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deltaH
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I'd avoid acetone at all cost due to it detonating if it were me (that would probably shred the cone), I'd rather go for the alcoholic version so as
to get a fast deflageration, but not a detonation (hopefully).
Again, safety first please! Goggles/face shield and ear muffs a must (the latter in case it detonates again).
Tightly rolled up paper is pretty strong and relatively safe should it blow (pieces don't travel far). Just be weary that the cone could shoot back
loose of your taping, so don't stand right behind it.
[Edited on 27-5-2014 by deltaH]
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PHILOU Zrealone
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When working in soap factory, alcohol (ethanol) or volatile solvents where used as foam killers!
So the use of aceton, ethanol, methanol, isopropanol tends to destabilise the foam...it will last much less time than without the solvents.
There can be options if you find a tickener stuff that gelifies with such solvents...we used special stuffs to make soap consistent in the high duty
liquid departement of Procter&Gamble but I don't remember the name.
I suspect polystyrene-aceton might be an option or methylcellulose glue for wall-papers.
The PS-aceton might allow to make a foam with H2O2/acetylen that becomes solid under drying since PS is fully soluble in aceton but leaves a fine
pellicule of PS if allowed to stay in the air. This becomes brittle when completely dry. For demo in closed environment don't play with it in big
amount and stay away from heat sources or glass!
If energetic properties are searched...for better OB a little excess of oxygen over acetylen is wished as polystyrene introduce some extra carbon rich
fuel.
One might even imagine a PS foam with only pure oxygen in it.  as a safer very
flammable plastic foam.
[Edited on 27-5-2014 by PHILOU Zrealone]
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deltaH
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Great and thanks for the suggestions PHILOU!
There are also various supermarket OTC gums available that should stabilise foams by adding a very small amount (~0.5 - 1 wt. %), things like xanthan
or guar gum for example, I have both in my kitchen.
The thickened liquid then probably wouldn't even require soap at all, it would form a dense mass of foam (very small bubbles). However, my gut feeling
tells me that such dense masses will tend to detonate instead of deflagerate when ignited because 'containment' is stronger and also the pressure in
the bubbles is slightly higher.
I remember when I was studying as an undergrad being taught that for very small bubbles in liquids, the internal pressure inside the bubble increases
as the bubble diameters decrease (due to surface tension) otherwise known as Laplace pressure. This becomes dramatic when bubbles become very small (e.g. microbubbles). This would make the gas mix far more detonatable I
would imagine.
Where γ = surface tension and dP = the difference in pressure between the inside and outside of the bubble.
This could be a big advantage for employing foams, but again, the bubbles need to be micron sized if you aiming for detonation I would guess.
A side effect of this principle is that as you form smaller bubbles, the need for a volatile fuel becomes more important because there may otherwise
not be as much fuel evaporating into the gas phase.
While perhaps purely academic/commercial, dimethyl ether could be a great fuel (maybe even close to 'ideal') for such purposes because it is very
volatile, but dissolves in water to the tune of 71g/l. Furthermore, it one of those special ethers that don't form peroxides AFAIK. Unfortunately,
it's not OTC in any products that I know of. Perhaps this might stimulate someone to suggest something a little more practical, but along the same
lines?
Ordinary diethyl ether is also slightly water soluble, though this can form explosive peroxides, so again the same danger as with acetone...
EDIT: PHILOU, won't the styrene solution in acetone precipitate as soon as one add it to the large volumes of hydrogen peroxide?
[Edited on 28-5-2014 by deltaH]
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PHILOU Zrealone
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The tinier the bubbles implies also more surface of defined thickness --> in theory at a certain stage the bubble diameter will be equal to the
bubble wall thickness (or even tinier) then the OB will be less good.
PS will precipitate if done in one shot but one can make drop by drop fall of aceton/H2O2 into PS/aceton/catalyst...under mixing. That way we made, at
P&G, 80% silicon solution into alcohol suspendable into water with a viscosity of 10 cps...that silicon was >200.000 cps.
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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deltaH
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Quote: Originally posted by PHILOU Zrealone  | | The tinier the bubbles implies also more surface of defined thickness --> in theory at a certain stage the bubble diameter will be equal to the
bubble wall thickness (or even tinier) then the OB will be less good. |
I didn't quite understand how this affects OB, can you ellaborate please?
[Edited on 28-5-2014 by deltaH]
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PHILOU Zrealone
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| Quote: Originally posted by deltaH | | Quote: Originally posted by PHILOU Zrealone | | The tinier the bubbles implies also more surface of defined thickness --> in theory at a certain stage the bubble diameter will be equal to the
bubble wall thickness (or even tinier) then the OB will be less good. |
I didn't quite understand how this affects OB, can you ellaborate please?
[Edited on 28-5-2014 by deltaH] |
-PS has a density of 1040g/L what is roughly 10 moles/L monomeric unit.
-Pure O2 being a gas, MM= 32g/mole with a molar volume of 22,41 L/mol at SPT --> 1L of O2 at standard T° and pressure weight about 1,428 g.
C6H5-CH=CH2 + 10 O2 --> 8 CO2 + 4 H2O
To get perfect OB (0%) one would need 10 moles of pure O2 per mole of PS monomer.
So 224,1 L O2 (320g) for 0,1L PS (104g)...
The weight ratio between O2/PS must be 320/104 = 3,077
The volumic ratio between O2/PS must be 224,1/0,1 = 2241
So if the volume of the bubble becomes equivalent to the volume of PS...it becomes evident that you will be very deficient at oxydiser/comburant (O2)
what means bad OB.
So tiny bubbles yes to favourise the intimate mix but not too tiny.
This effect is comparable to the effect of oxyd layers of Aluminium powders....
The oxyd layer remains relatively constant but if the size of the Aluminium spheres/granules becomes tinier at a certain point the oxyd layer can't be
neglected because it induces a dead weight...if the sphere becomes 2 times the oxyd layer thickness; then there is no more aluminium to burn!
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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deltaH
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Ah ok, I'm with you now, you were referring to the case where the bubble walls are the fuel, my brain was still stuck in the mode of thinking of
vapour fuels only... I have my blond moments 
On a side note, I was walking today on our beach promenade and noticed heavy persistant foams washing over again because of turbulent seas. We're
having stormy weather. Anyhow, the spots where this foam forms thickest is also the spots where we have a lot of brown algae washing up and these gets
churned and smashed on rocks by heavy wave action.
Why am I mentioning this?
Because brown algae is the source from which commericial alginic acid, typically as sodium alginate, is extracted, so... that reminded me that
alginate could also be an OTC foam stabiliser for the alcohol foam mixtures.
Where does one find this stuff? It's typically used to prepare liquid antiacid syrups, usually in the sodium alginate form with some sodium
bicarbonate added. In South Africa, this is sold as the popular brand Gaviscon. I also have this in my kitchen 
It's worth a try perhaps.
... poor cars (not my image and an old one at that gotten off the net!) A shot of the three anchor bay area in Cape Town after a storm showing the
foams I'm talking about
[Edited on 29-5-2014 by deltaH]
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DraconicAcid
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| Quote: Originally posted by Zyklonb | I did a little test with 10 mLs of 20% hydrogen peroxide and 20 mLs of 95% isopropanol. (And liquid soap for foam)
I don't have any iodides at the moment so I used MnO2.
The first time it made a nice "pop".
But after that it made some pretty good booms!
It splattered flaming liquid all over the lab too. |
I tried this, too. 5 mL each of isopropanol and 30% hydrogen peroxide, and a bit of dish soap. Adding KI caused a much slower foaming than I had
expected; lighting it caused a large flame, which went snap! crackle! pop! like a breakfast cereal, and spat brown flaming foam all over the place.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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kecskesajt
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Put some CaC2 and MnO2 into H2O2 with dish soap.Powaaaaaaful explosion.Use in really small amounts like a few bubbles.To make a deflagration,bubble
some propane or methane into soapy water. SS
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deltaH
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| Quote: Originally posted by kecskesajt | | Put some CaC2 and MnO2 into H2O2 with dish soap.Powaaaaaaful explosion.Use in really small amounts like a few bubbles.To make a deflagration,bubble
some propane or methane into soapy water. SS |
Hmm... interesting variation, thanks for sharing!
[Edited on 11-12-2014 by deltaH]
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chemrox
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Federoff ?complete references and an explanation of "elephant foam" would improve this thread for those of us not "in the know."
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Bert
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The acetylene/O2 bubble foam version could at least be a bit safer from premature electrostatic discharge ignitions than the balloons and plastic bags
filled from oxy acetylene torches that so many have injured themselves with-
Including myself, many years ago. Ouch.
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3. Mention anything you have learned from your target.
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deltaH
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The peculiar/wonderful thing about this experiment from a demo point of view is that your start with a fuel (CaC2) which goes on to produce a far
more energetic fuel fuel (C2H2) by "gaining of water" (strictly speaking by reacting with water) and an oxidant (H2O2) that goes on to
produce a far better oxidant (O2) with loss of water. So while CaC2 + H2O2 would not explode directly easily, suddenly you get something
that is extremely energetic in the gas phase even when very wet! Really cool chemistry I think.
****
Chemrox, there is such a HUGE number of demo's and explanations about the related "elephant foam" experiment on YouTube and online,
that I feel it is redundant...
****
Bert, I too was thinking about your misfortunes with acetylene!
****
An interesting question occurred to me, with the speed of sound being much greater through water than gases, does this mean that the acetylene/O2 foam
would detonate at a much higher velocity because of propagation of a detonation (in part) through the liquid phase that initiates the remainder?
This could be an awsome experiment for professionals with high speed camera's.
[Edited on 12-12-2014 by deltaH]
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Microtek
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I would think that the liquid layer (ie. the interface between bubbles) is too thin and that the density variation will cause too much diffraction of
the propagating detonation to actually speed up the process. In fact, I think it would slow it down.
Only one way to find out for sure though...
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careysub
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| Quote: Originally posted by Microtek | I would think that the liquid layer (ie. the interface between bubbles) is too thin and that the density variation will cause too much diffraction of
the propagating detonation to actually speed up the process. In fact, I think it would slow it down.
Only one way to find out for sure though... |
You are right - they would slow it down, to the extent that they do anything at all (which I question).
In general, detonation/shock waves slow down when they encounter denser materials, they do not speed up. They aren't sound waves - though sound waves
are the limiting case of a weak shock wave. Once a shock wave degrades into a sound wave it is no longer a shock wave.
But the thickness of a bubble wall is on the same order as the thickness of a detonation front. I doubt any discernible effect would be encountered
unless the foam bubble wall was unusually thick (dense polymer foams would be an example).
Plane detonation/shock fronts are stable, tending to suppress irregularities that develop.
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careysub
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A stoichiometric foam consisting of oxygen as the oxidizer, and a polymer fuel would have to be pretty light, like an aerogel.
If the average polymer composition was CH2 then the oxygen gas bubbles would outweigh the polymer 3.4:1. If it was highly unsaturated, and on average
close to being just C, then it would be 2.7:1.
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Metacelsus
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What if the polymer were energetic itself? (Polyvinyl nitrate, for example.) The oxygen would then just provide OB, but the polymer would be doing
most of the job.
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deltaH
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It could be beneficial for the energetic polymer to be soluble in the peroxide solution so that it could harden somewhat when the peroxide decomposes.
In fact, it would probably be even better if the starting mixture has the consistency of a putty that one mixes with a very weak peroxide decomposing
catalyst by kneading and then wait for the "dough" to puff up like bread.
Perhaps it could even be two putties that one mixes together by kneading, like what's done with epoxy putty.
Any ideas for a soluble energetic polymer with thickening properties anyone?
[Edited on 12-12-2014 by deltaH]
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careysub
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If you had an explosive polymer (or polymer mixture) and foamed it, then you would obviously have explosive foam, and the denser the "foam" the more
energetic per unit volume. In the high density limit, not very "foamy", and not what people have in mind here I think.
The other route is to use an explosive gas mixture, and the foam forming material simply holds the gas in place.
Or you could do both.
When I was a kid a few times I set off acetylene/oxygen explosions, with a balloon, or in a buried container. On one occasion I buried a heavy glass
bottle so that that the rim was flush with the ground.
I added CaC2, peroxide, and whatever I was using to catalyze oxygen release and set it off with a long kitchen match.
The first few times it made a nice loud bang. Then there was a very different explosion, I didn't really hear it exactly, it felt more like being
slapped in the face. And the bottle hole was gone. I excavated and discovered the bottle had shattered into little pieces. I presume the last
explosion was a true detonation.
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Bert
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Aim for 50% acetylene or just a bit under. Initiate with a small high explosive booster, not a flame. Much more reliable...
Potential Destructiveness of Gas Detonations -US Bureau of ia Mines
[Edited on 12-12-2014 by Bert]
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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