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Dany
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Quote: Originally posted by NeonPulse  | So i did finally get around to attempting a synthesis of RDX. it was a fairly sucessful attempt yeilding 19.3g dry RDX from 95ml HNO3 and 40g hexamine
dinitrate. ithe acid was incorrectly measured though as i used the wrong measuring beaker (doh!) so i doubt it was the full 100ml. but anyway i did
recrystallize it from acetone and got two nice clean crisp white crops sparkling RDX crystals. leaving the acetone to evaporate, the next night after
work i was surprized to see these rather large crystals in the bottom of the beaker somewhat like broken glass, these were many, many times bigger
than the first crops i got and hardly any of the acetone had evaporated. my question is: firstly are these crystals dangerous? like being prone to
detonate due to internal stresses like some energetics?
i2: is it normal to grow rdx crystalls this size?
how big can they actually get if left to grow?
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There is nothing to fear about single crystal RDX. Single crystal explosive have the highest possible Theoretical Maximum Density (TMD) thus the
highest detonation velocity compared to other RDX form (e.g., RDX powder). The sensitivity of single crystal RDX is far low then the powdery form of
the same explosive for a simple reason: single crystal RDX are voidless and contain no structural defects while powdery RDX contain many voids and
possibly other solid impurities. When subject to a shock wave, the voids (and other impurities) in powdery RDX will act as hot spot, concentrating the
shock energy around their structure via adiabatic compression or other hot spot formation mechanism (e.g, internal shear, jetting, friction [1],
etc...). The reaction start at these hot spot and shock wave from each hot spot coalesce to form the detonation wave. Since single crystal explosive
are lacking hot spot site, it is more difficult to initiate these explosive, so you need a more powerful shock wave to be able to initiate detonation.
Another beautiful example is the one given in paragraph entitled :"Hot Spots and Transverse Waves" which can be found in [1]. The author is
talking about powdery PETN and single crystal PETN. Experimental shows that powdery PETN (pressed to almost TMD) can detonate when subjet to a shock
wave of 2.5 GPa (or 25 kbar) while a single crystal PETN need a 11 GPa (110 kbar) to detonate the reasons are the same for the example of RDX given
above.
For the case of lead azide were spontaneous explosion have been seen in single crystal, the reason of this is not entirely an internal stress of
crystal. Other reason exist but poorly understood.
Reference:
[1] William C. DAVIS, High explosives-the interaction of chemistry and mechanics (LOS ALAMOS SCIENCE).
Dany.
[Edited on 19-4-2014 by Dany]
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VladimirLem
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Hi guys...
could it be possible to "grow" explsoives crystals into special shapes?
exmple: dissolving ETN into warm-hot (below meltingpoint of the explosive) ethanol/aceton and then filling the sollution into some shaped charge
container and letting the crystals gorw when putting that into a freezer?
when making ammoniumnitrate and "recystalize" it at a cold place it has exactly the shape of the container and a really high density, so could that
work at other HEs? (ETN, PETN, RDX...)
if that would work, there where no need for phlegmatised/plastic/cast explosives anymore and the possiblity for getting the max density seems pretty
good (only some percents [how many?] of solvent left)
Vlad
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Dany
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| Quote: Originally posted by VladimirLem | Hi guys...
could it be possible to "grow" explsoives crystals into special shapes?
exmple: dissolving ETN into warm-hot (below meltingpoint of the explosive) ethanol/aceton and then filling the sollution into some shaped charge
container and letting the crystals gorw when putting that into a freezer?
when making ammoniumnitrate and "recystalize" it at a cold place it has exactly the shape of the container and a really high density, so could that
work at other HEs? (ETN, PETN, RDX...)
if that would work, there where no need for phlegmatised/plastic/cast explosives anymore and the possiblity for getting the max density seems pretty
good (only some percents [how many?] of solvent left)
Vlad |
yes it is possible to grow explosive crystals in special shape. This is done by recrystallizing the explosive using different solvents. This will led
to different shape/polymorphs being produced. See this effect for the production of different HMX polymorphs
What is not possible is to grow single crystal explosive to a dimension suitable for shaped charge. Although you mentioned that
NH4NO3 has the shape of the container and seems like it is homogenous, this is not true. At macroscopic scale the materials will
look as if it was homogenous, but at the microscopic scale the material is non-homogenous but heterogeneous (polycrystalline) in nature. This is due
to the method of precipitation/recrystallization and to the temperature gradient encountered in the layer of explosive during cooling which led to
polycrystalline material. The best method in shaped charge to achieve the highest density materials is by casting the explosive (e.g., Octol) into the
shape charge body or by making the explosive into a Plastic Bonded Explosive (PBX). PBX are known to achieve high density approaching 99% Theoretical
Maximum Density (TMD).
Dany.
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Motherload
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If one really wants to use a single crystal ..... Grow one that is oversize using a seed crystal. And machine it to your needs with the proper safety
precautions.
All that work just seems unnecessary when you can achieve 99% ... As Dany mentioned, using PBX.
"Chance favours the prepared mind"
"Fuck It !! We'll do it live !!"
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simply RED
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It is not bad to be mentioned that the vast majority of manufactured shaped charges are made by using pressed explosives like 95% RDX/HMH 5% wax,
thermoplastic polymer, etc. Plastic bonded explosives are almost never seen, except in improvised devices. Casting (by melting or using polymers) is
also increasingly rarely encountered, except in high caliber devices.
Pressed explosives provide very high percentage nitramine load that is impossible to achieve in any other way.
[Edited on 21-4-2014 by simply RED]
When logic and proportion have fallen sloppy dead...
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Dany
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| Quote: Originally posted by simply RED | It is not bad to be mentioned that the vast majority of manufactured shaped charges are made by using pressed explosives like 95% RDX/HMH 5% wax,
thermoplastic polymer, etc. Plastic bonded explosives are almost never seen, except in improvised devices. Casting (by melting or using polymers) is
also increasingly rarely encountered, except in high caliber devices.
Pressed explosives provide very high percentage nitramine load that is impossible to achieve in any other way.
[Edited on 21-4-2014 by simply RED] |
What do you mean by improvised device??? PBX are special type of composite explosive which requires a high level of knowledge in manufacture. PBX are
used in high performance shaped charge or Explosively Formed Projectile. One example is the PBX called LX-19. LX-19 is composed of 95.8 wt. % CL-20
(Hexanitrohexaazaisowurtzitane) and 4.2 wt. % Estane binder [1]. It is one of the best PBX known for shaped charge design.
I should also mention that plastic explosive (e.g., C-4) is also desirable in shaped charge because it is easy to load and to shape the explosive into
the shaped charge body. However, plastic explosive do not offer the highest density of an explosive materials so their use may be limited where high
performance are required. Liquid explosive, have also been used because they offer a homogenous medium, so a non-disturbed detonation wave can be
expected from liquid explosive. It is well known that the symmetry of the detonation wave is critical when the latter interact with the liner. this
can be achieved via liquid explosives. It is difficult to make perfectly homogenous solid explosive inside a shaped charge body. Any air cavity or
density gradient in the explosive body will affect the detonation wave and the collapsing of the metal liner which may degrade the overall performance
of the shaped charge
Reference:
[1] Murphy, M.J.; Baum, D.; Simpson, R.L.; Monoto, J.; Montesi, L.; Newman, K.; Tuerpe, D.; Osborn, J., Demonstration of enhanced warhead performance
with more powerful explosives-UCRL-JC--127575.
Dany.
[Edited on 21-4-2014 by Dany]
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simply RED
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Dany, exactly! LX-19 is exactly "a PRESSED solid explosive formulation containing 95.2% by weight
epsilon phase 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) and 4.8% Estane binder".
http://www.osti.gov/scitech/servlets/purl/105039
Of course it is plastic bonded but it is formed by pressing and not by casting. This is completely different class of explosives than cast-polymer
bonded or "plastic" ones. Plastic explosives are never going to be found in anything other than improvised devices because of their poor mechanical
properties and high sensitivity in case of extreme acceleration (and often rotation) that munitions endure!!!! 100% of all "eastern" made shaped
charges munitions are press loaded and speaking from the literature, a very high percentage of the western ones are press loaded too.
""""It is not bad to be mentioned that the vast majority of manufactured shaped charges are made by using pressed explosives like 95% RDX/HMX 5% wax,
thermoplastic polymer, etc."""" in this case 95% Cl-20 and 5% thermoplastic polymer.
[Edited on 22-4-2014 by simply RED]
When logic and proportion have fallen sloppy dead...
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Dany
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The debate here is not about pressed or not. Of course LX-19 can be used as a pressed explosive but it's defenition is a PBX, not a plastic explosive
( PBX explosives can be made by pressing, casting or by injection moulding. Plastic explosive are made to be soft and moldable like C-4 or PE-4 explosive. I'm clarifying the
situation because you said that PBX are used in improvised shaped charge which in my knowledge is not possible because pressing a PBX to almost 99%
TMD require special techniques that are beyond the capability of an average pyroman (a good review on techniques used in PBX pressing can be found in
the book of Paul COOPER, Explosives Engineering). PBX explosive is used in almost all high performance shaped charge and warheads. The Tomahawk missile for example uses the the PBXN-107 explosive (the N in PBXN is for Navy).
beautiful pictures and informations on tomahawk missile can be found here.
Dany.
[Edited on 22-4-2014 by Dany]
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PHILOU Zrealone
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| Quote: Originally posted by VladimirLem | Hi guys...
could it be possible to "grow" explsoives crystals into special shapes?
exmple: dissolving ETN into warm-hot (below meltingpoint of the explosive) ethanol/aceton and then filling the sollution into some shaped charge
container and letting the crystals gorw when putting that into a freezer?
when making ammoniumnitrate and "recystalize" it at a cold place it has exactly the shape of the container and a really high density, so could that
work at other HEs? (ETN, PETN, RDX...)
if that would work, there where no need for phlegmatised/plastic/cast explosives anymore and the possiblity for getting the max density seems pretty
good (only some percents [how many?] of solvent left)
Vlad |
With the very low mp of ETN, it would be more easy to melt it externallly with hot water and allow it to harden slowly. Most of the time there is some
contraction of the media while cooling so an open cylindrical recipient filled with a molten stuff usually will have an incurved U or V surface shape
at the upper side in contact with the air.
The idea with the solvents is less good because in a recipient you have walls and this will prevent the evaporation of the solvents...what could only
escape via the open side...this side will by the way harden faster and the rest below will remain "wet" much longer following a gradient of
"wetness".The unevaporated solvent will have to travel the all material to be able to escape by the open side which upon time becomes harder to travel
through owing to increased viscosity/hardening.
In the case of sensitive explosive; the bigger the cristals, the higher the risk of inner cristaline stress and sensitivity to shock and friction...if
the cristals are growing in a closed recipient the walls will restrict their grow and favourise breaking/anomaly in the cristal partern...what means
stress. The cristals will also be limited by other cristals and interpenetrate increasing friction sensitivity. Last but not least, the cristals will
usually make voids between them so density might be less than finer powder filling and pressing.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Jimbo Jones
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| Quote: Originally posted by Dany | PBX explosive is used in almost all high performance shaped charge and warheads.
Dany.
[Edited on 22-4-2014 by Dany] |
Quite a bold statement.
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simply RED
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Improvised shaped charges are often made with plastic and not "polymer bonded" explosives, type mistake.
Manufactured (low caliber <130 mm) shaped charges are pressed because the cast formulations require (too much) at least 12% polymer. AFAIK no
russian shaped charge design uses polymers! They use A-9-1, okfol etc. mostly (95-5) - that substitute the polymers with parafines and ceresine. But
parafine is also a polymer, it is low molecular mass, low melting point polyethylene! So things can get confused in some point...
Being all PBX, pressed and cast formulations are completely different and are manufactured using completely different machines in the factories. I do
not see a reason why amateurs can't make cast formulations! I've done it numerous times! Pressed formulations on the other hand are not available for
the amateurs as special machinery is needed for them to be manufactured.
When logic and proportion have fallen sloppy dead...
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Dany
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The Truth, The Whole Truth, and Nothing But The Truth
Dany.
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Jimbo Jones
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OK Dany. OK.
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Dany
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Here's a quote that prove that PBX are widely used in army's weapons were high performance is required, from [1]:
"Polymer bonded explosives based on hexogene or octogene, aluminium and polymer binder (PBX) fall into castable secondary explosives. Besides
decreased detonation wave parameters, they are characterised by relatively slower delivery of energy in the detonation process and longer positive
impulse phase. These explosives are used for the laboration of warheads with strong blast effect, such as main charge explosives for Navy
underwater weapons (mines, torpedoes, bombs) and missile warheads"
Reference:
[1]Gordana Antić, Vesna Džingalašević, Milena Stanković, Zoran Borković, Explosive Characteristics of Cast PBX Based on HMX,
AmmoniumPerchlorate and Aluminium, Scientific Technical Review,Vol.LIV,No.3-4,2004.
Dany.
[Edited on 22-4-2014 by Dany]
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VladimirLem
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no not exactly one crystal...when cooling down ammoniumnitarte, then you can see large needles [Picture1] (around
1.5cm*0.4cm*10cm< filling the container up to the sollution is completely filled
with crastyls and become a hard crystal block [Picture2]
so im talking about a high dense HE-crystalblock
@ the other guy with the -ETN melting idea-
ETN was just an example and im not gonna melt that shit
@the guys saying PBX:
well how can i know that the explosive is pressed enough? and HOW can i see that i should stop pressing 
cause some HEs tend to get "dead-pressed" (extremely hard to ignite) and others may detonate when pressed to hard  lol
i dont know if pressing an HE is the way i should go since i dont habe professional equipment for that :-/
Vlad
 
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simply RED
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You can not do pressed, but you can do cast. Just cast it with HTPB binder for amateur rocket engines and you know it is okay  . RDX and PETN will not get dead pressed even if you cast under deep vacuum!
[Edited on 22-4-2014 by simply RED]
When logic and proportion have fallen sloppy dead...
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VladimirLem
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| Quote: Originally posted by simply RED | You can not do pressed, but you can do cast. Just cast it with HTPB binder for amateur rocket engines and you know it is okay . RDX and PETN will not get dead pressed even if you cast under deep vacuum!
[Edited on 22-4-2014 by simply RED] |
yeah, of course i could...i just wonder if this way i said could work
would be very easy to get high dense without much work
biggest doubts i have are if the detonation wave could be infuluenced by the different cristallayers in those HE-Block so that the detonatiopnwave
would act different than cast/pressed (some uniform det.-wave is very important for shaped charges, you know)
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Ral123
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Am I the only one here who wonders why the 95/5 material/phlegmatizer compositions aren't using TNAZ or TNT instead of wax? It would allow HMX based
composition to reach similar performance and stability to CL-20 composition. I've read CL-20 is significantly more sensitive then RDX/HMX.
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Ral123
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Dirty RDX synthesis
In my observation non recrystallized, washed only RDX is many times more stable then ETN, NG, Tetryl- again washed only. I suppose the acidic
components in the crude RDX evaporate easily and allow washed only RDX to be quite stable.
Is it a myth that heavily NOx contaminated WFNA is unsutable for straight hexamine nitrolysis? The clear WFNA gives off NOx during the process anyway
so why bother clearing the acid from NOx?
Here's the average Joe's possible plan:
Use whatever fuming nitric acid available. Well after the synth, carefully heat the batch to 50C, to purge the unstable non RDX nitration
products(IIRC). Dry in warm dark place. Recrystallization is optional under certain conditions. I believe RDX is a great way to learn about high R.E.
materials with not as much hazard as other materials. The only bothering RDX hazard compared to nitric esters and organic peroxides is it's annoying
flammability.
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Bert
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29-4-2014 at 08:53 |
caterpillar
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use hexamine dinitrate instead of hexamine- in this case reaction is not very sensitive to NOx, presenting usually in conc. HNO3. I used yellow nitric
acid and failed, trying to use hexamine. But reaction with hexamine dinitrate was successful.
Women are more perilous sometimes, than any hi explosive.
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Ral123
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I can't imagine that the hexamine will completely fail where the dinitrate will work. Was everything else the same? I'm more worried of forming
unstable products that would rot the storage stability.
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NeonPulse
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i cant understand why anyone would want to use the straight hexamine route given to the fact that the yeilds are greater and the synthesis proceeds
more smoothly with using the dinitrate. it does seem less picky about dissolved NOx in it. The acid i have used in the handful of times i have made it
was a light yellow and i dont believe it had any influence on the end result. i would think that if you are going to go to the trouble of preparing
RDX then the small amount of time and acid used to make the hexamine dinitrate is worth the extra effort IMO. Also if you do go to the effort in the
first place, then why not take the extra time to recrystallize the product. but then i could say the same on the effort of purging the NOx from the
acid....
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caterpillar
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| Quote: Originally posted by Ral123 | | I can't imagine that the hexamine will completely fail where the dinitrate will work. Was everything else the same? I'm more worried of forming
unstable products that would rot the storage stability. |
I can. I made such experiments. One problem with hexamine is that reaction with nitric acid is exothermic (base + acid), but reaction of didnitrate is
the mild one. According to russian book, written by Orlova, there is a special method for performing oxidization of unstable linear nitramines. One
have to mix solution of RDX in nitric acid with simple water- drop by drop. This mixture will boil and produce NOx, but simultaneously all unstable
nitramines will be destroyed (and BTW one will get large crystals of RDX). Final concentration of nitric acid must be something like 50% (or 60, i do
not remember now). This diluted nitric acid later can be used to make hexamine dinitrate.
Women are more perilous sometimes, than any hi explosive.
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Ral123
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As I know RDX can be stored for 20 years. What stabilising additives do you think are appropriate? Urea would form water with the decomposition
products. Sodium carbonate is quite a base. Magnesium bicarbonate, diphenilamine?
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caterpillar
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As I know, RDX can be stored for infinity and does not require stabilizing addictive at all. Do not worry about it- RDX is not NG.
Women are more perilous sometimes, than any hi explosive.
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