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DNA
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[*] posted on 18-1-2011 at 04:42
sheet explosive


Dear all,

I am planning on doing some research on sheet explosives.
Mainly with PETN as high explosive, but the point is I have found the formulation for primasheet which uses nitrocellulose and a plasticizer which is acetyl tributyl citrate.
They don't sell this at the regular chemical supply company so I was thinking about synthesizing it myself.
Unfortunately I don't have acces to beilstein or scifinder so could anyone tell me a synthesis for acetyl tributyl citrate?
I was planning on using NG and NC and PETN.

Or better, do you have experience or documentation on this subject.
I do have a patent using nitrostarch and TEGDN but apparently nitrostarch isn't really the nicest compound to nitrate, especially when filtering the product (honey like substance) etc.
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[*] posted on 18-1-2011 at 07:41


Perform independent search for : DuPont DetaSheet patent. Standard of industry. Used in separation of concrete via cracks in demo of large scale concrete slabs. Extremely common.



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[*] posted on 18-1-2011 at 08:21


You definitely don't need acetyl tributyl citrate for sheet explosive. It serves just as an inert plasticizer for nitrocellulose and although it is probably little better than others in view of migration and handling, you can use diethyl, dibutyl or dioctyl phthalate as well as TEGDN or TMETN with nearly the same results.

The problem is elsewhere - you probably don't have right kind of nitrocellulose, i.e. so called "dynamite" or "high viscosity" nitrocellulose. Using common 12,4%N low viscosity (lacquer grade) nitrocellulose you can try any ratio, but in all cases you'll obtain just some kind of more or less plastic explosive. You can roll it into sheets, but you absolutely won't get real DuPont-like sheet explosive.

Anyway, don't forget that you'll need fine (precipitated or underwater milled) PETN.
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[*] posted on 18-1-2011 at 10:41


Thanks a lot for the info maniak! I also looked into how to produce 13% nitrogen containing NC with certain ratio's of hno3 and sulphuric acid and water.

I'll use nitroglycerin then as plasticizer.

[Edited on 18-1-2011 by DNA]
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[*] posted on 18-1-2011 at 10:51


How will you go about extruding the gelatine?

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[*] posted on 18-1-2011 at 11:17


What about silicone, or Styrofoam & acetone as binder. I have tried the Styrofoam / Acetone combo, but without some type of plasticizer the whole mass is very crumble and hard to press. Maybe a few % of dibutyl phthalate will do the trick.
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[*] posted on 18-1-2011 at 11:56


DNA: this is not about nitrogen percentage. Nitrocellulose with 13%N is used for single base smokeless propellants and it is of low viscosity as well as lacquer grade. High viscosity nitrocellulose is a special type which is only prepared for munitions and explosives and can not be easily obtained. It has got some 12-12,5%N. Its preparation is described in Urbanski II - it needs special source of cotton, low esterification temperatures and stabilizing without strong bases.

Nitroglycerine is not a good choice for playing with sheets - mixtures are extremely viscous even beeing diluted with volatile solvents and processing (rolling) has to be done at high temperatures and using all power of your hands... Under these conditions, NG will be dangerously sensitive and in addition, you'll get a headache quickly.

Jimbo hit the nail on the head. Styrofoam combined with dibutyl phthalate can be used for quite useful sheets. Of course, they are not as good as DuPont products in view of mechanical properties, especially at elevated temperatures, but for an amateur they are good alternative for some experiments with LSC or explosive engraving.

[Edited on 18-1-2011 by Maniak]
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[*] posted on 18-1-2011 at 13:00


Quote: Originally posted by Maniak  

Jimbo hit the nail on the head. Styrofoam combined with dibutyl phthalate can be used for quite useful sheets. Of course, they are not as good as DuPont products in view of mechanical properties, especially at elevated temperatures, but for an amateur they are good alternative for some experiments with LSC or explosive engraving.



Hummm — the great advantage of sheet explosives e.g., Bickford
Primasheet 2000, Dyno HLX, Royal Ordnance Demex 200, &c,
is that they are flexible.


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[*] posted on 18-1-2011 at 14:36


It is quite easy to find proper ratio of PETN/polystyrene/dibutyl phthalate at which sheets are flexible at room temperature. Sheets keep their dimensions when bent, are little elastic and sticks to a flat surfaces. The problem is just keeping this flexibility at various temperatures. This can be solved for example using above stated high viscosity NC/plasticizer or more recently using mixtures based on thermoplastic elastomeric polymers.

In contrary, PETN/low viscosity NC/dibutyl phthalate can at best be dough like plastic which is not flexible and can be shaped by hands. It is useful, but not for sheet explosives.
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[*] posted on 18-1-2011 at 14:44


Okay, thanks a lot for all the input!
So high viscosity NC preparation is like almost out of the question as I understand. I'll try the styrofoam and a plasticizer with acetone and some inert fine powder (i.e baking flour) to test with.

Jimbo Jones, do you still have some data from your experiments, that way I have some guidelines where I can start with.

[Edited on 18-1-2011 by DNA]
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[*] posted on 18-1-2011 at 14:49
A suggestion ...


Run DuPont Flexible explosive through —

Google.com/patents

Or leave la DuPont out.
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[*] posted on 19-1-2011 at 01:08


I remember reading a patent about using liquid latex (or alternatively silicone) as binder in flexible explosive compositions. Liquid latex is an ammonia stabilized emulsion of latex in water that can be found in some hobby shops (it's used for making things for live role playing as well as other arts and crafts things).
IIRC, the VOD of the latex based composition was much better than the silicone based one, however since liquid latex needs to dry while silicone cures, there is a limit to how thick sheets you can make with it.

[Edited on 19-1-2011 by Microtek]
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[*] posted on 19-1-2011 at 02:49


I do have acces to dibutyl phtalate/styrofoam and also to liquid latex.
So I'll experiment with both of those and see what results I'll get.

The other thing I'm a bit concerned about is that if the concentration of PETN becomes too low that it will be very hard to detonate it.
Like with PBX they contain 90% HE, if you go too low then they become very hard to detonate.

@ quicksilver: I'll also try your "shaving" method to make very fine PETN crystals as I read in another topic.

[Edited on 19-1-2011 by DNA]
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[*] posted on 19-1-2011 at 06:44
this maybe the original dupont patent


NEW EXPLOSIVE
 Fassnocht et al.
Patent number: 2992087
Filing date: Nov 3, 1959
Issue date: Jul 1961

The present invention relates to an explosive composition. More
particularly, the present invention relates to a flexible self-
supporting explosive composition containing pentaerythritol
tetranitrate of specific particle size and to a method of fabricating
the composition.


FLEXIBLE EXPLOSIVE CONTAINING RDX AND/ OR
HMX AND PROCESS THEREFORE
 Hooper et al. Patent number: 3354010
Filing date: Jan 27, 1967
Issue date: Nov 1967

I believe Bickrord's Primasheet is rubber based. Byda
Bickford took over the Detacord copyright from DuPont.



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[*] posted on 19-1-2011 at 06:53


Latex is also useful for rubbery flexible sheets, but if mixed using latex emulsion alone, sheets will be nearly non-sticky. Addition of some plasticizer may improve this, but you must consider type of polymer base of latex in view of compatibility with it.
Next thing is that latex based compositions can have lower densities because of water content in latex emulsion.

In my experience, sensitivity to initiation is good at all these inert bonded mixtures with fine PETN content over about 60%. Detasheet with NC was 63% PETN, the one with polymeric binder is about 85% PETN (see Fedoroff's Encyclopedia III, D-99). 75-80% filling is easily reached with polystyrene/DBP.

You can check, if you speak czech ;) :
http://spisy.upv.cz/Applications/1995/PPVCZ1995_2130A3.pdf

[Edited on 19-1-2011 by Maniak]

[Edited on 19-1-2011 by Maniak]
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[*] posted on 19-1-2011 at 08:18


djh:
I think you're right Nov 3 rings a bell. And it was the early 60's that a lot of new construction & demo techniques were implemented from Dam construction and urban renewal projects. I think that may be the right one.




Kalifornia has always been wasteful of both it's intellectual and natural resources; that's a study that's indisputable :P


[Edited on 19-1-2011 by quicksilver]




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[*] posted on 19-1-2011 at 13:00


For sheet explosive I can recommend to use 1,2-PGDN+NC as a binder. I used about 3% NC, 17% PGDN and the rest PETN. (Or other crystalline HE) It has absolutely FABULOUS plastic properties and presumably a very high VoD. For sheet explosive you should probably use slighty more NC, I would try ratio's of NC:PGDN of about 6:14 or even 8:12. The NC needs very long to dissolve, even with 5% acetone added to aid solubilization. Volatility of the PGDN could be a problem though for storing this sheet explosive for longer periods of time. :)

[Edited on 19-1-2011 by nitro-genes]
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[*] posted on 20-1-2011 at 06:22


Would it also be possible (just by means of a test) to gelatinice NC with dibutylphthalate?
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[*] posted on 20-1-2011 at 09:13


I know for Diethyl phtalate + NC it does quit well actually...
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[*] posted on 20-1-2011 at 09:35


As I wrote in my first reply in this topic, NC is compatible with phthalates. I tried diethyl and dibutyl with good results for dough like plastic explosives. But with any ratio, sheets with low viscosity NC will have low tensile strength. Using higher NC content, they will be harder, but more brittle. If you bend these sheets twice, they will crack.
High molecular weight (viscosity) of dynamite grade NC can not be compensated by any plasticizer. It is why I prefer other polymers for a binder system, which I can obtain with high molecular weight (viscosity).
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[*] posted on 20-1-2011 at 10:20


I just tried with polystyrene foam dissolved in acetone, 4g of it and 1.5ml dibutylphthalate. And 16g very fine powder. First it was too sticky (too much plasticizer I guess) so I added 1g of extra polystyrene.

Is this in the right direction concerning ratios of plasticizer and polymer since in this topic also NC : PGDN ratio of about 6:14 or even 8:12 is suggested.
Or is this uncomparable to polymer(styrofoam) and NC.

I'll keep you updated

[Edited on 21-1-2011 by DNA]

[Edited on 21-1-2011 by DNA]
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[*] posted on 22-1-2011 at 09:32


Quote: Originally posted by DNA  
Okay, thanks a lot for all the input!
So high viscosity NC preparation is like almost out of the question as I understand. I'll try the styrofoam and a plasticizer with acetone and some inert fine powder (i.e baking flour) to test with.

Jimbo Jones, do you still have some data from your experiments, that way I have some guidelines where I can start with.

[Edited on 18-1-2011 by DNA]


It’s 9 gr. RDX, 1 gr. Styrofoam and some acetone to bind the ingredients. The whole mass was very crumble, so I just mold it by hand. The finished explosive is hard, with plastic appearance. No visible crystals of RDX on the surface, very hard to broken apart. Extremely difficult to initiation, so a big compound cap and some sort of cap attachment (a metal, or plastic clips) is also a nice thing to remember.

http://img339.imageshack.us/i/44033.jpg/

http://img193.imageshack.us/i/44039.jpg/

http://img7.imageshack.us/i/44074.jpg/

http://img441.imageshack.us/i/44081.jpg/
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[*] posted on 25-1-2011 at 01:58


I can also get ahold of polyisobutene and polybutene but what are the molecular weights of these polymers to be applicable here?
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[*] posted on 25-1-2011 at 06:14


I don't know any real sheet explosive with PIB binder, but check GB1082641 for some info
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[*] posted on 26-1-2011 at 10:08


So a PGDN & NC for all energetic sheets and silicone for more commercial looking product. By the way, on the old roguesci. someone have posted links to arabic terrorist videos. One of them was suicide vest based on trinitronaphtalene, EGDN and NC explosive sheet. Considering the poor equipment, the results was very impressive.
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