densest
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smokeless fireworks patent gone walkabout: nitrocellulose/dicyandiamide
There are a number of patents for smokeless fireworks using nitrocellulose fuel modified with accelerants for faster and hotter burning. One use is
for firework stars. Nitrocellulose alone doesn't burn fast enough or hot enough for that purpose..
The patents (Michael Hiskey US5917146A for instance) specify various high-nitrogen energetic compounds, the least complex being aminotetrazole and
derivatives. I don't want to use (or worse, synthesize) any of those if possible. A compound with 13 N's in a chain? Eeeek!
Once upon a time I'm sure I saw a patent using nitrocellulose and dicyandiamide for a low-smoke composition. I can't find it.
I'd rather not go into this blindly because various patents using accelerated nitrocellulose describe significantly differing compositions: one calls
for [sic] 0.01% to 20% accelerant, for instance. 0.01% sounds almost homeopathic! Other patents say 10% - 30%. Other components (colorants, chlorine
donors, oxidizers) vary a lot. Some of the patents call for ingredients like ammonium nitrate which is very rarely used in display pyrotechnics
because of its significant hygroscopic qualities and changes of crystal habit over temperature. Others call for metal aminotetrazolates which I
believe can be sensitive primary explosives themselves. Disinformation in a patent? Surely never!
I'd like to find the specific one using dicy if possible. If it doesn't exist I think I'll try a few test compositions anyway and hope for the best.
AFAIK cyanamides aren't readily available OTC in the US but cyanuric acid stabilizers are. Given that I could buy 12% NC in the US (haven't looked
yet) it would be fun to try this out. If need be I think I could have someone with appropriate credentials buy NC. I have access to people with a Type
20 fireworks manufacturing license so it (probably) could be done (mostly) legally & tested at a permitted shoot.
Clues, anyone?
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aromaticfanatic
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Quote: Originally posted by densest  | If need be I think I could have someone with appropriate credentials buy NC. I have access to people with a Type 20 fireworks manufacturing license so
it (probably) could be done (mostly) legally & tested at a permitted shoot.
Clues, anyone? |
Just want to point out that transferring explosives that civilians aren't meant to have, to a civilian without paperwork and credentials is pretty
freaking illegal.
I have read through most of the ATF manual for FEL holders and they point out that transferring what are classified as high explosives or even
commercial fireworks is indeed very illegal.
Nothing is illegal if you can't get caught 
So if you decide to go that route, be absolutely sure you won't get caught because you and your guys might get in big sh*t for that.
Regarding the rest of your post, I am likely not of too much help but I know practically all metal nitrotetrazoles are very powerful primary
explosives. Metal aminotetrazoles are also most often powerful primary explosives.
If you are looking into making cyanamides, look at the tetrazole series on the Youtube Channel, explosions and fire. He makes calcium cyanamide from
basically scrap chemicals literally laying around in his backyard. It's a fairly straight forward process too and is scaled up easily.
I'm not sure how much nitrogen content the following will have but I source my NC from concrete nail guns blanks. Look up the color coding on them and
get the most powerful ones. With leather gloves, face shield, and hearing protection (I've never had one go off with this method but when I was
shooting one with a pellet rifle (with proper PPE of course) the casing came right at me and struck my thigh. I was only at most two feet away and all
it did was bruise a little and sting. So no real hazard in terms of penetration, however if some metal pieces dislodge at the crimped end, those can
become dangerous shrapnel so I suggest you always point the opening/crimped end away from you.) you can hold one blank with one set of pliers and
using another set of pliers you can squeeze the crimped part. Squeeze a few times and the NC will fall right out. Be sure to not collect the priming
compound. In my case it is green so it's easy to see.
I'm not sure how much NC you'll need to the above method may prove too tedious. I suppose you can buy the 12% and nitrate it once more using as
anhydrous conditions as you can and boost the nitrogen content more.
As far as the rest of your question goes, I am not sure. I agree 0.1% is not going to have any major effect, I assume they will have 5% or up for any
accelerants. If I had to guess I'd say 20% accelerant seems pretty suitable.
I hope I was able to help a little bit. Best wishes.
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ShotBored
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| Quote: Originally posted by densest | There are a number of patents for smokeless fireworks using nitrocellulose fuel modified with accelerants for faster and hotter burning. One use is
for firework stars. Nitrocellulose alone doesn't burn fast enough or hot enough for that purpose..
The patents (Michael Hiskey US5917146A for instance) specify various high-nitrogen energetic compounds, the least complex being aminotetrazole and
derivatives. I don't want to use (or worse, synthesize) any of those if possible. A compound with 13 N's in a chain?
Clues, anyone? |
I know of the patent you are talkings about and I can't find it in my directory either. However, I have used cyanoguanidine(dicyandiamide) to
stabilize NC (12.5%N) effectively and have the thermal stability data to back it up. I know everyone nowadays derps about high N% NC, but for regular
fireworks, I found that I got fantastic smokeless compositions using lacquer grade NC, particularly blues. Just be aware of some carbonates; most of
us would look at carbonates and consider them good stabilizers but there was a paper recently that showed that some carbonates, such as strontium,
actually destabilize NC. I'll try and find it for your reference.
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ShotBored
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Here is that paper
Attachment: Katoh_et_al-2010-Propellants_2C_Explosives_2C_Pyrotechnics.pdf (356kB)
This file has been downloaded 294 times
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densest
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Thanks to both!
aromaticfantastic - I'm trying to -avoid- using anything that might be considered high explosive! I want to stay as far away from tetrazoles, etc. as
possible. I'd be using 12-12.7% NC.
Keeping the appropriate authorities placated is difficult and complex but necessary.
AFAIK transferring otherwise unrestricted ingredients to the holder of a manufacturing license and then constructing fireworks which are legal 1.3d
under their control & on their premises is OK. The result would then be taken to the shoot site correctly (CDL, placards, licenses, etc.) and
fired in a show with permits under the control of a licensed person.
The restrictions get worse every year. The unintentional consequences... At a show not too long ago the required electrical ignition system set off
every mortar due to a bug in the show program. Oh well...
Synthesizing aminoguanidine, I believe, is something that OSHA and EPA might object to but other authorities care little about.
I haven't seen solid NC sold by firework chemical suppliers. I'd like to purchase a kilogram or two of it without causing ripples given the ongoing
authoritarian paranoia. Where I live buying a case of nail gun blanks at Home Depot could cause notice.
ShotBored - I'm very curious about your star compositions. I use NH4ClO4 / Cu(C6H5)2 for blue with 1-2% red gum adhesive. The benzoate is a fuel as
well as a colorant and causes significant smoke. Replacing most of it with NC would be very helpful. I didn't know that aminoguanidine acts a
stabilizer. Have you noticed any change in burn rate?
The paper on NC stability is definitely informative. That SrCO3 destabilizes is unfortunate. It would be an interesting distraction to construct a
calorimeter to test KNO3, for instance.
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ShotBored
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I responded to you in U2U concerning formulas....don't want to make it too easy for people out there, and typically any formulas I share go on
Pyroforums. The cyanoguanidine does function as a stabilizer, it has an acceptable water solubility and seems to prevent the NC from acidifying as
much over time. The paper you brought up discussed this topic if I remember correctly, but I'll try and find it again in my records to figure out
exactly why.
To ensure I correct a slight error in your previous reply, 2-cyanoguanidine seems to stabilize NC, though likely not as effectively as arkadite or
centralite or DPA. I'm sure aminoguanidine bicarbonate would likely stabilize NC though as well if you're also interested in aminoguanidine compounds.
But no, the incorporation of 1-2% cyanoguanidine seemed to little, if any effect on the burn rate from my perspective.
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