Factice rubber-based propellants from vegetable oils

Quote: Originally posted by kecskesajt

I tryed to make hard margarine + KNO3 rocket fuel but it wont work.Even when I cooked out the water.It just dont want to burn.Isnt vulcanisation for hydrocarbons only?Like the tire on my bike or car.

Thanks Fulmen. Yes, most commercial factice seems to be made with low-cost oils like rapeseed and the like but I think one could target something harder by using a highly polyunsaturared oil like linseed oil, which is a 'drying' oil.

I've also dissolved sulfur in sunflower oil by strong heating which went brown and smelled horrible, but like you, I didn't see gelling, but commercial brown factice rubbers are solids, so it can be done. I think they need to be baked for long periods of time to fully cross-link, but I suspect it won't be more than a few hours with linseed oil. Temperature, of course, changes everything

At my hardware store, there's two kinds of linseed oil sold, one is 'ordinary' linseed oil, the other is boiled linseed oil. Supposedly, the latter is partially oligomerised already by strong heating, which would be a good thing, but I've read on somewhere that often this is ordinary linseed oil with a metal accelerant (catalyst) added, which could be a very bad thing or a good thing, who knows

Interesting what you said about the oxygen balance, I was thinking this might be the case but didn't have specifics to advise as you have. Thank you very much for sharing that. It would definitely help in terms of the physical properties of the propellant to have more factice in the composition.

Here's a picture of solid brown factice gotten from http://www.tradeindia.com/fp1157451/Brown-Factice.html because I know that people are going to moan that they're not getting theirs to solidify

[Edited on 15-3-2015 by deltaH]

"The siccatives could possibly accelerate the reaction to the point where runaway reactions become an issue. "

Yes, my worry as well.

"A curable composite propellant using household chemicals is pretty much the holy grail of amateur rocketry. "

In my country, KNO3 is available from commercial fertiliser companies that sell 25kg bags of it for something like $20-30 if I remember correctly. I recall seeing multi-kilo bags of "flowers of sulfur" available cheaply from the larger nurseries. So yeah... this could be a REALLY low cost way to build rocket motors if it can be made to work properly and if it doesn't spontaneously ignite during baking

Some more literature... discusses some activators and accelerators useful for making factice.

Attachment: Rubber seed factice.pdf (323kB)
This file has been downloaded 905 times

Also found this tidbit:

From:

https://books.google.co.za/books?id=2CYDAAAAMBAJ&pg=PA24...

So at least we know factice can also be made from linseed oil.

[Edited on 15-3-2015 by deltaH]



Ah ok, here's an in-depth article about linseed oil factice.

Attachment: Linseed factice article.pdf (378kB)
This file has been downloaded 598 times

Looks like adding magnesium oxide results in a much harder linseed factice and faster cure, interesting!

I suspect that it might be due to the formation of magnesium soaps from the oils and then cross-linking them... double wammy!

[Edited on 15-3-2015 by deltaH]

Yes exactly, also what I suggested earlier, first react the sulphur and oil until you get the sulfur dissolved and to thicken/gel the oil, then mix in the KNO3 powder, cast and bake to cure. I'd also add the MgO powder with the oxidant so as not to over thicken the initial phase. One still needs to be able to get out the air bubbles from the casting before curing.

I'm very excited about this, I wish you luck with the experimentations. Sadly, I now live in an apartment and can't experiment with this

[Edited on 15-3-2015 by deltaH]

Yes and I suspect the culprit is the glyceride component of fats which at high temperature can form all kinds of volatile and 'yummy' sulfur compounds. Oh well, no pain... no gain Organosulfur chemistry is nearly always going to be a stinker.

There are indeed a lot of things to explore with these formulations. Chemical inertness permitting, burn catalysts like freshly precipitated ferric hydroxide/goethite could be helpful.

Incorporation of aluminium or magnesium powder opens up another can of worms. Lots and lots of things to consider. Heck, I wonder if you could even make am oxidant free propellant by using high sulfur in the oil and aluminium, i.e. linseed, sulfur and aluminium powder only, using enough aluminium to form Al4C3, Al2S3 solids and H2

Quote: Originally posted by Fulmen

I've been digging through the literature in the hopes of finding something on odor control, but haven't had any luck yet. The stuff I just made is a stinky mess, hopefully there is a way to reduce the problem. Using strong bases wouldn't be my first choice as it might be incompatible with the propellant, nor do I see dangerous heavy metals as a good solution. Luckily most metal sulfides are insoluble so finding a safe candidate shouldn't be that hard.

One has to be careful with the use of sulfur scavengers lest it reverses the vulcanisation

Cobalt and manganese compounds would make great burn catalysts to, if they don't cause ignition prematurely during baking.

I'm excited to hear how linseed vulcanisation went. Particularly interested in the MgO 'trick', though I suspect it's not going to be easy to get it to react. I have a 25kg bag of industrial MgO product (mineral origin). It cost just about nothing, but it's very crude and impure and in the form of burnt flakes, a bit like burnt lime flakes. I suspect one would need to pulverise this really fine for it to work if my experience with lime saponification is anything to go on. Then again, 180°C is pretty hot...

To be honest, what I like about this idea (very much) is the low cost and simplicity... which in my opinion is worth having to deal with the smell, especially if the final set product is not going to be so bad. My factice soap bar I made only smells unpleasant when you stick you nose to it.

So honestly, I don't think it's worth the effort to remove glycerine as I've suggested before. Just need a fume cupboard for the initial stages or work outdoors far from people and stand upwind You need to setup an oven outdoors to bake it during the cure stage... one that you can afford to lose and also never use again for anything else.

Damn, I really wish I lived somewhere remote and owned a small piece of land... donations welcome of course, all in the name of science

[Edited on 16-3-2015 by deltaH]

I don't think "milk of magnesia" will settle out on its own

You can buy flocculant from the pool section of the supermarket or pool supplier, it's sold as "pool clarifier", in my country. Check composition.
Polymeric anions might work too... e.g. antacid that is based on sodium alginate, e.g. Gaviscon
Also xanthan gum, it's available in some health food retailers here.

Do dilute the flocculant heavily before using it.

I'm happy you're preparing magnesium hydroxide as this is likely the most active form. I don't think bulk MgO would be nearly as reactive.

[Edited on 16-3-2015 by deltaH]

Quote: Originally posted by Microtek

You could also try igniting the Mg turnings and collecting the ash (MgO)...

-- Speculation Alert --

It seems to me that there are some points to be gathered from this:

1. Degree of polymerization, and thus stiffness, is likely controlled by the number of unsaturated bonds in the starting oil.

2. Triglycerides in the starting product may yield glycerol if any strongly acid or base conditions exist. (MgO, H2S) which might lead to a runny, stinky liquid. (Insert poop joke here)

The following is a table of various oils with their percentage of unsaturated bonds, from Wikipedia:


I think a good approach (albeit a few more steps) is to:

1. Choose an oil which gives an appropriate degree of cross-linking when vulcanized
2. Saponify the oil with hydroxide and separate the soap from the glycerin
3. Acidify the soap to recover the unsaturated fatty acids
4. Form ammonia salts with the fatty acids, which dehydrate to amides on gentle heating
5. Add well-mixed oxidizer and sulfur blend to molten amides, cast, and bake to vulcanize.

In theory, the amides will scavenge H2S. The oil industry uses this to desulfurize petroleum. The amides also add nitrogen and hydrogen, which is a good thing for a propellant. (High delta-Hf for N2, low MW for H2)

Or, use transesterification instead of saponification to make maybe methyl esters of fatty acids, a la biodiesel. Separate the glycerol, add the oxidizer and sulfur to the oily part, and bake to vulcanize. In theory, the ester falls apart in heat plus H2S acid, and the alcohol flies away on the wind, which might help with hardening.

If runaway thermal events happen during vulcanization, there is a way around it. Simply pre-vulcanize an amount of propellant in a pan, then shred it into chunks and mix that with a fresh batch. The pre-vulc stuff reduces the heat generated per unit mass and would probably be effective at stopping a runaway. This is much like using grog (crushed and fired refractory) to prevent excessive shrinkage in uncured refractory mixes.

In any case, I would advise against leaving the glycerol backbone in any triglyceride intended for use as a propellant. Its abundance of hydroxyl and C-O bonds do not lend well to energy content or high flame temperature. Glycerol is difficult to burn in general. Have a look at the waste oil burner industry!

EDIT: Ahh, yes, amides are only very weakly basic. Amines are typical in hydrodesulfurization. Also, one might be trading the sulfurous reek for that wonderful fishy flavor.

As far as non-caustic and nicely soluble H2S scavengers, try NaNO2.

EDIT EDIT: No, I take that back! Ammonia salts of acids fall apart easily, so start with them. Just skip the conversion step to amides and use as-is. The conversion will happen during vulcanization and can go two ways: amide formation or entrapment of H2S, forming... err... ammonium hydrosulfide... Eh, on second thought I think it is going to positively reek no matter what!

EDIT 3: This is highly interesting: http://tenmasub.co.jp/en/products/sulfurchoride-factice.html

[Edited on 17-3-2015 by Praxichys]

Quote: Originally posted by Praxichys

-- Speculation Alert --

I simply have my speculation alert permanently on display as my tag, it's easier that way

Quote: Originally posted by Praxichys

1. Degree of polymerization, and thus stiffness, is likely controlled by the number of unsaturated bonds in the starting oil. .... The following is a table of various oils with their percentage of unsaturated bonds, from Wikipedia:

Quote: Originally posted by Praxichys

As far as non-caustic and nicely soluble H2S scavengers, try NaNO2.

I don't think H2S is the problem, it's probably thiols, the smell is much to terrible to be 'just' H2S. It's more like H2S on steroids
Removing glycerine may help reduce odour a lot as I suspect it's half of the problem (a la simple thiols...)

PS. Yes the white factice's are nice, but requires sulfur monochloride to make The whole point of this is to simplify propellants for the amateur.

PPS. On the bright side, the government will love this cause dogs would probably smell it being made from the next city (I'm reffering to the brown factice)

[Edited on 17-3-2015 by deltaH]

Whole linseeds are also sold by the packet as a health food these days. What about blending the whole linseed and then adding the other ingredients? All that fiber should stiffen the resulting factice a lot. If you're lucky and can find a bulk supplier of raw whole linseed, it might be fairly cheap (as opposed to heath food store prices which I find very inflated).

One might fake this effect by making use say blended newspaper and linseed oil for added stiffness. Hell, this is basically the propellant equivalent of linoleum flooring (made from linseed oil dipped cotton rags)

The carbohydrate content of the fibre might help the burn.

EDIT: Sorry keep saying linseed, for the whole seed, the name 'flax seed' is more appropriate.

The notion that you could simply blend flax seed, sulphur, potassium nitrate, then compress and bake to make a composite rocket fuel sounds mad though, I must admit Warning: blending together may lead to spontaneous ignition, blend seperately!

[Edited on 17-3-2015 by deltaH]

I think we're far enough off the beaten path as it is

Good news: The MgO is done, 1 hour @400°C should be enough. I tried heating 10 parts rape seed oil with 1 part MgO, no visible reaction occurred. So I added 2 parts sulfur and continued heating. The MgO wasn't fine enough to stay in suspension, and the precipitate quickly turned black. I'm assuming some sulfides are formed. Continuing heating and stirring the oil turned dark brown and thickened within 5-10 minutes. This time the smell isn't as bad, smells more like elemental or burning sulfur rather than that smell of death I got the other day. Whether it is due to the MgO or more gentle heating I don't know.
After 30 minutes the factice was still liquid, so I turned off the heat and let it cool. It ended up as a semi-solid sticky goo, not far off from the previous result. I will try heating it further tomorrow while I dig for the linseed oil.

STEP 1: Saponification of linseed oil

Bought a 750ml bottle of light brown raw linseed oil at my hardware store today. It was about halfway in cost between cooking oils and olive oil, so not too bad.

I dissolved 35g NaOH in 35g tap water with gentle swirling in a 500ml polypropylene plasticware with a good rubber sealed lid and side snap wings. Then 5ml didecyldimethylammonium chloride (30% w/w solution, black algaecide for pools) was added in one portion as phase transfer catalyst and formed a white milky precipitate (presumably sodium chloride). 250g Raw linseed (flax seed) oil was then quickly added to the very hot solution, the lid secured tightly and then contents was shook by hand, making sure to firmly hold the lid and base down in a pincer grasp because the pressure increases slightly. The hot emulsion was then shaken by hand at a leisurely pace for several minutes until it thickened (trace reached) and resembled mustard after which it was set aside to react further overnight.

I'm pleased with the saponification so far.



EDIT: I had a brainwave, I was going to acidify and isolate the fatty acids tomorrow, but I just realise that I can simply cook this soap up with a concentrated Epsom salt solution to form and salt out the magnesium soap directly (since it is insoluble). I can then mix this with catalyst, NaNO3 and sulphur, compress and then bake to vulcanise.

UPDATE: To quote fulmen, look like it's taking its sweet time Next morning, it's a little firmer but still not fully saponified in my opinion. I'm going to put the container in a small dish with water and boil it slowly for a couple of hours to speed things up. Perhaps my phase transfer catalyst isn't working as well as I'd hoped.

[Edited on 21-3-2015 by deltaH]

Quote: Originally posted by Bert

From personal experience, flammable oils, either of organic or mineral origin in VERY small percentages will greatly slow a solid fuel or other pyrotechnic mixture- This is done deliberately to make "oiled stars" that are intended to smolder all the way back to the ground (or water... I would only fire these over a body of water, deep snow, etc.). A friend who was less cautious calls these "FSAFOYH" stars (as in "flaming shit falls on your head"). Some will add a % or two of oil in a fast evaporating solvent to black powder rocket fuels that are too fast burning for the intended motor size, then dry off the solvent. If done correctly, the remaining oil slows the fuel down just enough to prevent a CATO- add just a little bit more, and they sometimes won't leave the ground!

I'm hoping (though can't promise) to ditch the really inert waxy unsaponifiable matter, saturated fatty acids and maybe monounsaturates as well. Their soaps aren't very soluble, so when I boil up my saponified linseed mass, I should be able to skim them off before adding magnesium sulfate to precipitate the magnesium soaps.

I should be left with something enriched in polyunsaturates if all goes well (which it seldom does ) which should be far more reactive.

Finally, I have a bottle of ferric nitrate nonahydrate. I'm going to add a few percent to the final mix with sulfur and oxidiser. This should decompose on heating (during vulcanisation) to a ferric oxyhydroxide/sulfide that I'm hoping will serve as a cracking catalyst for the organics when burning. I'm borrowing here from industry that use 'iron muds' to crack very heavy petroleum oils/tar.

[Edited on 21-3-2015 by deltaH]

STEP 1: Saponification of linseed oil - UPDATE

Yay, saponification complete, placing the PP container in simmering water for three hours did the trick and produced an interesting linseed oil soap... a first for me

Now on to salting out and Mg ion exchange with Epsom salt.

STEP 2: Magnesium ion exchange and salting out

[1] Simmered my linseed soap with 1000ml water for 90 minutes. Most of it dissolved, but a few gelatinous blobs remained insoluble.


[2] Carefully poured out the solution using a spoon to hold back the floating insoluble bits.


[3] The clear solution in a stainless steel bowl, hopefully somewhat enriched in unsaturated fatty acid soaps (wishful thinking )


[4] Added 100g Epsom salt (MgSO4.7H2O) in one go into the hot soap solution while stirring gently. It immediately precipitated 'curds'.


[5] Carefully poured out the slightly milky liquid using a spoon to hold back the curds. I was careful to not squish the curds in the process as they were very soft and I wanted to maintain their granular form for washing. I washed twice with tap water and stirred very gently when washing.


[6] After my final wash and decant, I used my hands to compress the magnesium linolate precipitate. It felt like a very soft and fatty dough.



[7] Spread out the product on several sheet of newspaper to soak up the excess water. Some ink transfer occurred on the underside, but I'm not too bothered by that.

All-in-all, this was great fun!

[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by PHILOU Zrealone

Just a few side notes! 1°) Ca(OH)2 would also provide precipitated unsoluble soap and may be cheaper than Mg soap. 2°) Mixing cationic soap with anionic soap result in a waxy precipitate and ruins the soap effect of both cationic and anionic surfactants. (C10H21)2N(CH3)2Cl + NaO2C-R --> (C10H21)2N(CH3)2O2C-R+ NaCl didecyldimethylammonium linseed-oleate

[1] Yes, but I had a packet of Epsom salts for the bath that I never used

[2] I've experienced this with close to one-to-one mixes, but not so much with small amounts. I cannot know if this helped or not for sure without rigorous comparison with a control, but I figured it wouldn't hurt much to have a little in there in case it could help.

***********
I decided against letting the product dry out as the little bit on my hand started to go slightly tacky as it was drying and I was worried this was the beginning of radical polymerisation.

Most of the excess water had been absorbed into my newspaper anyhow, the remaining product resembled a soft dough with a similar light yellow colour. I transferred to a sandwich bag and keeping it closed with air squeezed out until I decide what to do with it exactly.

The last thing that I want is for it to become really hard and useless.

[Edited on 21-3-2015 by deltaH]

They were still soluble in fresh water and were soapy, like store bought transparent soap. While I cannot discount this for sure, it also resembled what I frequently observed with ordinary saponification of other oils, e.g. olive oil etc. There's always hard to dissolve blobs that are nevertheless soapy. I don't think this was the complex of the two as you say, but it could be so. It could also be simple saturation

The one-to-one aspect is not that great, with things like Mg and Ca, you have at least two unsaturated 'strings' to cross link. Also the DMDD is completely saturated and large, not that great for the hardness of the final product I think, nor reactivity. I'm really trying to maximise the degree of unsaturation as much as possible, in that respect, I'm pleased to see yellow colours

****************************

[Oh, forgot to mention that I don't think the magnesium linolate is totally insoluble... I managed to wash it off my hands fairly easily and it was soapy to the feel. It might be less soluble than sodium, but I wouldn't say insoluble, it's more like another kind of soap and very soft like an oily dough.]

EDIT: I take that back, some of it clinging to the pot was really hard to wash out, I think there was some residual sodium linolate in the paste that made it easier to dissolve.

There's probably a fair bit of moisture in there still and not to sure what to do about it. From its marvelous consistency, I'm very tempted for a step 3 to just add the other powdered dry ingredients (S + NaNO3 + Fe(NO3)3.9H2O) and 'knead the dough' before baking in a mold to set, but the water in there could cause problems.

A desiccator with inert atmosphere/vacuum would have been handy right about now

[Edited on 22-3-2015 by deltaH]

I need some advice on my formulation stoichiometry for my step 3:

I've made a spreadsheet with the following design parameters:

[1] Amount of NaNO3 to target formation of CO and H2O from the fuel (in reality there will be some mix with H2 and CO2 because of the water-gas shift equilibrium and iron catalyst present which is active for this reaction). I'm using fulmen's suggestion to run fuel-rich, which I think is a great idea.

[2] Enough sulfur to form all Na2S from the NaNO3

...and assumed my magnesium linolate is in fact pure magnesium linolenate (the other fatty acids in there should make only minor differences to the final weight of oxidant required etc.)

Now for the ferric nitrate. In the presence of basic soap, it's not unreasonable to assume that the ions would swop to a degree, forming ferric linolate and magnesium nitrate. In a way I'm pleased about this if it happens as ferric linolate would be a three prong soap and so can result in a more cross-linked factice (harder?) as well as dispersing the iron catalyst better in the material to favour cracking of the oils.

This results in an iron mass fraction of 1.3%, but that will go up in drying. This seems like a reasonable number.

What are your thoughts/suggestions on my composition formulation I've laid out?



Simplifying, this rounds off to:

• 6 parts NaNO3
• 2 parts magnesium linolate
• 1 part sulfur
• 1 part ferric nitrate nonahydrate

all by mass.

Planning to grind a small amount of these together in a mortar and pestle and then see what to do next, compress and bake is one option. This is obviously not castable, would have to go the liquid free fatty acid route if one wanted to make something castable, but it's a good way to check what the final material would be like physically and if it will burn. Still worried about the water that needs to come off... hope that doesn't mess everything up.

***********
Just realised I should have salted out and ion-exchanged using ferric nitrate in step 2 to make ferric linolate directly, stupid of me If I had some ferrous sulphate, even better, oh well, next batch...



This is the structure of the iron clusters in ferric acetate according to Wikipedia. This seems too good to be true for my materials, now I have to try to make ferric linoleate using my ferric nitrate to salt out.

That beast has six freakin' legs!!!


[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by PHILOU Zrealone

The DDMDD ammonium chloride as phase transfer is of no use because as soon as NaOH/water hydrolyses the oil, it forms a soluble anionic soap that will be the phase transfert catalyst increasing the saponification speed.

I'd never heard of Factice until you started this thread. Thanks !

Trying it out (simple factice) was a little smelly and messy, and didn't work out too well.

Olive oil and Sunflower oil were used: 50g oil, 12.5g Sulphur, 5g Sodium Carbonate.
Air was bubbled through the oil for 15 minutes, then the oil heated to 140C, the reactants added, and the heat removed once the reaction kicked off.

Sunflower oil reacted a LOT faster than the olive oil.

Both results are a viscous orange/dark brown liquid. The sunflower version is a lot more viscous.



[Edited on 22-3-2015 by aga]

Wow aga, I'm amazed you tolerated the smell of that so well!
Nice photo's BTW, you make tar look about as good as it possibly can look in your third photo
The olive oil one looks like crude oil (probably smells similar but much stronger) and the final one looks more like tar.
To produce rubbery factices, you really do need a 'drying oil', cooking oils just don't have enough linolenic acid derived triglycerides.

My second batch of sodium soap of linseed oil is nearly finished, about to do the 90 minute dissolution before attempting an iron ion exchange and salting out of ferric 'linolate'.

Quote: Originally posted by deltaH

My second batch of sodium soap of linseed oil is nearly finished, about to do the 90 minute dissolution before attempting an iron ion exchange and salting out of ferric 'linolate'.

STEP 2b: Iron ion exchange and salting out with ferric nitrate

The ferric nitrate didn't yield as practical a result as the magnesium sulphate did.

The product appears to be a semi-fluid and the solution remaining still appears quite red. Not so sure what's going on here. I think the salting out effect is not working as well with the nitrate as it did for sulphate, but it worked in part, so letting it cool and will try to isolate the red-brown semifluid gloop that's floating on top. Definitely not as well behaved as the magnesium sulphate salting out.
Perhaps this would have worked better with ferrous sulphate?



In some way, this gloop resembles the oil dough consistency of the magnesium 'linolate', but it's so soft that it's actually runny. Seems like the higher the cation charge, the softer the resulting polyunsaturated soap, which makes sense.

I think I'm going to put this into my freezer to see if I can harden the ferric linolate... it's hard to work with it in this thick semi-fluid gloop state.

Interestingly, this might actually be close to a castable material!

[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by deltaH

The product appears to be a semi-fluid and the solution remaining still appears quite red. Not so sure what's going on here. I think the salting out effect is not working as well with the nitrate as it did for sulphate, but it worked in part, so letting it cool and will try to isolate the red-brown semifluid gloop that's floating on top. Definitely not as well behaved as the magnesium sulphate salting out. Perhaps this would have worked better with ferrous sulphate?

Thanks blogfast for the suggestions. I have an excess of ferric nitrate in there since I used 100g and there once again remained a fair amount of insoluble sodium linolate behind when I dissolved it in the step prior, so the pH of the solution is acidic. I'm relying on the insolubility of the product to force it out of solution.

It looks like it worked, it's just that the physical form of the product makes it cumbersome to separate, it's a runny gloop, but low temperature might help a lot (freezer). If I can just get it to firm up a little, I can manipulate it better and wash.

I definitely think using ferrous sulphate is the way to go, it should ion exchange and salt out in a similar fashion to what the magnesium suphate did, I just didn't have any on hand, but had the nitrate

In the end, it should matter what oxidation state the iron's in, the active catalyst I imagine would probably be reduced iron anyhow. I want a lot in there because the iron is going to be a lot less active with all that sulphur that probably poisons it. That said... I do know that ferric oxides speed up the burn of sugar+sulphur+saltpeter from personal experience, in-spite of the sulphur, but again, I used a few percent there, not hundreds of ppm's as one would normally work a catalyst.

Quote: Originally posted by deltaH

However, the iron soap is changing matters, since the ferric linolate is runny, it might be castable as is. Anyhow, early days and lots of work in store.

Praxichys mentioned using xylenes as a diluent on page 2. I'm not a fan of the paraffins, I think they will slow down the burn as Bert mentions somewhere thereabouts too.

Yes, the water may be a problem, particularly for the baking stage, as it might mushroom out the cast.

I'm thinking it might be carefully heat treated first to remove the water... like one would normally dry an oil. It is a semi-liquid after all, should be no problem to heat to around 100°C and hold for 30 minutes. I don't think it will froth because it seems to behave more like a hydrocarbon and less like a soap. I think it doesn't have the right shape to be a surfactant.

In fact, I'm probably going to boil down this mess I made to isolate everything and pray it doesn't polymerise, instead of sticking it in the freezer. It's going to contain sodium nitrate, but I'm adding more later anyhow and I know how much is in there which is what really matters

[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by Bert

From personal experience, flammable oils, either of organic or mineral origin in VERY small percentages will greatly slow a solid fuel or other pyrotechnic mixture-

Yes saponify linseed oil first with lye, then boil up to dissolve most of the soap, then use magnesium sulfate (Epsom salts) to salt out and produce the magnesium linolate that you can use to make factice. It should be far less stinky, but that is to be confirmed

[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by deltaH

I strongly advise making soaps from the oils first and ditching the glycerine, I have a strong suspicion that it's the main culprit for making the severest stinks by way of volatile thiols. Also the making of a soap also reduces the volatility of the fatty acid, particularly with Mg and Ca, this also helps.

Quote: Originally posted by blogfast25

Quote: Originally posted by deltaH   I strongly advise making soaps from the oils first and ditching the glycerine, I have a strong suspicion that it's the main culprit for making the severest stinks by way of volatile thiols. Also the making of a soap also reduces the volatility of the fatty acid, particularly with Mg and Ca, this also helps. I doubt is glycerol has much to do with it. I worked for years in material development, including oodles of sulphur vulcanised rubbers. Well, even these glycerol-free processes stink, even though the raw materials are of very high MW. Model studies of very low molecular weight dienes, sulphur vulcanised with accelerators, showed tens of sulphur bearing structures and byproducts to be the reaction product mix. And these stink to high heaven, as we know. I also kind of fail to see how sulphur would affect the ester bond. Factice producers use the oil rather than the fatty acids because a higher viscosity gel is obtained with the oil. Or so I've read...

Quote: Originally posted by aga

Sounds like i have to get some Linseed oil and do a whole series of experiments. Reminds me of the CHRIS25 Aluminium Sulphate Saga. Well, we succeeded on that one, so i guess it can be done.

It's really easy actually, there's a step by step photo essay on page three for making the magnesium 'linolate'

All you need is linseed oil, lye and Epsom salts, all OTC.

[Edited on 22-3-2015 by deltaH]

Quote: Originally posted by deltaH

At high temperatures triglycerides crack and release small amounts of glycerine which can then react with sulfur to make water and thiols, at least in theory.... Industrial factice is not necessarily a good rubber, it's blended with normal rubber to give a nice finish to it, that's why the industrial ones can be made from things like rapeseed oil, that gives gelatinous stuff, but not what we're after.

Quote: Originally posted by deltaH

The Ebewele paper on page 1 has the proof of the pudding.

Quote: Originally posted by blogfast25

So saponifying linseed oil does not strictly yield a 'linolate' but rather a mix of soaps. And, based on their fatty acid profiles I'm still at a loss why linseed oil does gel with (a lot of) sulphur but sunflower oil does not.

'Linolate' is my made up word for soaps of linseed (of all fatty acids), which is why I try to enclose it in quotes. Linolenate, linoleate, palmitate etc. on the other hand, is specific and real (referring to their respective acids) and so magnesium linolenate is a major component of a magnesium 'linolate'. It's a bit confusing, sorry

As for why linseed oil works better, I think that there are more 'sites' for vulcanisation with the triple unsaturated fatty acid oils and so more chance to have continuity in cross links between sulphur chains across the polymer network as a whole and so a more rigid structure.

Quote: Originally posted by blogfast25

Quote: Originally posted by deltaH   The Ebewele paper on page 1 has the proof of the pudding. Actually, assuming we're talking about the same paper: Polymer processing aid from rubber seed oil, a renewable resource: Preparation and characterization. R. O. Ebewele1, A. F. Iyayi2*, F. K. Hymore3, S. O. Ohikhena4, P. O. Akpaka2 and U. Ukpeoyibo2 ...then it does nothing of the sort. The paper isn't concerned with soaps and uses only rubber seed oil (RSO) in its experiments, not soaps of it, magnesium or other. It does evaluate MgO at 10 parts per 100 parts of RSO, as an accelerator/modifier in the vulcanisation of RSO. I'm surprised they don't seem to realise that in sulphur vulcanisation of rubber, zinc oxide (ZnO) is considered the invaluable and indispensable component. No sulphur vulcanising system goes without 5 to 10 parts of ZnO, per hundred parts of rubber. So that might be something to consider, to improve crosslinking and obtain a simpler (read: shorter S links) crosslink network. [Edited on 23-3-2015 by blogfast25]

The devil's in the details blogfast I've mentioned earlier in this thread that I noticed in that paper that their rubber seed oil is unusual in that it has a very high content of free fatty acids (FFA), some 38% in fact (it's in the 'materials and methods' section), so yes, mixing that with MgO and cooking up would make the Mg soap. It's a simple neutralisation reaction, not saponification, that proceeds easily. I also made the point that our everyday oils are typically quite low in FFA's by comparison and so replied to fullen's posts that I didn't think he achieved any significant saponification when he simply heated MgO with rapeseed and linseed oils because those don't contain such large amounts of FFAs and require traditional saponification methods if you want to convert them fully to Mg soaps.

Look, I might be barking up the wrong tree here with working with the Mg soaps, but I have a hunch they might (a) help to reduce the stench and (b) make a harder factice. This is hypothetical, of course, which is why I am doing the experiments to see...

The ZnO you speak of, does it have to be freshly precipitated high surface area stuff? I still have lots of ZnO left over from my experiments with zincates, it's calcined pharma grade. It seemed rather inert and I struggled to dissolve it as is in sodium hydroxide solutions back then. It did, however, dissolve in acid, so in you experience, do you think that would work as is, because I'd be very happy to use it

[Edited on 23-3-2015 by deltaH]

Managed to boil my ferric 'linolate' only for a few minutes before masses of dark and viscous red oil prevented me from continuing. Because of it's viscosity, it started to balloon instead of releasing the water vapour bubbles nicely. Looked like boiling lava mounds

It smells and dries very much like wood varnish... I really wish I owned a garage with a garage door that needed painting

Anyhow, I get the feeling this red oil is just ITCHING to harden up, I just need to get the bubbles out and to separate the water entrapped in it. I'm not keen to dilute it to drop the viscosity, sigh... it's a pain in the ass.

Finally got some sulphur and have two substrates to play with... stinky time

UPDATE: Okay, mixed 50 pho sulfur (yes I know it's very high, but about what would be necessary for a propellant) with my nice yellow magnesium linolate paste. Made a butter like material, but still very soft, like an oily paste. I placed a pea-sized bit on a SS spoon and attempted to gently/gradually heat it over a flame.

This produced an intense sulfur smell and small amounts of white fume, exactly as melting sulfur over a flame smells and looks. I'm pleased to report that it didn't produce any nasty organosulfur type smells, just strong sulfur fumes. It took me back to my childhood, making black powder.

I struggled to cook the factice in my spoon, the back charred while the top turned dark brown, but soon everything was char

Overall, it looks promising in terms of smell reduction, but a pea-sized experiment won't do. I'm less scared of it now that I've established it appears like 'just' sulfur fumes coming off. The residue wasn't too smelly either, so I'm really happy about that.

I need to buy some test tubes and repeat with slightly more of the 'special butter' and try to heat it more slowly this time around. I have a high-temperature thermometer, beaker and gauze, so I might use a small oil bath and target 160°C and immerse the test tube into it with some foil over the top. If the factice gets hard and stuck, I can always smash the test tube to free the melt.

I'll be heating incrementally and taking some photos.

[Edited on 23-3-2015 by deltaH]