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HellstormOP
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How to thicken acetone
Hi,
I want to turn acetone into some kind of a semi-solid mass or a gel. For this purpose, I need an organic, preferably thixotropic or shear-thinning
thickener which should only be needed in small quantities. Does anyone know which would be the best substance for this?
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Fusionfire
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Polystyrene dissolves in acetone, making a nice gloopy gel. The thickness of it can be varied depending on how much polystyrene you dissolve...
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HellstormOP
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How much polystyrene do I need to get a nice gel? And is it shear-thinning or thixotropic?
[Edited on 13-8-2011 by HellstormOP]
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Fusionfire
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It varies with the density of the polystyrene you have to start with. I used polystyrene foam from old boxes I wanted to flat pack. From recollection
I think I dissolved about 5 litres of expanded polystyrene foam from an old computer monitor box into 250ml of acetone. I was left with something
resembling putty.
I don't know if it is shear-thinning/thixotropic but once the acetone evaporates it would harden. Therefore unless sealed up, not only will it display
time dependent properties it will also display depth dependent properties (outer surface dries first).
May I ask what are you planning on using it for?
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HellstormOP
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Yes, but I don't know if it is appreciated here. It is a bit about pyrotechnics and fire. If that is OK, I will start a second thread where I explain
the actual purpose and the state of play.
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Fusionfire
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Quote: Originally posted by HellstormOP  | Yes, but I don't know if it is appreciated here. It is a bit about pyrotechnics and fire. If that is OK, I will start a second thread where I explain
the actual purpose and the state of play.
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Hmm I am quite new here too so I don't know what the threshold of acceptability is here. I suppose you could try to ask anyway and see what the mods
think (or U2U them first).
Reading between the lines if you are planning on building a flamethrower why use acetone? It is volatile (higher likelihood of flashback) and more
expensive than other organic fuels. Also your nozzle would get clogged after use by the polystyrene/acetone mixture.
Also a near empty tank with lots of flammable vapours mixed with air can explode, splashing you with burning fuel. To avoid this you either
pre-pressurise with an inert gas (meaning reinforced tanks) or have a system of pumping the liquid out of the tanks (probably means air breathing with
attendant fuel-air risks, or a syringe-type approach).
To start with it is better to use fuels with low vapour pressures.
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HellstormOP
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It is not about a flamethrower - at least not yet. Recently I saw a thread here about how to make a detonator cord, so I guess the acceptance here for
stuff like this is higher than on other, similar boards especially the German (versuchschemie.de).
[Edited on 13-8-2011 by HellstormOP]
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HellstormOP
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Here is the thread where the purpose is explained:
http://www.sciencemadness.org/talk/viewthread.php?tid=17268
From now, this thread should be about how to make the mass semi-solid - this is an important part of the project.
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Fusionfire
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I can confirm you can easily make the acetone - polystyrene mass to any degree of solidification you need by varying the acetone:polystyrene ratio.
Just experiment a little... 
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HellstormOP
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OK, I just have concerns about the burning properties of polystyrene... it burns slowly and with a yellow flame, while I need something that burns off
very quickly, preferably with a blue flame (OK, no polymers do this, but I think there are polymers which need to be used in so small quantities that
the blue flame of acetone doesn't get affected.).
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Bot0nist
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A great gel can be had by dissolving an excess of cellulose nitrate into acetone. This gel will eventually harden if the acetone is left to evaporate.
This may also provide the extra flare without having to try and add KNO<sub>3</sub> directly, as you postulated in the projects thread.
It may even be possible to impregnate as semi-solidified mass of the gel with bubble of a desired gas.
*CAREFUL* Cellulose nitrate, when in proper densities and under extreme conditions is detonable IIRC.
[Edited on 14-8-2011 by Bot0nist]
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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HellstormOP
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Well, actually I want to add the acetylene in a pressurized container, not by bubbling. And: How much NC do you need in percent to thicken acetone?
Can I also use the lower nitrated ping-pong balls for it, which also contain campher?
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Bot0nist
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I suppose, though using homemade hexanitrate will make the best lacquer. Start with around 10g of cellulose nitrate and add pure acetone drop-wise
while stirring until the desired viscosity is reached. It really doesn't take much acetone to render all the cellulose to a thick, sticky goo.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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HellstormOP
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Well, actually I want to use very much acetone and very little NC. Does this work with NC or do I need lots of it?
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HellstormOP
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Hmm, I looked at some screenshots again and realized the thickener has to be very strange indeed. During the fireball being fired, the thickener has
to hold together the mass at velocities approx. beyond 100 mph (160 kmh), while it is burning and most likely acetylene gas is trying to escape from
it. As soon as the mass impacts, the thickener has to lose nearby all its properties and release both the acetylene gas and the acetone, without
forming clumps. Is something like that possible at all?
[Edited on 14-8-2011 by HellstormOP]
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Fusionfire
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| Quote: Originally posted by Bot0nist | A great gel can be had by dissolving an excess of cellulose nitrate into acetone. This gel will eventually harden if the acetone is left to evaporate.
This may also provide the extra flare without having to try and add KNO<sub>3</sub> directly, as you postulated in the projects thread.
It may even be possible to impregnate as semi-solidified mass of the gel with bubble of a desired gas.
*CAREFUL* Cellulose nitrate, when in proper densities and under extreme conditions is detonable IIRC.
[Edited on 14-8-2011 by Bot0nist] |
Nitrocellulose burns with a bright orange flame. It doesn't meet his blue flame criteria...
I'm not sure what would, apart from As/Cu/Pb/In/Cs/Zn salt dopants or an extremely hot flame that shifts the emission spectra to predominantly
blue/violet/UV.
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HellstormOP
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Hmm, the orange flame color refers to pure NC. However, I think when it's dissolved in acetone, and when acetylene is dissolved (shifts it to rather
white because it's so hot) and dust-fine KNO3 is dispersed in it, the flame color may change.
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Fusionfire
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No it won't shift it to white.
NC is oxygen deficient.
Acetylene + acetone is still oxygen deficient. Your rate of reaction will be limited by your oxygen diffusion rate.
Adding KNO3 will help but not by much. I've burnt rocket candy (KNO3 + sugar), black powder and ammonpulver (ammonium nitrate + charcoal) rocket fuels
and they all burn with an orange flame, except rocket candy where some purple colour from the potassium ions is evident.
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HellstormOP
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Well, the NC in the mixture will probably burn firstly (and maybe release the oxygen from the KNO3), then the heat will vaporize and ignite the
acetone, and the acetylene. Don't forget the additional oxygen provided by the wind - the ball will fly, not just burn standing still. I've also burnt
a 50/50 KNO3/sugar mixture recently, and although it was not ground and mixed very finely, the flame was mostly violet without a trace of yellow
color. As I burnt a mixture of acetone, with 25% ground KNO3 and about 5% silica (the acetylene was missing completely because I had no carbide left),
it burnt with a normal acetone flame, even without a purple trace from the KNO3 (only at the end, there was a small trace). But then, as I
accidentally set the spoon on fire where the rest of the mass was, and then I shaked the burning mass off the spoon, it showed a pure blue flame while
it was falling to the ground.
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Fusionfire
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| Quote: Originally posted by HellstormOP | Well, the NC in the mixture will probably burn firstly (and maybe release the oxygen from the KNO3), then the heat will vaporize and ignite the
acetone, and the acetylene. Don't forget the additional oxygen provided by the wind - the ball will fly, not just burn standing still. I've also burnt
a 50/50 KNO3/sugar mixture recently, and although it was not ground and mixed very finely, the flame was mostly violet without a trace of yellow
color. As I burnt a mixture of acetone, with 25% ground KNO3 and about 5% silica (the acetylene was missing completely because I had no carbide left),
it burnt with a normal acetone flame, even without a purple trace from the KNO3 (only at the end, there was a small trace). But then, as I
accidentally set the spoon on fire where the rest of the mass was, and then I shaked the burning mass off the spoon, it showed a pure blue flame while
it was falling to the ground.
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I am telling you NC + acetone + acetylene + KNO3 mixture will be mostly yellow/orange. But if you are so confident it will give you a blue flame why
not go ahead and try instead of armchair hypothesising and wasting everyone's time?
It is not true that a 50/50 KNO3/sugar flame was mostly violet without a trace of yellow. Even a 65/35 KNO3/sugar mixture is mostly orange with a
little trace of violet.
http://www.youtube.com/watch?v=7yQVHRInO6s
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HellstormOP
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I simply wanted to gather all available information about what I'm doing, so I don't need to do so much experiments which wi inherently fail. I will
try it as soon as I get the ingredients and the gear. The acetone is already there, the KNO3 is already there and ground finely like dust. Now I have
to wait for the CaC2 to arrive and I have to get some ping pong balls. Also I'm waiting for my flame resistant suit.
Why I don't believe you? Very simple, my results until now strongly deviate from your experience and results.
Also, my experience with KNO3/sugar is that it will have way more than a trace of violet. A NurdRage's video on YT proves this (watch from 2:35) :
http://www.youtube.com/watch?v=6iMeBxNcZf0
(Here you have a rather pink-purple flame with some yellow in it, but I guess at night it will look different. Just like mine looked.)
BTW: Will KClO4 actually do a better job on making the ball blue burning and explosive?
[Edited on 16-8-2011 by HellstormOP]
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Fusionfire
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| Quote: Originally posted by HellstormOP | I simply wanted to gather all available information about what I'm doing, so I don't need to do so much experiments which wi inherently fail. I will
try it as soon as I get the ingredients and the gear. The acetone is already there, the KNO3 is already there and ground finely like dust. Now I have
to wait for the CaC2 to arrive and I have to get some ping pong balls. Also I'm waiting for my flame resistant suit.
Why I don't believe you? Very simple, my results until now strongly deviate from your experience and results.
Also, my experience with KNO3/sugar is that it will have way more than a trace of violet. A NurdRage's video on YT proves this (watch from 2:35) :
http://www.youtube.com/watch?v=6iMeBxNcZf0
BTW: Will KClO4 actually do a better job on making the ball blue burning and explosive?
[Edited on 16-8-2011 by HellstormOP] |
Even in nurdrage's video it doesn't look "the flame was mostly violet without a trace of yellow color"!
Check out this video of rocket candy burning at night. It is clearly orange.
http://www.youtube.com/watch?v=nZfJ1L-q8EI
| Quote: |
(Here you have a rather pink-purple flame with some yellow in it, but I guess at night it will look different. Just like mine looked.)
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I'm sorry but this is rubbish.
At night the human eye is sensitive to yellow and orange colours because detection under low light conditions is mostly done by rod cells, maximally
sensitive at 500nm wavelengths (orange).
http://en.wikipedia.org/wiki/Color_vision
| Quote: |
In very low light levels, vision is scotopic: light is detected by rod cells of the retina. Rods are maximally sensitive to wavelengths near 500 nm,
and play little, if any, role in color vision. In brighter light, such as daylight, vision is photopic: light is detected by cone cells which are
responsible for color vision. Cones are sensitive to a range of wavelengths, but are most sensitive to wavelengths near 555 nm. Between these regions,
mesopic vision comes into play and both rods and cones provide signals to the retinal ganglion cells. The shift in color perception from dim light to
daylight gives rise to differences known as the Purkinje effect. |
If anything what looks like mostly orange with some violet in it will look even more orange at night!
[Edited on 16-8-2011 by Fusionfire]
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Fusionfire
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| Quote: Originally posted by HellstormOP | I've also burnt a 50/50 KNO3/sugar mixture recently, and although it was not ground and mixed very finely, the flame was mostly violet without a trace
of yellow color. As I burnt a mixture of acetone, with 25% ground KNO3 and about 5% silica (the acetylene was missing completely because I had no
carbide left), it burnt with a normal acetone flame, even without a purple trace from the KNO3 (only at the end, there was a small trace). But then,
as I accidentally set the spoon on fire where the rest of the mass was, and then I shaked the burning mass off the spoon, it showed a pure blue flame
while it was falling to the ground.
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Please provide videos (preferred) or pictures of your "tests".
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HellstormOP
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Ok, I've tried it again. Seems like KNO3/sugar really looks mostly orange. I think that I had the impression of a purple-violet flame, bceause the
amount was very small (< 1g) and I ignited it with a small gas burner, so that it immediately burned off. It also wasn't well mixed. I've noticed
that at ignition you really have that purple-violet burst, but when it continues to burn, it turns orange. I could explain this with the fact that at
ignition you have plenty of O2 available around the mixture (just like when the mass moves).
Now I got some ping pong balls and I'm gonna test how a mixture of acetone/NC/KNO3 will burn, especially when I throw it at something. I'm also gonna
get some CaC2 in the next few days, then a test will follow which includes acetylene in the mixture. I will construct a small blowpipe from an
aluminium pipe and simulate "fire breathing" that way.
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Random
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Does the gel made from acetone and polystyrene when evaporated get it's properties like the original polystyrene? Maybe I could shape objects from
that 
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