Sciencemadness Discussion Board - To everyone using peroxides (important!)

To everyone using peroxides (important!)

Tweenk - 4-1-2005 at 12:53

After seeing dozens of reports of organic peroxides accidentally exploding while being loaded into metal blasting cap casings, and especially seeing people saying that "it exploded without a reason" I must give all of you who are using peroxides a warning: NEVER use ANY metal parts with peroxides. All of them decompose exothermically in contact with metals, especially copper, and this in most cases this causes detonation. This fact seems to be omitted from most HMTD preps on the US sites but in Europe it's widely known. HMTD in plastic casings (i. e. juice straw sealed at one end with hot melt glue) is also a very potent priming agent and there's no need to risk your health. Metal casings are designed for substances like lead azide and PETN which do not react vigorosly with metals. For the purposes of amateur pyrotechnics it is better to use plastic of paper casings no matter what primary you use because there is no shrapnel produced in an explosion.
If you MUST use peroxides with metal casings then at least paint the casings on the inside with a car paint or nail enamel. This prevents HMTD from reacting with metal.

BTW I see that in the US much more people use dangerous metal parts in their devices... Posting anything about a device that contains metal parts (especially casings) at my Polish pyro-chem forum would result in immediate banning or at least the post containing such info would be removed.

I second that...

Mickhael - 4-1-2005 at 13:48

This is a fact I've noticed and are taking care never to do, but thankyou for the warning. Even with MEKP, it reacts instantly to the metal in my syringe, and starts bubbling! So without a doubt I will NEVER use metal casings! Plastic water line or PVC is easier to work with, easy to seal and you will never have metal shrapnel sticking in your gut from it!

Taaie-Neuskoek - 4-1-2005 at 15:02

Quote:

Plastic water line or PVC is easier to work with, easy to seal and you will never have metal shrapnel sticking in your gut from it!

I prefer metal in my gut, as it can be seen on X-rays, in contradiction to PVC...
(hard) PVC makes also flying scrapnel....

[Edited on 4-1-2005 by Taaie-Neuskoek]

true,

Pyroz - 4-1-2005 at 20:00

It happened to me once with a very small amount, and i know why it happened. I tested my theory as to why it happened in a controlled environment--and got a better picture. I know understand the problem very well.

Most people completely dry their organic peroxide based explosive and tamp it into their metal lined charge casing. The problem is that the crystals chafe and cause friction --- causing a detonation. So I keep my organic peroxides ever so slightly damp with water while packing the explosive against metal . Never once in all my 1000's of firings have I ever had a charge go off using this method. Once the charge dries out it is less sensitive to shock due to the compacted crystal mass.
The other problem is left over acid interacting with the metal sufaces causing instability of the compound--- this is a real problem--- organic peroxides when fully neutrallised take a while to destablize in such a fashion. The peroxide-metal interaction does not occur instantly...it can't cause a detonation unless the crystalline material is saturated with left over acid...this much I have experienced.

Generally it is much better sense to use plastic to house organic peroxides--- just because it IS safer in the long run.

[Edited on 5-1-2005 by Pyroz]

Mickhael - 4-1-2005 at 23:03

Quote:

[I prefer metal in my gut, as it can be seen on X-rays, in contradiction to PVC...
(hard) PVC makes also flying scrapnel....

[Edited on 4-1-2005 by Taaie-Neuskoek]

Thats partially true...however PVC is alot less likely to pierce through thick protective clothing or other barriers then metal...which will slice through kevlar at high enough speeds...so I've heard. Don't quote me on that though

Pyroz - 5-1-2005 at 00:22

Kevlar can't even stand up to a modern high powered rifle (.300 Weatherby Magnum sabertip, .308 sabot round or 50BMG--- so why would anyone think kevlar vest could survive a blast from a powerful shattering explosive?

[Edited on 5-1-2005 by Pyroz]

Rosco Bodine - 5-1-2005 at 01:02

Actually not just any plastic will do either .

There may be problems with styrene , and some others .

Polypropylene , polyethylene , teflon seem to be inert to the peroxides .

But I wouldn't use vinyls , including PVC which is vinyl , or styrene . Silicones and urethanes or polycarbonate , acrylics I wouldn't trust either .

Taaie-Neuskoek - 5-1-2005 at 01:16

So.... just don't use peroxides??

Mickhael - 5-1-2005 at 01:20

Quote:

Originally posted by Rosco Bodine
Actually not just any plastic will do either .

There may be problems with styrene , and some others .

Polypropylene , polyethylene , teflon seem to be inert to the peroxides .

But I wouldn't use vinyls , including PVC which is vinyl , or styrene . Silicones and urethanes or polycarbonate , acrylics I wouldn't trust either .

I see, i didn't realize that about PVC...hmmm, guess i'l have to watch out for that as well...tyanks for the nfo.

neutrino - 5-1-2005 at 03:25

Quote:

Originally posted by Rosco Bodine
But I wouldn't use vinyls , including PVC which is vinyl , or styrene . Silicones and urethanes or polycarbonate , acrylics I wouldn't trust either .

Your post is a little confusing. Styrene is not a vinyl. Also, don’t forget that PE is technically THE vinyl.

chemoleo - 6-1-2005 at 14:58

Quote:

There may be problems with styrene , and some others .

Polypropylene , polyethylene , teflon seem to be inert to the peroxides .

But I wouldn't use vinyls , including PVC which is vinyl , or styrene . Silicones and urethanes or polycarbonate , acrylics I wouldn't trust either .

Why is that? Why would polyvinylbenzene (polystyrene) react with peroxides, and why would polyvinylmetylene (polypropylene) not?
I assume you mean some unwanted reaction that occurs with some plastics (causing what, detonation?), but not with others. Or do you mean the tendency to accumulate static charge? I don't get it

Quince - 4-2-2005 at 02:20

I've used polystyrene. Softening styrofoam with acetone and stuffing a ball with acetone-wetted AP. When it dried, it didn't detonate until I burned it.

Rosco Bodine - 5-2-2005 at 14:22

Quote:

Originally posted by chemoleo

Quote:

Why is that? Why would polyvinylbenzene (polystyrene) react with peroxides, and why would polyvinylmetylene (polypropylene) not?

Good question . Why are some of these attacked by other chemicals like ordinary concentrated nitric acid and others are not ?

Quote:

I assume you mean some unwanted reaction that occurs with some plastics (causing what, detonation?), but not with others.

You assume correctly . especially in the presence of solvents and other materials which may accompany the peroxide in contact with such plastics leading to unknown reactivity scenarios.

Quote:

Or do you mean the tendency to accumulate static charge? I don't get it

I stand by what I have said for my own opinion and my own safe handling protocols . Other folks can experiment with organic peroxides materials compatability range as much as they please . As for me , I will stick with what I know are the safe compatabilities which are proven and stay away from those which are unproven or suspect .