Sciencemadness Discussion Board

High VoD explosives suggestions?

IndependentBoffin - 1-6-2011 at 14:20

I've been looking to prepare a small quantity of high detonation velocity secondary explosives to act as a very fast switch in an invention of mine.

Ease of manufacture (bearing in mind I am not experienced in organic synthesis), non-toxicity and low sensitivity (including due to contamination by secondary products (e.g. NOx in conc. nitric acid, lower nitrated products) are my main criteria.

At the moment I've settled on ETN because it seems to satisfy all of the criteria, but I am open to warnings, suggestions and comments :)

Can anyone suggest a suitable de-sensitiser and stabiliser for ETN? I intend to use it within about a month of manufacture at most but will be mechanically manipulating it to various shapes and don't want any accidents :)

Instead of melt casting it, would slurry casting it work? Mix it with a volatile solvent such as diethyl ether, pour it into a mould and let the ether evaporate?

[Edited on 1-6-2011 by IndependentBoffin]

mabuse_ - 2-6-2011 at 00:45

You will need some primary explosive to set it off properly.
Some people use setups to detonate ETN alone, but I seems to be difficult.
Quote:

to act as a very fast switch


If reaction time is a factor too, you definitely need a primary, otherwise you will always have some unsteady delay.

IMHO you don't need any stabiliser if your ETN is recrystalised and PH neutral.

IndependentBoffin - 2-6-2011 at 01:00

Quote: Originally posted by mabuse_  
You will need some primary explosive to set it off properly.
Some people use setups to detonate ETN alone, but I seems to be difficult.
Quote:

to act as a very fast switch


If reaction time is a factor too, you definitely need a primary, otherwise you will always have some unsteady delay.

IMHO you don't need any stabiliser if your ETN is recrystalised and PH neutral.


The time between when I flick the switch and when the ETN goes off is not important. The effect I am trying to measure will happen sooner or later.

Hence I was thinking of just using the primary explosives in a blank firearms cartridge, initiated by thermal cookoff from flash powder, to set off the ETN.

What is important is a very fast shockwave of high shock pressures - hence a high VOD explosive.

Later on I can look into HMTD detonators but frankly I am not comfortable putting any primary explosive into a casing. Blank firearms cartridges are safer because someone else has done the dodgy filling/pressing business and we do know the cartridges don't tend to go off on a bad day.

mabuse_ - 2-6-2011 at 01:43

To my knowledge priming caps contain a primary explosives to make them sensitive enough.
They LIGHT the propellant charge, but do they deliver a proper shockwave...?

OK, ETN IS quiet sensitive but I doubt that it will detonate properly from that stimulus.


Quote:

initiated by thermal cookoff from flash powder

Could be tricky, as takes some time to heat the cartridge.
I think flashpowder will just wooosh away before the priming cap has reached the right temperature. Better use something that burns slowly.

I would prefer some simple device that hammers the cap.



I think you wont get away without a real primary.
And with that ETN looses it's advantages. In that case PETN is better suited, as it is a little less sensitive (you wrote about mechanical manipulation...).



[Edited on 2-6-2011 by mabuse_]

IndependentBoffin - 2-6-2011 at 03:17

Quote: Originally posted by mabuse_  
To my knowledge priming caps contain a primary explosives to make them sensitive enough.
They LIGHT the propellant charge, but do they deliver a proper shockwave...?

OK, ETN IS quiet sensitive but I doubt that it will detonate properly from that stimulus.


What if the ETN is filled as a powder into the .22 blank?
Quote:

Quote:

initiated by thermal cookoff from flash powder

Could be tricky, as takes some time to heat the cartridge.
I think flashpowder will just wooosh away before the priming cap has reached the right temperature. Better use something that burns slowly.


Magnalium thermite?
Quote:

I would prefer some simple device that hammers the cap.


I could get my workshop to build a spring loaded firing pin to fire the .22 blank....
Quote:

I think you wont get away without a real primary.
And with that ETN looses it's advantages. In that case PETN is better suited, as it is a little less sensitive (you wrote about mechanical manipulation...).


Pentaerythritol is harder/more expensive to acquire than erythritol.

I can buy it as a commercial company but am looking at a few thousand USD for a minimum order size of a metric ton. I'll probably use a few kg and then have much hassle trying to dispose of the rest of it :)

Can't seem to find it in kilo-quantities from my usual lab chemical suppliers, but my list of chemical suppliers is by no means exhaustive.

[Edited on 2-6-2011 by IndependentBoffin]

hissingnoise - 2-6-2011 at 04:54

Quote:
Pentaerythritol is harder/more expensive to acquire than erythritol.

Since journalists have, of late, developed this questionable habit of referring in print to the PETN used by terrorists, as pentaerythritol, popping into a crowded pharmacy looking for the stuff could become a disquieting experience for all involved . . .
Pentaerythritol looks good to the syllabically challenged, I suppose!

Here's a patent for a 'safe' detonator!

[edit] I posted the wrong patent-link - the correct patent describes a cap containing nitromannite as base-charge with a flash-producing pyrotechnic pressed on top of it!






[Edited on 2-6-2011 by hissingnoise]

quicksilver - 2-6-2011 at 05:04

+1 on that issue.
Not only has Pentaerythritol become a focused agenda but it HAS a history of high price for the reagent level material. There is good reason to avoid the technical / "paint" grade Pentaerythritol that occasionally is available from the vinyl industry as lower nitrated products are typical with that level of purity.

IndependentBoffin - 2-6-2011 at 05:49

Is pentaerythritol itself a controlled substance in many countries (by law) hence being taken off the shelf or were pharmacies just "persuaded" to stock alternative chemicals by our fear mongering political masters without a law outlawing it ever being written?

Just trying to gauge whether I will have problems selling on 99% of a metric tonne once I am done with it :)

Am I likely to have a steady supply of orders for PE from the Sciencemadness community if I were to decide to start selling it?

quicksilver - 2-6-2011 at 11:42

I had thought you were joking. But I will answer from a wider level so that someone who may not think you were kidding would understand.
Yes, there would be a problem. I would advise individuals not to purchase precursors in commercial volume in any circumstance.

Many years ago typical organic chem classrooms had nitration's as part of lesson planning. A standard was the synthesis of TNT in a under-grad chemistry lab. However, those days are gone; perhaps for good.
We live the the "age of 911 & 7/7", litigation, & paranoia. It's one thing to have a science-oriented, mature curiosity about energetic materials and another to purchase ridiculously large amounts of a precursor.

Is pentaerythritol a "controlled substance"? Not in the USA. However there are what is known as "Watch Lists". One exists for DEA another for Homeland Security. A Watch List chemical may have what is known as "Threshold Limits" or be "Open; No Level" (yes, & List 1, List 2). An example for DEA would be less than a liter of acidic anhydride, while the ephendrines are watched down to the single dose-level individual retail purchase. DEA & DHS lists had been published on public basis. However due to efforts to circumvent precursor limits & analog potentials, updates from DEA became more frequent & troublesome to maintain & distribute. Their individual web sites will contain additional information as to specifics.


NOTE:
There exists (possibly) older watched chemical tables within older threads. It is inadvisable to use dated material as a guideline for understanding legal ramifications, present day. Please obtain any & all guidelines as currently as possible when making equipment purchases from BOTH a national and local level.






[Edited on 2-6-2011 by quicksilver]

gregxy - 2-6-2011 at 16:15

A .22 will not work. When hit with a hammer it just burns with a small flame. A primer in a firearm is designed to ignite powder not detonate it.

Some primers give a loud bang but I doubt they are forceful enough to act as a detonator.

froot - 2-6-2011 at 22:21

IIRC according to Van Nostrand's scientific encyclopedia, a mixture of H2 and O2 has a higher det velocity than nitroglycerin, cannot remember the ratios though. You would set that off with a high voltage discharge (gas barbeque igniter), you can pressurise it, it can fit in any space you provide it, it is easy, clean and makes water.

And you can reload it on site if the design allows.

[Edited on 3-6-2011 by froot]

hissingnoise - 3-6-2011 at 01:26

Quote:
IIRC according to Van Nostrand's scientific encyclopedia, a mixture of H2 and O2 has a higher det velocity than nitroglycerin.

That would be surprising, though possible, but the VoD of nitro is somewhat dependent on method of initiation, type of confinement, temperature, volume of explosive, etc . . .
And frozen nitro, though insensitive, has higher VoD than the liquid; EGDN, too, being a mobile liquid, has a higher VoD than nitro!
Frozen EGDN might be expected to have a still higher VoD!


Microtek - 3-6-2011 at 03:56

I find it very hard to believe that any hydrogen/oxygen mix would have a higher VOD than NG. Simply by virtue of being a gaseous mixture, the propagation velocity of a shockwave must be much lower than that of solid or liquid explosives. I realize that there is more to it than that, but my doubt remains.

IndependentBoffin - 3-6-2011 at 05:38

Quote: Originally posted by Microtek  
I find it very hard to believe that any hydrogen/oxygen mix would have a higher VOD than NG. Simply by virtue of being a gaseous mixture, the propagation velocity of a shockwave must be much lower than that of solid or liquid explosives. I realize that there is more to it than that, but my doubt remains.


And, 3 moles of gas reacts to produce 2 moles of gas, some of which may condense.

Unlike conventional explosives that produce excess gas and heat, the only reason why a H2/O2 mixture explodes is because the evolved heat produces an increase in gas volume.

I wonder whether that is why you get a "pop" in the classic school lab hydrogen test?

Because the expansion of gas is quickly followed by condensation of water vapour and cooling, resulting in an implosion?

[Edited on 3-6-2011 by IndependentBoffin]

hissingnoise - 3-6-2011 at 07:09

Quote:
I wonder whether that is why you get a "pop" in the classic school lab hydrogen test?

It pops because atmospheric oxygen is very dilute!
Splitting water by electrolysis produces a stoichiometric mixture of the gasses . . .
If you try it, wait until the water saturates and then collect a small quantity of the evolved mixed gasses.
On ignition you won't get a pop . . .
Treat it as if it were a type of nitro which detonates when ignited!