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Author: Subject: ETN Plastic - Best Combination Methods for Uniformity?
Farnsworth
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[*] posted on 16-8-2012 at 19:44
ETN Plastic - Best Combination Methods for Uniformity?


A new health food coop store has opened in my area, and they stock Erythritol. I've used ETN before in boosted detonators for initiating AN-based experimental charges for about a year now, so I have a bit of cautious experience in making it. So far though I've only ever employed it in 1-4 gram pressed charges in pure recrystallized and neutralized form.

With a greater quantity now available I'd like to tinker with small gram amounts of plasticized ETN as a main charge, but I have some questions. (I know I ask a lot of questions here, and I apologize for being a bother sometimes).

From the research I've done in amateur ETN plastics, not the least of which came from SM, I'd like to inquire as to the following:

1: The gold standard plastic seems to be an approximately 9% blend of polyisobutylene rubber and ETN with a percent or two of silicone oil. This mimics the formulation of compound C4 using ETN as the energetic. The question is, is it a feasible idea to melt the ETN itself, raising the temperature of the PiB to similar, and blending the two in a liquid state via mechanical agitation for a good homogeneous mix? I'm concerned with the more obvious solvent method causing a loss of crystal uniformity in the ETN. I'd like a very homogeneous, uniform plastic with very uniform shockwave propagation.

2: Following from the method used by the British to desensitize RDX back in the 1940's, a combination of ETN nine parts by weight and paraffin wax one part by weight should form a usable plastic if combined with a viscous binder. I have in mind petroleum jelly. The question is in the method of mixing: In theory, one would melt the ETN and the wax together and agitate for some time, allowing the mixture to cool to ensure that the ETN crystals were well coated. Then the petroleum jelly would be added and the materials mixed through hand kneading. Or would it be better to melt only the wax and petroleum jelly, add the ETN to the molten mixture, and agitate? Which would be more likely to give a plastic of high uniformity and homogeneousness?
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Ral123
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[*] posted on 16-8-2012 at 20:03


Can somebody give us idea how an explosive with 10-20% inerts performs. My best mixture so far is etn/ng/nc. I mix well and dissolve in a little acetone. When it evaporates it gives quite constant mixture, but repeating may be necessary. http://www.youtube.com/watch?v=Djpni2Lhehg
Physically may be I shouldn't even call it plastique. It handles badly, but I don't see any other non exotic explosive that would beat it.
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Kalium
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[*] posted on 16-8-2012 at 20:25


I'm not too sure about how to answer your second question so I'll provide some information regarding your first. I found some photos of a mix consisting of 65g PETN, 3.1g motor oil and 4.7g PIB. I also remember reading on a a Slovenian forum that he used a small amount of acetone to help remove the PIB from the glue trap.
Mixing the components:
http://s242.photobucket.com/albums/ff11/NUKEpyro/?action=vie...
http://s242.photobucket.com/albums/ff11/NUKEpyro/?action=vie...
http://s242.photobucket.com/albums/ff11/NUKEpyro/?action=vie...
http://s242.photobucket.com/albums/ff11/NUKEpyro/?action=vie...
The final product:
http://s242.photobucket.com/albums/ff11/NUKEpyro/?action=vie...
There was also a video of it detonating, which has since been removed from YouTube. I have on my computer; would anyone want to see it? It pulverised the rock it was on top of, but I wouldn't expect any less from such a mixture.
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Farnsworth
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[*] posted on 16-8-2012 at 22:18


I've read about the NC based plastics, but to be honest, NC is probably my least favorite EM synth. I rarely distill nitric because of my poor apparatus quality (due to lots of meth production, getting decent glassware here is VERY hard) and most of the local sources of cotton are too impure. For me, getting the NC for such a plastic is harder than making the ETN. The in-situ synth is very simple and has always been quite enjoyable to me for some reason.

PiB, however, is actually easy to come by around here. I don't even need to extract it, I have a source for it in ~90% pure form. And wax is wax.
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hissingnoise
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[*] posted on 17-8-2012 at 01:02


<i>"The question is in the method of mixing: In theory, one would melt the ETN and the wax together and agitate for some time"</i>

Melted ETN is dangerously shock-sensitive ─ agitating it is <b>not</b> advisable . . .

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Farnsworth
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[*] posted on 17-8-2012 at 08:10


That's exactly the type of tip I was hoping for. So it'd be best to ignore potential mixing methods that would rely on melting the ETN.

That leaves mechanical combination. What are your thoughts on the melting of wax and petroleum jelly, and adding the ETN crystals and kneading?

Or am I overcomplicating the problem trying to avoid solvents?
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hissingnoise
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[*] posted on 18-8-2012 at 02:44


That raising the temperature of an explosive will increase its sensitiveness is something that one should always bear in mind . . .
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[*] posted on 18-8-2012 at 12:10


Look into a thread or two here that discusses, in some depth IIRC, the effect that the properties (shape, meshsize, densitiy, uniformity, etc.) of the individual crystalls of the EM employed in a plastiuqe formulation effects the preformance, functional flexability, and consistancy of said composition.

According to those reads, fine tuning your recrystalization to produce the idea crystal may be an impactful variable.

I'll search for the threads and amend my post shortly. im on a phone,s browser currently.




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[*] posted on 19-8-2012 at 00:33


So far I've always relied on the dissolve - cold water crash method to get the smaller crystal sizes. I've never used a mesh to screen it for uniform crystal size before, but that was already an idea for the plastic experiment.

I'm just concerned that if I dissolve the ETN and PiB together in a solvent like white gas, mix, and evaporate ala the common PETN plastic combination, that I'll lose the uniformity of the crystals and get a product with a more irregular shockwave propagation. I'd like to see just how consistent the stuff can be.
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CaliusOptimus
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[*] posted on 19-8-2012 at 11:51


I remember reading a thread about blending ETN for use in plastique. I think the idea was to add the ETN to a running blender 75% full with water. The idea being that ETN dispersed beyond a certain point (10-20% by volume?) would not sustain a detonation. There were several successes and no detonations. Keep in mind that starting the blender after the ETN has settled to the bottom would most certainly lead to detonation.

The ground product was apparently extremely fine and perfect for plastique.

If anyone decides to try this I recommend keeping yourself behind a blast shield and using very small quantities of ETN. The source of this info is no longer available.
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pyro10%school0%
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[*] posted on 26-11-2012 at 01:42


maybe you can use the composition of 88.3% ETN (by weight) with 11.1% mineral oil, and 0.6% lecithin
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[*] posted on 7-7-2016 at 15:19


I hope necro-posting isn't frowned upon, but this thread caught my attention. The main drawback of ETN is it's sensitivity, so phlegmatization seems like a good idea. But it seems many get greedy and go straight for a plastic explosive. It so happens it's OB at appr 1% hydrocarbons, which should be enough to phlegmatize it effectively. But I can't seem to find any references to such a composition.



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[*] posted on 8-7-2016 at 01:51


ETN is not overly sensitive (same ballpark as PETN), but yes, phlegmatization makes it number and more reliably compactable. I've used castor oil for the purpose (5% if I remember correctly), but I see no reason why mineral oil or other hydrocarbons should not deliver a comparable result. It greatly helps when acetone is added during the phlegmatization stage, just enough to soften the mass and partly dissolve the energetic. It will recristallise as the solvent evaporates during gentle mixing and a very fine and uniform blend is achieved.



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Fulmen
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[*] posted on 8-7-2016 at 09:03


Sadly I'm having trouble finding much data on phlegmatization. I've attached one document (COATING OF EXPLOSIVES, HERMANN SCHMID,
Nobel Chemicals AB), seems it is far more complex than I thought.


Attachment: schmid1986.pdf (1.4MB)
This file has been downloaded 746 times

[Edited on 8-7-16 by Fulmen]




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[*] posted on 12-7-2016 at 08:18


A good way to safely distribute a binder into ETN is to use a suitable solvent.

You can easily and cheaply extract a good MW polyisobutylene from glue boards designed to trap rats and mice. Soak them in mineral spirits*, filter the solution, and evaporate outside in the sun or with gentle heating. You will end up with an amber substance which is syrupy when hot and a tacky solid when cool.

A known amount of this (Something like 2% of the ETN weight) is scraped out and dissolved into some more mineral spirits* along with 2% motor oil to obtain a thin liquid. The ETN is mixed with this thoroughly to form a homogeneous paste, adding more solvent if necessary. The ETN paste is then spread out on a pan and left out where the solvent can evaporate.

What is left will be crumbly ETN that can be kneaded into a stiff dough.

* "Mineral spirits" are simply aliphatic hydrocarbons with a specified range of boiling points. Some substitutes:

Naphtha
Petroleum ether
Charcoal lighter fluid
Zippo fluid
Toluene
"Xylene" (xylenes)
White gas
Coleman fuel


Note that the boiling ranges on these are different, so some may make the evaporation process difficult and lengthy (VM&P Naphtha) while others can cut processing time down to less than an hour (Zippo Fluid).

Indeed the key to a good plastic is to achieve fine and consistent crystals of the starting product. This is achievable by recrystallizing the ETN from hot methanol, first making a saturated hot methanol solution of ETN and then crashing it into at least 20x its volume in rapidly stirred ice water with 4% sodium bicarbonate and 1% urea as a stabilizer. Crystallization in this way will ensure an acid-free, buffered product that will store for years.




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