CuBr blue composition

[greenlight]

A significant trend that is emerging is to try and find replacements for perchlorate oxidizers in pyrotechnics. The main reasons being some of the chlorine byproducts from burning are toxic and the perchlorate anion messes with thyroid function.

 

I decided to try one of the new non-perchlorate blues from a paper I downloaded a while ago by klapotke group. I think it was a user of this forum that linked it and I cannot find the download link again.

 

The new formula uses bromate oxidizer (which is toxic to breathe I know), bromide colourant and hexamine as the fuel.

The formula I used is B6 and comprises:

 

Potassium bromate. 58%

Copper (I) bromide. 18%

Ammonium bromide. 12%

Hexamine 12%

 

I synthesized the Copper(1)bromide from copper sulphate and sodium bromide with sodium sulfite addition before filtering and drying which yields the Cu+1 salt. Method can be found on prepchem website.

 

The ammonium bromide was synthesized by neutralizing a solution of 30% ammonia with azeotropic hydrobromic acid and boiling off the water.

 

I pelletized one batch with no binder which is pictured below and another batch was binded with 5% parlon, wet with alcohol and cut to small stars. The final small batch was bound with 5% dextrin and cut when wet too.

 

The worst burning was the unbinded batch and formed quite a large snake firework type ash pile upon burning.

The dextrin bound stars were much better but still leave a lot of ash.

 

The winning mix for me would have to be the parlon bound stars. They are nice and hard, have a good burn rate, and leave the least ash behind upon ignition. They also have a larger flame envelope.

 

The blue is quite deep and they look quite similar to a decent perchlorate blue with hexamine.

I noticed that the blue became slightly paler and whiter towards the end of the burn sometimes. I think the temperature was getting too high. I noticed that when thrown through the air after ignition they maintain the deep blue because of the extra air cooling I believe.

 

I think this composition does quite well and it is interesting and maybe helpful for some people to be able to make a decent burning blue without using restricted oxidizers that are hard to obtain in some countries.

I would like to try them primed in a starmine next to see how they compare to some perc blues.

Edited October 15, 2018 by greenlight

[rsambo]

Hi fella,

 

that's pretty much how I did it to the letter, I'll dig out the link to the paper and post it again.

I found the same issue with the whitening and the temperature rise, so that might be helpful to you.

I found binding with Ixan released a strong smell of chlorine after a few days

I also found that Copper (i) bromide oxidizes readily in air to Copper (ii) bromide which is deliquescent so the stars had no useful shelf life.

There are excellent blue stars that can be made with potassium bromate, and I still think it has promise for strobes but not with the formulas given in the paper unfortunately.

[rellim]

Potassium perchlorate was used in 100 milligram doses to control hyperthyroidism.

The tiny amount you might get from fireworks is falsely promoted as a hazard by the professional greenies.

Bromine can be toxic, see https://en.wikipedia.org/wiki/Bromism.

[greenlight]

@Rsambo, yes it does oxidize to the copper(ii) bromide so I have it sealed in a bag. The parlon and dextrin stars still burn exactly the same and it has been two days since I made them.

I wonder if the parlon and prime coating would stop them oxidizing in air?

 

@relim, yeah I had a feeling that thyroid disruption may have been a bit overexaggerated. Otherwise I am sure some of the members on here would be suffering from it:).

Edited October 16, 2018 by greenlight

[Arthur]

And how many people watch a NASA solid booster rocket launch without dying from perc poisoning? That booster mix is 70% perc in multi ton loads!

[Crazy Swede]

The perchlorate issue is not about getting poisoned, it is about perchlorate ions reaching ground water and maybe affecting the thyroid function of babies that theoretically could inhibit their growth.

[Crazy Swede]

I wonder what the purpose of the ammonium bromide was in the formula from the Klapötke group?

A coolant maybe?

 

The mixture looks very fuel lean and maybe that explains why parlon made it burn better, even though chlorinated rubber normally is a lousy fuel.

[Yus]

Is you idea from: https://phys.org/news/2015-09-benign-blue-pyrotechnics.html ???

[greenlight]

@crazy Swede, Yeah the ammonium bromide is the coolant, it states it in the paper somewhere.

 

@ Yus, Yeah that looks like a report on the article I got the formulas from. I don't know why they have only listed copper bromate and ammonium bromate though. That was one of the other formulas which was not as good as the bromide salts.

 

I have had about 10 of the parlon bound bromide stars sitting out in the open for about 6 days now and they show no signs of changing to Cu+2.

They also behave exactly the same as when I first made them so maybe the parlon protects the chemicals from decomposition and oxidation by coating everything.

Edited October 19, 2018 by greenlight

[PyroMan LTU]

Hi Guys,

 

Nice to see you trying these bromate compositions. I actually took part in this project at Klapotke group in 2015.

 

Our objective was just to proof a principle and show that you can make a simmilar blue flame with a bromate oxidizer. Hence I am quite sure you can tune them to an even better performance and compatability. In my memory the best comps for practical use were:

 

B4 B7

KBrO3 65 58
CuBr 20 18
hexamine 15 12

Nitroguanidine 12

 

B6 had a deep blue color indeed, but it created too much slag. NH4Br was a coolant. Right now I am still looking up the compatability of these comps due to 1) the possible NH4BrO3 formation risk, 2) Cu bromate amino complex fromation, which is a potential primary explosive.

 

Wish I could attach the publication here... Anyways It's nice to see that my account here still works as my last login was perhaps 5-7 years ago.

[greenlight]

Wow, amazing to hear from someone who was actually involved in the project.

 

The large amount of slag is a problem and I noticed it most in the unbound compositions that where just pressed as is.

 

I am interested in the results of that publication. Lucky I dont plan on keeping the mix around too long or making an actual shell with it.

[Mumbles]

Ammonium chloride acts also acts as sort of a crude chlorine donor, since it decomposes at fairly low temperatures to ammonia and HCl. I would hazard a guess that ammonium bromide acts in a similar way.

 

The main chlorohydrocarbon that is the major environmental hot topic are dioxins. If this is really a concern, you should drop the use of parlon which is probably the primary source of them.

 

These are neat proof of principle examples. The formulas do have some environmental, safety, stability, and economic concerns for eventual large-scale usability though. Still like this. Ionized CuBr theoretically gives a purer blue.

 

There are some brominated fire-retardants that I think might be useful as bromo-substitutes for conventional chlorine donors.

[Arthur]

BUT KBr used to be put in prisoners' tea to reduce sex drive. Apparently it's been discontinued, but spraying it around has it's own risks, that are properly documented.