Sciencemadness Discussion Board

Best way for getting high density ?

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VladimirLem - 4-10-2011 at 08:11

Hi Guys

Im a hugh fan of shaped charges and optimizing them.

But after some different tests, im not sure which way ist the best to get a high density und especially high velocity compound.

Possible:


Gelantine - maybe with Cellulose Hexanitrate and NG
Pro: All stuff of the compound is reactive (and much powerful too :-) ) but the density is not really high which gives not the "maximum" of velocity...

Wax - Dunno if normal wax would work...the "montan wax" seems not to get easily AND is an unreactive stuff - pro: only around 5-7% are needed

PIB - Have it already but would need 3-8% and some oil or NM to make it kneadable - Pro: able to get high density without many problems, but the velocity is fucked :mad:

another question...is it possible to get a velocity of around 8000m/s when usind PETN(~87)/RDX(~5%) and then the plastic/wax/gelantin stuff?

nitro-genes - 4-10-2011 at 12:35

Some pointers:

1. After neutralization, don't crash the PETN/RDX in cold water, as you will get a very fine crystal fraction that needs more binder
2. Recrystallize slowly from warm solvent, I normally used a styrofoam box as insulation and stored it at -20 overnight to recrystallize.
3. Precipitate the last fraction instantly with cold water, which will give the fine crystal fraction
4. Dry and add 5-10% binder, roll plastic explosive for long period of time, this will remove all air and abbrases the crystals to obtain optimal packaging (higher density)

You can get above 1.6 g/cc easily this way, even with inert binder, and will get you close to the 8000 m/s mark

PIB + suitable plastcizers is superior to wax in my experience, if you do want to use wax, use a microcrystalline one

[Edited on 4-10-2011 by nitro-genes]

quicksilver - 4-10-2011 at 13:38

Plastiques have a great deal of information regarding their performance levels available. P.I.B. was not the appropriate material; it was Polybutene or Polybutylene w/ a Methylricinoleate. The fact that Czechoslovakian plastique was exported with up to 30% of inerts or "scrubbed" energetics was simply a matter of old Soviet economics.
The "real thing" was certainly a match for Semtex & had the somewhat sophisticated element of both a plasticizer and a tackifier in it's makeup.
For all clarity, ricinoate esters are derived from ricinoleic acid, which makes up 90% of the fatty acids from castor oil or Rapeseed oil. There WAS a period of use of silicone oil but it proved too expensive. The distinction was that some read a patent that described "motor oil" & thought in was an organic petroleum. It was not. It was silicone oil.

The styrene-butadien rubber in the Soviet product is available as flooring adhesive and can be reduced to approx 5% level in a true industrial setting with rollers, etc. A true plastique has density as a focus of it's manufacture. Once that is achieved, the energetic is not all that important as long as it shoots at above 5000mps @ it's raw density level.

Candidates are obviously RDX, PETN, HMX, TATB, or HNS. Even TNT & salvaged nitroguanidine had been used in the Czech products. I imagine that given the level of expertise of the chemist in re-crystallization, ETN, PEN, or MHN could even be used. US & EU products (C4 and C6) were mostly RDX because it was cheap & constantly re-cycled from "de-mil" warheads, etc.

I've said this before but the big issue about C-4, apart from how they cram in 91% RDX without loosing coherency (bimodal crystal size), is the high content of softener (tackifier) compared to rubber binder (1/50th part!). This can only take place via industrial roller or TIME. Once the proper binder is used TIME will allow it to "coat" the crystal as it IS actually liquid (both SBR & poly-B +). Once that is understood & the chemistry of [whatever energetic] re-crystallization is at a comfort level (using a microscope to I.D.) a plethora of plastques could be drawn up. Also it depends on how much one wants to spend.....

It took me the better part of a month of really reading and studying to find all the patents and sources.

U.S. Adhesives Industry (1991 circular)
Shell Chemical aka Resolution Performance Products
Octyl phthalate energetic binder patent + C4 pat.
"Analysis of Semtex Explosives" J.R.Hobbs.
Chapter 39. p.409-428 in " Advances in Analysis and
Detection of Explosives" edited by Jehuda Yinon
Kluwer Academic Publishers ISBN 0-7923-2138-3 (1993)
Hurst's Gravimentric Analysis posts & his material on Semtex "A1" and "H"
I have more but can't find them.....these would get anyone up to speed on the subject of plastiques.



Use of Nitromethane is not appropriate. It evaporates VERY quickly and is actually hygroscopic. The real thing (see above) - behaves and lasts. It can have a shelf life for decades!! But the chemist had damn well better know how to make a material neutral and professional.





[Edited on 5-10-2011 by quicksilver]

VladimirLem - 5-10-2011 at 08:01

Quote: Originally posted by nitro-genes  

1. After neutralization, don't crash the PETN/RDX in cold water, as you will get a very fine crystal fraction that needs more binder
2. Recrystallize slowly from warm solvent, I normally used a styrofoam box as insulation and stored it at -20 overnight to recrystallize.
3. Precipitate the last fraction instantly with cold water, which will give the fine crystal fraction


great idea :)

how about substutuation of oil (when using PIB) with some liquid/kneadable energetic coumpounds like sorbitol hexanitrate ?
(not compleately SHN, just a few percent instead of the oil)

for example:

Main Explosives 90%
PIB 5%
Oil 3%
SHN 2%?

cause SHN also have an positive oxygen balance - if i dont calculated it wrong :D - which sould increase the coumpound...

Phantom - 6-10-2011 at 05:21

Have you ever tried NG/PETN ? Density >1.6 g/cm*3 and it's VoD=~8000m/s

VladimirLem - 6-10-2011 at 08:34

Quote: Originally posted by Phantom  
Have you ever tried NG/PETN ? Density >1.6 g/cm*3 and it's VoD=~8000m/s


i have read some post from a guy used it at a chaped charge and got an awesome result...BUT...the use of NG was many many too much and really dangerous i think...about 1/3 PETN, 2/3 NG...

Positive is, that NG got an positive OB and increase the power of the PETN...AND, PETN disolves in NG...but whatevere i would try, i wouldnt go for more than...lets say 10% NG...

Phantom - 8-10-2011 at 01:13

And what about ANNMSA ? It's pretty effective.

VladimirLem - 8-10-2011 at 01:44

Quote: Originally posted by Phantom  
And what about ANNMSA ? It's pretty effective.


ur kidding me right?

Phantom - 8-10-2011 at 01:49

Nope

VladimirLem - 8-10-2011 at 02:56

Dude, seriously...we are talking about high performace explosives and your saying some mixed bullshit which may be able to get up to the power of ~TNT...

There are no informations of its density, VoD, OB and TNT-Äquiv.

What the hell...

Phantom - 8-10-2011 at 06:30

Well this is not a bullshit. Even Axtran used it in his shaped charges that you can read in the firs topic and it worked very well.

It is basically a mixture of ammonium sulphate, nitromethane and conc. HNO3

VoD is around 8100m/s

hissingnoise - 8-10-2011 at 06:40

Quote:

Patience Vladimir. . . The explosives you've mentioned aren't really suitable for use in shaped charges because their power and VoDs are on the low side.

Quote:
Bullshit...ANNM has up to 500 at lead block...THATS Power !
So why doesn't NU or even UNNM could do that job ?

Quote:
Dude, seriously...we are talking about high performace explosives and your saying some mixed bullshit which may be able to get up to the power of ~TNT...

So, Vlad the Bullshitter, consistent inconsistence!



hissingnoise - 8-10-2011 at 07:47

Quote:
It is basically a mixture of ammonium sulphate, nitromethane and conc. HNO3
VoD is around 8100m/s

While an oxygen-balanced binary mixture of NM/HNO<sub>3</sub> will have a VoD which can exceed 8000m/sec, it will also be very shock-sensitive!
In ANNMSA, the presence of H<sub>2</sub>SO<sub>4</sub> will greatly reduce brisance!



PHILOU Zrealone - 10-10-2011 at 10:21

Quote: Originally posted by hissingnoise  
Quote:
It is basically a mixture of ammonium sulphate, nitromethane and conc. HNO3
VoD is around 8100m/s

While an oxygen-balanced binary mixture of NM/HNO<sub>3</sub> will have a VoD which can exceed 8000m/sec, it will also be very shock-sensitive!
In ANNMSA, the presence of H<sub>2</sub>SO<sub>4</sub> will greatly reduce brisance!

First assumption is correct but don't be so sure of the second one!
If you read Axt tread thereover...you may read some of my 50 cents comments on it...roughly summarized:
AN/NM/SA is a mix of NH4NO3, CH3-NO2 and H2SO4...thus in the mix, you get some crossed reaction products NH4HSO4, HNO3, CH2=O, CH2=N-OH, NHOH.HNO3, etc and NOx, CO2 bubbles...all this participating at sensitization and high VOD!

[Edited on 10-10-2011 by PHILOU Zrealone]

hissingnoise - 11-10-2011 at 01:16

Quote:
First assumption is correct but don't be so sure of the second one!

Not quite assumptions, PHILOU --- the sulphur atom, contained in an HE, has an unfavourable effect on VoD!


simply RED - 11-10-2011 at 01:48

The sulphuric acid in this mixture contributes with nothing to the energetic output of it. It is just ballast. And adding acid to any explosive decreases stability great. This is the reason I don't recommend such mixtures.

The idea of PETN plus NG is good indeed. Maybe a better (less sensitive) option is PETN plus 10-20% PGDN, just to fill the air space between PETN crystals.

[Edited on 11-10-2011 by simply RED]

Maniak - 11-10-2011 at 03:19

1.) using liquid mixture of sorbitol nitrates as a part of plasticizer is a bad idea because of stability. The stability of sugar nitrates decreases with increasing chain length, i.e. liquid SHN mixtures will be much less stable than EGDN, PGDN and even NG. In a solid state, there is a stabilizing effect of crystalline matrix so that crystalline SHN or MHN may stay alive for longer time.

2.) NM + HNO3 stechiometric mixture will have a density about 1,25g.cm-3 and at this density, there is no chance to have over 8000m/s. I think some 7500m/s may be a possible maximum.

hissingnoise - 11-10-2011 at 04:05

In liquid explosives, VoD is affected by density, OB and viscosity!
Viscosity in NM/HNO<sub>3</sub> is lower than in EGDN and much lower than NGl.
Lower viscosities increase VoD.



Phantom - 11-10-2011 at 09:25

Well if you mix the ANNM with the H2SO4 at "ground zero" you don't need to worry about the sensitivity of the explosive mixture.

Nitroglycerine/PETN has a really good density for shaped charges. Density >1.6 g/cm*3 and it's VoD=~8000m/s
I had seen some really good videos from NUKEpyro's shaped charges and they worked very well for example the 90mm 1500g NG/PETN shaped charge.

Had seen a couple videos on the internet with only EGDN based shaped charges. They didn't work because in my opinion and knowledge the problem was with the VoD.

Liquid --> steel pipe --> 8# commercial cap --> 7830m/s

Liquid --> steel pipe --> 80g picric acid --> 8200-8300m/s

Liquid --> plastic cup --> 8# commercial cap --> ONLY 1000-3000m/s

Solid(-70*C) --> plastic cup --> 8# commercial cap --> above 8000m/s

Warning: Never use a steel pipe for casing! Sharpnels can kill you !

[Edited on 11-10-2011 by Phantom]

hissingnoise - 11-10-2011 at 11:10

Data such as those above are of little use without the pipe-dimensions!



quicksilver - 12-10-2011 at 06:36

I didn't think I needed to point this out but -=source=- of documented material needs to accompany statements of activity, structure, synthesis, & history. Many of the posts have no documentation what so ever and that is not the way we do things here. You have all read the rules of the Forum & it's vital that every effort be made that the material here have documentation so that it could be depended upon to be factual.

Often times the functional level of a thread goes up but in this case it's taken a turn for the worse. If you want to keep this thread alive then please put some professionalism into it. As I saw this thread flounder I was willing to let it stay self-policed as many of you have no problem raising the level of professionalism with no comment from me. However once I started getting complaints about the sophomoric level of some of this material, I realized it would have to be closed unless the quality of posting changes.

simply RED - 13-10-2011 at 04:34

Very good experimental information on the point including data on bicyclo HMX nitramine.
http://www.ipo.waw.pl/wydawnictwa/cejem/3-2010/PDF/Elbeih.pd...

Maniak - 14-10-2011 at 15:36

Viscosity has much lower influence on VoD than density. Even mixtures of NM with TeNM have VoD below 7000m/s (Fedoroff VII, L-29). At such a low density (1,25g.cm-3) there is not even one explosive mixture detonating at 8000m/s (I mean measured and published, not theoretical values or wishes). According to my experiments with pure NM/fuming HNO3 mixture, it possesses less brisance than some usual PETN inert bonded plastics.

hissingnoise - 15-10-2011 at 04:59

Quote:
According to my experiments with pure NM/fuming HNO3 mixture, it possesses less brisance than some usual PETN inert bonded plastics.

Do you know the density of the HNO<sub>3</sub> you used and how did you determine the brisance of the mixture?



Phantom - 15-10-2011 at 22:49

By the way C-4 works great which is plastic RDX. I`m pretty sure you all had seen this video-> http://www.youtube.com/watch?v=LudNqf56AFo

VladimirLem - 15-10-2011 at 23:41

Quote: Originally posted by Phantom  
By the way C-4 works great which is plastic RDX. I`m pretty sure you all had seen this video-> http://www.youtube.com/watch?v=LudNqf56AFo


C4 is a strong explosive, thats for sure, but the VoD suffers exremely from the 9% plastic stuff.

AND:

RDX needs around doubble as much high concentrated HNO3 than PETN needs - when not having Acetic anhydride...so thats for the most users nearly impossible to build huge (CD 6cm<;) chaped sharges with pure RDX...


Phantom - 16-10-2011 at 09:23

Still has around 8000m/s that's for sure.

It is easy to make WFNA out from H2SO4 and KNO3.

If you want a big charge and you can't make that much of RDX than use NG/PETN or ANNMSA which is much simpler.

VladimirLem - 16-10-2011 at 09:51

Quote: Originally posted by Phantom  
Still has around
It is easy to make WFNA out from H2SO4 and KNO3.


sure...but are the results much better then with normal "pure" HNO3 (~97%) ?

hissingnoise - 16-10-2011 at 10:25

Quote:
sure...but are the results much better then with normal "pure" HNO3 (~97%) ?

What do you think WFNA is . . .?


Maniak - 17-10-2011 at 02:05

hissingnoise: the acid was checked using pycnometry, it was surely around 98% HNO3. Unfortunately, I wrote about about my older experiments so that I can not provide you any exact values. I detonated it on usual 1cm thick steel plate and examined indent and back side spalling. If somebody performed exact tests with HNO3 based explosives, I'll greatly appreciate measured data..

VladimirLem - 17-10-2011 at 07:38

Quote: Originally posted by hissingnoise  
Quote:
sure...but are the results much better then with normal "pure" HNO3 (~97%) ?

What do you think WFNA is . . .?



WFNA...W stands for White - means adding urea to the normal "pure" - yellow colored HNO3...

I made RDX without using urea, and just "normal" HNO3

or did i get something wrong? :(

hissingnoise - 17-10-2011 at 08:24

RFNA is distilled @ atmospheric pressure --- WFNA under strong vacuum; they're both normal for the methods used . . .



quicksilver - 20-10-2011 at 10:47

Newer (2004) energetic putty-type. Density demands clearly spelled out. expanded base (from Czech and NATO types); US Patent.

Attachment: plastic_2004_6833037.pdf (77kB)
This file has been downloaded 1452 times


VladimirLem - 27-3-2012 at 09:16

*bump* ^^


what about "phlegmatizing" some (lets say PETN) H.E. with FTN ?

fine powdered PETN into a ethanol-FTN -solution (7% FTN of PETN weight)

stirring the solution and then wait up to the ethanol is "away"...(1-2 days dunno)
then a thin layer of FTN is around the PETN crystals...if that would work, there are very high VoDs possible...

good idea? bad idea?


quicksilver - 27-3-2012 at 15:35

Quote: Originally posted by VladimirLem  
*bump* ^^


what about "phlegmatizing" some (lets say PETN) H.E. with FTN ?

fine powdered PETN into a ethanol-FTN -solution (7% FTN of PETN weight)

stirring the solution and then wait up to the ethanol is "away"...(1-2 days dunno)
then a thin layer of FTN is around the PETN crystals...if that would work, there are very high VoDs possible...

good idea? bad idea?






You have a complication there. ETN and PETN use differing solvents for optimum results. Acetone (best @ sub-boiling) is actually too STRONG a solvent for ETN - which does a great job of solvency and re-crystallization in ethyl/methyl alcohol. It is obviously possible to experiment with percentages of both solvents to produce a clean well formed result. However acetone alone is too strong a solvent for ETN - PLUS commercial (paint-grade) acetone has petroleum distillates as adulterants within it (leaving that "unclean smell"). This can occasionally be problematic for ridged crystal formation; trapping unwanted materials in the final product. Not all acetone has this problem but most 'hardware store" brands do.
As more and more drug cooks use OTC chemicals, the purity of those products becomes lower. The common source of sulfuric acid is blackened due to it's use in metal treatment surplus. It is more cost effective to leave the garbage and metals in the acid since it's only drain cleaner. Denatured alcohol may on occasion contain acids (phosphoric most commonly) as a means of De-naturing. This presents a serious problem when a pH of neutral is demanded, etc, etc, etc

VladimirLem - 28-3-2012 at 07:48

dude...i'm talking about Fructose-Tri-Nitrate...(sticky stuff)

ETN mouldnt make sense as a wax-substi cause crystals and shit...

quicksilver - 28-3-2012 at 08:11

Sorbitol hexanitrate as a compounding medium may be functional energetic density increasing mechanism.

Materials that have limited background study (nitrated fructose) may impose undocumented complexities.
Of the work Tenny Davis did with the Sugar industry in the 1940-50's I could find little of great worth on nitrations of fructose, sucrose, etc. There was some commentary on the difficulty in shelf life longevity with the above. Do a SEARCH on "Tenny Davis" and you should find an old reprint I put up on some material that's not in the COPAE.
And remember some of us are 60 yrs old+ and and "F" looks like an "E".

Goorlap - 29-3-2012 at 12:14

Quote: Originally posted by VladimirLem  

C4 is a strong explosive, thats for sure, but the VoD suffers exremely from the 9% plastic stuff.


Don't think so, otherwise it wouldn't be used by the military

VladimirLem - 30-3-2012 at 06:40

Quote: Originally posted by Goorlap  
Quote: Originally posted by VladimirLem  

C4 is a strong explosive, thats for sure, but the VoD suffers exremely from the 9% plastic stuff.


Don't think so, otherwise it wouldn't be used by the military


C4 isnt used as a anti-tank charge in combat...most use for C4 is to blow up captured ammonition from enemies

its just easy zu handle, powerful, dont need some container to get the maximum power and dont have to mixed first (like much cheaper other explosives)...i think thats why its used, not because high VoD...

And yes...sure RDX is used in Antitank ammunition, but that most times RDX/TNT (75/25) or RDX itselv but with only 5% Wax...
And last but not least, most plastizieser have a horrible OB...that could decrease of the VoD (alot?)...

quicksilver - 30-3-2012 at 06:42

A great many materials shoot even at 30% inerts. Semtex has had 1/4 inerts and all sorts of surplus energetics for export. Their Vod is the same as the lower weight energetic if roller mixed & the inert-bulking agent is infused with the energetic. That is a fact from PATR & the old Soviet-block military reports on exported Czech explosives. Even Jerry Hurst wrote about that 10+ years ago.

Propellant approach???

albqbrian - 6-4-2012 at 03:21

The patent QS referenced certainly provides some ideas. It suggests you can use the basic approach used to make ammonium perchlorate composite propellants. Just add your energetic solid (AP, PETN, etc.) to your binder system. Certainly 88% solids loading is quite doable; I've done it with AP and HTPB as a binder no problem. I briefly perused the patent, but I didn't notice them giving any actual results though.

You could get wilder and "soup up" your binder system with an energetic (ETN, NG) plasticizer; though that would be certainly increasing the risk level.

The one thing I'm unsure about is if the catalyst would react with the energetic solid in some unpleasant way. These systems are usually hardened by some sort of isocyanate (isophorone diisocyante for example) or an epoxy depending on the exact binder (HTPB, CTPB).

One feature of this approach is that the needed chems are easily available and relatively inexpensive. Now if we only knew if they worked :)

Hennig Brand - 24-4-2012 at 16:06

Sorry for the long post. I was on a roll!

Plastic explosives made from PIB seem to work fairly well even if they are not the perfect thing.

I think Quicksilver quoted Gerald L. Hurst, well I remember reading archived material from the old Alt.Eng Explosives forum and he said (in my own words) that the type of inert material used in a plastic explosive was of very little importance as far as the performance of the explosive goes.

From Yarchive, in section on plastic explosives:

"There is no particular magic in the specific plasticizer mix other
than that it has good stability and low-temperature plasticity. It
may be viewed as an inert diluent as far as explosive properties go."

Jerry (Ico)


At the bottom is a picture of some ETN plastic explosive made a couple of weeks ago. It weighs 54.3g and has a volume of ~ 30.7cc. That’s right, the density is about 1.77g/cc, and I couldn't believe it myself.

The volume was estimated by rolling it into a nearly perfect ball and then taking the average of three diameter measurements. The diameters were measured on the three perpendicular axes, the x,y & z axes if you will.

Volume of Sphere = 4/3 *pi * r^3

I measured the volume twice, the first time gave a density of 1.78 g/cc the next time 1.76 g/cc. I took the average of these, which as I said before gave a density of 1.77 g/cc. This seems awfully high to me.

The explosive was made from PIB, methyl ricinoleate and SAE 30 non-detergent motor oil/compressor oil (I think that is what the auto parts store guy said people buy the non-detergent stuff for mostly, compressors).

The methyl ricinoleate was made from castor oil laxative. It was made basically the same way one would make biodiesel. I guess biodiesel made from methanol & castor oil is ~90% methyl ricinoleate.

The 15% inerts (PIB, oil, methyl ricinoleate) are all dissolved in white gas, and then the ETN is added and mixed well. I have to find my notes but I think I last used about 5% of each, or close to it. After it is mixed well the gas is allowed to evaporate, not in the light, especially not sunlight.

I have a little table with a smooth plastic surface on it. I found a really good way to knead the dough .....er I mean plastic explosive. Once the gas is gone or almost all gone, put the mass on a nice clean smooth surface, and use a glass rolling pin to knead it. Knead it really well, just like making pizza dough. I found that an old beer bottle with the labels cleaned off makes a great rolling pin.

A little more methyl ricinoleate usually needs to be added during kneading to get the right consistency (few drops at a time while kneading).


Last year I did a little explosive test with 30g or so of this type of plastic explosive. I stuffed the 30g or so into a plastic pill bottle and used a paper blasting cap to initiate it. I normally use about 1.5 g of ETN, MHN or PETN with a little primary on top, all well pressed in a paper tube to initiate this stuff. The inerts make the explosive surprisingly insensitive to initiation.

The charge was duct taped to the side of a large barrel (that old barrel is nothing but holes now). It was fired with safety fuse. When it detonated it formed shrapnel, 6 or 8 pieces about the diameter of a pencil eraser went through the other side of the barrel like tissue and embedded themselves in a woodpile 15 ft behind the barrel. None of the dynamites I ever made created shrapnel like that.

It is unbelievable the difference in brisance of this stuff relative to most dynamites and the common blasting agents.


ETN Plastic Explosive.JPG - 255kB


I would like to thank nitro-genes for outlining his process to produce a plastic explosive using PIB in the thread PETN vs RDX. I used his work as a guide, which helped me when I was first attempting this a great deal.



[Edited on 25-4-2012 by Hennig Brand]

Hennig Brand - 25-4-2012 at 15:24

OK, I am starting to wonder if it is possible that I had as high a density as I measured. I looked up the densities of the individual components of the plastic explosive.

PIB (amorphous) = ~0.84 g/cc
SAE 30 oil = 0.912 g/cc
Methyl Ricinoleate = 0.925 g/cc
MHN = 1.604 g/cc

I didn't find the density of ETN quickly so I included the density of MHN, it should be close I would think to that of ETN.

I checked the weight again with much better scales and the difference was negligible.

Is it possible that I got a density higher than all the individual components, or is this impossible?




inspector071 - 25-4-2012 at 15:51

Perhaps your volume measurement is off. Wouldn't a better way of measuring the volume be to place an amount of the plastic explosive into a graduated cylinder filled with water, then calculate the volume change? Then you can use your accurate scales and calculate density from there.

Hennig Brand - 26-4-2012 at 05:30

I agree, I would say that the volume or more specifically the measurement for the ball diameter is off. I couldn't find my vernier calipers so I used a ruler instead, bad idea. In the equation for a sphere the radius is to the power of 3 or cubed, this can result in much larger errors than expected. For example, say we have a sphere with an actual radius of 1 cm, which would produce a calculated volume of 4.19 cm^3. If we measured the radius to be 1.1 cm, or greater than actual by 10%, the calculated volume would then be 5.58 cm^3 which is a 33% error from the actual value for volume. Measuring volume in this way, especially with a ruler, was a bad idea.

Someone suggested that I should use a container with a known volume and pack it full of the plastic explosive to find the density, which is basically what I have done.

I took a plastic pill bottle and weighed it empty and then recorded its mass. I next filled it with water and weighed it again, subtracting this weight from the weight taken when the container was empty to find the weight of the water. I measured the temperature of the tap water and went to a table to find the density of water at that temperature. From the density and mass of the water I was able to easily calculate the volume of the container. I carefully dried the container and then packed it full of my plastic explosive. I weighed the container and plastic explosive and then subtracted this weight from the weight of the empty container. This weight divided by the container volume gave me the explosive density.

Mass of empty container = 4.63 g
Mass of container filled with water = 32.74 g
Water Temperature = 10.5 C
Density of water @ 10.5C from table = 0.999 654 g/cc
Mass of container filled with explosive = 44.72 g

Volume of container = (32.74g - 4.63g) / (0.999654g/cc) = 28.1 mL
Density of Explosive = (44.72g - 4.63g) / 28.1 mL = 1.43 g/cc

I think I may have fluffed the explosive up a little, or included a little air getting it into the container, but probably not that much. This value of 1.43 g/cc for the explosive is much closer to the actual value and seems more reasonable.


I included a density table for water, which I thought others might find useful.

Attachment: Density of Water at Various Temperatures.pdf (72kB)
This file has been downloaded 3701 times



[Edited on 26-4-2012 by Hennig Brand]

Jimbo Jones - 26-4-2012 at 06:10

Press the plastic explosive in precise graduated syringe. Just cut some small holes for the trapped air on the end of the plunder and the rubber piston. Works fine.

hames - 26-4-2012 at 07:54

I was wanting to plasticize my etn,I have few litres of dioctyl phthalate, would this be suitable with pib as a binder,according to wikipedia semtex is plasticized with n-octyl phthalate, could they be substituted?.

Hennig Brand - 26-4-2012 at 12:19

I think that is normally used with styrene-butadiene, in Semtex, not PIB. I assume there is a good reason but I don't know yet.

I found a very interesting pdf, on line just now, with specs for some of the common grades of Semtex. Notice that Semtex 1H in the pdf has a density of 1.43 g/cc, the same density as my ETN plastic explosive. I wonder what the percentage of inerts is in Semtex 1H. Mine is around 16% inerts, but I plan to drop that some.



Attachment: SEMTEX.pdf (532kB)
This file has been downloaded 3845 times

Ok, according to Wikipedia Semtex H is 17.9% inerts. This is a little more than I am using, however I am not using PETN and RDX either. PETN and RDX I believe are both more powerful explosives than ETN.


Here is another spec sheet for some Semtex products, from the Explosia a.s. company website. This company appears to be an older more established company than the one above. The data tables look identical though, so maybe they are affiliated in some way.


Attachment: Plastic Explosive Specs.pdf (44kB)
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According to Wikipedia:

"Explosia a.s. is an explosives manufacturer in Semtín, a suburb of Pardubice in the Czech Republic. The company was established in 1920. Its most famous product is the Semtex malleable explosive, the name is formed as a combination of the first letters of the Semtín village and the company name."



[Edited on 27-4-2012 by Hennig Brand]

Maniak - 27-4-2012 at 09:03

The reason why there is SB rubber and not PIB is very simple. When the manufacture was started in sixties, SB was much more readily available than PIB in Czechoslovakia and there is no reason to change the composition now, when the manufacture is optimized.

The first pdf file you attached is just from some distributor of Explosia a.s., because this is the only place where S is prepared on the world (maybe exception are some amateurs' labs).

Hennig Brand - 27-4-2012 at 12:00

So there is no difference in suitability between the two? I assumed, but didn't know, that every binder might have a plasticizer that it works best with. I am in the process now of trying to find some good information on plasticizers.

I found what I think is a really good book, "Handbook of Plasticizers by George Wypych". I haven't found a download yet and the book goes for around $300, which is out of my price range right now for a book.




Maniak - 27-4-2012 at 13:16

Sure, binder needs right plasticizer. It depends on nature of polymer if it has double bonds or not, if it has more or less polarity, etc. PIB needs paraffinic oil while naphthenic oil is better for SB. More polar "oils" like phthalates are more useful for polymers like nitrocellulose. However, exact choice may also depend on mw of the polymer binder.

Hennig Brand - 27-4-2012 at 14:00

I would like to have a conversation about plasticizers and binders, unfortunatelly right now I don't know that much about them.

One thing I have wondered about, as I am sure many have, is how well an ETN based plastique stands up against a PETN based plastique. I know that PETN is much more stable, which is mostly because of a chemical structure which is different than the other common nitric esters. It has that fifth carbon that ETN doesn't have. I am just interested in the explosive performance right now though. I didn't find data on ETN of course, but I did find some for MHN which should be close.

The following values were taken from a report by Dave Everest called "The power of high explosives in theory and practice". His references include several of the "usual sources".

Explosive..........Trauzl Lead Block........Ballistic Mortar
RDX...........................1.64...............................1.50.......
NG.............................1.86...............................1.40......
PETN..........................1.81..............................1.46......
MHN...........................1.68..............................1.36......

TNT was taken as 1.00 for both sets of tests.

Here are some Lead Block results taken from "Explosives 5th edition" by Meyer.

RDX.......1.60
NG.........1.73
PETN......1.74
MHN.......1.70

Its not an exact science but the numbers are fairly close to the first set.

I have noticed that ETN doesn't work as well as PETN in small quantities, like in a cap. I think it was Rosco that mentioned this in another thread as well. I think it was also said that after the charge size had increased to 1.5-2g or so that ETN performed much better. I could be wrong as I am going by memory. I should try and find the old posts.

Anyway, if the performance of MHN can be taken as a close approximation of what we can expect from ETN, then ETN's performance is not far behind that of PETN and RDX. I know this is not news, but I just wanted to do a side by side comparison mostly for my own benefit.



[Edited on 27-4-2012 by Hennig Brand]

hames - 27-4-2012 at 17:45

I tried to initiate 200ml of nm+5% monoethanolamine with 2g of etn+200mg of colloidal lead azide and it failed but I'll have to add that it was in a plastic bottle so there wasn't much confinement to help it along.

quicksilver - 28-4-2012 at 07:30

Many people get confused on this score: the "motor oil" is actually a synthetic in the patent often quoted. Most commonly a silicone oil with a small amount of tackifier.
There are generally two ingredients in Deta-sheet: a tackifier and a plasticizer This is not found in SBR as one material does "double duty" and the "C4" blocks are often not used to mold and shape. Semtex, Deta-Sheet, C6(PA) and others ARE used to mold into door hinges or shaped charges. Unwrapping a 1/2 lb block of C4 will show a simple, low level plastizer, that easily breaks apart and only forms when very warm. (See "Shaped Charges" published by the ISEE) That was one reason why poly- ISO-butylene is generally made in situ from polybuelene (like "bird repellant") and a rhinocyte. The level of particulate material to adhesive is phenomenal: yet this frequently requires rollers or a great deal of "hand manipulation". A 1/2 lbs of material is generally about the size of a billiard ball, the density is so remarkable.
"Diamond-Charges" from PETN Deta-Sheet are wonderfully effective for the amount of weight [of explosive] used therein. Superficially, it seems that even though RDX and PETN are similar in powder, speed, etc - RDX is more efficient in larger amounts such as warheads where as PETN is somewhat more efficient in smaller weights such as base charges in det-caps.


Obviously it wouldn't be appropriate to post actual advertisements for energetics but there OCCASIONALLY are rather in-depth ads with ingredients in some ISEE publications. There was a very interesting book re: explosive mfg at the turn of the 20th century and there were pictures of the "roller machines" that did the mixing (titled "100Years of Explosive Manufacture") available through Amazon as a Used book for a few dollars that has a great deal of information regarding the development of flexible / mold-able energetics.

[Edited on 28-4-2012 by quicksilver]

Hennig Brand - 28-4-2012 at 12:27

I just noticed something really interesting when I was looking at the Semtex composition numbers on the Semtex Wikipedia page. I had a hunch and I plotted the data just to show that my hunch was correct.

Here is the data table taken from the Wikipedia page on Semtex.


Semtex Compositions Table - taken from Wikipedia.jpg - 32kB


Here is a plot of percentage Inerts vs. percentage PETN, for the three different Semtex types, done in excel. Now I don't know about you, but I don't think I have ever gotten an R^2 value of 1, for any straight line graph, unless of course the data was deliberately set up that way.


Attachment: Percent Inerts vs Percent PETN (23kB)
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Makes sense really, that Semtex would need more inerts than C4 in order to meet the sensitivity requirements. Simply adjusting the amount of inerts in proportion to the amount of PETN is quick and easy and obviously gets the desired results (more or less).



[Edited on 28-4-2012 by Hennig Brand]

Hennig Brand - 29-4-2012 at 06:03

Ok, I am now convinced that C4 produced in North America and Great Britain uses silicone oil. After reading some patents and a journal on characterization of C4 explosives, I am convinced.

This does not mean that other oils are entirely unsuitable!


The reasons I see (so far) for using silicone oil are as follows.

1. Much more stable viscosity over a wider temperature range than other oils. This is the same reason why some vehicle shock manufactures switched to silicone oil.

2. Chemically very stable and unreactive with most other chemicals. This helps ensure longer shelf life even in severe storage conditions.

3. Essentially Non-Toxic. This is important from a handling prospective.

4. Non-Flammable. Having a flammable hydrocarbon mixed with a high explosive seems like added liability.

If people could add, or make changes, to my list I would appreciate it.


Anyway, I have included a couple of figures from the journal I was reading. The journal article is from "Analytical Chemistry", 2010, and is called.

"Characterization of Composition C4 Explosives using Time-of-Flight Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy"

By

Christine M. Mahoney, Albert J. Fahey, Kristen L. Steffens, and Bruce A. Benner, Jr.
All from the "National Institute of Standards and Technology"

And Richard T. Lareau, from "Transport Security Laboratory"



English C4 XPS survey spectrum.jpg - 98kB C4 C to N ratios.jpg - 33kB

Notice the amount of Si and Oxygen, in the X-Ray Photoelectron Spectroscopy (XPS) results, for English C4. Apparently all three samples, American, American commercial and English, showed the same general make up, but with variations in proportions.

note:
X-Ray Photoelectron Spectroscopy (XPS), is a quantitative test. There is a good Wikipedia page on it if interested.


Also notice, from the C:N ratios chart, the large variance in the proportion of inerts and RDX between the American, American commercial and English C4 samples. The English sample had the highest C:N ratio, therefore the highest amount of inerts. The American commercial sample had the lowest C:N ratio, therefore it has the lowest amount of inerts.

It is obvious from this journal that there are several different types of C4, each with its own composition. It was also clear that all three types of C4, studied in the journal, are made from the same or very similar components.



[Edited on 29-4-2012 by Hennig Brand]

quicksilver - 29-4-2012 at 10:57

I had experimented with a British patent some years back and it appeared that the synthetic didn't "weep" from the whole of the mass once it had been standing for some months.
On another subject the Semtex for export is really very poor quality and very inconsistent in it's composition. The general consensus was that almost any salvageable energetic was blended into it (that's the "orange" 1/2 lb blocks not the red cylinders). Somewhere I have some scanned material from the Czech Republic on the government factory and it had some fascinating pictures.

Hennig Brand - 29-4-2012 at 11:35

So, the Semtex specs from the Explosia, a.s. website are most likely "best case scenarios" then, and what is sold usually falls short, unless it is going to the military. I have read posts by Gerald Hurst saying basically this as well.


quicksilver - 30-4-2012 at 07:49

Oh, they would put TNT, or just about anything in it and in different proportions. So the only means of getting ANY consistency was the lot number (which was ink stamped). Many people use the term "Semtex" but there are now several world-wide companies that make a plastique.

One of the most inter4sting stories I had read was about Saudi Arabia and it's design to interrupt it's own oil production of oil if the Kingdom were overthrown. The major problem was that by using Czech Semtex they had only a true shelf-life of 20 years - then the material would need to be replaced. Much of this problem had to do with design. The "Petroleum Scorched Earth" concept in oil production is outlined in several books and is one of the reasons why there is continued work on plastic binders and tackifiers.The ideal material needs to have both, yet last for many decades.

Hennig Brand - 30-4-2012 at 09:41

Patent 3173817 issued in 1965 describes compositions which are nearly the same as modern C4. The key difference is that it specifies the use of motor oil and in brackets it states specifically (SAE 10) in several different places. Is there any type, or weight, of Silicone oil that is specified as SAE 10?

This patent was issued about the same time that C4 was replacing C3. Is it possible that the early formulation did in fact include nondetergent SAE 10 motor oil and somewhere along the line it was changed to silicone oil?

It is really strange that the proportions used, for the plastic explosives in the patent, match so closely the proportions of modern C4.



Maniak - 2-5-2012 at 03:19

As it was said here, C4 can not be compared to Semtex in view of mechanical properties, because its desired form is different. C4 is designed to be used as large blocks where high density is given by rolling. Semtex is designed to be easily hand shaped without changing its explosive properties.

Wiki is wrong about Semtex composition, because octyl phthalate and dibutyl citrate are polar plasticizers and they are not much compatible with SBR. SBR is used with mineral oil.

Oil used with PIB can definitely be just usual mineral oil. If silicone oil is used in modern composition, it is because of storage or environmental characteristics.

Hennig Brand - 2-5-2012 at 11:03

This is a quote by nitro-genes from another thread on plasticizing explosives:

"It is no coincidence that all plasticizers contain some hydrophilic groups. My theory is that the repellant action of these groups towards the hydrophobic environment allows for a much better separation of the long chain molecules of the polymer to be plasticized, giving them far better mechanical properties."

I also found a section a week ago in the book "Handbook of Plasticizers", which also said basically the same thing. I don't own the book and I am having a hard time finding that exact section in the book again, but I am sure it is there.


Regarding C4 and handling properties; I don't have a reference right now, but I think most of the time you are right about C4 and it is not made to be molded by hand, etc, but used as is in blocks. However, from memory I seem to remember reading that some C4 is made to be molded and the key difference is the amount of mixing and kneading which has been done to it. The C4 that is more thoroughly mixed and kneaded has handling properties more similar to Semtex, I think.

I have included a pdf of chapter 11 out of the "Handbook of Plasticizers", by George Wypych. The chapter is titled "Plasticizers Use and Selection for Specific Polymers". Section 11.3 is on PIB and section 11.5 is on SBR.

Section 11.5 says it is common to use mineral oils but also dibutyl or dioctyl phthalate to plasticize SBR.



Attachment: Handbook of Plasticizers Ch11.pdf (1.1MB)
This file has been downloaded 82365 times



[Edited on 2-5-2012 by Hennig Brand]

Maniak - 3-5-2012 at 06:33

Thanks for the piece, it's interesting! But in 11.50 SBR section there is nothing about phthalates.. Maybe you skipped to 11.51 section where they are, but it is about SBS polymer which is much different. In 11.50 section they mention just some resins and various oils.

About C4 - in my opinion, with 9% of plasticizer-binder you can not reach both high density and moldability in one moment. You can have just one of them. If you'll knead C4, it will become moldable after some air will be entrapped and therefore density will fall down significantly, followed by detonation parameters.. In other hand, semtex with around 16% inerts can be shaped and even kneaded without large density decrease.

Hennig Brand - 3-5-2012 at 09:23

Oh, sorry about that. I was moving a little too quickly, I guess. As you say, I thought I was still looking at the section on SBR.

You could be right about C4; I don't have the answer right now. I now think though that C4 is not always, 9% inerts, as it is often described in the more accessible references. I found a modern journal article (2010) which had the results of a detailed quantitative analysis on C4 from different sources. It was obvious from the results that C4 from different sources can have quite large differences in the amount of inerts. I referenced the journal article a few posts up.



[Edited on 3-5-2012 by Hennig Brand]

killswitch - 3-5-2012 at 09:42

I have a question regarding picric acid. Is crystallization from solution the best method for acquiring high density?

A picture of crystals of TNP:

Hennig Brand - 3-5-2012 at 11:44

Picric acid can be melt-cast for highest density. Pure picric acid melts at ~122.5C. Unlike water most substances, including TNP, increase in density when they solidify from the liquid state. When picric acid crystals are simply compressed there are many tiny air spaces, which lower the overall density relative to a solid cast of the explosive. The tiny air pockets make the explosive much easier to initiate though.



Hennig Brand - 3-5-2012 at 12:48

I found another interesting journal article. I have included a couple of lines from the abstract below. I am trying to get ahold of the whole article, but so far no luck. The article is titled,

"Characterization of Semtex by supercritical fluid extraction and off-line GC-ECD and GC-MS"
by
Gregory C. Slack, Harold M. McNair, Lou Wasserzug
Journal of High Resolution Chromatography
Volume 15, Issue 2, pages 102–104, February 1992


"Researchers using electron capture for the detection of explosive vapors currently claim the ability to detect the presence of RDX in Semtex – a plastic explosive comprising hexahydro-1,3,5-trinitro-1,3,5-triazane (RDX) in a matrix of styrene-butadiene copolymer and hydrocarbon oil."

This would seem to be in agreement with Maniak's assertions about the plasticizers used in Semtex.



Ok, I just found another good article.

"Characterization of Three Types of Semtex (H, 1A, and 10)"
by Stephanie Moore, Michele Schantz, William MacCrehan

Received: November 13, 2009; revised version: December 14, 2009

From Propellants, Explosives, Pyrotechnics

I have included a couple of the results tables from the report.


Semtex Components Table 1.jpg - 152kB Semtex Components Table 2.jpg - 176kB


It seems like they do rely heavily on hydrocarbon oils, but some other plasticizers are used as well. It also seems like many different things that could end up in the mixer.

You know, I don't see any octyl phthalate or dibutyl citrate in either of those lists.



[Edited on 3-5-2012 by Hennig Brand]

Maniak - 3-5-2012 at 23:03

Sorry, but when I see these analytical articles... I think that it would be better if autors will throw away their costly instrumments (or give it to us) and then they will just ask manufacturer which materials are used and of which purity. For forensic analysis, manufacturer will probably give them correct numbers so that they can write some review article ;)

Hennig Brand - 5-5-2012 at 14:06

This is the abstract, from the article referenced in my last post, which should have been included.

"Abstract
Solid phase microextraction and solvent extraction were used
with GC/MS to determine the vapor and compositional profile
of three samples of Semtex (1A, H, and 10). Semtex is reported
to contain PETN and/or RDX, along with plasticizers, binding
materials, and fuel oil components. In an effort to differentiate
and compare these three variations of Semtex, this report summarizes
the headspace and solvent extraction results for each
material. Components that can be used to differentiate varieties
of Semtex were identified and all three Semtex profiles were distinguished."


I thought I should add the following quote from the same journal as well. It explains why Styrene Butadiene did not show up in the results tables.

"The styrene/
butadiene copolymer took the longest to dissolve in
dichloromethane and once injected, did not provide any
components that eluted from the column. A higher
column temperature (300 C) was applied, but still no
peaks were observed. In a similar fashion, Sudan IV did
not result in any detected peaks."

and also:

"As
previously mentioned, 4-phenylcyclohexene was seen in
the SPME profile of the styrene/butadiene analytical
standard. Since 4-phenylcyclohexene (4-PCH) has no recognized commercial use, it is safe to assume that detection
of 4-PCH at 16.3 min suggests the presence of the
reported styrene/butadiene copolymer in Semtex 1A."


I probably should have included tables 1 & 2 which have the results of testing the standards. Tables 1 & 2 show the results gotten from testing pure samples of known/suspected Semtex components, obtained from chemical supply houses. Here are tables 1 & 2, from the journal referenced in my last post.

Table 1.jpg - 110kB Table 2.jpg - 187kB

[Edited on 6-5-2012 by Hennig Brand]

killswitch - 6-5-2012 at 09:27

Quote: Originally posted by Hennig Brand  
Picric acid can be melt-cast for highest density. Pure picric acid melts at ~122.5C. Unlike water most substances, including TNP, increase in density when they solidify from the liquid state. When picric acid crystals are simply compressed there are many tiny air spaces, which lower the overall density relative to a solid cast of the explosive. The tiny air pockets make the explosive much easier to initiate though.




I tried that... While parts of it melted, chunks of it seemed to be vaporizing and condensing on the upturned beaker I'd placed over the container. It was transparent, though. Was it actually water?

Hennig Brand - 6-5-2012 at 18:36

I don't have any personal experience with casting Picric Acid. I do know that it was done a lot, especially in WW1. For safety an oil bath should be used and no open flame (use a hot plate). I would make sure the Picric Acid is as pure as possible; some contaminants can increase sensitivity and add to the danger(metallic impurities especially). Keep in mind even pure picric acid is much more sensitive in the hot, molten state. Picric Acid is often mixed with other lower melting point explosives, making a mixture with a lower melting point than pure picric acid.

The vaporizing chunks could maybe be vaporizing or subliming dinitrophenol. Taken from Wikipedia:
"2,4-Dinitrophenol is a yellow, crystalline solid that has a sweet, musty odor. It sublimes when carefully heated and is volatile with steam, boiling point 113 C....Picric Acid boiling point > 300 C, explodes."
Maybe all one has to do to remove the DNP from their TNP sample is to distill it off.;)

I think I am starting to see why I always seemed to loose a little weight during the times I was experimenting with Picric Acid. There are times during a TNP synthesis when a person could be exposed to more DNP than you might think. When recrystallizing TNP I noticed anywhere the vapor would condense that there would be a bit of yellow stain. DNP being so much more volatile than TNP, if present, would have been the major component of the dye in this "yellow steam" (I think).

I hope I have helped some. I have made TNP quite a few times, but truthfully I have never cast it.

[Edited on 7-5-2012 by Hennig Brand]

caterpillar - 6-5-2012 at 19:10

Shellite in England or Sprengstoffe 88 in Germany, used during WWII to fill large caliber shells for battle ships was TNP plus few percent of nitrophenole, added most likely to decrease melting point. I made experiments with melting TNP. Sulfur bath works well. But I used some shit instead of good primer- Ag2C2 and was unable to detonate TNP. (Complex salt Ag2C2.AgNO3 had to be used instead). It was not very simple to fill shells with TNP. These shells had to be covered inside with pure Sn without Pb and cooling had to be done under hi pressure (compressed CO2), otherwise there was porous in solid TNP. Finally I stopped experiments with TNP and converted it to its ammonium salt. Nice compound, insensitive (less than TNT) and can be mixed with AN.

Hennig Brand - 7-5-2012 at 09:20

You initiated cast TNP with double salts? From my experiences with picric acid, at least in caps, I am surprised double salts (in reasonable amounts) even detonate compressed crystalline TNP. The ammonium salt (explosive D or ammonium picrate) is quite a bit less powerful than picric acid and is very insensitive. The only advantage of explosive D (militarily) was that it was so insensitive that it could be driven through the side of a steel target without detonating and then be detonated on the inside. I find for normal/non-military uses even pure picric acid is more insensitive than I would like most times.

So you mix ammonium picrate with AN, kind of like they do with TNT? I have read the section in Fordham several times regarding TNT powder. IIRC it is normally around 10% TNT / 90% AN and it is certainly cap sensitive. What proportions did you use when you mixed your ammonium picrate with AN? How sensitive to initiation was it?

caterpillar - 7-5-2012 at 13:04

You misunderstood me a little. I did not cast mixtures of TNP with its salts. I made one experiment with pure TNP and did not repeat it. I used later mixtures of ammonium picrate with AN and Al. I do not remember proportions, most likely they are of no great importance. Make your own experiments. I used TATP to initiate aforementioned mixture and according my own experience it is powerful primer and not as dangerous as many people think (HCl must be used as catalyst, not H2SO4 !). I read about solid propellant, based on ammonium picrate: 45% of AP, 45 % of NaNO3 and 10 % of some binder (epoxy?) but I've never tested it. Another advantage of AP is that it is not an acid. Kalium picrate is an interesting salt too. It is more sensitive than pure TNP but does need a primer- it explodes, been ignited in confinement.

Hennig Brand - 7-5-2012 at 15:08


I don't think I know much about ammonium picrate/AN/Al, but the aluminum would probably be most responsible for sensitizing the mix.

You find TATP to be a powerful primary; what did you compare it to? I found TATP was fine for initiating dynamites and some other sensitive secondaries. I found it was next to useless for setting off TNP in a compound cap. TATP is very powerful when compared to something like potassium picrate though.

I have experimented with potassium picrate a few times and see that it may have some uses in a flash igniter or something. Potassium picrate is really very weak, I think one of the lead salts would be a much better option. If you can get the process down and have good reactants, basic lead picrate is really quite impressive (much better than the potassium salt).

TATP is dangerous like all primaries are dangerous, but worse than most primaries used by hobbyists it is considered very unpredictable. You might get away with using it a certain way 100 times and then at 101 you lose two fingers. I have never had any problems with it, but I consider myself fortunate.

I am not saying I would never experiment or use TATP, but I would be much more cautious with it than most of the other explosives I experiment with.

caterpillar - 7-5-2012 at 15:34

It was me who misunderstood you. English is not my mother's tongue, as you might guess. I tried to initiate cast TNP using not the double salt, but Ag2C2, that is much weaker initiator compared with double salt- Ag2C2.AgNO3 (which is less sensitive). Result was very simple- cast TNP was broken for some pieces, but did not explode. I used mercury fulminate too (and was at nearly killed) but it is at least as dangerous (if no more) than TATP. I read some info about TATP in one thick russian book (Bagal Lev Ilyitch Chemistry and technology of priming explosives - translation is mine). At this book only one bad thing was told about TATP- it is very volatile. Double salt is a good choice for amateurs. May be, DDNP is a good primer too and its preparation doesn't look very complicated. Lead picrate can be used as well, but it is (as I know) relatively weak primer.

Bot0nist - 7-5-2012 at 15:54

Don't be fooled by DDNPs simple looking synthesis that you find in most "black books." The sodium hydroxide and sulfur preparation results in a very dirty end product that preforms very poorly. There are a few threads here by experience members who had many problems with the synthesis. A source of relatively pure picramic acid is probably needed.

Your right about Ag2C2.AgNO3 being a great primary, and the ease of it's synthesis and availability of it's precursors put it firmly in the realm of possibility for most amateurs and hobbyists.

caterpillar - 7-5-2012 at 17:04

Ridiculous, but in my youth I saw picramic acid in a shop ( but I did not know, if this compound was freely available). What about sulphuril nitride? Bubble at the first chlorine through sulphur in toluene, then dry ammonia gas. It doesn't look very problematic.

Hennig Brand - 7-5-2012 at 17:56

The Lead picrates are all fairly weak primaries, the basic lead salt especially though makes a really good flash igniter. For some reason I have had a lot of trouble making basic lead picrate, but when I did make it was something similar to lead styphnate in explosive properties (a little weaker though). I was not trying to indicate that basic lead picric would make a good primary to replace TATP for initiating secondaries.

I would like to experiment with DDNP at least once. I should try and track down some picramic acid at some point. I think others including Rosco have indicated that there are other primaries that would make better use of time and resources. Just for fun though it would be nice to make DDNP once.

I agree Bot0nist that double salts is one of the better ones. Even though it is fairly low powered it has quite good initiating abilities. Have you ever tried it on something insensitive like TNP though? I think I tried once, but it didn't work out. It is possible though that I didn't use enough, or that something else wasn't right.

[Edited on 8-5-2012 by Hennig Brand]

caterpillar - 7-5-2012 at 23:25

As I told you, I used mercury fulminate, silver carbide (basic one and without success) and TATP. I was quite satisfied with the last one. I have no intention to discuss its properties here- corresponding tread was closed and I cannot add something interesting. May be, I just was lucky. I prepared solution of magnesium stiphnate but I did not make lead salt- just at that same time list of restricted reagents had been enlarged and all salts of nitric acid was included into it. My indolence prevented me from preparing lead nitrate for myself and I found that TATP is very powerful primer. In that book on primaries I read that lead acetate shouldn't be used for preparation of lead stiphnate, only salt of nitric acid. There are some organic salts of perchloric acid that are very powerful initiatiors, but they are too damn sensitive.

VladimirLem - 8-5-2012 at 08:59

guys please...back to topic...

i have read that parafin-wax is soluble in benzine (normal gasoline)...so would it work to mix, lets say 7g of parafin-wax into warm benzine, then some (93g) HE (PETN/RDX/MHN - all insoluble in benzine) and let the mixture dry...would that work to get a phlegmatized explosive?

and more importand is, is parafine-wax (like that in those tealights with that AL-case) really soluble in benzine?

Maniak - 8-5-2012 at 09:53

Yeap, this works. It is desired to mix it by some wooden spatula while drying. For sure, you can add some benzine-soluble dye into the wax solution and then examine the phlegmatized particles under microscope.

Hennig Brand - 8-5-2012 at 12:03

My ETN plastique has a measured density of only 1.43 g/cc, however it still packs a mean punch. I have used large marble sized pieces to puch holes in steel plate up to 1/4 inch thick. A friend and I placed 12g on a 1/4 inch plate and it punched a nice neat hole (well it ripped a scab off the back actually). I don't have a picture because the piece of plate was given to my friend and I didn't have a camera at the time. He was very impressed and asked to keep the piece of plate, so I let him have it.

Here are a few pictures from the other day, which show the result of initating 10g of the same plastique on a piece of rectangular structural steel. The steel is 1/8 inch thick. Notice how it cut out a disc and then drove it through the other side and deep into the ground. I still didn't bother to dig up the piece, but can tell it went down at least a few inches.

Hole Punch 1.JPG - 470kB Hole Punch 2.JPG - 461kB Hole Punch 3.JPG - 470kB Hole Punch 4.JPG - 480kB

[Edited on 8-5-2012 by Hennig Brand]

caterpillar - 9-5-2012 at 00:53

Some words about importance of hi density. In 1905 Russian fleet was destroyed by Japanese one at Chushima channel. One of the reasons of Japanese's victory was sort of explosive, used in shells. Volume of chamber in a shell is restricted- a shell must withstand tremendous acceleration when gun is shooting, therefore walls of chamber must be thick enough. Russian used pressed gun cotton, but due to the fibrous nature of NC it could be pressed only to 1.0 g per cm^3. Japanese, one the other hand, used cast TNP- shimose, that had a density about 1.7 g/cm^3 and their shells of the same caliber was more powerful.

Hennig Brand - 10-5-2012 at 05:28

I have several books and papers with different formulae for calculating the theoretical blast pressure of an explosive. I decided to use the formula from this explosive engineering paper, there are much more involved ones which have constants specific to the type of explosive, etc. This is a reasonable approximation however.

From "The Fundamental of Blast Design" by, Wesley L. Bender

P = [(2.16 * 10^-4)(0.45)(pc^2)] / [1+0.0128(p)]

where,

P = detonation pressure in (lbs/in^2)
p = explosive density (lbs/ft^3)
c = detonation velocity (ft/sec)

Using published values for Semtex at 1.43 g/cc, I chose a conservative detonation velocity value of 7200 m/s for my 1.43 g/cc ETN plastique.


Convert Units

p = 1.43 g/cc = 1430 kg/m^3 (since: 1000 mL per liter & 1000 L per m^3 & 1000g per kg)

p = 1430 kg/m^3 * (2.2lb/kg) * [m^3/(3.28ft)^3] = 89.2 lb/ft^3

c = 7200 m/s * 3.28 ft/m = 23 600 ft/s


Using above equation

P = 2.26 Mpsi (million pounds per square inch)

Note:
This formula was meant to give an approximate value of detonation pressure in a borehole, and under strong confinement. It was also meant for commercial explosives used in rock blasting. It is still probably a reasonable approximation of what the plastique is capable of.

Notice that the detonation velocity of an explosive has much more influence over the detonation pressure than the density does. The formula varies with the square of the detonation velocity and varies directly with the density.

[Edited on 10-5-2012 by Hennig Brand]

Maniak - 10-5-2012 at 06:33

I'm not sure if I understanded what you wanted to say, but detonation pressure calculated using detonation velocity and density of explosive has nearly nothing to do with boreholes and confinement. It is a dynamic pressure generated by detonation wave and its calculation is derived from hydrodynamic model of detonation IIRC.
The pressure in a borehole is another thing - it is a function of volume of explosion gases, temperature, heat of explosion etc.

In another words, you will reach detonation pressure without any confinement, but only in the detonation wave. Presures in the borehole are probably few orders of magnitude lower..

quicksilver - 10-5-2012 at 13:20

Gentlemen, I think we're going in differing directions here.
According to Rock Blasting & Explosive Engineering (Peerson) we have more than one method. One is "work delivered", another is defining wave characteristics.

Hennig Brand - 10-5-2012 at 15:49

I think quicksilver is right. I have looked at several journals and texts now and it appears that detonation pressure can mean two different things depending on the source. In some references it is the CJ pressure, and in others it is the pressure the detonation can generate on its surroundings. It seems like the CJ detonation pressure is close to double the "blasters" detonation pressure for the couple of examples I checked.

The following is mostly stuff I wrote last night. I was a bit confused.

I am not an expert and I may have spoken too authoritatively. I read a little about detonation pressure lately, found it interesting and was surprised how high they could go. I posted the calculation just for interest, because energetic materials producing millions of psi truly is amazing.

Now, you could be right. In the case of military explosives it may make little difference (maybe). I don't know about the hydrodynamic model but, in most explosives especially with small charge size (like ours usually), confinement has a lot to do with the detonation velocity of the charge. All the equations I have seen show detonation pressure as a function of the detonation velocity squared. This means a small drop in VOD can dramatically affect detonation pressure.

I suppose military explosives (ideal explosives), probably do not suffer diminished detonation velocity caused by poor confinement or small charge size the way commercial explosives do. For many commercial explosives the published VOD is best case scenario, often not obtained. The formula and information I referenced in my last post came from an explosives engineering paper on rock blasting. Many of these explosives are not ideal explosives and will behave differently than a military explosive.

Yeah, I suppose I wasn't thinking and the ETN plastique's VOD would be affected much less by confinement and charge size than the explosives used for rock blasting (like in the paper I referenced).

Unless we have equipment for measuring detonation velocity, most of us will use the published values. The note in the last post was meant to acknowledge that this may be over optimistic. In the case of more ideal explosives maybe it isn't.


edit:

Ok, I have been trying to read a little about this. The hydrodynamic model is made to model pure explosives, not mixtures. Apparently the biggest reason non-ideal explosives are not well defined by the model is because of incomplete reactions during detonation. Can a plastique with 16% inerts be treated like a pure/ideal explosive?

I found this Los Alamos paper online:
"Quantification of Non-Ideal Explosion Violence with a Shock"
by
Scott I. Jackson and Larry G. Hill

It would seem to indicate that C4 behaves in a way which is very closely represented by the thermodynamic model. So my homemade plastique most likely would behave similarly.


A snip-it from the report:

Ideal C4.png - 66kB

[Edited on 11-5-2012 by Hennig Brand]

Hennig Brand - 12-5-2012 at 11:19

I apologize if some of what I wrote above is incorrect. I found this in the course notes for an engineering rock excavation course from the university of Arizona. It seems to agree fairly well with what Maniak said. The problem I am having is, one not being all that familiar with the material but also, finding that the terms are not necessarily always used in the same way (I think).

"MGE 415 – Rock Excavation 2004

2.3.2.6 Detonation Pressure
The detonation pressure is the maximum theoretical pressure achieved within
the reaction zone and measured at the C-J plane in a column of explosives.
The actual pressure achieved is somewhat less than this maximum due to
non-ideal loading conditions always present in practice and due to certain
explosive formulation. Most commercial explosives achieve pressures in the
range of 0.29 to 3.48 x 106 psi (2 to 24 GPa). Although detonation pressure
is related to the temperature of the reaction, a number of simplifying
formulas are available for estimating detonation pressure for granular
explosives based on detonation velocity and density, for example

(in English units):
P = 0.00337 ρ V2
where P is detonation pressure in psi,
ρ is density XXX
V is detonation velocity in fps.

2.3.2.7 Borehole Pressure
Borehole pressure is the maximum pressure exerted within the borehole
upon completion of the explosive reaction measured behind the C-J plane.
Such measurements cannot be made directly and are done during
underwater tests performed for energy and strength determinations. With
the use of hydrodynamic computer models, theoretical calculations of
borehole pressures are made. There is little agreement in the literature
regarding specific estimates of actual borehole pressures. In general,
pressures after detonation within the borehole are estimated to be less than
30% of the theoretical detonation pressure."


edit:

I did a little explosive testing today and took a few pictures. Here are 5 of the better pictures. The charge in the picture is 14g of ~1.43 g/cc, 16% inerts plastique (using polybutene binder instead of PIB this time). In the final picture is included the disc from the bottom of the steel tubing (I think), which was retrieved from 4 inches below the surface of the rocky ground. The target is as before, rectangular structural steel tubing. Tubing sides are 1/8" thick.

It seems like the steel next to the explosive got pulverized and the steel disc is what was left of the bottom piece. The side of the disc facing out in the picture was ground off, because I was trying to see if the disc was two discs welded together. I now think it was just the bottom piece, because it has a seam that matches the bottom and no other pieces could be found.


1.JPG - 488kB 2.JPG - 469kB 3.JPG - 519kB 4.JPG - 495kB 5.JPG - 374kB

[Edited on 13-5-2012 by Hennig Brand]

Hennig Brand - 27-5-2012 at 12:25

Here is a measured value for the density of ETN, taken from the following journal, which should be very close to the actual value.

"Characterization and Analysis of Tetranitrate Esters"
Jimmie C. Oxley, James L. Smith, Joseph E. Brady IV, and Austin C. Brown

Pycnometer Density of ETN = 1.7219 g/cc

They also did PETN and got a value of 1.7599 g/cc, which is fairly close to the value of 1.77 g/cc I have seen in several other sources.


Drop weight/impact sensitivity testing was also done. I was a little surprised at their results.

Using a 4 kg fall hammer:

ETN = 24.0 cm
PETN = 25.2 cm

Hennig Brand - 18-8-2014 at 06:05

Just for fun, and a bit of affirmation, I initiated 13.5g of the same 81-82% ETN plastique, twice, using caps made of all the same materials. The difference between the tests was that for the first test the PETN base charge was hand pressed as hard as could be comfortably done and for the second test the PETN base charge was pressed much harder using a simple lever press.

The caps were 3/16" id aluminum tubing with about 25-27 thousands of an inch wall thickness. The base charges were 0.5g of PETN, initiated by 0.1g lead azide and a bit of basic lead picrate as flash igniter. Black powder, core burning, fuse was used for delay and ignition. The target was structural steel tubing with 1/8" wall thickness.

What a difference! The hole on the left is from the first test. The first test resulted in a larger top hole with a lot of tearing, but the hole on the bottom side was much smaller. The explosion from the first also sounded much more impressive; the second explosion was a much sharper crack rather than a huge boom like the first (at least that is how it was perceived by me and two others). Because of the greater roar, and the tearing, the two others thought that meant that the first explosion was much more powerful than the second. The second explosion obviously had much higher velocity and power. The explosion was a very sharp snap, which cut out nearly a perfect hole, on both sides of the tubing. The holes top and bottom where also of nearly the same size, while in the first test the bottom hole was significantly smaller than the top.

The hole on the left is from the first test (hand pressed base charge). The hole on the right is from the second test (lever pressed base charge). The last picture is of the bottom of the target.


1.jpg - 514kB 2.jpg - 514kB 3.jpg - 525kB 4.jpg - 505kB 5.jpg - 516kB


[Edited on 18-8-2014 by Hennig Brand]

Vpatent357 - 18-8-2014 at 07:32

Good demonstration, yes the charge pressed by lever is obviously more powerful :)

What kind of press and how you pressing your blasting caps?

Hennig Brand - 18-8-2014 at 07:58

You can find pictures, and a description, of the press used in the DDNP thread.

Gargamel - 18-8-2014 at 11:22

Your reports are really good. A very valuable contribution.

Say, did you measure the density of both PETN base charges?

I'm disappointed by this plastique stuff. I would have imagined it reach it's full velocity itself once it starts to detonate. This shows that well made blasting caps are really needed for serious experimentation...

Hennig Brand - 18-8-2014 at 15:07

Thanks for the compliment. I didn't measure the density because it would have been difficult to do accurately with the equipment I had on hand, especially since the cap and the base charge were so small. This was a crude test, but still a very useful one. The best way to measure loading density is probably to have a way of accurately measuring loading pressure and from there density can be found since density is directly related to loading pressure. There are tables for loading density versus loading pressure for various solid explosives which can be easily found in many explosives texts.

roXefeller - 18-8-2014 at 16:28

I had suspected that the granulated product would need some stout pressing to make it dense and cohesive. Wasn't it suggested to measure the plastique density by putting a gram into an oral syringe and pressing it by hand? The syringes that come with my kids' medicine are up to 5mL though I've seen some that are 2.5mL , so a gram should fall somewhere between 0.5 and 1mL.

Hennig Brand - 18-8-2014 at 17:09

The syringe idea would probably work, but it would likely be very difficult to retrieve all the plastique after measuring. The syringe should be reasonably accurate, if it is medical grade, but lack of accurate scales is a problem for many (especially with small masses). I used a polypropylene pill bottle of carefully measured volume to measure the volume of a fairly large amount of plastique a while back and it was very difficult to retrieve it all from the container (very sticky). Maybe we could use the displacement method Archimedes used to measure the density of the king's gold crown. Plastiques are generally quite resistant to water, and the exposure could be very brief. Fill a suitable container to the brim, and then carefully submerge the pre-weighed plastic explosive while carefully collect the overflow. The volume of the overflow should be the same as the volume of the plastic explosive, if done carefully. Or simply submerge the plastique in a suitable graduated vessel containing enough water and measure the volume increase. Then simply divide mass by volume to find the density of the plastique.

I believe he was talking about PETN base charge density in the blasting cap. I haven't had many problems forming cohesive masses of plastique. A glass beer bottle is normally used as a rolling pin and with the right amount of softener/plasticizer, and once all the particles have a coating of binder, the material sticks together quite well. I usually use about 15% inerts though. If I went much lower on inerts I would have difficulties with cohesiveness given the low molecular weight of the binders available to me and the less than perfectly prepared explosive crystal size and shape. This time I went a little over board on plasticizer, because I wasn't paying attention which resulted in a sticky, oily plastique of only 81-82% solid explosive content.

I suppose I could get a fairly good approximation of base charge density by using the depth probe on a set of Vernier calipers. This could be reasonably accurate if the calipers are decent quality, the bottom of the cap is flat, the loading pin has a flat end and the cap casing diameter is uniform.


[Edited on 19-8-2014 by Hennig Brand]

nitro-genes - 25-8-2014 at 15:29

Just noticed this thread, nice results! Have you tried the silicon oil as plasiticzer with the PiB/PB? Does it form a clear mixture when dissolved in gasoline + binder? Depending on the source of the binder/MW etc, I noticed even with MR you can get some clouding/emulsification when too much is added upon evaporation, with extra motoroil, this doesnt occur anymore.

The eureka method for determining density was what I used as well. For best results, take a long narrow graduate cylinder, add a small predetermined measure of water. Then roll the plastique to a sausage of the same diameter. This way you only need as little water as possible, so youre mostly measuring the volume change due to the plastique. If done a couple of times, you can get a really good estimate down to two decimal numbers. :-)

[Edited on 25-8-2014 by nitro-genes]

Hennig Brand - 25-8-2014 at 19:08

I have actually been using polybutenes for quite a while which requires that no solvent be used at all. I also found, as Maniak suggested earlier in this thread, that mineral oil works quite well to plasticize polybutenes. The softener/plasticizer can be added to the binder before adding the solid explosive. A little careful heating can also be used to make the mixing process easier. The reason this works so well without solvent is likely because of the low molecular weight of the polybutenes used, but it still makes a nice plastique if enough binder is used. I have tried silicone oil with PIB and PB and it made a very nice plastique. Silicone oil also has extremely low vapor pressure (varies but always low), and is extremely inert, which are real pluses.

I noticed the same thing with the MR and clouding, thanks for the tip. Sounds like a good method for measuring plastique volume also.

NeonPulse - 25-8-2014 at 20:47

I thought the solvent was to give an even coating to all the explosive before the rolling. How much extra work is involved without using solvent? I guess that you would have to add the powder a little at a time to ensure the mixture uses it well without pockets of unmixed binder before adding the next portion. I also noticed the clouding of the MR too but I don't believe it to have any adverse effects on the process so I pretty much ignored it I. also found that using a light oil like "singer" sewing machine oil worked a little better than motor oil for me as I couldn't get motor oil without the added detergents. I would like to test silicon oil or paraffin oil in fact there is quite a few id like to test but since they all would work pretty well there's no real need to. I'm pretty happy with the results I'm getting now.
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