313

[dr thrust]

yeah! heres one from the web,
[/list]strontium nitrate 35

pot prec 40

sculpy 22 which is a polymer modeling clay

fe203 2

heres the tricky bit! youve got to bake it in a " remote cheapo electric oven" at 135, but then again lots of people cure ther composite rocket motors that way, you could add ali to start with to see how it go's whats your thoughts? it could be a 30 minute and ready to go comet !

[Arthur Brown]

It was the APC article that started my interest. The present trouble is that the resins I have seen are thick and viscous and getting all the powder in the mix before it hardens could be a problem. Initial searching brought up only an aerospace supplier of the quoted resin at aerospace prices.

My first aim was to produce a compound without needing a major press instalation, and associated tooling.

[icarus]

i read an article that said fimo modelling clay was the uk equivalent of sculpy not tried it though my interest would be as a casteable rocket motor fuel i await any reports

[Mumbles]

I'm sure it's in the thread, but the person in question, qwezxc thins it down with methanol I do believe first.

More information is available on rec.pyro somewhere by lightnpyro@yahoo.com I do believe.

[BrightStar]

I have often come across Laminac (ie Polyester) as a binder in flare compositions, but with no details on how it was utilised. Presumably liquid resin could be used, but you might have to allow it to set in a partial vacuum to remove air bubbles.

It was the APC article that started my interest. The present trouble is that the resins I have seen are thick and viscous and getting all the powder in the mix before it hardens could be a problem.

Arthur, take a look here: http://www.cfsnet.co...E_RESINS_2.html. I believe that casting resins are generally thinner and intended to accept a higher loading of filler.

Edited by BrightStar, 07 January 2008 - 12:44 PM.

[Daedalus]

You could try East Coast Fibreglass Supplies for casting resins. They do both epoxy (laminating) and Polyester (laminating and casting). Both of these will be thin compared to tube epoxy adhesives. I haven't dealt with them but they are recommended by a friend who uses them for boatbuilding supplies and their prices are pretty good.

Dave

[pyrotrev]

It seems the Chinese are using some resin binders in current production. We had some mines in the NYE display that got rather wet (well there was 6cm of rain that evening), rather than try to deal with possibly dodgy damp misfires, I left the tubes with standing water in them for 7 days before trying to extract the contents. Whilst the lift was black soup, the stars were not only intact, but quite solid and lit first time (had to try it - at a distance on the burn site ) from a bit of PIC. The other interesting thing about these stars was that they didn't appear to have any priming on the outside - they had a slight reddish brown tinge (which would be normal for a lot of phenolic resins), with a few metal particles visible.

Edited by pyrotrev, 12 January 2008 - 01:24 PM.