Sciencemadness Discussion Board

Plasticiser question.

kecskesajt - 7-8-2015 at 11:20

Sorry for the n00b question but.
Today I bought some rat glue.
MSDS says:contains polybutylenes and polyisobutylenes.
It is a very thick paste,it doesnt flow from a paper.
How much should add?2% or 2%+ 2% oil?
I want to plasticise ETN an ammonpulver.
I have ethylene glycol so I can nitrate.Can be used instead of oil,No?
Thanks for the anwers.

Jnas480 - 8-8-2015 at 19:00

It appears has other ingredients in it.

Bird Gel has 98% polybutene

kecskesajt - 8-8-2015 at 20:31

I mixed 5% with 95% flour.It doesnt seem to hold together.

greenlight - 8-8-2015 at 21:46

Your going to need at least 10-12% bare minimum using just PB on its own and it has to be rolled into the powder to be plasticized for even distribution.
PB and PIB are only binders in plastic explosive and mixtures like C4 also contain a softener/plasticizer like Dioctyl sebacate.
I use motor oil to help it hold and soften it acting as a plasticizer so it is more malleable.
I have only plasticized PETN so far with PB but I use 14-15% PB and 1% motor oil which does wonders to the end product.

[Edited on 9-8-2015 by greenlight]

kecskesajt - 9-8-2015 at 11:44

PETN + 15% plasticiser? Would not make the OB too negative?

Jnas480 - 9-8-2015 at 12:20

The polybutene is a binder, you need plastiszer such as Di Sebcate, no detergent motor oil also 1% up to 2% (the Di Sebcate is expensive).

Not sure what u doing with flour, Flour is soulable in water,
(Are you testing it before, you use ETN, not to waste it)

Pretty much what greenlight said

greenlight - 9-8-2015 at 21:45

I think it is fine with the 15% binder, even though it is not all binder, the commercial Semtex has 20% inerts. I think it would lower VOD mostly.

[Edited on 10-8-2015 by greenlight]

kecskesajt - 9-8-2015 at 22:21

Dioctyl sebacate?I saw it only at Sigma-Aldrich, Czechoslovakia is my neighbour,go to the semtex factory and:Hi,do you have some dioctyl sbacate?Why do you need?And you are not permitted to get here!
For science experiments.
And yes,I used flour because I dont wanted to waste.
I asked,can EGDN used insted motor oil?
And I is good to dissolve the PIB into benzine(more purified gasoline) and the add to ETN?
Anyway,thank everybody for the anwsers!
Have a nice day.

greenlight - 10-8-2015 at 00:08

I'm pretty sure Dioctyl sebacate is used in C4 with Polysobutylene and Semtex has a different mix of binder/plasticizers.
I read somewhere that EGDN used to be used as a detection taggant not a plasticizer in Semtex but has since been replaced.
I think you should just stick with standard motor oil.
Yes I think you can do it that way but maybe choose something like white spirits or ethanol which I have seen people use. If I am correct you dissolve PIB and plasticizer in the solvent, add explosive, mix together and evaporate solvent.

kecskesajt - 10-8-2015 at 00:49

Ethanol,acetone,Isopropanol,nitro-solvent(toluene,acetone,butylacetate),Don't dissolve the glue.
Only petroleum,naptha and benzine dissolve the glue.
Yes,you are right.Dissolve PIB,add oil,explosive,stir and evaporate.

greenlight - 10-8-2015 at 02:49

Ah, yes maybe white spirits could work as well if you have it in your country as it isn't carcinogenic and not such a health hazard otherwise I suppose its benzene.
I wonder if you could somehow find out what exactly the glue is and extract it before using the PIB in your plastic.

kecskesajt - 10-8-2015 at 04:01

Only says polybutenes and polyisobutenes.Does not flamable,non-toxic.
Petroleum=white spirit.Evaporates slowly.

NeonPulse - 10-8-2015 at 15:36

Petroleum based solvents will dissolve pib easily so this is the way to go- there is a huge amount of information on plasticising on this site. I know the search engine is not the greatest but if you spend a bit of time trawling this site there are tidbits in a lot of the threads. Myself have gotten basic procedures for plasticising from here and with a bit of experimenting have gotten a product as good as or better than the real item with excellent handling properties and a pretty good density with 12% plasticisers/binders. It's all here, just spread out in different parts of SM.

kecskesajt - 10-8-2015 at 21:09

Quote: Originally posted by NeonPulse  
Petroleum based solvents will dissolve pib easily so this is the way to go- there is a huge amount of information on plasticising on this site. I know the search engine is not the greatest but if you spend a bit of time trawling this site there are tidbits in a lot of the threads. Myself have gotten basic procedures for plasticising from here and with a bit of experimenting have gotten a product as good as or better than the real item with excellent handling properties and a pretty good density with 12% plasticisers/binders. It's all here, just spread out in different parts of SM.

Always using search engine.But I dont want to get missinformated.At one post it says 2% the other says 7%.This is why I made another topic.

NeonPulse - 11-8-2015 at 15:14

I guess it's really up to you since there's no real set instructions on exactly how much of whatever to use. It's really whatever works and wether or not you Are happy with the results. There's many ways to approach the plasticisation and you can't really say one way is the correct way.after trial and error you'll find the best way that suits you.

XeonTheMGPony - 26-1-2016 at 13:53

I got some rat glue traps and have had moderate success.

for 10 grams etn I used 2 grams of the glue with .6g of oil, and kneaded it for about an hour with folding it into its self with a bit of xylen as solvent.

I'm showing pics of the 4gram sample that I used for determining the amounts.

and then the pictures of the 10 gram test.

The issues I find is they are too tacky, and then when loaded with enough material to make less so it is too dry and cracks too much

but det chararistics are quit good when fully driven, the det had a .3g bas charge of heavy compressed etn

Silly power putty 1.jpg - 116kBcharge + Tamping.jpg - 237kBPost det 1.jpg - 265kBPost det 2.jpg - 323kB

Antiswat - 28-1-2016 at 07:41

you could use gasoline or some more fancy solvents for dissolving the PIB to then leave a more or less hard mix, you may even keep a bit of the gasoline in it, or mix it up with motor oil and let the gasoline evaporate out
just keep in mind gasoline contains benzene

XeonTheMGPony - 28-1-2016 at 08:25

The issue isn't the solvent, the issue is in the glue compound, though I will be switching to gas as it is faster in evaporation then the Xylene, or I'll still use a bit of Xylene as it yields a longer working time.

For all those making plastics I can share one secret that is easily don: LOTs of kneading! If your wrists don't hurt you haven't mixed it enough!

I think I may have some PIB containing tape here will test out and need to buy gear to make methanol ricinate, and want to test out making PGDN (Propylene glycol dinitrate) as an energetic plasticizer

The stuff I produced is readily mold-able, but super tacky, so perhaps a different or more oil need be used. Main thing is to say that the glue traps can be used with limited success.

NeonPulse - 28-1-2016 at 18:19

You roll it like dough. A smooth rolling pin and glass surface are your best bet. I've rolled slot of plastic and using methyl ricinoleate is the go. It gets nice and soft like plasticine without cracking. Rolling really is not the fun part. It's not a secret it is the procedure and wou will not get a high density and malleable plastic without it. Also less oil will help with the stickiness. Also try the bird repellent polybutene. You get a very nice result.

magicchemist - 29-1-2016 at 17:06

http://www.ebay.fr/itm/4-The-Birds-Transparent-Bird-Gel-Repe...


This is good as source of polybutene ?

NeonPulse - 29-1-2016 at 19:40

Quote: Originally posted by magicchemist  
http://www.ebay.fr/itm/4-The-Birds-Transparent-Bird-Gel-Repe...


This is good as source of polybutene ?



Perfect, its the same stuff i use . it makes quite a nice plastic but due to is viscosity it is a pain to work with.

magicchemist - 30-1-2016 at 02:18


Someone has a good protocol to make methyl ricinoleate ?

NeonPulse - 30-1-2016 at 03:08

search the thread: PETN vs RDX toward the end of the thread. and there's this:

[Edited on 30-1-2016 by NeonPulse]

Attachment: methylricinoleate.pdf (42kB)
This file has been downloaded 576 times

Attachment: Rape-Seed-Oil-Conversion_2001.pdf (663kB)
This file has been downloaded 448 times


magicchemist - 30-1-2016 at 05:21

ok thank you and it's really important to wash the methyl ester with sulfuric acid ?

XeonTheMGPony - 4-2-2016 at 07:29

I made a nitrogell bound etn charge, it was moderatly moldable. When it still had the acetone solvent in it, it was very very moldable and pliable.

5% - Gun cotton
16.7% - NitroGlycerin
82.5% - ETN

Out side would form a dry hard skin, so needs to be hand rolled again on use to homoginize it.

.3gram etn cap fired it at high ordered. Punched a nice clean fist sized hole through the steel test plate.

So this mix is good for packing a shell such as a EFP or Shaped charge.

[Edited on 4-2-2016 by XeonTheMGPony]

markx - 27-2-2016 at 06:48

A simple yet effective mix for plasticizing actions:

80-90% low polymerisation degree PIB from rat glue
10-20% high polymerisation degree PIB from "self amalgamating" tape


Below is the example with 20% of the mentioned binder in action:
DSCF1009.JPG - 587kB

DSCF1010.JPG - 733kB

DSCF1011.JPG - 702kB

Judging by the excellent mechanical properties one can do with much less than 20% of this particular binder in the mix.

Microtek - 27-2-2016 at 11:43

That does look very promising. What else is in it? Or alternately, how did you prepare it? I haven't had the opportunity to examine rat- or bird glue myself, but I'm assuming there must be some plasticizers in it as well.

markx - 27-2-2016 at 12:24

Quote: Originally posted by Microtek  
That does look very promising. What else is in it? Or alternately, how did you prepare it? I haven't had the opportunity to examine rat- or bird glue myself, but I'm assuming there must be some plasticizers in it as well.


I really can't figure out if there are any plastifying additives in the rat glue composition...as far as the package label or sds card say it only contains polybutene (copolymer of butylene and isobutylene). The tape might have some additives that leech into the extraction solvent together with the pib mass, but again I have no information on what these additives might be. The fact is that either one of the PIB based binders used alone or in conjuction with additional plastifiers (methyl riccinolate, different oils etc) do not produce a similar effect.

The composition on the pictures is as follows:

18% rat glue pib
2% tape pib
80% energetic of choice

The binder was dissolved in alkene mixture and added to the energetic in aforementioned proportions. The mass was mixed and kneaded manually until the solvent evaporated (approximately 30min) resulting in a highly elastic mass that can be streched out very much like bubble gum without breaking apart. The mass was not rolled, just kneaded and stretched manually.

Microtek - 28-2-2016 at 08:04


Quote:

The binder was dissolved in alkene mixture


Do you mean alkane? using alkenes as solvents for polymers seem a little exotic and toxic...

As for the rat glue composition, I've been googling it a little, and found an msds that listed the following ingredients (the company name is SX Environmental):

Butyl rubber 2-10%
PIB 10-20%
White mineral oils 30-50%
Polyethylene 1-5%
Oil resin 15-25%

The mineral oils and the "oil resin" (though I'm not quite sure what they mean by that) probably both have a plasticizing effect, and comprise 45-75 % of the composition. The product may not be at all identical to yours, but I think it quite likely that yours also contain a lot of plasticizer.

markx - 28-2-2016 at 10:34

Quote: Originally posted by Microtek  

Quote:

The binder was dissolved in alkene mixture


Do you mean alkane? using alkenes as solvents for polymers seem a little exotic and toxic...

As for the rat glue composition, I've been googling it a little, and found an msds that listed the following ingredients (the company name is SX Environmental):

Butyl rubber 2-10%
PIB 10-20%
White mineral oils 30-50%
Polyethylene 1-5%
Oil resin 15-25%

The mineral oils and the "oil resin" (though I'm not quite sure what they mean by that) probably both have a plasticizing effect, and comprise 45-75 % of the composition. The product may not be at all identical to yours, but I think it quite likely that yours also contain a lot of plasticizer.



True that, alkanes are solvent media that I used (what a difference one letter can make!) :) The glue that I used is from the company Kollant SRL and they only mention the polybutenes and 0-0,25% cyclohexane on the sds. But then again the sds does rarely expose the true composition of a product and I'm sure that there are many different formulations out there...

Hennig Brand - 28-2-2016 at 11:18

The MSDSs for the few bird repellent products I have looked at stated as low as 88% to as high as 98% polybutenes, I always figured there was probably some plasticizer(s) added as well, but it was (or they were) never listed in the MSDSs. Nice looking putty by the way!

NeonPulse - 29-2-2016 at 15:22

Here's the one I use and it works great although it is not 100% pure. The MSDS said only 70% + polybutene, but not sure what the inert fillers could be and what the synthetic resins comprise of. It is preferable to the rat traps or fly paper since all you need is a caulking gun. Very little mess. And easy to work with, but if you get it on stuff it is a real pain in the ass to clean up.

image.jpeg - 2.1MB

[Edited on 29-2-2016 by NeonPulse]

image.png - 419kB

[Edited on 29-2-2016 by NeonPulse]

XeonTheMGPony - 6-3-2016 at 08:40

http://www.ebay.com/itm/The-glue-is-non-toxic-from-rodents-a...

Well searching for sources of PIB I found this, all the chararistics they discribe sounds exactly like streight up un modified pib! of the right weight. Thoughts?

magicchemist - 14-3-2016 at 11:27

markx what the brand of your ratglue ?

deadpool - 29-6-2019 at 13:11

Well I know this is an old topic, but I was trying to binding ETN using the best products and related work here
used :
(per wiki c4)

5.3% dioctyl sebacate
1.6% mineral oil
2.1% Pib from "bird repellent"

The results were extremely poor, the product was brittle and woudn't adhere, I ad to keep increasing the quanity of the PIb to get some final product which was still poor and ended up containing large quantities of inert compounds. I think the problem is the bird repellent, it's nasty stuff and not very rubber like, just a sticky mess. perhaps the trick is getting longer chains, next Ill try the amazing results w/ glue traps and tape as mentioned by markx

XeonTheMGPony - 29-6-2019 at 14:04

Bike inner tube glue I have found to work very well.

twelti - 29-6-2019 at 14:26

Is this of any interest:
https://www.ebay.com/itm/2-oz-Pro-Grade-Styrene-Butadiene-Ru...

Thanks Xeon!

deadpool - 5-7-2019 at 22:47

Quote: Originally posted by XeonTheMGPony  
Bike inner tube glue I have found to work very well.


I'll give that a try, currently working with scapa 2504 tape (also claims to be pib) not sure what the difference is between the 2501 & 2504 (think just the dimensions)

HTPB Binder

wessonsmith - 9-7-2019 at 11:31

Very quick and easy method. Let the machine do all the work.

https://youtu.be/1BCsG84-rIo

Microtek - 10-7-2019 at 00:01

I'm a little uneasy about the prospect of machine tumbling a material as sensitive as ETN. IIRC, TNT based composites such as cyclotol have occasionally been initiated in very similar mixing machines. Granted, the temperature must have been around 90C, but given the lower sensitivity of RDX and TNT I still find it a little unsettling.

wessonsmith - 10-7-2019 at 06:35

Quote: Originally posted by Microtek  
I'm a little uneasy about the prospect of machine tumbling a material as sensitive as ETN. IIRC, TNT based composites such as cyclotol have occasionally been initiated in very similar mixing machines. Granted, the temperature must have been around 90C, but given the lower sensitivity of RDX and TNT I still find it a little unsettling.


First, the blades of the mixer don't touch each other or the surface of the bowl. Secondly, you add the ETN in batches so that the HTPB has a chance to coat the crystals. You do this at low speed first. Once the crystals are covered, the sensitivity goes WAY down — no chance of detonation.

The accidents that you refer to are not the heating and mixing but when they allowed the TNT to harden and left it in the mixer overnight. When they restarted those powerful mixers, which broke free of the TNT, it was enough energy to detonate.

I am employing simple math with my method. There isn't enough friction or force generated against the ETN crystals to cause any problems.

Once the ETN is completely coated, you can hit it with a hammer against steel and it won't detonate.

[Edited on 10-7-2019 by wessonsmith]

MineMan - 10-7-2019 at 09:47

What is the math, I would like to learn this?

twelti - 10-7-2019 at 13:38

Quote: Originally posted by MineMan  
What is the math, I would like to learn this?

I'm also curious. It seems that trying to equate sensitivity values measured in one very specific way to this different situation would be tricky. I mean, I'm guessing that one could calculate the total energy being imparted to the "dough" by the mixer, and try to compare to the minimum energy required for initiation or something on that order. But, I would think that the actual frictional energy, shear and stress etc. is not evenly applied throughout the mass. If it is a distribution of energy levels, then some small parts could have much higher energies and initiate the rest. At the very least, it doesn't sound simple.

Microtek - 10-7-2019 at 14:16

I agree that the probability of initiation is likely very low, but many things behave in a non-ideal manner (eg. mix is not completely homogenous or forces are not applied evenly). Also, sometimes you discover a phenomenon that hadn't occurred to you before, like adiabatic heating from liquid sloshing (has been known to initiate nitromethane). NM can be fired upon with 12.7 mm HMG rounds and not go off, so on the face of it, you wouldn't think there would be any problems driving it around in tanker cars. It turns out that if the tank isn't completely full, it can actually detonate from sudden stops.
Things like this can be hard to predict, so who's to say that there isn't some other phenomenon that could be of relevance in this instance? If I were you I would at least place the kneading machine far from buildings and people, and switch it on remotely.

Microtek - 11-7-2019 at 11:35

Some years ago, I (like several other members here) frequented the Explosives and weapons Forum. One of the members there was someone who called himself NBK2000. He was not a pleasant person, but he posted something he called the RTPB (Rules To Prosper By). One of these rules was to "Plan for failure", and I have since found that to be sound advice indeed (though obviously not invented by this person - I was taught the same thing at technical university), especially in relation to energetics.
So, to play devils advocate: What would happen if your mixing machine failed in some manner? Maybe the blades are warped, or maybe there is an electrical malfunction possibly due to overheating (I'm guessing the machine isn't designed for making plastique, so maybe this places a higher than designed load on the components). A warped blade could result in metal on metal grinding, an electrical problem could possibly result in a fire.
I realize that you can't eliminate all risk (we'd never get anything done that way, and we'd still not live forever), and you are of course free to do things in whichever way you please.

twelti - 11-7-2019 at 17:15

Quote: Originally posted by wessonsmith  
Quote:

"Plan for failure", and I have since found that to be sound advice indeed (though obviously not invented by this person - I was taught the same thing at technical university), especially in relation to energetics. So, to play devils advocate: What would happen if your mixing machine failed in some manner? Maybe the blades are warped, or maybe there is an electrical malfunction possibly due to overheating (I'm guessing the machine isn't designed for making plastique, so maybe this places a higher than designed load on the components). A warped blade could result in metal on metal grinding, an electrical problem could possibly result in a fire.



I agree, I always plan for failure, that is what I meant by using common sense. For example, I chose a mixer that was powerful enough to handle the job of mixing my composition. I also stand there the entire time that the mixer is on. If for some reason there was a problem, I could pull the plug. Even if somehow the blade bent at lower speeds no big deal. Once I transition to the higher rates, the ETN has been thoroughly coated and can withstand direct blows from a hammer on steel without detonating. (Yes I have thoroughly tested my plastic:)

The bottom line my method is the safest way for ((( ME ))) to mix explosives. With the blender, I eliminate my fatigue, which can cause accidents, and the mixer also ensures consistency of the process.


I haven't been around long, but I get the impression that sensitivity can go up for larger amount of energetic material. For example, my tests of ETN with a hammer have been using very small amounts, since when heating in foil, it detonates easily and loudly. It is insensitive in those amounts, but I have been told that if using a larger amount, it should detonate with hammer easily. I'm going to try that soon. But that, and other various things I have heard or read, makes me wonder if larger amounts can be more sensitive than the small amounts normally tested. The amounts you deal in are very large by my standards. Also wondering if the trapped air in the mixture is a factor. Does that increase sensitivity? Finally, you are using large and small crystals to start with. Will that optimal mixture still be intact after the shaving resulting from the mixing process?

twelti - 11-7-2019 at 19:41

Quote: Originally posted by wessonsmith  

Quote:

I haven't been around long, but I get the impression that sensitivity can go up for larger amount of energetic material. For example, my tests of ETN with a hammer have been using very small amounts, since when heating in foil, it detonates easily and loudly. It is insensitive in those amounts, but I have been told that if using a larger amount, it should detonate with hammer easily. I'm going to try that soon. But that, and other various things I have heard or read, makes me wonder if larger amounts can be more sensitive than the small amounts normally tested. The amounts you deal in are very large by my standards. Also wondering if the trapped air in the mixture is a factor. Does that increase sensitivity? Finally, you are using large and small crystals to start with. Will that optimal mixture still be intact after the shaving resulting from the mixing process?


A crystal explosives sensitivity doesn't change with the amount used. The situation you were having was that you were missing the ETN with the hammer due to the small amount used. His suggestion for you to use more ETN was intended to increase the probability of hitting the ETN inside the foil. FYI, 50mg of ETN in foil is hazardous if you are not wearing eye and ear protection.

Trapped air decreases the density of the plastic explosive; that is why I always use a vacuum chamber once I am done mixing. Low density means less brisance and power.

I use a mixture of small and large particle sizes, 31.5% small, and 68.5% large. Using the two different particle sizes is crucial in getting the most ETN possible into the HTPB matrix.

I don't think I am missing the ETN. I mean the foil is flattened and then some! Even if so, that just illustrates the point: the larger the amount, the more probability of an (improbable) event that can result in detonation.
Doesn't air spaces increase sensitivity? Hotspots, cavitation and all...
I just wondered if after all that mixing the larger crystals get reduced in size. Maybe both the large and small get reduced the same amount?

MineMan - 11-7-2019 at 21:28

Wesson, we appreciate how much you have researched this, and your confidence.

But what makes us nervous is it’s ETN...you could do this a 1000 more times and not have an incident..

But, ETN is rather sensitive. This would make me nervous with PETN... but with ETN I would say your quite brave. I wouldn’t recommend this procedure with anything less than RDX.

When quanity goes up. So does uncertainty... you say crystal sensitivity doesn’t change with the amount, but you have a higher chance of having a crystal with more internal stress...

Wesson. This just makes me uneasy. Wish Bert and some of the others that know industry better were here to comment.

[Edited on 12-7-2019 by MineMan]

wessonsmith - 12-7-2019 at 00:57


Probably best if I just delete my posts. My intention wasn’t to make people uneasy.

[Edited on 12-7-2019 by wessonsmith]

Microtek - 12-7-2019 at 00:58

My own hypothesis about the Al-foil bias is that the soft aluminum deforms around the individual crystals with the first few hammer blows, and then cushions them against the subsequent strikes. This would also explain why a slightly larger amount responds more reliably (since there would be more crystal on crystal interfaces), and gives a more accurate impression of the sensitivity.

wessonsmith - 12-7-2019 at 06:02

Quote: Originally posted by twelti  

I don't think I am missing the ETN. I mean the foil is flattened and then some!


You were missing the ETN. Microtek offered a plausible hypothesis on how your hammer blows could miss the ETN, but the hammer did miss.

ETN's properties don't change with the amount. If you strike 1mg or 100mg of ETN with a hammer against a steel plate, the ETN will detonate. I can't stress this point enough. ETN is just as sensitive in the 1mg amount as it is in 10g. ETN particle size doesn't change this either. So small VS large particles will both be as sensitive.


[Edited on 12-7-2019 by wessonsmith]

twelti - 12-7-2019 at 09:07

Quote: Originally posted by wessonsmith  

Probably best if I just delete my posts. My intention wasn’t to make people uneasy.

[Edited on 12-7-2019 by wessonsmith]

Hopefully not, your posts are informative and starting useful discussions.

wessonsmith - 12-7-2019 at 09:10

Quote: Originally posted by twelti  
Quote: Originally posted by wessonsmith  

Probably best if I just delete my posts. My intention wasn’t to make people uneasy.

[Edited on 12-7-2019 by wessonsmith]

Hopefully not, your posts are informative and starting useful discussions.


Not all my posts, just the posts pertaining to my plastic manufacture.

OneEyedPyro - 13-7-2019 at 00:21

Quote: Originally posted by wessonsmith  
Quote: Originally posted by twelti  

I don't think I am missing the ETN. I mean the foil is flattened and then some!


You were missing the ETN. Microtek offered a plausible hypothesis on how your hammer blows could miss the ETN, but the hammer did miss.

ETN's properties don't change with the amount. If you strike 1mg or 100mg of ETN with a hammer against a steel plate, the ETN will detonate. I can't stress this point enough. ETN is just as sensitive in the 1mg amount as it is in 10g. ETN particle size doesn't change this either. So small VS large particles will both be as sensitive.


[Edited on 12-7-2019 by wessonsmith]


Particle size absolutely does matter when it comes to impact sensitivity, this is widely known and well documented.

The physics behind why this is true is simple.
With a fine powder each impacted crystal can more easily impart its energy to other surrounding crystals via friction thus reducing the peak forces applied to a single area.

With larger crystals there is less surface to share the impact, the crystals drag across each other with more force and see higher peak forces.

This is a big part of why milling powders becomes progressively harder as particle size decreases.
This is why loose sand hurts less to fall on than a loose pile of golf ball sized rocks.

wessonsmith - 13-7-2019 at 06:15

Quote: Originally posted by OneEyedPyro  
Quote: Originally posted by wessonsmith  
Quote: Originally posted by twelti  

I don't think I am missing the ETN. I mean the foil is flattened and then some!


You were missing the ETN. Microtek offered a plausible hypothesis on how your hammer blows could miss the ETN, but the hammer did miss.

ETN's properties don't change with the amount. If you strike 1mg or 100mg of ETN with a hammer against a steel plate, the ETN will detonate. I can't stress this point enough. ETN is just as sensitive in the 1mg amount as it is in 10g. ETN particle size doesn't change this either. So small VS large particles will both be as sensitive.


[Edited on 12-7-2019 by wessonsmith]


Particle size absolutely does matter when it comes to impact sensitivity, this is widely known and well documented.

The physics behind why this is true is simple.
With a fine powder each impacted crystal can more easily impart its energy to other surrounding crystals via friction thus reducing the peak forces applied to a single area.

With larger crystals there is less surface to share the impact, the crystals drag across each other with more force and see higher peak forces.

This is a big part of why milling powders becomes progressively harder as particle size decreases.
This is why loose sand hurts less to fall on than a loose pile of golf ball sized rocks.


There is no appreciable difference. Are you trying to argue that there is a noticeable difference between small and large particle sizes when it comes to the sensitivity of ETN?

Rocinante - 13-7-2019 at 06:55

The problems in your tests come from the impactors. Those steel surfaces aren't completely flat and thus small samples can hide in those gaps - not being hit by anything.¨

I had severe problems detonating TATP/HMTD that way.
It is well known that particle size has medium effect on impact sensitivity. But we're talking 50 % or so in most cases. That's why your hand test don't differentiate between them. But the difference is there.
Also, your PBX machine is no different than those used in the production of Semtex. Still, I wouldn't feel completely comfortable around it. A long cord and a wall solves that problem.

twelti - 13-7-2019 at 08:18

Uhh, are we talking about particle size or sample size? I don't find my ETN easy to detonate in small amounts with a hammer. Maybe I need a bigger hammer? Or a larger and more sturdy piece of steel. The one I have is around 3/4" thick, and hammer is a medium sized ball peen.

wessonsmith - 14-7-2019 at 05:51

Quote: Originally posted by twelti  
Uhh, are we talking about particle size or sample size? I don't find my ETN easy to detonate in small amounts with a hammer. Maybe I need a bigger hammer? Or a larger and more sturdy piece of steel. The one I have is around 3/4" thick, and hammer is a medium sized ball peen.


An interesting experiment for you to try is to put some paint on your hammerhead and lightly tap a piece of paper. You will see the actual point of impact and how small it is as compared to the head size. You will get a sense then of how easy it is to miss a small amount of ETN with the real hammer blows.

Microtek - 14-7-2019 at 08:13

Another problem with a manually wielded hammer is that it is very difficult to ensure that you hit the anvil at a perfect 90 degree angle. This will also make it difficult to predict the exact point of impact.

OneEyedPyro - 14-7-2019 at 13:57

@wessonsmith

I'm not sure what the relationship between crystal size and sensitivity is with ETN in particular, but with primaries crystal/particle size is an important factor and I'd assume the same applies to ETN.

As for hammer testing... I prefer use a rounded surface like a large diameter steel pipe, this allows for a good pinch point even when not impacting at a perfect 90° angle. A large steel or concrete sphere would be even better.

wessonsmith - 14-7-2019 at 18:02

Quote: Originally posted by OneEyedPyro  
@wessonsmith

I'd assume the same applies to ETN.


It does not. There is no appreciable difference for ETN.

OneEyedPyro - 14-7-2019 at 21:10

Quote: Originally posted by wessonsmith  
Quote: Originally posted by OneEyedPyro  
@wessonsmith

I'd assume the same applies to ETN.


It does not. There is no appreciable difference for ETN.


I'm interested in your reasons for believing that.
Have you heard this elsewhere or done testing?

I've done some fairly extensive sensitivity testing with ETN but that was with the dissolve and crash type recrystallizations which tend to produce very fine crystals.
I didn't find the friction/impact sensitivity to be too unnerving with that product, but of course ETNs inherent potential for DDT upon strong heating or ignition is always something to be weary of.

As far as I'm concerned it's a sensitive secondary explosive that demands respect regardless of crystal size.

MineMan - 14-7-2019 at 22:42

My understanding is crystal size influences the sensitivity of all explosives... even insensitive ones like RDX... the smaller the crystal the less internal stress. This is a known.

Microtek - 15-7-2019 at 00:46

Yes, I also remember reading papers about the sensitivity of RDX as a function of crystal size and shape. I don't remember the exact relationship, but the trend was that the smaller (and possibly the more rounded) the crystals were, the less sensitive.

wessonsmith - 15-7-2019 at 05:18

Quote:

Have you heard this elsewhere or done testing?


Yes, and yes. I think you guys are missing the operative phrase in my statement "no appreciable." Is there a difference in sensitivity between melt-cast and powdered, yes. Is it large enough to make a bit of difference to us when using ETN, NO! The same is true for different particle sizes of ETN.

I think you summed it up for me
Quote:

As far as I'm concerned it's a sensitive secondary explosive that demands respect regardless of crystal size.



Quote:

My understanding is crystal size influences the sensitivity of all explosives... even insensitive ones like RDX... the smaller the crystal the less internal stress. This is a known.

This statement is true, however with ETN, please read above.


I am interested in how you all are achieving you're fine particle size of ETN. The only way I have ever been able to make sub-40-micron particle size ETN consistently has been to dissolve ETN in warm alcohol and then place the container in a -20C bath and mix the solution until nearly all the ETN crashes out. Once crashed out, and the ETN reaches -10C, I then directly vacuum filter from ethanol, no water crash.


solo - 16-5-2020 at 17:25

Does anyone know of a green catalyst to make tributylcitrate (TBC).i have found many with imidazoles, ionic solutions , solid acids and zeolites.
I want something with minimal handling and an inexpensive catalyst,that can be recharged and reused.....thanks....solo


Note, ....."different catalysts such as as
phosphotungstic acid,modified silica gel supported
phosphotungstic acid, carbon-based solid acid, solid
superacid SO4 2- /ZnO-TiO2, strong acidic resin, cerium-
dopedmesoporousMCM- 41, acid ionic liquid
and dealuminated USY"

see..."An overview on synthetic methods of tributyl citrate
Xiaoli Zhang"....attached

[Edited on 17-5-2020 by solo]

Attachment: an-overview-on-synthetic-methods-of-tributyl-citrate.pdf (249kB)
This file has been downloaded 168 times


Microtek - 18-5-2020 at 22:43

That paper seems pretty amateurish (for instance, they do not specify what kind of "carbon-based solid acid" they are using) but of the methods presented, I think the one with acid ion exchange resin is the most promising. Strongly acid ion exchange resins are cheaply and widely available on ebay for use in water treatment. Just make sure you get the right kind of resin.
You then treat the resin with strong acid, filter off the liquid and add the resin to the mix of butanol and citric acid. After the reaction, you filter off the resin, wash it, treat it with strong acid, and it will be ready for another batch.
Another possibility would be to try toluene sulfonic acid as a "carbon-based solid acid". I don't think you will be able to easily regenerate it for repeated use though.

solo - 19-5-2020 at 09:59

...thank you Microtek, I had found this study and was on route to your suggestion.....

Green and Efficient Esterification Method Using Dried Dowex H+/NaI Approach
Petri A. Turhanen,
ACS Omega
2019, 4, 8974−8984
DOI: 10.1021/acsomega.9b00790





ABSTRACT
The usefulness of dried Dowex H+ cationexchange
resin with or without sodium iodide (NaI) as a
catalyst system for different kinds of esterifications using
carboxylic acids and alcohols as starting materials has been
systematically investigated. The Dowex H+/NaI approach is
very effective, generally high yielding, energy-efficient, and nontoxic, and the Dowex H+ resin is reusable. Since the whole
procedure from start to product isolation is also very simple, these features make the method environmentally friendly. The
method is regioselective, and its potential for separation of valuable carboxylic acids like resin acids from mixtures containing
other kinds of carboxylic acids has been demonstrated. Examples for green and straightforward esterification of highly important
natural amino acids are also presented.

Attachment: Green and Efficient Esterification Method Using Dried Dowex H+_NaI Approach (1).pdf (1.5MB)
This file has been downloaded 220 times