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Etanol
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Quote: Originally posted by pjig  | I think for “simple detonators etc” a low density material would be sufficient to kick off other materials.
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PETN is quite sensitive to detonation. If you are not planning to make a non-primary detonator, then I see no reason to strive for low density. The
higher the density, the higher the brisance and efficiency of the detonator.
Yes
| Quote: Originally posted by pjig |
The Re crystallization process of the hot acetone + Petn and a pinch of urea, taken and crashed into cold water created a wet sand like low density
material that reduces into a very fine material.
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If this is recrystallization of pure PETN, then I see no reason to add urea. Urea is too weak a base. Ammonia is much better.
This is due to the needle-like shape of the particles.
| Quote: Originally posted by pjig |
First, in this form of avalanche Re crystallization is this process enough to remove unwanted byproducts, and acids? Second is it stable for long term
storage ? |
I do not understand you.
For the recrystallization of pure PETN for the purpose of crystal modification, urea is not required.
For recrystallizing dirty PETN to remove acids and other impurities, urea does not work. Such PETN will not be stable.
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Microtek
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The function of urea in this context is not to act as a base, but as a NOx scavenger. The same reaction can be employed to remove NOx from RFNA.
During decomposition of PETN in storage, NOx is evolved which increases the rate of further decomposition. By incorporating small amounts of urea in
the PETN crystals, this feedback loop can be broken.
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pjig
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Im speculating about crystal formation and its ability to release its waste acids , other slow crystal growth , or immediate upon a crash (avalanche
method) . I believe the slow method is more effective in purifying and density. The trade is manipulation to reduce large crystals (shave) to desired
size (for its function ).
Now the ease of the fast crash method is appealing, (fast results) but I’m not 100% sure it’s as effective at removing trace acids(hense the use
of urea) , and it reduces to a very fine particulate. I assume that is low density. It takes on a unique caking problem due to crystal structure.
The fast crash material also presented another weird trait . It almost seems (under normal pressures ) to go max density when pressed and it’s need
for more initiating power required. Making it less predictable with normal priming methods.
Any experiences or results other have to back this up or explain unique processes?
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Microtek
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You could do both. First a slow crystallization for obtaining a pure product, then redissolve in fresh solvent and crash precipitate for fine powder.
From my perspective, the main advantage of fine powder is the smaller critical diameter and better performance at the microscale. I prefer
crystallizing by addition of water to the neutralized acetone solution. Then I can adjust temperature, agitation and speed of addition to tune the
crystal size and morphology to the application.
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pjig
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Excellent ideas.. ty
As per your crystallization process are you doing this at higher temps, rm temp , or cold to precipitate out your solution? Stirring will obviously
aid in the shaving process ( how long are you continuing to stir after all water is added and precipitation is done ?
[Edited on 10-6-2024 by pjig]
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Etanol
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It is better not to dilute the acetone solution with water, but by a mixture of 40% alcohol and 60% of water. Then yellow resins and pentaeritritol
trinitrate remain in the solution.
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Microtek
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@Etanol: My PETN does not contain the impurities you mention, possibly because I synthesize it from 100% HNO3 rather than mixed acid.
@pjig: I usually do the precipitation close to the boiling point of acetone, then maintain stirring until it has cooled most of the way to room temp.
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pjig
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Ty microtec
The hot PETN acetone solution instant crash may have some undesirable variants (less sensitive forms of the petn family . This Leaving the final
product less sensitive to initiating, but in a way, safer for an industrial level where munitions may call for insensitivity . Unfortunately for
sensitive initiators it is counter productive. Soi assume a slow process is more desirable for the precipitation being more sensitive . Never seen
the oily yellow derivatives, but that may be from the heating after nitration process to max yield, and destroy impurities . Losses from the “cold
only “ process is minimal in small scale production… not worth the risks and potential near ddt temps if residue resides on sides of reaction
glass . Just my 2 cents
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pjig
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This is a good section to discuss some general questions on precipitation and the Crystal modification.
Couple methods suggested : (1) a hot acetone saturated solution crashed into cold water for a precipitate. (2nd) suggestion was cold water added too
hot saturated solution acetone. (3rd) was cooling of the hot acetone solution not disturbed = large crystal formation, to be broken up by manual
shaving.
Curious the performance, sensitivities, and Benefits of different Re- crystallization methods . Both RDX and Petn seem to be similar in there crystal
formations from this process. So processes should result in similar results for either E.M. Utilized.
[Edited on 7-11-2024 by pjig]
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