Sciencemadness Discussion Board

RDX, PETN Blast effects..??

Missileom - 14-12-2012 at 11:43

I can now manufacture both PETN and RDX with about the same cost..

I want to know which is the best in the following cases:
Bombing of cement, broken steel, fragmentation grenades and other..

I've collected some information and characteristics about these explosives from several references and typed in the following table:



its Hard to me to say which is the best explosives or more powerfull... I do not know if the velocity and pressure of gas and its Volume is more important or heat is more important?

Note that the RDX is very disturbing when preparation because of the fumes and the large amounts of nitric acid its need and a long time..

I want to know which is better effect... If you could help..



[Edited on 14-12-2012 by Missileom]

[Edited on 14-12-2012 by Missileom]

[Edited on 14-12-2012 by Missileom]

[Edited on 14-12-2012 by Missileom]

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Ral123 - 14-12-2012 at 13:45

Both specific energy and heat of explosion are in kj/kg, why are the values so different. If PETN is so much lower, why it gives better expansion?
Nitric esters give a louder bang, rdx is kinda sharper lower noise but when you go to the test target it's ripped just as brutally. Both will make fragmentation grenade to dust, specially at good densities. For concrete I'd take maximum density mixture (with liquid component) of whatever high R.E. available. RDX is the mercedes, good shelf life, and doesn't have low order detonation.

Microtek - 15-12-2012 at 06:53

It depends (it always does). Those two are nearly identical in experimental brisance and VOD (it is easier to get PETN close to its theoretical maximum density than it is with RDX). However, PETN is a lot more sensitive than RDX, so if you are going be making a plastique, PETN will give you more reliable initiation than RDX. On the other hand, if making pressed charges it is safer to use RDX.
Then there is the matter of critical diameter: If you are making very small shaped charges or similar, PETN or maybe pentolite is a better choice than RDX based comps.

shadow31 - 15-12-2012 at 07:07

You can use the both to make Semtex which should be a little more powerful than those alone
PS: Why i cant find any where formula for making HMX

Ral123 - 15-12-2012 at 09:31

Do you know what 20% inerts by weight means? It means farewell brisanse, semtex is made to be used in kilograms.
HMX, no problem if you have Ac2O :D
RDX will always give reliable initiation, the problem is with PETN's low order problem.

shadow31 - 15-12-2012 at 13:47

Quote: Originally posted by Ral123  
Do you know what 20% inerts by weight means? It means farewell brisanse, semtex is made to be used in kilograms.
HMX, no problem if you have Ac2O :D
RDX will always give reliable initiation, the problem is with PETN's low order problem.

Can you explain why semtex has a low brisance

acetic anhydride is not impossible to be made if you dehydrate glaceil acetic acid with concentrated H2SO4 (here will have poisones gases right ?) or by dehydration of acetic acid at 700-900°C (but a serious heating device is needed)

Ral123 - 16-12-2012 at 06:31

It's not low, it's better then cast TNT, but good old EGDN is way more powerful.
For the Ac2O you need thorium dioxide catalist and other suspicious stuff.

shadow31 - 17-12-2012 at 02:56

Quote: Originally posted by Ral123  
It's not low, it's better then cast TNT, but good old EGDN is way more powerful.
For the Ac2O you need thorium dioxide catalist and other suspicious stuff.

Please be a little more detailed why EGDN with detonation velocity 8000 is more powerful than semtex, and why Ac2O can't be made with H2SO4
some search on internet gave me this

Quote:

As the name indicates, an acid anhydride is a compound that is related to an acid by the loss of water. Acetic anhydride can by prepared by the dehydration of acetic acid at 800°C. Alternatively, the reaction between the acid chloride and a salt of acetic acid (e.g. sodium acetate) yields acetic anhydride and a salt.

By the way today i was in the chem. store to buy some reagens for PETN they had run out of pure nitric acid but i asked about acetic anhydride and they had, i can buy it in liters if some day i decide to make XMH

Ral123 - 17-12-2012 at 09:54

Try then :D you'll either be a rich man after or you'll be arrested.
EGDN has 7390kj/g and semtex 5000?
Tests show that EGDN-ETN-NG are much more potent then explosives like TNT, tetryl and picric acid.

shadow31 - 17-12-2012 at 11:20

Quote: Originally posted by Ral123  
Try then :D you'll either be a rich man after or you'll be arrested.
EGDN has 7390kj/g and semtex 5000?
Tests show that EGDN-ETN-NG are much more potent then explosives like TNT, tetryl and picric acid.

But i don't want to try, either you don't understand what i am trying to ask, or you just lack the knowledge to answer it...
i just wanted a little more detailed answer about PETN's low order detonation, why semtex has such a low detonation velocity compared to RDX or PETN but still it is a little more powerful then those when it is in large quantity

Ral123 - 17-12-2012 at 13:54

With good initiation the low order is never a problem. Semtex cant be more powerful, if the rdx/petn are well pressed. semtex will never do that
http://www.youtube.com/watch?v=w0Xk-TgGcDE

here's my own micro test
http://www.youtube.com/watch?v=Djpni2Lhehg

Missileom - 17-12-2012 at 13:57

thanks everyone..

semtex is not just petn & rdx.. semtex contains about 8% unexplosive materials.. to make it Plastic..
that reduces the density and power for the total weight..

what about mixing rdx with egdn? will that reduces the high sensitivity of egdn?

Aco2.... i Hate it... i cant buy .. its forbidden in my country..
i try prepare it with p2o5+ch3cooh.. but failed...
the true method needs acetyl chloride + sodium acetate..
acetyl chloride = ch3cooh + pcl3..

what about replace Aco2 by p2o5 in k-method..????

[Edited on 17-12-2012 by Missileom]

[Edited on 17-12-2012 by Missileom]

Ral123 - 17-12-2012 at 21:41

You want to "pay" the "big" price for RDX and reduce it's storage stability with EGDN? It'll be very good explosive however. And EGDN on paper is no easier to detonate then RDX.

virgilius1979 - 17-12-2012 at 21:54

Missileom,
There's a very long acetic anydride preparation thread. IMO it's not worth the effort if you don't have acetyl- or benzoyl- chloride. PCl3 is even more difficult to acquire, not to talk about its toxicity.

[Edited on 18-12-2012 by virgilius1979]

shadow31 - 18-12-2012 at 02:07

Quote: Originally posted by virgilius1979  
Missileom,
There's a very long acetic anydride preparation thread. IMO it's not worth the effort if you don't have acetyl- or benzoyl- chloride. PCl3 is even more difficult to acquire, not to talk about its toxicity.

[Edited on 18-12-2012 by virgilius1979]

It is not impossible to be made, since they make it in industrial scale and it is not that expensive in the chem. store i can buy it for 9 euro per liter, so how do they make it ?

virgilius1979 - 18-12-2012 at 03:06

Industrial processes are much more efficient, so cost effective, but most of the times they cannot be used in usual labs, as they require sometimes high temperatures and pressures, inert or anhydrous environment, or hard to find catalysts. Of course, large volumes is the key to low price.
Sorry for the off topic.

Missileom - 18-12-2012 at 12:08

http://www.globalspec.com/reference/55654/203279/explosive-p... :o

hissingnoise - 18-12-2012 at 13:25

Anything from Akhavan needs to be taken cum granum salis . . .

Microtek - 18-12-2012 at 13:58

If you have P2O5, theres no need for acetic anhydride when making HMX. Look for the hexamine->DAPT->DADN->HMX route.
One advantage to this method is that you can be certain that the end result is actually HMX and not just RDX.

@ Ral123: I am not aware of any low order problem with PETN. Do you have any sources to back it up?

Missileom - 18-12-2012 at 18:24

Quote:

If you have P2O5, theres no need for acetic anhydride when making HMX. Look for the hexamine->DAPT->DADN->HMX route. One advantage to this method is that you can be certain that the end result is actually HMX and not just RDX.


thank u Microtek....but i read that DAPT needs in preparing to Ac2o?



what about HMX from DPT without Ac2O:
http://www.sciencemadness.org/talk/viewthread.php?tid=4729

Ral123 - 19-12-2012 at 00:58

I've heard maximum density nitric esters tend to do so, including mixtures PETN/NG and PETN/ETN. That guy uses booster http://www.youtube.com/watch?v=w0Xk-TgGcDE
also there was a funny guy who couldn't penetrate like 1cm iron with 300g+ ETN/NG He used tiny straw of AP for detonator. I agree that in the specific powder for that the use for det cords and blast caps, there isn't much possibility for the low order problem.

Missileom - 19-12-2012 at 17:40

there are an error in this pdf... he say that the heat of rdx more than petn, !!!
http://publications.drdo.gov.in/gsdl/collect/defences/index/...

what about"R.E. factor examples" in:
http://en.wikipedia.org/wiki/Relative_effectiveness_factor

Microtek - 19-12-2012 at 23:17

That someone uses a booster does not mean that it is strictly necessary to do so. Also, there are more reasons to use a booster than just wanting to avoid low order detonation. For instance wanting to establish a fully formed detonation front before entering the main charge (which means that you get a sort of additional virtual head height over the apex of the cone).

I have never experienced a low order event with PETN despite pressing it at up to about 8000 psi in small diameter charges with weak confinement.


Missileom:
Quote:

thank u Microtek....but i read that DAPT needs in preparing to Ac2o? What about HMX from DPT without Ac2O


Yes, you could do that. And you are right, DAPT does (AFAIK) reqiure Ac2O. However, the reaction is very economical and gives 1 g of HMX per ml Ac2O.

[Edited on 20-12-2012 by Microtek]

[Edited on 20-12-2012 by Microtek]