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Author: Subject: NG + Nitrocellulose Problems
MindHive
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sad.gif posted on 1-7-2016 at 07:40
NG + Nitrocellulose Problems


Hello sciencemadness forums. This is my first post but I have used this forum as a resource for quite a while. I have successfully synthesized several energetic compounds including: acetone peroxide (big mistake, won't make more than a few mg's and will NOT store, even if wet.), hmtd (same opinion as ap), ammonium perchlorate (haven't synthesized, have just dealt with it extensively), aluminum-oxidizer mixes (same as ammonium perchlorate, although I have made my own <3 micron), ammonium nitrate compositions, trinitrophenol and picrates, nitroglycerin, nitrocellulose, black powder compositions, flash powder compositions, urea nitrate, EGDN, and various others. Basically, I'm not new to these materials. But enough about me and more about the science and my current predicament.

For the past week or so I have been making NG and NC, the NG I have used to make dynamites. Unfortunately, I have been having quite a troubled time trying to make blasting gelatin by dissolving Nitrocellulose cotton into nearly anhydrous NG. The NC just soaks up the Nitroglycerin and does not turn into the gelatinous mass that I have heard so much about. Can someone please explain the manufacture process for making a successful NG/NC jelly/plastique? I don't understand, am I missing something? Both the NG and NC have been synthesized via nitrations using homade RFNA and concentrated commercial H2SO4. Thank you for your time...
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Jimbo Jones
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[*] posted on 1-7-2016 at 08:14


Gentle heat the two components or just use suitable solvent. Acetone for example.
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XeonTheMGPony
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[*] posted on 1-7-2016 at 09:04


yup couple drips of acetone does wonders.
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Praxichys
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[*] posted on 1-7-2016 at 09:29


Your nitrocellulose is either under or over-nitrated. Cellulose is insoluble in solvents like acetone or NG, but solubility increases with degree of nitration, until about 12% N. After that, solubility rapidly decreases up to a minimum at the theoretical maximum nitration of about 13.8%.

If your NC deflagrates almost instantly and leaves no ash, it is probably too nitrated to dissolve. Likewise, if it burns slowly and leaves residue, it is probably under-nitrated. The addition of a small amount of acetone can certainly help as long as the NC is not ridiculously over-nitrated, but this decreases brisance, increases volatility and flammability, and and throws off oxygen balance.

For high-quality soluble nitrocellulose, nitrate a bunch of cotton under milder conditions. Shake this with acetone, and filter out the residue. Pour the filtered acetone on a glass pan and let it evaporate. The soluble nitrocellulose will be left behind as a sheet which you can scrape off and dissolve into NG to make blasting gel.




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MindHive
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[*] posted on 1-7-2016 at 11:47


Thank you for all your replies! I'm glad I joined sciencemadness and will certainly follow all of your advice. :)
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ecos
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[*] posted on 1-7-2016 at 18:07


Quote: Originally posted by Jimbo Jones  
Gentle heat the two components or just use suitable solvent. Acetone for example.


this is very risky ! please don't do that!
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OneEyedPyro
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[*] posted on 1-7-2016 at 18:11


Like Praxichys said try doing it under less extreme conditions, you're probably getting highly nitrated NC.

I just use a nitrate salt and drain cleaner sulfuric acid for soluble NC, RFNA and 98% sulfuric seems a bit overkill :D

I recall NG/NC gel having inferior properties to plain NG like worse storage stability, I also heard it has a much lower VoD than you'd expect. This is just hearsay though.
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simply RED
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[*] posted on 1-7-2016 at 21:13


Use acetone and then evaporate the acetone...



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Jimbo Jones
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[*] posted on 2-7-2016 at 02:13


Quote: Originally posted by ecos  
Quote: Originally posted by Jimbo Jones  
Gentle heat the two components or just use suitable solvent. Acetone for example.


this is very risky ! please don't do that!


http://www.google.com/patents/US2421536
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ecos
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[*] posted on 3-7-2016 at 04:46


Quote: Originally posted by Jimbo Jones  
Quote: Originally posted by ecos  
Quote: Originally posted by Jimbo Jones  
Gentle heat the two components or just use suitable solvent. Acetone for example.


this is very risky ! please don't do that!


http://www.google.com/patents/US2421536

I know about warming the mix using special tools.
this process need good control to the heat
for an amateurs they can be in trouble !
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[*] posted on 5-7-2016 at 03:06


What was your exact preparation on the NC? Its the only EM I cannot get perfect every time.



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AngelEyes
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[*] posted on 6-7-2016 at 03:49


I can't speak for anyone else, and it's been quite a while since I last made it, but I was able to produce pretty good NC (burnt quick, little or no residue, storage stable for a few years) using this method:

69% HNO3
96% H2SO4 (drain cleaner stuff)
Cotton wool balls from pharmacy or supermarket

Roughly 1:3 (nitric:sulphuric) by volume in a glass dish and then put into the freezer for a bit to cool down. Cover it otherwise it'll fume like mad.

Once cooled, take your cotton (I used cotton wool balls) and fluff it up a bit before placing slowly in the acid mix. Prod gently with a glass rod or something suitable (a thermometer is ideal), to make sure the cotton is covered.
Keep (slowly) adding cotton until the liquid won't easily take up any more. You don't want to add so much cotton that it soaks up all the liquid though.

Once all the cotton has been added and the temperature remains constant, I leave it overnight in a place where it will not be disturbed. I may prod it again every hour or two to make sure it gets the best chance of fully reacting.

Next day, take it out (carefully) and drop into a large amount of clean water. Squeeze it all as best you can, then transfer to another load of clean water. Squeeze, and then dump into a weakly basic solution (sodium carbonate for example) and if no bubbles or fizzing is observed then it'll be neutralised.
For best results, leave to soak in the carbonate solution overnight.

Remove, dry fully and then test a small amount - it should go somewhere between 'poof' and 'whoompf' with a nice yellow/orange flame.

I have always managed to get decent NC, despite the fact I use 69% nitric, drain cleaner sulphuric and standard cotton balls. I reckon this is due to the excess of sulphuric mopping up every last bit of water and also the fact I leave it overnight to react.

It dissolved in acetone nicely and left me with a stiff sheet after that also burned cleanly, but less fiercely than 'raw'.

As usual, this was my experience and your mileage may vary.


Angel.




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Hennig Brand
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[*] posted on 6-7-2016 at 23:50


I forget the exact details, but I know from experience that it is very easy to make NC that has surpassed the level of nitration that will allow it to be readily soluble in NG. The following link shows up to 12.6%N for use in dynamite manufacture, but I know I have seen much lower specified in some texts for dynamite, for example. IIRC, 12.2 or even 12%N I think has been used.

http://nitrocellulose.synthesia.eu/eng/energetic-nitrocellul...

I made an Excel sheet, which I posted in the bullet propellants thread, which should help you find quantities and strengths of acids needed to produce whatever level of nitration you want.



[Edited on 7-7-2016 by Hennig Brand]




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ecos
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[*] posted on 1-8-2016 at 08:11


Quote: Originally posted by simply RED  
Use acetone and then evaporate the acetone...


it works but you will have porous product !
a lot of air bubbles will be trapped inside this will decrease the density.
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[*] posted on 6-8-2016 at 16:37


Yeah, viscous liquids can hold onto air bubbles sometimes. A good pull with vacuum should get any bubbles out easily, once the NC has been dissolved. Maybe a bit of vacuum would be good during acetone removal too?


[Edited on 7-8-2016 by Hennig Brand]




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PHILOU Zrealone
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[*] posted on 7-8-2016 at 09:53


Quote: Originally posted by Hennig Brand  
Yeah, viscous liquids can hold onto air bubbles sometimes. A good pull with vacuum should get any bubbles out easily, once the NC has been dissolved. Maybe a bit of vacuum would be good during acetone removal too?


[Edited on 7-8-2016 by Hennig Brand]

Nope, since aceton has such a "low" boiling point, the vaccum may generate a lot of bubbling and foaming.

If NG was not so sensitive, I would propose the use of ultrasounds...

So better leave the mix to slowly evaporate...up to a certain point propeller blade slow speed agitation will drive the bubbles upwards...but once too viscous, it has to be stopped and taken away otherwise it will incorporate air by breaking the gel.




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[*] posted on 7-8-2016 at 18:31


Well I don't have a lot of experience with it, but for starters we should probably specify a viscosity (dependent on composition and temperature), a vapor pressure for acetone (dependent on temperature) and then depending on that a level of vacuum/reduced pressure. I believe he was talking about air bubbles incorporated during mixing or maybe included with the, between the fibers of, the NC. It depends on several variables but conditions should be able to be controlled so that the air bubbles can be removed without producing a lot of acetone vapor bubbles or having them be there by the end.

This is all speculation anyway. Maybe I used an excess of acetone(very low initial viscosity), but from experience when using MCNC I found with simple atmospheric drying that I ended up with a dense sheet of propellant with no or very little air or vapor voids.

With the right amount of reduced pressure, or no reduced pressure, eventually the percentage of acetone lowers and viscosity rises to such levels that the acetone tends to not easily form bubbles anymore and travels mostly by diffusion to the "sheet" surface where it then leaves by evaporation (I think).




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[*] posted on 8-8-2016 at 00:23


you might have a problem in case of MCNC if you couldn't get rid of all remaining acid traces (HCL)
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