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Author: Subject: PETN-based Cast Explosives
Nitrojet
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[*] posted on 22-10-2006 at 13:04
PETN-based Cast Explosives


In my experiments with Dinitrodimethyloxamide which is suggested as an ingredient for castable mixtures from PETN, i got an Eutectic which actually melts @ 103'C, but the density of the cast explosive varies between 1.35-1.56gr/cc depending on the cooling procedure. with the given density range i think the detonation velocity can be far less than the value given by Davis, as 8500m/s. does anybody have any special castin technique by which the density could be increased to higher ranges? more specifically i'm working on a binary mixture comprising of 70% by weight of PETN.
Thanks In advance
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Rosco Bodine
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[*] posted on 22-10-2006 at 18:28


2/5 ETN/PETN is about 71% PETN and d. 1.69 .
Like most casts it is difficult to initiate at highest velocity , but it is very brisant when it does high order .

To find more , enter into the search box :

ETN/PETN
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Nitrojet
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[*] posted on 24-10-2006 at 02:11


Yeah, I checked the EDN/PETN eutectic mixtures. In many ways, they are suitable for loading blasting caps rather than being directly used as Adobe charges for demolition purposes. The reason for this is the EDN itself which is costly to manufacture and too downright dangerous for preparation and use. As it is cited by Urbanski, the material is as sensitive as Nitroglycerine and is also of powerful and lasting physiological effects. So instead, one can go for making the highly powerful Penthrinite which can be easily prepared by mixing Nitroglycerine with PETN in 20/80wt. ratio. This plastic explosive is safe to handle and the liquid ingredient does not exude from the bulk of PETN even under elevated temperatures. The only strong point with EDN/PETN mixtures is the melting point of the eutectics which is claimed to be well below 100’C. On the other hand Dinitrodimethyloxamide is relatively safe to manufacture in larger quantities and also it is less expensive. Moreover, no physiological effects yet reported to be attributable to this material. Dimethyloxamide can be easily prepared through condensation of methylamine and ethyl oxalate. The product if nitrated in anhydrous nitric acid gives Dinitrodimethyloxamide which then separates out through pouring of the solution into iced water. As mentioned by T.L.Davis, a eutectic can be achieved when PETN is mixed with Dinitrodimethyloxamide in 70/30wt. ratio. The same author claims a rate of detonation as high as 8500m/s for the resulted cast explosive which is equal to PETN itself if detonated under the best conditions. If true, such a mixture is an excellent candidate for manufacture of high-brisance demolition charges. Actually I tried to examine the explosive power of such eutectics, but the only problem is the density of the cast material which is far less than being promising! In a report I found that by means of “a special casting technique” the density can be increased to 1.70+. But at time I’ve not the slightest idea of what they mean by “a special casting technique”
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Nitrojet
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[*] posted on 27-10-2006 at 09:16


Explosives at test! A cast mixture of PETN-Dinitrodimethyloxamide was successfully detonated by means of a composite detonator while being buried 1.5ft underground.

Specifications:

Main Charge:

Type: PETN-Dinitrodimethyloxamide (70/30)
Charge Weight: 55gr
Charge Density: 1.41gr/cc

Detonator:

Primary Explosive : Mercury Fulminate (1gr)
Base Charge: Pressed PETN (PETN/WAX 90/10), (1gr)
Tubing: Copper Tube (5mm OD)
Firing Mechanism: Electrically Stimulated Bridge Wire

Conclusion:

The blast effect was really great. The only problem with such melt-cast mixtures is their relatively low density which in turn can signifacntly reduce their Brisance. Yet I have not been successful in Preparing dense charges.

NRGite.JPG - 28kB
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Rosco Bodine
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[*] posted on 28-10-2006 at 12:24


Erythritol Tetranitrate with PETN gives a dense charge directly from a low temperature melt cast .

You were going on above about " EDN " Are you speaking
of EGDN , ethylene glycol dinitrate ?

Anyway the low melting point is not the only positive
aspect about a 2/5 ETN/PETN melt cast composite .
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Nitrojet
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[*] posted on 28-10-2006 at 23:42


Let's have a quick review of the available literature on properties of EDN (Erythritol Tetranitrate):

" Its Chemical stability and sensitiveness to impact resembles those of nitroglycerine"

T. Urbanski, Chemistry and Technology of Explosives, V.2, 1st edition, Pergamon Press, Oxford, 1964, Page 167.

" Erythritol Tetranitrate,
Deflagration point: 154-160'C=309-320'F, Violent Explosion.
Impact Sensistivity: 0.2 kpm = 2 Nm"

Rudolf Meyer, Explosives, 3rd rev. and extended ed., Weinheim; New York; VCH,1987, pages 125-126

Certainely, the low melting point is not the only strong point of EDN-PETN cast explosives. But when compared with Dinitrodimethyloxamide-PETN mixtures, the low melting point seems to be the only advantage. As i discussed earlier in this chapter, the latter explosive is not as sensitive as EDN and is of exceptionally high chemical stability. The raw materials to its synthesis are easily available and unlike EDN is of not known intense physiological properties. (EDN is a powerful vasodilatory agent)
on the other hand the low melting point of EDN/PETN mixtures can well compensate for the drawbacks associtaed with them. and a question! how much is the maximum attainable density with EDN/PETN mix when poured? do you know the corresponding detonation parameters of this eutectic?
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Nitrojet
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[*] posted on 29-10-2006 at 03:40


Sorry for wrong spelling! You can replace all "EDN" with "ETN" in my previous posts.
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Rosco Bodine
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[*] posted on 29-10-2006 at 07:56


Spelling isn't the only problem . You seem to not know that the physiological effects of ETN and PETN are
just about identical , and aren't any issue for people
who aren't prone to eating either material .

It seems that you are intent upon lecturing me or schooling me about Erythritol Tetranitrate based upon
what you assume to be valid conclusions from what you have read in available references , writing your own book
concerning a material which you have no direct knowledge about from doing your own experiments .

Did you actually do a search of this forum for ETN or
for ETN/PETN and read what has been written by myself ,
and by Axt , and others ? Also search at the E&W forum ?

In what world is it that the dimethyloxamide precursor is more easily and cheaply available than a dietary sweetener like erythritol ?

[Edited on 29-10-2006 by Rosco Bodine]
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[*] posted on 29-10-2006 at 11:20


Once i apologized for wrong spelling. I'm not about to have PETN or ETN as part of my daily meal, but well, skin absorption is a matter of some importance. Due to its very low solubility in water, PETN, if touched by skin, simply does not cause severe headaches, but Nitroglycerine certainly does. ETN is mentioned to be of similar vasodilatory effects as Nitroglycerine while Urbanski cites the effects of the former material to be slower and more prolonged. That's why i'm addressing the physiological effects of this material. Definitely i'll search more on this issue.
Moreover, i'm personally here to learn and share my ideas with others. It is true that, here, the digital milieu, has many things in common with ordinary classrooms, but it does not necessarily mean that we have to draw the commonly accepted borderlines between a student and a teacher. I don't mind who is teaching and who is learning. As a human being i'm perpetually immature and capable of learning, i'll be grtateful to all my teachers.
At any rate i'm sorry if my words made you irritated. Your irritation was the only thing i really did not mean by my words.
Yes actually i checked out this forum for ETN/PETN eutectics, it was interesting enough to rouse a ferver inside me to experiment personally. As i noted earlier i want such casts for making adobe charges for demolition purposes. As prolonged heating of a sensitive explosive as ETN and also occassional stirring, are absolutely unpleasant especially when you are dealing with weights as high as half a pound of explosive or even more. This is one of the reasons that i'm considering ETN vis-a-vis dinitrodimethyloxamide which is less sensitive. hence, i do not feel any innate tendency to oppose your points of view.
Finally, in my country Hexamine, HCl and Oxalic Acid are readily and cheaply available. They are the precursors to Dimethyloxamide.
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Rosco Bodine
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[*] posted on 29-10-2006 at 14:45


Why do you assume that cast ETN alone or as part of mixed compositions is unduly sensitive ?

From experiments of my own it was my wish to *increase* the sensitivity of the cast material
after discovering its propensity for low order detonation
unless it was overdriven by a very heavy initiating charge .

I have not yet experimented with melts of ETN with
Inositol Hexanitrate or Mannitol Hexanitrate , using
a dicyanamide or betaine stabilizer ....but those are
possibilities .....as well as having PETN as a component
of the melt phase , along with PETN comprising the
solid filler component of the composition , bonded
by the melt phase .

Purity and stabilization are really key elements in
any such compositions .

Anyway there isn't much extensive information about
ETN in the literature , a few patents and a paragraph or two from a couple of other sources is insufficient data
for making any sweeping generalizations dismissive
of the potential usefulness of ETN as compared with
dinitrodimethyloxamide .....which is moisture unstable ,
gotten with difficulty from non-OTC sources , and is
otherwise less convenient than ETN , producing casts
which are less powerful , less dense , and harder to detonate .

Your reports concerning the usefulness of the eutectic
of dinitrodimethyloxamide and PETN are interesting .
But the basis for some of your assumptions and conclusions lacks substance .

The source of my irritation is that this composition is
not necessarily superior in any way other than stability in a heat test to purely nitrated polyol compositions , which
you seem to be declaring inferior on the basis of false
assumptions and inadequate data .
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[*] posted on 30-10-2006 at 03:17


Casting larger amounts of ETN based compostitions is really not to be taken lightly IMHO. The critical temperature becomes lower for larger charges and longer timescales fast depending upon the amount of confinement. The critical temperarature for PETN drops rapidly from almost 200 deg. C. to 100 deg. C. with the diameter of the charge increasing from 0 to 50 cm in diameter. Of course we are talking ridiculous amounts of explosives here but PETN is by far the most stable nitroester so I expect the curve of ETN to be far below the one of PETN! Personally, I would never consider casting 100 grams or more to be an option...
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[*] posted on 30-10-2006 at 06:53


A wonderful thing is the easy re-crystalization of a mix of ETN & PETN. One can simply mix the desired proportions of each and re-crystalize same with a methanol-acetone solvant. This and proportionate crystal seeding would yield a workable large crystal which in turn would be cast when a simple hot water bath benieth the cast-mold itself was applied. ETN would substantially lower the melt point. The temp spread of water would certainly effect a (fast, effectient) melt.
The toxicity of either has been seen as low. And IIRC it was Urbanski that made a point of noting that skin obsorbtion factors are uniquely difficult in polyol-nitric esters. Now if they were reduced to dust (sub-sieze particulate) - that would be a different matter... but skin obsorbtion issues have not been a caution where PETN has been used commercially.




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Rosco Bodine
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[*] posted on 30-10-2006 at 10:45


My interest in the melt cast nitrated polyol composites
is limited to small sized charges as would be base charges in detonators or boosters or small munitions
filler , and probably at 100 grams or larger it would
transition to a plastique with active binder as the
more practical choice . And then at perhaps some
still larger scale of 1 upwards to a few kilograms , the preference would shift to something like a Tetryl/TNT melt bindered RDX composition .
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[*] posted on 30-10-2006 at 22:16


Quote:
Originally posted by Rosco Bodine
Anyway there isn't much extensive information about
ETN in the literature


With that said what basis do we have to assume that ETN alone doesn't perform as good or better than PETN as a high VoD, high gas output explosive? Is there any reason or piece of literature or metal plate test that has demostrated the superiority of one or the other? If ETN is as good as PETN, with the exception of slighlty more chemical, thermal and impact stability, what's the point of mixing the two?

These are not critical questions, but curious ones. I have prepared ETN and seen what it can do to metal plates, but I haven't ever prepared PETN. I was just thinking that if ETN performs just as good or better than PETN in reality than I see no point in preparing the more expensive PETN for metal cutting charges for example.
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Rosco Bodine
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[*] posted on 30-10-2006 at 22:33


PETN is more powerful and stable than ETN
and is cheaper and more efficiently nitrated in high yield .
Yeah there are tests that show the PETN is more
brisant . The ETN is useful in a couple of ways
because the precursor is OTC and fairly cheap ,
and the ETN has a low melting point which makes
it easy to cast as a charge of ETN alone or as a
densifying matrix which solidifies entrapping other
partiulate filler explosives as a high density charge .
ETN also forms eutectics having lowered melting points
with other nitrated polyols which would otherwise
not be practical to cast . In my estimation that is
where its greatest potential value resides as a
component of binary or ternary mixtures .

[Edited on 31-10-2006 by Rosco Bodine]
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[*] posted on 30-10-2006 at 23:05


Quote:
Originally posted by Rosco Bodine
PETN is more powerful and stable than ETN
and is cheaper and more efficiently nitrated in high yield .[Edited on 31-10-2006 by Rosco Bodine]


Well, Rosco. please sell me on PETN! Exactly what makes it cheaper, I know about the other aspects of the qoute? Where do you cheaply get or how do you cheaply make the main precursor pentaerythritol as it would seem like a suspicious chemical to purchase?

What I mean is that I have a procedure for making pentaerythritol copied down that involves paraformaldehyde or formaldehyde, acetaldehyde, and quicklime, with hydrochloric acid and norite being mentioned in the recrystallization part. These chemicals don't sound very available or cheap to me compared to 6 bucks a pound for ETN. The yield from this procedure doesn't look economical either! Please explain! How are you able to make PETN cheaply?
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Rosco Bodine
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[*] posted on 30-10-2006 at 23:16


Well what I meant was that on a commercial scale
for example you can buy a fifty pound bag of pentaerythritol more cheaply than a fifty pound bag
of erythritol . And you can nitrate all of the pentaerythritol to PETN in greater weight and yield
for a lower expenditure for acid than is the case for ETN .
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[*] posted on 30-10-2006 at 23:24


I believe most of the Erythritol sold on the OTC market is natural(see NOW Foods brand as an example). This means that the Erythritol has to be grown a certain way without the benifits of pesticides certain fertilizers and other things. Not to mention in order to isolate the Erythritol it has to be sorted through a bunch of other organic shit along(like other polyols/sugars/etc).

Another possibility for the Pentaerythritol being cheaper is that those are fairly common chemicals. Formaldehyde is used in photography/trioxane fuel bars. Calcium hydroxide fertilizers/chalk/cement. Hydrogen Chloride --> muratic acid. Acetylaldehyde ???.
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[*] posted on 30-10-2006 at 23:39


Rosco,

Going back to the ETN vs. PETN comparison, You mentioned that the brisance of PETN is higher than ETN, to what degree? A few hundred meters on a density for density basis?

You said that PETN is more stable than ETN, I agree! However as far as storage goes, if ETN is properly recrystalized with diphenylamine or betaine and stored in dark, cool and dry, should it not last for 50+ years?

I think maybe ETN should not be downplayed so much as just a simple "energetic binder", but rather regarded as one hell of an explosive of it's own right, not just as a compliment to PETN or whatever!

DeadFX! I don't know what country you live in, but my erythritol is always FDA approved, 99.5% pure and cheap as hell! It is produced by a fermentation process!

[Edited on 31-10-2006 by Sickman]
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[*] posted on 31-10-2006 at 03:44


The problem with a single compound cast is used is the density decrease and cracking of the charge upon cooling, just like Nitrojet experienced with his cast. I did some testing with ETN lately and I found this to be highly annoying. Castings of more than 5 gram result in no more than 1.5 g/cc densities and upon cooling many voids are introduced as the ETN tends to stick at the side. PETN/ETN is at 1.65-1.69 g/cc. The lack of any crystal surfaces in an amorphous ETN melt can also give rise to LVD firing...

[Edited on 31-10-2006 by nitro-genes]
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[*] posted on 31-10-2006 at 06:10


Part of the interest in experimenting with the combination
of ETN with other nitrated polyols as eutectics is to observe the dimensional stability upon solidification .
It could be that some specific combination will be neutral
in its solidification ......and that would be a very handy
formulation to know about , wouldn't it ? Actually
ETN is a great candidate for experimentation since it
has a lot of potential uses that are untested , but
would seem obvious possibilities where it could be useful .

And so far as the power of ETN alone , just offhand observation tells me it is something like 90% or better
in comparison to PETN , a bit less brisant ...but not way
less to a point there is anything other than PETN that
is the closest comparison . It reminds me a lot of the
comparison between styphnic acid and picric acid , there
is a little difference there ....but they are not far apart .

Stability for the purified and stabilized ETN is about like
double base commercial smokeless powder , or better
by some as yet determined margin , and yeah I'd say
that under mild storage conditions fifty years is not
unreasonable , perhaps longer . The stuff is very
similar to nitroglycerin , so much so that it is almost
like nitro in solid form and the only other thing than
PETN that is a close comparison .

The pressed crystalline loading for ETN is one I have not even tried , but I would expect that it has plenty of usefulness in that regard . ETN is likely the most stable powerful practical energetic solid explosive that is easily attainable and economical in terms of informal pursuit by a hobby experimenter or blaster who is looking for materials which can be made from off the shelf items for off label uses . MHN is a bit more powerful , but more difficult to make and less stable , and more expensive , but would be similar .

Actually it may be me who is responsible for sort of stirring up the recent years renewed interest in ETN ,
followed by Axt posting a no nitric acid synthesis and
some videos showing ETN is a definite metal mangler
which can be made straightforwardly from mundane
materials . It is something of a treat being tossed
to folks who are just habitually on the prowl for new
" things to nitrate " ......to find another OTC material
that is thirsty for nitrogen :D and really wants to
be all that it can be , before disappearing in an
interesting manner and doing its thing when expected ,
with reasonable predictability .

Anyway , both Nobel and DuPont had sufficient regard
for ETN to secure patents mentioning its usefulness ,
so it does have its value in certain ways , and probably
not all the possible uses have been fully explored ....
so we can experiment away at discovering what uses
ETN may have .
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[*] posted on 31-10-2006 at 06:45


IIRC when initial reserch was done with ETN it was rather exotic; in that isolation was unique to reasearch chemiisty and not a common industrial material. And it was not used at that point in history as an alternative sweetener (there were very few alternative sweeteners at that point in time). Thus isolation was costly. Today pentaerythritol is used by the ton in the plastics industry, however it is not the ultra pure material sold by chemical suppliers for research. It is often differing hues and not the very pale yellow-white of the pure material. It's sold in drums (I think by rough volume!) often with foreign material included. It's cost is quite a bit lower than erythritol if not bought through a chem supplier.
Erythritol on the other hand is most always manufactured as a USP grade, human comsumtion purity level material. I believe manufactured from the "Seaweed industry" in differing countries and often sold in small amounts (pound lots).
It appears that both are very easy to nitrate--- but when tested for impact sensitivity by backyard means, ETN seems highly sensitive and it's proformance suprisingly powerful. Recrystalization, however, of pentaerythritol is more streight forward. ETN appears to need a dual solvant or carefully choosen alcohol/temp combination for best results.




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[*] posted on 31-10-2006 at 14:02


Quote:
Originally posted by Sickman
If ETN is as good as PETN, with the exception of slighlty more chemical, thermal and impact stability, what's the point of mixing the two?


Keep in mind too that a melt of PETN/ETN will have greater power than each, ETN's excess oxygen balance being consumed by PETNs negative oxygen balance. So in theory a mixture of the two, if it was cast well and fired at high velocity, should have greater power than PETN at the same density.
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[*] posted on 1-11-2006 at 13:07


Oxygen balance is a parameter which is of highest importance when we are dealing with a strongly oxygen-deficient explosive. Incorporation of oxidizers so has been recommended for enhancement of the blast parameters for such explosives. TNT is a good example of an explosive with a low oxygen-content. As a matter of fact such a deficiency is one of the reasons that led to the development of Amatols. PETN, on the other hand is an oxygen-rich molecule that with the assumption of full conversion of the detonation products into CO2 and H2O and N2 it is almost 10% deficient in its oxygen content. Likewise Nitroglycerine, ETN is a strong explosive of Nitric Esters family with positive oxygen balance (+5.3%). A full balance so can be attained in a mixture of ETN/PETN with 2/1 weight ratio. However, here, the eutectic that we are specifically discussing about is in 2/5 weight ratio for which the oxygen-balance percentage can be easily calculated out as -5.7%. The high brisance of the cast explosive, hence, can not be wholly attributed to the slight enhancement of the oxygen-balance. Brisance is strongly dependent on the velocity of detonation of the explosive which itself is directly proportional to its density. What ETN actually does is converting PETN from a low-density powder ( 0.9-1.1gr/cc for acetone-recrystallized material) to a dense binary cast (1.69gr/cc). ETN itself also possesses strong explosive properties which yet further improves the explosive performance of the cast mixture.
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[*] posted on 1-11-2006 at 15:02


The eutectic of ETN and PETN is ETN 95 : PETN 5 so that
is about what is the composition of the melt phase ,
and the rest of the compsition is simply the remaining undissolved solid particles of PETN which is most of it , in an ETN 2 : PETN 5 composite . It is actually a slurry of
solid PETN particles wetted by the ETN/PETN melt ,
a solid PETN aggregate in a cementing material ...like concrete .
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