Student32
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Forming nitrocellulose to solid block?
I've been reading the forum for years, but never had the need to post anything. Thank you for all the useful information you've posted!
I have a question on forming nitrocellulose (NC) into a solid block for use as a propellant.
Background
I've been doing amateur rocketry since I was a kid. This is uncommon here because of all the restrictions (for example the most powerful engines
availible are D-class), and the lack of useful open fields. The amount of information available was non existent until the internet became big, and in
the early years of the internet most sites with information on pyrotechnics were neither accurate nor safe.
I now have access to a workshop which is licensed for manufacture and storage of certain pyrotechnic devices. I only mention this because through that
connection I have done some work on applied pyrotechnics, and the staff there have taught me a lot about working with those materials and the science
involved. The goal of this thread is NOT for me to actually make it, I'm interested in the theories and science of the subject. I am of course
also interested in information and experiences by anyone who has hands on experience on working with NC as monolithic blocks.
Issue
There is little information available on casting NC for use as a monopropellant. Most other energetic materials I have dealt with have two issues with
casting; uneven solidification and block deformation by shrinkage.
Regardless of casting with a solvent or by heating, most materials will shrink slightly when they solidify. When casting, the outer edges and top
surface will usually solidify first. When the volume inside these walls solidify it shrinks, but the walls don't shrink with them. Shrinking inside an
inflexible wall, cracks, defects and air pockets will form.
The other issue is shrinkage of the entire block. If cast as a cylinder, the block will shrink slightly resulting in a concave outer surface which is
slightly smaller than the original cylinder. This is a problem when the block is a rocket propellant; upon ignition the outer surface could start
deflagrating, resulting in a higher combustion rate than intended, causing a CATO. Or the pressure in the burning core could expand the fuel block,
causing it to crack. Each crack would now expose a greater surface area also resulting in a CATO.
Previous Research
There are some materials available on the theories about getting a heat cast material solidify in a controlled way to prevent volume defects.
Unfortunately these methods only work on melt-casting, not on solvent casting.
Most of the material I have on that subject is from classified sources, sharing that information by posting it on a
forum (or via PM) could result in high treason charges, at the very least I'd loose my access. I like my access. I'll gladly share the knowledge I've
learnt from open sources, but not what I've learnt from those sources. I don't mean to be rude by not sharing it.
Those information sources have almost no information on NC as a monolith, since rockets and flares used by gvt.
authorities and agencies use other energy sources with a higher energy density than NC.
Information Requested
I would be very grateful for any information, experiences or if someone knows where to look for more information.
I'm interested in any experiences from anyone who has worked with NC as a monolithic block, for example as a rocket propellant.
Any information about working with NC as a monopropellant block or as an energy source in a monolithic block. (Example; there is a
lecture on youtube by Lancaster [1] where he demonstrates a clean burning red flare consisting of NC and strontium carbonate. The only way to get a
slow even burn like that with NC would be to make it into a monolithic block. There is almost no visible smoke indicating there were no plasticisers
or binding agents added in the NC.
Does anyone know how to deal with or prevent the formation of internal cracks when it solidifies, and the shrinkage deformation?
Sources
[1]: Lecture "Chemistry of Fireworks - Reverend Ron Lancaster" Source YouTube Begin at 1:14:20
[Edited on 12-4-2015 by Student32]
[Edited on 12-4-2015 by Student32]
[Edited on 12-4-2015 by Student32]
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NitratedKittens
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http://youtu.be/f_AvqnMTJjg I don't know for sure but this might work with nc ??
If so then you could just make a solid blob of nc then test
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ecos
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for NC as propellant , please review : http://www.sciencemadness.org/talk/viewthread.php?tid=14608#...
I would also like to take ideas of other experts to use this method for confinement : https://www.youtube.com/watch?v=wqtdfb1dJ5I
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Bert
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If you wish to form pure NC into a solid block as a rocket fuel grain, I believe you may be better off using a hydraulic press than a solvent process.
As you noted, solvent processes are often not dimensionally stable on drying- Most such small NC based devices I use or encounter are prepared by
pressing, rather than casting.
Your situation seems quite curious. Access to sensitive, secret defense related information? And a licensed pyrotechnics/propellant lab? But you ask
here? For general, (and not intended to be implemented) amateur rocketry theory?
Bovine ordure.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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caterpillar
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You may press NC as much as you wish, but its fibrous nature won't go away. If pressed NC is used in rocket engine, it will burn too quickly. There is
no alternative to gelatinized NC.
Women are more perilous sometimes, than any hi explosive.
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PHILOU Zrealone
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Add some % of CH3-NO2...it will gelify the NC and you will get a block...the fibers will stick to each other and interpenetrate.
I would be more concerned by D2D transition of the NC block if used as a propellant.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Spartan
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Quote: Originally posted by Bert  | If you wish to form pure NC into a solid block as a rocket fuel grain, I believe you may be better off using a hydraulic press than a solvent process.
As you noted, solvent processes are often not dimensionally stable on drying- Most such small NC based devices I use or encounter are prepared by
pressing, rather than casting.
Your situation seems quite curious. Access to sensitive, secret defense related information? And a licensed pyrotechnics/propellant lab? But you ask
here? For general, (and not intended to be implemented) amateur rocketry theory?
Bovine ordure. |
I am also interested to forming NC to solid block. I have try with acetone and smokeless powder but it doesn't work well. I will try with hydraulic
press. i am thinking of using double base smokeless powder that contains ~50 nitroglycerin. Do you think it will be safe to use hydraulic press with
dbsp??
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PHILOU Zrealone
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If one use a tiny amount of solvent like aceton or nitromethan...not enough to dissolve wel the NC...then the core of the fibers will remain dry and
only superficial solvatation will occure.
With help of an hydraulic press the fibers (or grain) will glue to each other and interpenetrate like a patchwork/mozaic or puzzle forming a coherent
block.
Since the amount of solvent is low the evaporation will be slow or will even not happen...most likely the solvent will penetrate deeper into the
fibers/grains and upon time the distribution of the low solvent % will become homogenous.
The pressing must happen quite fast otherwise the superficial gel will evaporate its solvent in the open air.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Praxichys
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What about making a thin solution of NC and dipping a core repeatedly with drying between coats, kind of like dipping a candle? You might then be able
to (carefully) machine it into a proper core shape.
If you poured it into a closed pipe and quickly dumped it out, then let the shell inside the pipe harden, and repeat, you might be able to slowly fill
the entire pipe with cast NC.
Didn't they used to make billiard balls from nitrocellulose? Billiard balls are hard, dense, and smooth. How did they do that? US patent 50359 has
some info, but it appears this type has a cloth core.
On Celluloid, from Wikipedia - "A typical formulation of celluloid might contain 70 to 80 parts nitrocellulose, nitrated to 11%
nitrogen, 30 parts camphor, 0 to 14 parts dye, 1 to 5 parts ethyl alcohol, plus stabilizers and other agents to increase stability and reduce
flammability."
After nitrating the cellulose - "The product then must be rinsed to wash away any free acids that did not react with the fibers,
dried, and kneaded. During this time, a solution of 50% camphor in alcohol is added, which then changes the macromolecule structure of nitrocellulose
into a homogeneous gel of nitrocellulose and camphor. The chemical structure is not well understood, but it is determined that it is one molecule of
camphor for each unit of glucose. After the mixing, the mass is pressed into blocks at a high pressure and then is fabricated for its specific use"
On loss of the camphor - "The most inherent flaw is as celluloid ages, the camphor molecules are ‘squeezed’ out of the mass due
to the unsustainable pressure used in the production. In detail, that pressure causes the nitrocellulose molecules to bind back to each other or
crystallize, and this results in the camphor molecules being shoved out of the material. Once exposed to the environment, camphor can undergo
sublimation at room temperature, leaving the plastic as brittle nitrocellulose."
Just some thoughts.
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goldenoranges
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| Quote: Originally posted by Bert | If you wish to form pure NC into a solid block as a rocket fuel grain, I believe you may be better off using a hydraulic press than a solvent process.
As you noted, solvent processes are often not dimensionally stable on drying- Most such small NC based devices I use or encounter are prepared by
pressing, rather than casting.
Your situation seems quite curious. Access to sensitive, secret defense related information? And a licensed pyrotechnics/propellant lab? But you ask
here? For general, (and not intended to be implemented) amateur rocketry theory?
Bovine ordure. |
Why say you have access to classified information at all. Pretty sure the smart thing would be to just not mention it at all, it's not like we would
have known he supposedly has clearance.
Knowledge is the Ultimate Power.
PGP Key is in Bio
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Fulmen
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Pressing alone will not produce a grain suitable for use as a propellant although it can be used as an explosive. If I'm not completely mistaken
artillery propellants can exceed 1" cross section and is extruded in a colloided state like most other NC propellants. So the science has been done,
you just need to find it.
From the images I've seen there is significant shrinkage, producing a slight hour-glass shape, but I'm sure that can be controlled to some degree by
careful control of solvent removal. Most propellants will have a perforated core, by restricting the evaporation to the core it should be possible to
keep the external dimensions tighter.
We're not banging rocks together here. We know how to put a man back together.
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Fantasma4500
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i have have a way to turn cellulose into a fine powder.. somehow i managed to create abit less than 500mL of very strong formaldehyde solution, dont
ask me how.
i put this in a jar and put a sticky not ontop
the lid kept popping off for whatever reason, put a plastic bag over it, airtight. now a year later i take a second look at the jar, and as i touch
the paper it crumbles into dust, i didnt do much more than throwing the paper in the trash can, pretty stupid of me.. but i guess if the cellulose
havent been totally broken down this could be very interesting to nitrate? possibly it would crumble into dust even when nitrated, as you would prefer
having large particles for the washing process
formaldehyde could possibly be made from ''melamine'' plastic, which is melamine*formaldehyde, 100 sponges cost 6 euro over ebay with free shipping
i would like to play abit around with this myself, but i dont feel like i should be doing such right in these times
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Microtek
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It is quite easy to produce microcrystalline cellulose via hydrolysis of cotton wool. Discussions can be found here on SM. Formaldehyde can be bought
on ebay, if you need it.
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ecos
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hmm , I have an idea but not sure.
I think it is possible to make NC as powder. you can press it and use binder to make a grain.
any body have idea how to make NC powder?
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