lots of questions

[Choscura]

going by what I've seen around this site and on the web, it seems like explosives are just compounds of three types of chemicals: oxidizers (potassium nitrate, or whatever saltpeter is called), combustibles (charcoal/sugar), and stabilizers (sulfur).

 

granted, not every chemical of one type can be used with chemicals of another type, due to things such as acidity/alkilinity and whatnot, but what are the exceptions to this rule, if this is a rule at all? does this only apply to low explosives/high explosives?

 

also, what are binders, and how are they used?

 

with plastic explosives (don't answer this if it requires HE qualification or whatever), why doesn't the plastic agent- whatever it may be- seriously impede the explosive, or does it?

 

why do some explosives (c4, off the top of my head- no, I'm not asking for a recipe) simply burn when ignited but explode when pressure is put on them?

 

thanks in advance to anyone who answers these competently.

[Caleb51]

Well, for the c4 question, I'm pretty sure it's the same concept as flash powder, black powder, and any other explosive. When you put something in a container, and it gets detonated, whether that be by a fuse, a primer, or whatever, it will basically catch on fire, burning at different rates depending on its composistion. Since it can only burn for so long in the tube before its bi product fumes fill the tube, it eventually blows that tube up to make more room for its exhaust. Is this right? And a binder is basically something that BINDS two things together. In high power rockets, epoxy resin is used as a binder in a lot of motors. In some fuses, dextrin is a binder, holing the black powder on the fuse better.

[[w00t]]

Well firstly c4 detenonates,  which means u have to use a blasting cap.If you light c4 it burns at about 24,000 degrees numerous grunts in the vietnam war would take lumps off and use it to burn stuff.why i do not know lol. And binders are used to stop compostions from crumblying.

weknowpyro, capitalise your posts and don't use 'u' instead of 'you'.

It reflects baddly towards the forum.

[Mumbles]

Wow, weknowpyro, it's obvious you don't really know shit. I also suggest you stop posting shit before you get banned. Where is hell did you get that C-4 burns at 24,000 degrees? It burns because RDX, as well as the plasticisers in it are flammable. TNT is also flammable, it is how excess is destroyed actually. Detonation is when there is actually a shockwave being sent through the material breaking bonds beyond the reaction front. I have heard some say that detonation is just the material burning, and the gases expanding within a material at higher than the speed of sound within the material.

 

By the way, sulfur is a fuel, not really a stabilizer. It does however lower the ignition temperature, so in a way, it is a destabilizer.

 

Binders are usually polymers that adhere things together. There are of course different kinds of binders for different purposes.

 

As far as the plasticising of HE's it depends on the plasticiser. There are some energetic plasticisers, that actually assist, but there are some that do inhibit. I won't go into much more detail outside of the HE section.

[Frozentech]

I don't know the temp, but's far lower than that ! "Grunts" ( not just grunts, a lot of military in the field in Vietnam ) would use it to boil water in canteen cups to make coffee, because it was faster than using the issue hexamine tabs.

[Choscura]

thanks everyone, especially you mumbles. the shock wave thing was the answer I was looking for on that. just to make sure I have this mostly right, for example in a black powder charge (just an m-80 or something), the shock wave is created by the expanding gasses of first the fuse burning and then the powder in direct contact with the fuse, which compresses the rest of the powder against the outside of the charge (don't know if theres a better word for this, but it seems like this kind of language would be restricted to HE).

 

anyway, thanks everybody.

[Pyrohawk]

Errr....no not really. For starters M-80's use flash powder (BP is to weak an explosive. Secondly both black powder and flash powder are Low Explosives.

 

Low Explosives = "Deflagration" these are usually simple reactions which release energy (heat/light aka flame) and gasses at speeds below the speed of sound. There is no shockwave in these. Usually these are just oxygen and a fuel combusting.

 

High Explosives = "Detonation" These are more complex and release their energy when the actual molecuar bonds are broken. The "shockwave" is hard to explain much less understand. It's kinda like the energy from the first ignition is hot enough to break the bonds on the explosive around it and the energy released from that detonation moves through the rest breaking those bonds and releasing serious amounts of energy. It moves in a wave pattern of sorts... This occurs much faster and the gasses released are actually forming at speeds faster than the speed of sound. This creates a sonic boom of sorts....that's why in large detonations you feel that feeling like you get when a jet flies by.

 

Sorry if thats confusing and I'm no expert so someone feel free to correct me if I'm wrong.

[justanotherpyro]

One interesting fact about the soldiers who used lit C-4 to heat something, many of them lost legs trying to stamp it out. It is safe to be handled fairly rough as is, but once its hot enough a strong gust of wind can set it off.