Sciencemadness Discussion Board

Plastiques of RDX vs. ETN

golfpro - 25-9-2013 at 14:41

I'm wondering about ETN vs. RDX in a plasticized state, seeing how ETN is OB positive it would outperform RDX if both are plasticized with exact same ratio using an inert plasticizer 91:9 (polystyrabutadiene rubber)? How about a half and half mix of ETN and RDX? This way you could likely get a lower Critical Diameter.

I wonder how the velocities would compare etc..


BTW, we will talk in amounts of 50-100g

[Edited on 25-9-2013 by golfpro]

Fantasma4500 - 26-9-2013 at 01:52

RDX is hard to press of what i know, by hand you will reach approx 1.1g max where machinepressed can reach densities of 1.6 with more than just alot of force
however plasticizing it is said to easily reach the density of 1.67, im not entirely sure how this is possible, if anybody is interested in this i can ask the guy further about this

i dont see why you would like to plasticize ETN, considering that it can just be cast, but thats about efficiency / brisance and also VoD and not handling ita very effective plasticue i with ETN would be nitromethane and ETN, perhaps depending on how much it needs HNO3 would be needed to be added, perhaps just vaseline? i know that the correct OB for ETN and Al is 94.5 5.5, but the Al does not react with the ETN in the shockfront (i recall Dany explained this to me)
could be that vaseline would react, could be it acts just like Al and forms a thermobaric wave

golfpro - 26-9-2013 at 13:04

Because I like the idea of a plastic. I couldn't really understand the last paragraph???

VladimirLem - 27-9-2013 at 08:44

Quote: Originally posted by golfpro  
Because I like the idea of a plastic. I couldn't really understand the last paragraph???


i think, that the means, that aluminium wouldnt be the best choice for getting the OxyBal. of ETN at near zero, when you want to use your (plastic-)explosive in an shaped charge or an EFP (both are armourpiercing devices) - for nearly every other use it should work good.

If you want to use your (plastic-)explosive in SC or EFP, better go for come crabon-containing compuonds like vaseline, oil, whatever...that, i guess/think that would bring a better performace to the detonationwave...

hard to describve, but aluminium is kinda "special"/unconventional at explosives...

Dornier 335A - 27-9-2013 at 12:05

I did some calculations for these two plastic explosives. I assumed that the plasticizer fills out all voids between the particles so the density becomes 0.91*ρexplosive + 0.09*ρplasticizer.
Densities of RDX and ETN are 1.82 g/cm3and 1.72 g/cm3 respectively, and the density of SBR is 1.04 g/cm3 according to a quick googling.

I calculated the detonation velocity of RDX/SBR to 8100 m/s, which is in good agreement with measured DCJ of C-4.
The DCJ of ETN/SBR is slightly lower, 7950 m/s, due to the lower density. Same thing goes for detonation pressure and brisance. The ETN based composition will most likely have higher strength thanks to the better oxygen balance.

[Edited on 27-9-2013 by Dornier 335A]

Praxichys - 27-9-2013 at 12:29

Quote: Originally posted by golfpro  
I'm wondering about ETN vs. RDX in a plasticized state, seeing how ETN is OB positive it would outperform RDX if both are plasticized with exact same ratio using an inert plasticizer 91:9 (polystyrabutadiene rubber)?
[Edited on 25-9-2013 by golfpro]


Certainly not.

A cursory search of Wikipedia gives the VoD of C4 as ~8100m/s, which is higher than pure ETN at theoretical density. Considering RDX started at 8750m/s, I really doubt there is anything that you could mix with ETN, fuel or not, and achieve higher performance characteristics than pure ETN. Packing density will suffer greatly unless you find some miraculous liquid "binder/fuel" with a density greater than 1.6g/cc.

This, of course, depends on what you mean by "outperform." Higher VoD? More energy per mass? More gas per mole?