Sciencemadness Discussion Board - PETN-based Cast Explosives

PETN-based Cast Explosives

Nitrojet - 22-10-2006 at 13:04

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

Rosco Bodine - 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

Nitrojet - 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”

Nitrojet - 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

Rosco Bodine - 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 .

Nitrojet - 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?

Nitrojet - 29-10-2006 at 03:40

Sorry for wrong spelling! You can replace all "EDN" with "ETN" in my previous posts.

Rosco Bodine - 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]

Nitrojet - 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.

Rosco Bodine - 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 .

nitro-genes - 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...

quicksilver - 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.

Rosco Bodine - 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 .

Sickman - 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.

Rosco Bodine - 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]

Sickman - 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?

Rosco Bodine - 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 .

DeAdFX - 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 ???.

Sickman - 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]

nitro-genes - 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]

Rosco Bodine - 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

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 .

quicksilver - 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.

Chris The Great - 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.

Nitrojet - 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.

Rosco Bodine - 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 .

Nitrojet - 2-11-2006 at 13:23

I observed the same phenomenon when I tried to fuse a mixture of PETN-Dinitrodimethyloxamide 70/30 in a water bath. A 10gr sample of mechanically-mixed PETN-Dinitrodimethyloxamide was put in a test tube while the tube was externally heated by means of a water bath assembly. A sufficient quantity of Ammonium Nitrate then was added to water to increase its boiling point to 110’C. Constant stirring (10 RPM) was held throughout the test in water bath to insure a uniform heat flow to the sample. The mixture began to melt at 103’C and when the temperature reached 108’C the salted-water medium was boiling. Melting of the mixture continued and after an approximate time of 20 minutes (since the start of melting), no more change was observed in solid-liquid phases both quantitatively and qualitatively. In actuality, a considerable portion of PETN remained unchanged thus making a suspension together with the molten phase. I did not try to stir the suspension for getting more uniformity mostly because PETN in the liquid form can be extremely sensitive to any kind of mechanical stimuli. I removed the heat source and let the mixture solidify upon cooling. After 1hr I had a cast charge with a cylindrical geometry which was perfectly white in color. For this charge a density value of 1.41gr/cc was obtained through careful measurements. To overcome the non-uniformity of the resulting suspensions, I tried to have casts from a mixture previously co-precipitated from Acetone. The results were quite satisfactory. In this regard, I made an acetone solution of PETN-Dinitrodimethyloxamide in proper weight ratio and then precipitated the binary mixture by adding water to the solution. The crystals being obtained this way are of uniform distribution and upon casting they form a highly homogenous syrupy suspension which is optically translucent. Unlike the mechanical mixtures of the two explosives, the molten slurries from acetone-co precipitation contain no bulk of solid PETN crystals and the solid particles are of uniform distribution all throughout the molten phase. The densities, however, show no drastic change when practicing this technique while they merely exceed 1.50gr/cc.

Rosco Bodine - 2-11-2006 at 13:48

I suspect that if you take your translucent melt and add little by little to it twice its weight of crystalline PETN , you may be able to increase the density of the finished composition . You have to go slowly so as not to cool
the melt and you will probably have to " fold in " the
dry material portionwise to get it evenly wetted by the melt and freeing entrapped air . Keeping the mixture a bit above the melting point where it is thinner will
help the mixing , but it will still be about like trying to
wet granulated sugar with corn syrup or honey , and
getting the air out of it . Don't overstir it , once it is
fairly well mixed it should be like mixed epoxy which
is very viscous also , but if disturbed only slightly at
intervals the tiny bubbles will rise to the surface and
escape the thick slurry . If you stir it too much or too
vigorously it mixes air into the slurry instead of helping it to coalesce and escape . It is very much the same
as working with concrete where a vertical agitation
with a rod inserted and jiggled up and down a bit will settle the mix and bring any air to the surface , but any stirring which swirls the mixture only puts more air into it .
You might be able to gain a point or a point and a half on the density by special technique of loading the melt in this manner , unless of course the added solid PETN
disrupts the eutectic ....only an experiment will tell .

Nitrojet - 3-11-2006 at 11:33

PETN gives an Eutectic with Dinitrodimethyloxamide in 37% Wt. ratio. So you mean i should prepare the eutectic beforehand and after complete fusion i can go on adding the rest of PETN in small portions to the point that i get my favorite 70/30. occassional stirring is also needed to drive off all the entraped air bubbles from the PETN crystals.

Rosco Bodine - 3-11-2006 at 12:09

Yes . And it wouldn't hurt to make the initial Eutectic
a bit poor in PETN , by maybe 10-15% so that it must get the remainder from wetting the surface of the greater amount of PETN which you will be adding as a filler .
Doing this , and heating the initial melt which is not exactly eutectic above the temperature of the known eutectic enhances the wetability of the bulk filler PETN ,
and makes it easier to mix , and makes the thermodynamic more favorable for the mixing , because
even if the mixture is cooling a bit as the filler is added ,
the mixture is also forming the eutectic which resides
at a lower temperature than the initial non eutectic
" solvent " melt which is at a mildly higher temperature ,
if you follow the logic . The approach towards the eutectic tends to offset the cooling of the mixture from the added filler . Every little trick helps .

Also , disregard the eutectic ratio as applicable to the
total finished composition ....the eutectic is only the melt phase of what is a slurry of the melt liquid , loaded with an aggregate of additional crystalline PETN , until it is a consistency of a gritty sticky goo like wet concrete .
The eutectic portion is simply the glue that sticks the
solid PETN together .

[Edited on 3-11-2006 by Rosco Bodine]

Sickman - 3-11-2006 at 22:10

Hey Rosco,

I am just sitting here scratching my head trying to understand what exactly determines the final density in a melt.

I use the following example to try to illustrate my question:

Let's suppose you have an explosive with a crystal density of 1.5 and another explosive with a crystal density of 1.6
and what I mean by crystal density is supposing you had a large crystal of each explosive that just happens to measure 1 cubic centimeter each, but amounts to 1.5 and 1.6 grams respectivly. Now suppose these explosives had a melting point within a few degrees of each other and are in fact melted together and then solidified. From my basic understanding I would think that in order to estimate what the density will be you add 1.5 + 1.6 = 3.1 then 3.1 / 2 =1.55
Now, am I going in the wrong direction here, as far as my method of estimating what the density of the finished melt will be?

I've read in some literature that usually if a melt is cooled faster it retains a higher density than if it is cooled slowly.

What are the principles that dictate the finished density of a melt? Are ther non explosive materials that can be added to increase the density in a good way?

Is the best way to increase density in a melt to perhaps add materials that will modify the resulting crystals in a way that makes them more dense?

Rosco Bodine - 4-11-2006 at 00:16

I never really thought much about such matters ,
I suppose the same effects of volume compression
of melted mixtures are possible in some cases
as for when liquid solutions are mixed . Barium nitrate
has been used as a densifier for TNT mixtures ,
and I think lead nitrate also . I don't know of any
particular rules or principles in regards to such mixtures
other than to just make 'em and measure the density
to see what you have .

Boomer - 4-11-2006 at 06:44

The volume compression Rosco mentioned, if it does happen, will have a small effect on the final density, especially if you add over 50% crystals that don't dissolve. So as a first aproximation you can probably use the average of the TMDs as the TMD of the mix.

Note the "T", as in theoretical? Ever had a look at PETN, RDX etc under a 500x microscope? What we think are single crystals are often *agglomerates* of crystals with trapped air between. Due to the fine structures involved this air gets stirred into the melt, and does *not* rise to the surface like the air stirred in mechanically does. Hence the low density, which can be 25% under the theoretical.

Plus, for non-perfect HEs with either impurities, or low thermal stability, very small gas bubbles are generated on heating the melt. These don't escape either, lowering the density of the cast. As an example, if there is HDN in the melt/cast AN mix I described elsewhere, density goes from the theoretical 1.75+ to 1.50 and below. Before solidification, the cast was spongy, I could press it further into the casing and it 'sprang' back (read: expanded outwards slowly).

This property does not have to be a disadvantage. If the effect is not too pronounced, it can make initiation much easier, plus lower the critical dia quite a lot. 25% below TMD is too much though, that's also why I will stop adding HDN for future melt/cast-AN tests.

[Edited on 4-11-2006 by Boomer]

Nitrojet - 4-11-2006 at 11:59

It is so much better if we restrict ourselves within the realm of practicalities. In actuality the very primary purpose of casting an explosive compound or a mixture of explosives is to reach the highest possible density in favor of more brisance. Crystal density of a given explosive is the upper limit to which we can reach under ordinary conditions. In many applications, however, the charge needs not to be necessarily compressed to its crystal density to have effective functioning. A review of most military cast explosives reveals that the densities fluctuate between 1.55 to 1.75gr/cc depending on the nature of the explosive ingredients and their percentage. In other words manufacture of cast explosives essentially means not to drive off all the entrapped air bubbles and the micro-cavities inside. The left micro bubbles within the lattice can greatly facilitate the ease of detonation through their adiabatic compression. So as long as we can go on making cast charges within the mentioned density interval, our products will be brisant enough to be serviceable in many practices. Focusing on PETN itself as the base explosive for a pourable mixture, if the cast density exceeds 1.65gr/cc, the pertinent VOD will go beyond 8000m/s which makes the explosive highly brisant. I think such a density is attainable with ETN and Dinitrodimethyloxamide as the second ingredient for a binary mixture.

P.S I think a good account of ETN is available in “Nitroglycerin and Nitroglycerine explosives” by Naoum. Does anybody have any kind of access to this book??

Rosco Bodine - 5-11-2006 at 13:01

The same special crystallization techniques which have
been worked out as industrial methods for producing
clean well formed high density crystals of complementary
mesh sizes for having a high volumetric density as aggregates , are equally applicable to casts as to plastiques for which such methods were developed .

If the process starts with low volumetric density material , then that is what you end up with , unless
is exhaustively milled , extruded , rollered repetitiously
to squeeze all of the entrapped air out , which will be done anyway . But if the starting materials are optimum
then it greatly reduces the manipulation , particularly for a melt . At a certain particle size , the occluded air will
coalesce and rise to the surface , and the density of the
composition will approach more closely the theoretical
maximum .

Boomer - 6-11-2006 at 08:39

Just noting, the max density for most HEs is achieved by pressing, not by casting.

And FYI, it is a common misconception that *adiabatic compression* plays a role in detonation transfer. It may play a role in starting a LVD in liquid explosives, but detonation transfer works through *voids* not necessarily gas bubbles. Quoting Jerry once again:

"LE uses interstitial space (which is usually filled with air on earth)
as room in which to spurt hot gases to neighboring surfaces. HE, on
the other hand, uses these voids as volumes through which pressure
can be readily exerted such that PV work can be expended and turned
into heat (hot spots). Some people like to think of this process as
the adiabatic compression of entrained gas because they know that
gases get hot when compressed.

In reality, the HE does not care if there is gas present to compress
or not. Even an empty void acts as a place where heat can be generated
by impact with the same end effect as if gas had been present.

Insensitive HE tends to benefit most from dispersed void. Your ANFO (...)
TNT is another example of an explosive that needs a teeny bit of space.
The cast material will not shoot with a 50 gram primer, but the ground
and pressed material shoots fine with a cap even if it is pressed to
*near* its crystal density (...)

Nearly all commercial explosives rely heavily on entrained gas (void)
for sensitivity and will not shoot without its presence. It sometimes
happens that hydrostatic pressure in boreholes is great enough to
compress the voids to the point where the material loses its primer
or cap sensitivity. For such situations there are many formulations
which rely on microballoons of glass or plastic to preserve void volume.
At least in the case of the glass material the void is a pretty good vacuum."/ end quote

Note the last sentence about micro balloons! And:

"Void volume is the operative phrase. Solids
and liquids are not very compressible and therefore do not readily
allow the conversion of PV energy into heat under the influence of
even very high pressures. Add some well distributed void and the
pressure can now do work on the porous mass and reappear as heat
energy within that mass. This enabling of compression explains
the sensitization of detonating explosives by voids. Note however
that this has nothing to do with the adiabatic compression of
any gas in those voids. If there is gas in the voids, it can reach
astronomical temperatures, but in condensed explosives it makes
relatively little difference.

Please be aware that many books refer to the "adiabatic
compression of air" or "gas" in dealing with bubbles in high
explosives such as NG. I base my statements on this matter on my
own experiments in sensitizing both solid and liquid explosive
formulations. I first used the term "void volume" in a patent I
wrote 25 years ago." / end quote

He's advertising kinepack again..... but seriously, I have thought about this myself too, and came to the same conclusion: If it was adiabatic compression of gas, it would start a *burn* reaction at the bubble wall. This then had to make DDT. A material that has to make DDT layer-wise, again and again for every sub-millimeter, will not shoot even near it's normal VoD. Convinced?

pdb - 7-11-2006 at 00:35

Quote:

Originally posted by Nitrojet
P.S I think a good account of ETN is available in “Nitroglycerin and Nitroglycerine explosives” by Naoum. Does anybody have any kind of access to this book??

Unfortunately, you r belief is wrong: ETN accounts for a mere half a page in Naoùm's work, and teaches nothing you don't know yet...

quicksilver - 7-11-2006 at 05:07

On occation I really look for information on specific materials and ETN is a shallow pool. Aside from some patents and short (one page or muich less) blurbs in some popular older works, the most material is actually in the boards on the internet (kitchen chemisrty mostly). As you can imagine I am quite familiar with Naoum's work. What's more there is alot more then just "Nitroglycerin & Nitroglycerine Explosives” but he was involved with nitric esters more than anything else. At least that was what he published. At that time in histrory eurythritol was very tough to get....it was very exotic. They nitrated everything and it's dog but those things that got the most study were that which had some commercial future are far as the scientific community was concerned. Exotic materials were mostly left as lab curiosities.

Nitrojet - 28-11-2006 at 02:14

I obtained Erythritol in the form of pressed tablets directly from a pharmacy. I’m not sure about the purity or the possible presence of any other additives in my tablets but I observed that the whole material went into solution when treated with strong Nitric acid. With the temperature being kept below 2’C, I got a totally colorless solution with no trace of insoluble material. Crystalline ETN after precipitation from acid was dissolved in 95% Ethanol and then recrystallized in the form of very thin flakes. Before trying to fuse the explosive with Nitropenta, I made some sensitivity tests to evaluate the possible dangers involved with this particular type of the Nitric esters family. To test the behavior of the material to heat, small quantities of ETN was dropped onto a hot plate previously heated to 300’C. In all the tests carried out this way, ETN deflagrated as soon as it came into contact with the plate. But no detonation observed at all. The test continued for the weights as high as 0.4gr but the mere result was a rapid deflagration with a very luminous flame. Impact sensitivity tests was rendered with wrapping 0.35gr of the material in thin Aluminum foils and the small packages made so, was glued against the very smooth surface of a piece of marble. The whole assembly was set perpendicular to the floor and then shot with leaden pellets from a 0.22 air-rifle (Diana 48-52). A distance of 10ft was kept off the target. Of the total 10 tests performed this way, ETN detonated 8 times with a very loud report causing the Aluminum sheath to be shattered into hundreds of pieces. In the remaining two tests ETN actually did not detonate but made yellowish flames resembling that of Mercury Fulminate when fired in open. Considering the fact that the mechanical conditions under which such tests were carried out, were too strong for evaluating the impact sensitivity of a sensitive explosive like ETN, I made several ball drop tests in a simple apparatus which I made myself. It consists of a steel-made cylindrical anvil with a very smooth top to minimize the effects of friction on triggering the charges under test. This anvil is of the height of 1 in and a cross-section area of 0.08 square inch. It is filmy fixed on a heavy steel plate (pin and box connection), steel balls of various sizes so can be let drop on the charges being emplaced on top of the anvil from different heights. In my tests with such a ramshackle apparatus ETN sensitiveness to impact was found to be comparable to that of Mercury fulminate, certainly I did not follow the Military standards for testing of explosives, but Fulminate of mercury gives the same account of impact sensitivity when being tested in the same apparatus. It did not, however, stop me to proceed more and try to make the highly controversial cast-melt of ETN-PETN. Yet I have not managed to get my favorite results with such mixtures as firstly the highest attainable density was 1.58gr/cc and I am about to go as far as 1.65+. Secondly the sensitivity of molten ETN is a big difficulty on my way to Adobe Charges. Once I read somewhere that molten TNT is as sensitive as MF. Based on this piece of fact, what can we say about molten ETN? Anyway, anybody can confirm/Discredit this claim that molten TNT is about as sensitive as Fulminate of mercury?

nitro-genes - 28-11-2006 at 03:53

Drop test apparatus with 2 kg weight, 50% explosion:

TNT at 22 deg. C. --> 60 cm

TNT at 110 deg. C. --> 6.5 cm
TNT at 130 deg. C. --> 4.5 cm

I think the idea that explosives become more sensitive with higher temperature is without exceptions indeed. Don't know exactly for ETN, since it would also depend on the purity and size of the sample. All in all, I do think with ETN @ 80 deg. C you have good reason to be VERY carefull IMHO...

[Edited on 28-11-2006 by nitro-genes]

quicksilver - 28-11-2006 at 07:55

ETN is unique in it's sensitivity in that depending upon how it is re-crystalized, one may increase it's sensitivity to impact. IF the crystals are dense enough the reaction is suprising. The use of methanol for re-crystalization is possible. Acetone is too strong a solvant leaving behind leaflettes and lessing the solid granular crystals that respond well to impact. testing. Ethanol appears to be best suited for large granular crystals. (Bring to boiling, desolve at satuaration level, re-crystalize over ice = large multi-facited crystals; hexagonal shapes predominate)
However if the alcohol is not used at temp extremes the leafletts may appear but they can be shaved / crushed to a point wherein the density level (powder) could be achieved through moderate compression. Quality ETN will yield a marvelous report at 1-1.5 mg level in a small fold of Al foil struck with a hammer upon a steel surface (eye protection is sufficient at that weight - it's only noise). It may be an interesting experiment to clean out a primer cap; use ETN-cast and determine if the blow of a firing pin is sufficient for detonation. & if so would this impart a useful train effect on a cartridge via SBSP or DBSP.

Nitrojet - 30-11-2006 at 13:40

Anybody if he is of the slightest idea of the great power of ETN/PETN mixtures, will definitely think twice about it. a 20gr sample of the cast explosive @ density of 1.58gr/cc shattered a thick conceret block into atoms. The charge was simply put on the concrete block ( 2ft * 1.8ft * 0.4ft) without any confinement and primed with a blasting cap containing 3gr of pressed Mercury Fulminate. Parts of a wooden box which roomed the charge and the concerete block were blown off as far as 200 yards away. Shattering power of the test sample was DISTINCTLY more than those of other HEs in my previous experiments. Now i'm more encouraged towards fining some effective ways of curbing the too downright dangerous sensitiveness of ETN, thus It becomes feasible to have highly brisnat charges for demolition purposes. I have always kept in my mind that premature detonations of even small quantities of ETN can be fatal. as reported in "Encyclopedia of explosives" a British pharmacist experienced his divine existance when he tried to pulverize the material in a mortar! anyway, on my next step I will focus on ETN crystallization for getting crystals of less sensitivity. Methods recommended by quicksilver look promising and worth considering to be tried out in lab.

Sickman - 30-11-2006 at 22:09

I don't see what the trouble is!

Just add a few percent of a desensitizer. Parrafin wax works well for this purpose and generally has a melting point of around 50-57 degrees celsius. Davis reports that adding parrafin wax to high explosive, compressed or cast, causes it to become 'distinctly less sensitive to mechanical shock", but still "responds satisfactory to the impulse of a detonator."

Since ETN is oxygen positive just calculate in the additional fuel to the melt.

A few percent of desensitizer may decrease the density and VoD a bit, but will result in more gas release upon detonation, not to mention a much safer explosive.

The addition of a few percent wax to military explosives is a well established practice and has many benefits, incuding low cost.

Nitrojet - 1-12-2006 at 01:15

Phlegmatization is definitely a widely practiced method for desensitizing high explosives. It renders the explosive suitable for press loading while here we are not talking about pressing. The potential danger involved with ETN/PETN cast melts, is the prolonged heating of a highly sensitive explosive which sometimes needs occasional stirring for effective removing of the entrapped air. We can have some crystals of less sensitiveness by either waxing them or controlled crystallization. It is however true that upon heating, such methods can not satisfactorily eliminate the hazards. Molten ETN as stated before can be extremely sensitive to any kind of stimuli. Melting ETN/PETN can be safely practiced for making small charges for detonator fillings but what about a half a pound of a brick demolition charge?! If it was not because of the great power of such mixtures I would easily put this discussion aside trying to enjoy my waxed PETN which is about as powerful as C-4.

Axt - 1-12-2006 at 01:44

Quote:

Originally posted by Nitrojet
I made several ball drop tests in a simple apparatus which I made myself.........

Posted this before but I too done some drop tests on ETN using the rig in the attachment. It regularly detonated with a drop of 30-35cm, PETN was used as a standard for comparison which detonated at a drop of 40-45cm. This was for bicarb washed ETN, not recrystalised. Acetone peroxide for example required only a drop of 0-5cm (it has 5cm increments).

Attachment: droptest.mpg (1.6MB)
This file has been downloaded 1156 times

Boomer - 1-12-2006 at 03:04

I can understand his worries. If molten TNT is an order of magnitude more sensitive than solid TNT, molten ETN could end up more sensitive than NG or MF. Not a nice thought if working with a pound.

Another thing is Tc (critical temperature). Even PETN will self-heat catastrophically below 100C given enough material. ETN's figure will be below that, possible below 80C (it's melting point). The PETN figure was for a 1m sphere, but still....

Edit:

"... enjoy my waxed PETN which is about as powerful as C-4"

Have you tested both?

I mean he's right, density has the biggest impact on brisance. Brisance (det pressure): P ~ d*VoD^2, with VoD being roughly proportional to density *too*, making P~d^3 , i.e brisance goes with the *third* power of the density!

[Edited on 1-12-2006 by Boomer]

nitro-genes - 1-12-2006 at 05:19

Quote:

Originally posted by Nitrojet
Melting ETN/PETN can be safely practiced for making small charges for detonator fillings but what about a half a pound of a brick demolition charge?! If it was not because of the great power of such mixtures I would easily put this discussion aside trying to enjoy my waxed PETN which is about as powerful as C-4.

The original idea of Rosco was use of the PETN/ETN meltcast for detonators and small booster charges IIRC, personally I would never cast more than 25 grams at most...

With properly recrystallized PETN or RDX you can reach densities of 1.7 g/cc with about 5-6% of inert plasticizer. To fill up the same volume with ETN you would need twice as much. (Even more because rolling the plastique reduces sharp edges on the crystals, further decreasing intercrystalular space). That is why the PETN/ETN meltcast uses as much as 30% ETN. You should further consider that ETN is not as brisant as PETN. Sure, if it comes to total poweroutput, the SLIGHTLY better oxygenbalance would be in favor of the PETN/ETN meltcast. But if it comes to shear brisance, I would place my money on the PETN with 5% inerts...

[Edited on 1-12-2006 by nitro-genes]

AlbertV - 4-12-2006 at 19:03

Sorry to come in with a question at this point, but can anyone comment on what is commonly used as inert binder to produce formable PETN putty mixtures? What about energetic binders that could yield a formable plastique, are there any suitable which exist?

My real question is, are these putty mixtures at a Vod sacrifice in comparison with cast melts such as ETN/PETN where 100% of the mixture is energetic?

As was said above, PETN with 5% inerts may have comparabe brisance against the ETN/PETN melt, but I would assume a formable putty uses a higher percentage of inert binder than 5%...maybe I'm wrong however.

[Edited on 5-12-2006 by AlbertV]

Boomer - 5-12-2006 at 02:27

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

Also look here: http://www.sciencemadness.org/talk/viewthread.php?tid=5469#p...

And no, I won't say what is used. Search for yourself!

nitro-genes - 5-12-2006 at 03:22

Quote:

Originally posted by AlbertV
I would assume a formable putty uses a higher percentage of inert binder than 5%...maybe I'm wrong however.
[Edited on 5-12-2006 by AlbertV]

With 5% binder it behaves incredibly stiff, but can be kneeded with some force without losing coherency. When kneeded too long the density will decrease slowly, just like with C4 and it will become more spongy due too entrapped air. The same crystal fraction with 10% binder is much more mouldable and can be shaped easily, though density is somewhat lower than the theoretically attainable 1.68 g/cc... (usually around 1.6 g/cc instead)

An ordinary crashing in water yields crystals that need about 30% binder to fill all voids, just like the cheaply produced semtex uses...

Microtek - 7-12-2006 at 05:20

Nitrojet, on the first page of this thread you mentioned using hexamine, HCl and oxalic acid to synthesize dimethyloxamide. Could you elaborate on this please?
I have experimented a bit with the same dinitrodimethyloxamide/PETN compound and ran into the same problems with much lower density than expected, but due to the difficulty of producing ethyloxalate from esterification of oxalic acid with ethanol, I never got far.

ZoSo357 - 7-12-2006 at 06:39

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]

nitro-genes - 18-12-2006 at 10:04

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

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]

Nitrojet - 19-12-2006 at 04:40

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.

Nitrojet - 19-12-2006 at 04:42

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.

quicksilver - 19-12-2006 at 06:35

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) ?

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)

Microtek - 20-12-2006 at 01:46

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 ?

Nitrojet - 20-12-2006 at 10:45

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?

Microtek - 20-12-2006 at 13:30

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.

grndpndr - 13-7-2010 at 00:41

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

nitro-genes - 8-1-2019 at 14:23

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 349 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 489 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]

FeedMe94 - 12-1-2019 at 17:53

Thank you very much for sharing those results Nitro-Genes. Looks very interesting and very well made

nitro-genes - 13-1-2019 at 13:55

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]

Microtek - 15-1-2019 at 22:52

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.

nitro-genes - 17-1-2019 at 00:26

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]