Slow burning propellant

[IrvinLuker]

Good day.
I am a civil engineering professor researching the testing of structural foundations by applying to them a sudden force. My idea is to burn a propellant material in a steel tube, pushing on a piston which then pushes on the foundation. We have experimented with a common nitrocellulose gun propellant which produces a satisfactory force, but it burns too quickly. A burning rate (and hence rate of pressure generation) 1/4 (or less) that of the NC is needed. Can anyone suggest a suitable material?
Irvin Luker

[PyroJoeNEPA]

Might I suggest using a hydraulic system? What you are doing now is bordering on a pipe bomb which I am sure the authorities would not look kindly on.

[displayfireworks1]

Joe
Let’s not be too quick to judge this question. He is from South Africa I spoke with him by email and suggested he ask this question on the forums. I am not sure exactly what he is working on. Sir, perhaps if you can explain further we will understand. The question looks a little different than you sent to me.

[IrvinLuker]

Thank you for your comments gentlemen. With the guidance of a specialist pyrotechnic chemist/mathematician I have been using nitro cellulose (NC) gun propellant in another aspect of our foundations testing research project and can mathematically model its burning behaviour quite well. When using the model to predict NC's behaviour in a tube behind a piston, which pushes on the foundation, I find that the time period over which the force would be applied (5 to 10 milliseconds) is too short. I need a time at least 4 times longer. I thought that fireworks experts would know of a material that might do the job?

Irvin

[valmo2379]

you can test slow burning black powder ? i thing is probably better, and slower

[chris v]

Compression will always increase the speed of decomposition I will do some tests and see if I can find something

[chris v]

So you are testing to see at what point will the foundation will fail and cause separation between the structure and the foundation. The only application I see this test with a sudden force used for is to reduce the damage to a structure during an explosion

[chris v]

Flash mixed with a 10% NCL will make it burn a lot slower while keeping the amount of pressure released the same

[displayfireworks1]

What is NCL? Nitrogen trichloride?
Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (for example, in swimming pools).
http://i115.photobucket.com/albums/n313/mbrown3391/Picture1.jpg
http://i.ytimg.com/vi/yHMEvt1tcsc/0.jpg

[chris v]

NCL is nitrocellulose lacquer

[displayfireworks1]

I see, what is the name of that liquid used to roll cherry bombs in saw dust, for some reason I am drawing a blank.
http://www.skylighter.com/images/web_pictures/Nitrocellulose-Quart.jpg

[displayfireworks1]

Buy it on ebay
http://i.ebayimg.com/t/Nitrocellulose-Lacquer-Aerosol-Clear-GLOSS-or-SATIN-/00/$(KGrHqN,!l0E1F2GWImuBN,q)4kIjQ~~_35.JPG

[Chris H]

I have no idea what relevance the adhesive on the exterior of cherry bombs is, but it's typically a thinned waterglass solution.

Additionally, no one buys aerosol NC lacquer for use in pyro. It'd make kind of a mess when adding it to a powder, don't you think? You can very easily make it from a source of nitrocellulose lint or commonly from smokeless powders. The most common solvent is acetone or an acetone/xylene mix to help control evaporation rate. The other common solvent is just "lacquer thinner". It's composition is fairly variable, even though the properties are more or less uniform. I prefer acetone or acetone/xylene as I can be confident what is in it.

[displayfireworks1]

Waterglass, that is it. I could not think of the name. All I remembered is it was supplied in the same type of can.
http://www.skylighter.com/images/web_pictures/Sodium-Sililcate-quart.jpg

[PyroJoeNEPA]

Waterglass, that is it. I could not think of the name. All I remembered is it was supplied in the same type of can.
http://www.skylighter.com/images/web_pictures/Sodium-Sililcate-quart.jpg
Waterglass is the "common name" for Sodium Silicate. Na2SiO3. You can use it to coat cardboard mortar tubes & extend their life.
As for the NitroCellulouse Lacquer, it can easily be made by cutting up ping pong balls & dissolving them in Acetone [or nail polish remover]. This is then mixed with BP to make a slurry to coat fuse ends, spolettes, etc.

[IrvinLuker]

So you are testing to see at what point will the foundation will fail and cause separation between the structure and the foundation. The only application I see this test with a sudden force used for is to reduce the damage to a structure during an explosion
The foundation is tested before the structure is built on it. What we are doing in our research project is not quite the same as is normally done in the testing of foundations, but basically the reason for the rapid application of the force is that it enables more foundations to be tested in a day.

[IrvinLuker]

Flash mixed with a 10% NCL will make it burn a lot slower while keeping the amount of pressure released the same
Please excuse my ignorance, but what is "flash"?

[displayfireworks1]

http://i.ytimg.com/vi/7q72ALpJ2BA/0.jpg
http://cdn.gunaxin.com/wp-content/uploads/2009/07/m80-1.jpg
Read Here
http://en.wikipedia.org/wiki/Flash_powder

[RunBang]

Good day.
I am a civil engineering professor researching the testing of structural foundations by applying to them a sudden force. My idea is to burn a propellant material in a steel tube, pushing on a piston which then pushes on the foundation. We have experimented with a common nitrocellulose gun propellant which produces a satisfactory force, but it burns too quickly. A burning rate (and hence rate of pressure generation) 1/4 (or less) that of the NC is needed. Can anyone suggest a suitable material?
Irvin Luker

Have you ever tried to put some baking soda in your NC? it creates a delay without changes the reaction

[Firework Crazy]

I'd like to see a picture of what IrvinLuker is talking about...I've never heard of such a thing.