Sciencemadness Discussion Board

dissolving hexamine into paraffin

koshkadrook - 10-12-2005 at 18:51

Hello, help out the new kid on the block?? :D

I started myself by asking what fuel has the most BTU
(heat content) per cubic centimeter. I learned that it
is most likely going to be paraffin wax:

Paraffin wax has got from about 19 to 36 carbons on
each molecule.

Now then, I want to increase the BTU content per cubic
centimeter. One way, effectively, might be to add oxidizer
so its more intensely burning. But that leads to explosives
and I am fearful of that type of experimenting.

Can I dissolve hexamine into paraffin? I want to think it
is like dissolving a bunch of salt into water-----the volume
does not increase, but I have added molecular mass to
the paraffin. When it solidifies, the paraffin should have the
extra fuel embedded at the molecular level. True or false?

If the hexamine will dissolve, then it seems
like the hexamine ought to stuff into the gaps between
the long-chain paraffin and the volume of the mixture
maybe will not increase. True, or false? Will it be stable?
Will it stink, or melt or will the hexamine sublimate out of the
finished wax compound? :o

I like to think it is safe, because this is only to mix fuels
together, and no oxidizer has been added. :)

I ordered the materials but nothing showed up yet.
If it will not dissolve what do I add?

By the way, I am a chemistry amateur but I welcome if
you can demonstrate how off-base I am, and what to
expect based on your higher level of experience.

Also, why doesn't candle wax have double-bonds (partially
hydrogenated). Seems like more energy would be liberated
out of double-bonds while combusting in the atmosphere?

Thank you. :D

DeAdFX - 10-12-2005 at 19:20

I would say melt about 10-20grams of parafin. Then measure out a gram of hexamine and see if it dissolves in the molten paraffin.

If it doesn't "appear" to dissolve it is either insoluble or insignificantly soluble. If its soluble keep adding hexamine in small amounts until you reach a limit

The only solvent that can dissolve hexamine to a large extent would be water(that I know of). So I do not know if there are any energetic things that can dissolve hexamine

I believe when you add NaCl to water the volume increases a bit. I don't know for certain but when I added Ammonium Nitrate to water the volume did increase. Ill assume that the same thing would happen to non polar compounds(wax)

[Edited on 11-12-2005 by DeAdFX]

BromicAcid - 10-12-2005 at 21:06

Hexamine could really have from almost non-existent solubility to slightly noticeable solubility (found references to it being soluble in water [of course] and non-polars like chloroform [but paraffins are even more non-polar]). You're right in that some things can be mixed to give a volume lower then the sum of the volumes of the ingredients, this is because, in the case of a solid going into a liquid the loss of the rigid crystaline structure which can lead to this effect, it can also be seen in the liquid phase, if you mix 50 ml water with 50 ml 100% ethanol your total volume will be less then 100 ml, because the ethanol slightly disrupts the hydrogen bonding (or something to that extent) so if your hexamine is fairly soluble in paraffin (which I honestly doubt, but I have been suprised before) then you may end up with a solution less in volume then the sum of both beforehand. But really the effect will not be all that dramtic.

What type of paraffins are you using? There are brands of liquid paraffins and solid paraffins, in either case you could probably end up with a solid in the end that contains a colloidal hexamine mixture that won't separate as long as it is solid, you might just kneed them together. Who knows how it will burn though, paraffins are used in a different manner then hexamine correct, you use paraffins with some sort of wick and hexamine is used as tablets, if that is the case you might just end up with hexamine left at the bottom of a wick and all of your paraffin might be gone at the end.

koshkadrook - 11-12-2005 at 00:40

Thanks for input so far. I'll mention when I have tried the materials. Sounds like
hexamine may not want to dissolve in the wax. :(

When you let wax cool to room temperature, the paraffin contracts into a solid block. I want the solid block of fuel, with purpose of burning in the ordinary
atmosphere. The wicking is being handled separately, and is taken care of.
It would not matter if the fuel is a block of paraffin, or a block of hexamine (sold as "Esbit" for steam engines), or whether i can combine them together.

I would sure like to combine them and get higher BTU per CC. Did anybody
check the link, it shows the BTU per CC of a lot of materials. It is interesting
that paraffin (candle wax) is one of the best. When I study a 3D diagram
for fuels like paraffin, it surely looks space-wasteful. Even benzene has
appearances of higher density. Ha, but then is much more toxic.

There must be molecules, solid at room temp, that have higher BTU per CC.
I still wonder about partially hydrogenated chains having more power?
Or what about pure carbon compounds based on charcoal? Can you burn
a diamond? What is its BTU per CC?

NASA is impressed with paraffin BTU per CC, they are working to make
new designs of rocket engine that run on a block of paraffin:

halogen - 13-12-2005 at 13:22

Yes, most certainly can burn a diamond but unless your a millionair, I see no point in doing so. BTW ever seen that mythbusters episode where they made the nitrous rocket? Nitrous oxide oxidiser and parafin with charcoal in it. Quite powerful...