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ZoSo357
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I was wondering about plastic plate-explosives. If you've ever seen the "reactive armour" the millitary uses on tanks to defend against shaped
charges, then you know what I'm referring to. If not, it's basically an explosive, binded with plastic (PBX) that is compressed into sheets. I was
looking for a way to do this in smaller amounts. (sizes ranging between 10 to 25, or 50 to 100 gram sizes).
I've read some stuff about the chemicals the millitary used for this type of material in the preperatory manual of explosives, but i'm looking for
something that would work well, and not be too exotic of a chemical to bind the explosive. ETN or PETN would most likely be the explosive of choice.
What kind of binder would help in the process of making such a material?
EDIT: Also, any idea's for methods of compressing(safely) ?
[Edited on 7-12-2006 by ZoSo357]
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nitro-genes
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| Quote: | Originally posted by Boomer
VoD does suffer from inerts, but less than one would think. The 9% inert binder/plasticiser in C-4 do not lower VoD by 9%. Semtex has up to 30% inert
crap (rubber, oil, ...) btw, but is not slowed down 30%. Instead, all materials have a "characteristic velocity" which enters the calculation of the
resulting velocity of the mix. Air (voids, empty space between crystals) has 1.5 km/s, most inerts used as binder are around 4-5 km/s. This does not
mean they speed up slow HEs which are below that speed if pure 
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Calculations show the characteristic velocity of the plasticizer component to be about 5500 m/s for semtex and 5800 m/s in C4. I expect it to be
dependant of the detonation pressure of the explosive, as the shock velocity of most materials becomes higher at increasing pressure. (Shock velocity
of plasticizer is about 3300 m/s at ambient temp and pressure) This is also the reason why the critical machnumber of copper is 20% higher at 250 kbar
than under normal conditions (1.23 instead of 1)
The increase in shockvelocity with higher pressure is density and material dependant, that is why at 250 kbar the shockvelocity of air becomes 500%
higher, while for copper at 250 kbar it is only 23% higher...
[Edited on 18-12-2006 by nitro-genes]
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Nitrojet
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In actuality, “Brisance” cannot be defined in terms of one single parameter, but it is known to be strongly density dependent. In his attempts to
quantify “Brisance”, Kast suggested a product of density, detonation velocity and specific energy as a yard-stick for evaluation of various
explosive substances. Detonation velocity itself can be expressed as a linear function of density while detonation pressure varies with the square of
the detonation rate. Hence the term “detonation velocity” in Kast equation can be further broken to yield a square of density. Together with the
first term which is density itself, we can come into conclusion that the Brisance varies with the cube of density, thus making any attempt to increase
the charge density, utterly reasonable. A virial-type equation also was suggested by Paterson which expresses detonation pressure as a function of
density terms with an increasing power sequence;
P = Z. (1 + A. d + B. d*2 + C. d*3 + D. d*4)
From “ Waxed PETN” I simply mean a PETN\Montan Wax, 90\10 which can be obtained with rigorous agitation of measured quantities of the two
materials in a water bath heated above the melting point of the wax. Unfortunately I have never tested my explosive versus the standardized C-4
because firstly I have never had a chunk of the latter explosive for testing purposes and secondly the plastic material which I call it C-4 uses DOP
as the plasticizer. Actually I could not find DOS and DOA in the market so my homemade C-4 has everything in common with the standardized C-4 but the
plasticizer. Since the weight ratio of the main explosive component in both compositions (PETN\Wax & C-4) is the same and PETN when compared with
Cyclonite is known to be an explosive of similar strength and brisance, Waxed PETN when hydraulically press-loaded to high densities should be as
powerful as C-4,
(Densities up to 1.66gr/cc are attainable with hydraulic pressing)
Regarding explosive properties, the plastic binders which are commonly used in C-4 formulations remain essentially the same with Montan Wax if merely
explosive output is to be considered.
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Nitrojet
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To Microtek
On the way to a successful synthesis of Dinitrodimethyloxamide, you can more conveniently use the Methyl ester of the oxalic acid thus avoiding the
highly cumbersome distillation process associated with the corresponding Ethyl ester synthesis. Methyl Oxalate is a solid material which actually
melts at 54’C and can be recrystallized from ethanol in the form of thin flakes. It boils at 163’C. The starting materials for its preparation,
Oxalic Acid and Methanol are readily available and you can follow this route for its synthesis in laboratory scale:
The oxalic acid is powdered and heated in a basin on a water bath, which is kept boiling briskly, until no more water is given off (One to two hours).
It must be occasionally stirred and powdered up. It is then heated to 110-120° in an air-bath or in a Victor Meyer drying apparatus until it loses
the weight corresponding to two molecules of water. The dehydrated and powdered oxalic acid is mixed with the methyl alcohol, and the mixture heated
on the water-bath for two hours with an upright condenser. The liquid is then distilled, with a thermometer. When the temperature rises to 100° the
receiver is replaced by a beaker, and the water-jacket of the condenser is removed. The thermometer rises rapidly to the boiling-point of methyl
oxalate, 160—165° and the distillate solidifies in the receiver. It is drained at the pump and dried. Yield, 20-25 grams.
The product can be further treated with methylamine (alkaline solution of Hexamine.HCl), to give Dimethyloxamide.
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quicksilver
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| Quote: | Originally posted by ZoSo357
I was wondering about plastic plate-explosives.
I've read some stuff about the chemicals the millitary used for this type of material in the preperatory manual of explosives, but i'm looking for
something that would work well, and not be too exotic of a chemical to bind the explosive. ETN or PETN would most likely be the explosive of choice.
What kind of binder would help in the process of making such a material?
EDIT: Also, any idea's for methods of compressing(safely) ?
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First of all the material(s) are generally available. Patents describe them in individual instances (That's why I read Patents - the answers are out
there for the taking)...Mostly they are either synthetic rubber or latex and the use of a simple rolling-pin for kitcken use would be quite safe and
controllable. - Pull the .PDF file I posted in the ETN thread; it has a few specific examples of the types of binders you would need. (& even
where to get some of them IIRC)
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Microtek
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To Nitrojet:
Thanks, but the problem is that in my country, methanol is banned due to the high toxicity. It is possible to apply for permits, but I prefer to avoid
contact with the authorities where possible. Ethanol and oxalic acid on the other hand is freely and cheaply availible, so that was what I used.
However, the low yield of the esterification discouraged me from making more than a few experiments, hence my interest in what I read as a route from
hexamine, HCl and oxalic acid to methyloxalate.
Did I read that erroneously ? Did you simply refer to the hexamine*HCl --> methylamine*HCl reaction ?
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Nitrojet
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Based on the assumption of Methanol or Ethanol being readily available for an experimenter, Dimethyloxamide can be successfully synthesized with the
oxalic acid being esterified and further treated with methylamine solution. Ethyl ester however is very difficult to synthesize due to the cumbersome
distillation stage which is absolutely necessary for purifying the material. Methyl ester on the other hand is a crystalline solid which rapidly
solidifies upon cooling and can be purified to near reagent grade chemical via a simple crystallization step from Ethanol. In my first attempt to
manufacture Dimethyloxamide, I could purchase the Diethyl ester at the cost of 30 USD for 250cc of the reagent grade substance. Methylamine also was
prepared from Hexamine.HCl solution in the presence of caustic soda and the ethyl ester was let to go into methylamine solution in a drop-wise fashion
while a constant stirring was held whole through the addition stage. The white crystals obtained this way was filtered out of the liquor and dried on
a piece of wax-paper. The dinitro derivative (MNO) also can be synthesized through a simple nitration which is our final product. A 70/30 PETN/MNO
mixture then prepared from co-precipitation from acetone to give a uniform distribution. The melting point of such a mixture actually exceeds 100’C
(109-112’C) and a portion of PETN remains intact making a non-uniform suspension with the bulk of the fused material. For complete fusion you have
to increase the temperature to 121’C. Upon cooling you get a cast explosive with relatively low density which at the first glimpse can not match
with the VoD stated by T.L.Davis as 8.5km/s. the charge density under the best conditions can hardly go beyond 1.55gr/cc. I am curious to know more
about your test results with such a mixture. How much is the maximum attainable density? Did you try to detonate your cast?
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Microtek
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No, I didn't detonate the sample that I prepared, I just measured density ( getting almost exactly what you did ) and then stored it to get a feel for
the shelf life of such charges. The cast stores quite well apparently; it hasn't changed in appearance since the day it was made ( more than a year
ago ) although the sample of MNO that I didn't use for casting has developed an acidic odour.
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grndpndr
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Quote: Originally posted by ZoSo357  | I was wondering about plastic plate-explosives. If you've ever seen the "reactive armour" the millitary uses on tanks to defend against shaped
charges, then you know what I'm referring to. If not, it's basically an explosive, binded with plastic (PBX) that is compressed into sheets. I was
looking for a way to do this in smaller amounts. (sizes ranging between 10 to 25, or 50 to 100 gram sizes).
I've read some stuff about the chemicals the millitary used for this type of material in the preperatory manual of explosives, but i'm looking for
something that would work well, and not be too exotic of a chemical to bind the explosive. ETN or PETN would most likely be the explosive of choice.
What kind of binder would help in the process of making such a material?
EDIT: Also, any idea's for methods of compressing(safely) ?
[Edited on 7-12-2006 by ZoSo357] |
If the Idea is to mimick reactive armor it uses very stable extremely difficult to detonate explosives nothing as sensitive as ETN!
A more suitable HE would be EXP D/ammonium picrate.The explosive must be able to withstand extremes w/o detonation for safetys sake.An explosive that
were to detonate from a bullet strike etc would be a serious liability to crew and vehicle as well as any unarmored friendly forces near the
vehicle.The reactive armors designed to detonate disrupting the SC jet ideally by impact of a SC warhead only.FWIW
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nitro-genes
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Sorry for bringing up this old thread. The increase in sensitivity of molten ETN was discussed before in this thread.... Well, the results are in and
it ain't pretty!!!  Note that the impact sensitivity (Table 1) was only tested
at 65 deg C., and also note the substantial error bar. Be EXTREMELY careful with molten ETN!
Attachment: Increased Handling Sensitivity of Molten ErythritolTetranitrate (ETN).pdf (295kB)
This file has been downloaded 413 times
Once solidified/cooled again, the sensitivity of the cast material seems to be sightly lower than the crystalline/powdered, so it seems to be mostly a
temperature effect or just an effect of being in a liquid state (Probably the latter). Very odd though...
Attachment: Explosive Properties of Melt Cast Erythritol Tetranitrate.pdf (975kB)
This file has been downloaded 595 times
Still think adding an detergent to produce molten ETN as very fine droplets (or almost emulsion) in water and/or using some co-solvent (perhaps with
some stabilizer added) might be a safe way of handling molten ETN and altering it's physical shape in probably a very controllable and reproducible
way.
[Edited on 8-1-2019 by nitro-genes]
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FeedMe94
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Thank you very much for sharing those results Nitro-Genes. Looks very interesting and very well made
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nitro-genes
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Would have been better if the plastic spacer was used for all impact tests. Would also have been nice to include at least one other liquid explosive,
like NG for example or interesting to look at a re-molten pellet of vacuum cast ETN, so without any bubbles or ETN at >65 deg C. Since 1 cm
dropheight may be smallest increment available, using a lighter weight (0.5 kg or so) would have provided a better resolution, in comparison with some
primary explosives. Still, more sensitive than acetone peroxide leaves little room for debate, this stuff should never be casted in large
amounts...
[Edited on 13-1-2019 by nitro-genes]
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Microtek
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It would also be interesting to measure the sensitivity of a molten mix of ETN and PETN. IIRC, Roscoe reported that such a mixture was surprisingly
difficult to detonate (in the solid state), so maybe it is also less sensitive when molten. It would not be difficult to prepare such a mix without
much risk, simply by mixing the powders in a beaker of hot water during constant stirring.
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nitro-genes
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Wasn't sure which topic was most suitable to post the article about the sensitivity of molten ETN, maybe a different thread would be more suitable.
Not familiar with the Neyer d-optimal test used in the article, so what does 1.0 cm +/- 0.6 cm represent? If it is like the mean +/- standard
deviation there is significant overlap, in principle the results may not be statistically different from 0 cm dropheight. That is why it might have
been more informative using more repetitions and a lower weight. What is the DH50 for nitroglycerin with 2.5 kg weight, anyone knows?
[Edited on 17-1-2019 by nitro-genes]
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