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Author: Subject: Plasticizer problem
Fulmen
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[*] posted on 10-1-2017 at 15:50


Could be useful for loading charges, but probably not for the manufacture itself. Kneading it is bound to reintroduce air, so wouldn't any increase in density is lost unless you handle the product very deliberately with a minimum of reshaping?



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Dornier 335A
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[*] posted on 10-1-2017 at 15:51


The data was calculated with a rather simple (only 1000 lines of code...) program of mine. It guesses the reaction, calculates temperature and finally other detonation parameters using a few empirical equations. It has surprising accuracy, almost approaching that of expensive programs like EXPLO5. A complete JCZ3 implementation is on its way though...

Anyway, at 40% wax (OB = -146%) the VoD is calculated to 5450 m/s and P to 132 kbar at 1.28 g/cm3. More than that and the temperature starts to drop too low for my model.
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DubaiAmateurRocketry
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[*] posted on 11-1-2017 at 00:27


dornier you havent posted a video in a while ;)
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PHILOU Zrealone
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[*] posted on 11-1-2017 at 09:52


Quote: Originally posted by Bert  
Having seen vacuum degassing used to eliminate or at least minimize bubbles and voids when casting composite rocket fuel grains, I wonder if anyone has tried adapting vacuum processing to plastic explosive manufacture?

This would be indeed an effective way to reduce the air incorporation...but the all kneeding system must be under vaccuum.

Since following the perfect gas law: p*V=n*R*T
--> then reducing the pressure will proportionnally reduce the quantity of air incorporated.

If 10% air is incorporated into a normal process at ambiant pressure; then into identical conditions but the pressure, reducing the pressure by 2, 5 or 10 will reduce the air incorporation to 5%, 2% or 1% respectively (vs the initial 10%).

Theorically if pressure can be set to 0 mm Hg (or close because 0 is unreachable) then the air incorporation will be negligible.

Practically of course one has to work with non/least volatile HE, plasticizer and oils...considering the fact any solid has a vapour pressure...lowering the overal pressure will increase the apparent/relative volatility of all the ingredients: so even PETN or ETN may start to sublime from the kneeder compartiment to other unsuitable parts of the system and reduce the % of ingredients of the kneeded mass based on their respective vapour pressure.




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PHILOU Zrealone
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[*] posted on 11-1-2017 at 09:56


Quote: Originally posted by Dornier 335A  
The data was calculated with a rather simple (only 1000 lines of code...) program of mine. It guesses the reaction, calculates temperature and finally other detonation parameters using a few empirical equations. It has surprising accuracy, almost approaching that of expensive programs like EXPLO5. A complete JCZ3 implementation is on its way though...

Anyway, at 40% wax (OB = -146%) the VoD is calculated to 5450 m/s and P to 132 kbar at 1.28 g/cm3. More than that and the temperature starts to drop too low for my model.

Nice program and project. Thank you for the calculation at 40% wax.

Sadly I don't have such programming abilities (although I understand the concept behind code lines and iterative calculations), so I work more on feeling, raw datas comparison and extrapolation from graphics.

But as I can see, I'm not too bad since it took me less than 1 minute to guestimate/extrapolate the VOD and pressure at 40% wax ;):P

I wish that one day you will do like Engager and let the forum benefit from your ingenious calculation program.

[Edited on 11-1-2017 by PHILOU Zrealone]




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[*] posted on 11-1-2017 at 10:03


Some nagging thoughts I have had for a while.

I don't know chemistry well enough to answer this, but is there any other plastizer options that can get the job done with only 1-3% inerts?

Or another option that I have confidence in, increase the grain size so less inerts are needed, like this...

https://www.walmart.com/ip/Educational-Insights-Play-Foam-Co...

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[*] posted on 11-1-2017 at 10:04


I have played with this product (children's toy) and the air gaps can be compressed quite well.
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PHILOU Zrealone
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[*] posted on 11-1-2017 at 10:35


Quote: Originally posted by MineMan  
Some nagging thoughts I have had for a while.

I don't know chemistry well enough to answer this, but is there any other plastizer options that can get the job done with only 1-3% inerts?

Or another option that I have confidence in, increase the grain size so less inerts are needed, like this...

https://www.walmart.com/ip/Educational-Insights-Play-Foam-Co...


Everything is a matter of scale.
You may enter the field of nanomaterials if the film of plasticizer becomes too thin, it will loose part of its macroscopic properties (stretching ability, elastic ability or sticking ability) because to keep those you need to keep several molecular radius of like molecules.

You are right that increasing the particle size will reduce the surface of particle to coat with the plasticizer (active surface will be less) and thus the quantity of it...
but it may:
1°) become less kneedable (increased viscosity)
2°) become more breakable.
3°) become more sensitive because the weakest link remains the large crystals of HE (ETN, RDX and HMX for example)
--> To test.

Sole alternative would be to foccus on active binders/plasticizers...that are dense and contribute to the explosive properties.
--> Nitrocellulose and non volatile explosive gellifiers for example.
--> Other known technical compounds, glycidyl azide/ nitrate polymers, ...
--> Other unknown polymeric compounds (I have a lot of ideas because polymers usually induce higher densities and better stability (heat and shock) than monomers)




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[*] posted on 11-1-2017 at 10:42


I don't think its possible to get a moldable plastic explosive with <3% inerts. The lowest I have seen is C4 with 9% inerts.
All the new explosives testing seems to be focusing on PBX's which are bonded with a plastic polymer and have as little as 5% inerts.

Large grain size would be hard to obtain and they would probably get broken down in size a lot while incorporating the binder with rolling and kneading.
It looks like that playfoam is small rubber balls coated in some sort of binder that makes them stick to each other so I am guessing air gaps would be a problem.




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[*] posted on 11-1-2017 at 10:48


Philou,

To avoid the sensitivity problem I was going to form large grains from small crystals with smokeless powder and acetone. TACP if a perfect candidate because of the small crystals, low sensitivity and positive OB! The children's product is quite mold able, maybe I can dissolve that in acetone... but the foam might dissolve also...

Laboratory of Liptakov... this could be your claim to fame! I want to experiment with this but I can not find any PIB tape in the US...

And Dornier, I am legitimately jealous of you, remember me when you go places ...and when you are a chief engineer....
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PHILOU Zrealone
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[*] posted on 11-1-2017 at 12:53


Quote: Originally posted by MineMan  
Philou,

To avoid the sensitivity problem I was going to form large grains from small crystals with smokeless powder and acetone. TACP if a perfect candidate because of the small crystals, low sensitivity and positive OB! The children's product is quite mold able, maybe I can dissolve that in acetone... but the foam might dissolve also...

Laboratory of Liptakov... this could be your claim to fame! I want to experiment with this but I can not find any PIB tape in the US...

Beware that the TACuP may be storage inadvisable into contact with smokeless powder and/or aceton.
TACuP is a complex of NH3 and as such the NH3 is held by the Cu(ClO4)2 but not at 100%...
so the NH3 may react:
1°) with the aceton to make aceton-imin and dark polymerisation tars (only if exposed for long)
2°) most of all, with the nitric esters to hydrolyse or amonolyse it...

The children product you referenced is said to be non-sticky. (At first I thought it was magnetic core, with rubber arround)
--> So i guess the coating is stiking to itself but not to other stuffs.
--> I wonder what it is

No PIB tape...
I'm sure bird repellent/rat glue should work just fine but you have to find the right process and order of addition of the ingredients...
--> When working at Procter&Gamble on silicon additive to allow for wrinkle resistance of clothes and easy post wash ironing...
We did make an aqueous 50% silicon solution from 80% silicon into ethanol (about 5000 cps)...allowing the 80% to fall into water resulted into immediate precipitation and hard (very viscous) plastic chewing-gum totally unworkable (>100000 cps); reversely when allowing the water to fall drop by drop into the 80% silicon ethanolic solution, despite a transitory moderate increase of viscosity (not unworkable at all 15000), we ended up with a very thin liquid only 10 centipoise (thus about 10 times as viscous as water) composed of sub-micron-sized silicon beads into a water-ethanol mix.

[Edited on 11-1-2017 by PHILOU Zrealone]




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[*] posted on 13-1-2017 at 10:01


No PIB tape #2

This is a question I've been asking myself everytime someone said that they cant find PIB:
Why dont you guys try to get it from somewhere else ?

Gloves first come to mind. You all have rubber gloves right?
And for those living in the land of the chewing gum and Ford you probably can find some chewing gum at your local convenience store.
Or go tear some tires to get at the bladder that holds the air.
Dont cut your gasmask to pieces though ;)

It probably is as easy to get PIB from those sources as from bird/rat traps.
Am I failing to see something?
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[*] posted on 13-1-2017 at 11:29


Quote: Originally posted by Herr Haber  
No PIB tape #2

This is a question I've been asking myself everytime someone said that they cant find PIB:
Why dont you guys try to get it from somewhere else ?

Gloves first come to mind. You all have rubber gloves right?
And for those living in the land of the chewing gum and Ford you probably can find some chewing gum at your local convenience store.
Or go tear some tires to get at the bladder that holds the air.
Dont cut your gasmask to pieces though ;)

It probably is as easy to get PIB from those sources as from bird/rat traps.
Am I failing to see something?

Bird/Rat glue I have bought is only PIB (90-80%) and solvent like hexane (10-20% by weight) nothing else...for 2,5-3,5€/100 g into brico shop...you can't hardly make it easier to get.
The product is also immediately mixable as such with mineral oil or organic solvent.

I was also thinking to chewing-gum (after use/chewing so you get rid of most sugar, aroma) or to Multi-fix by Pritt/Henkel for Poster (glue/paste without solvent containing Polybuten but with a mineral charge).




PH Z (PHILOU Zrealone)

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