B1 + dextrin strand fuel test

This strand was from the modified B1 mix with dextrin.

Exact composition, calculated:
58% KN
33.15% simple sugars (saccharose mostly)
7.4% dextrin polysaccharide
1.45% Fe2O3 - TD202 pigment

total fuel content: 40.55%

Burn rate 1 inch in 5.3 seconds exactly (measured frame by frame - 159 frames at 30 fps.)

Using manganese dioxide as a ferric oxide replacement? Looking back at results.

Manganese dioxide. Mn is closest neighbour to iron, molecular weight is one less than that of iron. 54.938g/mol. Win for manganese.

1. MnO2 has more oxide content than Fe2O3, as 2:4 is better than 2:3. Win for burel (MnO2).
2. Standard enthalpy of formation for MnO2 is −520.9 kJ/mol, while for Fe2O3 it is −825.50 kJ/mol. MnO2 has more energetic potential per oxygen and per molecule. Double win for MnO2.
3. Fe2O3 decomposes only at its melting point of 1566 °C (1838 K). MnO2 releases first oxygen at 535 °C (or 553°C for 95% purity paint grade) and this process continues up to 800°C. 2*MnO2 -> Mn2O3 + O2. Mn2O3 melts at only 940°C. By heating Mn2O3 or MnO2 over 800°C~1000°C further oxygen is being released when Mn2O3 molecules transform into Mn2O3.MnO complex. Mn2O3.MnO is very catalytically active, reducing nitrogen oxides and oxidizing CO, both reactions we need for more heat in combustion. Total combustion of light organics has been observed at only 400°C on Mn2O3.MnO! Quardruple win for Mn2O3+Mn2O3.MnO!
   
4. Fe2O3 melts at 1566 °, and Mn2O3.MnO melts at 1590°C. While we typically have much higher surface area in the Fe2O3, the Mn2O3.MnO has been already in liquid form at lower temperatures and released one third of the oxygen by that time and now all hell will break loose with this strong catalyst as it gets liquid! A win for Mn2O3.MnO I guess.

Some of the sources:
Iron (III) oxide
Manganese dioxide
Manganese (III) oxide
Manganese (II,III) oxide
Problems? Yes.

1. You will not get MnO2 in the same superfine powder as you can get the ferric oxide. The MnO2 particles will be about double the size and I think the ultrafine dust will not be present between them. A big lose point for MnO2.
2. The same variety of manganese compounds has higher stability than its iron counterparts. KMnO4 for example exists in solid state, KFeO4 exists only in certain solutions and decays quickly. Iron compounds are easier to decompose.
3. For superior performance of MnO2 you need very high combustion temperatures, or at least localized burn points of over 1600°C. This can be helped by introducing magnesium powder into the mix. Most rockets can't affort that complication.
4. Fe2O3 and iron compounds react with saccharose and glucose to form saccharates and gluconates.
5. Fe2O3 dissolves in molten KNO3.

In the large comparative test Richard Nakka made here you will see that the surface area of the CuO and MnO2 was far, far inferior to the "brown iron oxide" which is perharps just the finest milled alpha-Fe2O3 that is sold, red iron oxide, that is so finely milled that it appears as dark brown.

One other explanation yet to be proved is that the brown pigment was fine mix of either Fe2O3.FeO+Fe2O3 like pigments SHD or the Fe2O3 + MnO2 pigment HM.

Links:
Color chart of the concrete pigment types
Table of composition of various pigments.

Also note that I still insist on existing chemical reaction between sugar and the superfine TD-202 pigment I use. Burn rate of 4.79mm/s on air.

Effects of sulphur on KN-sugar mix

I mixed some sulphur powder into the B1 powder and heated. It takes long to get it mixed at all, but then it happens and you have a very plastic mix with decreased viscosity and supposedly no intercrystalline water content. Classical recrystallized rozketry as Yawn does it works with saccharose hydrate that released the water to make the mix somewhat formable when heated.
When you use dehydrated powder instead and mix some sulphur in, firstly you notice the smell of SO2 in your nose and eyes as the SO2 reacts with water to form H2SO3. Ouch. I used heater which kept the temperature jumping from 130-145°C due to the thermostat hysteresis.
Results: shortly after the mix is formed, whitish sulphur is noticeable, but when hot is is plastified enough. I took four small samples. One fresh as soon as the mix was complete and paste-like. The other three were taken in some ~1h intervals. The viscosity and plasticity of the other three samples was much lower than of the fresh one, the latter three were about the same. I suspect less sulphur in the last sample due to sublimation. It also became apparent some chemical changes happened as mix retained much of the plasticity well under 100°C.

Chemical reactions, tests

TESTS: the four tiny samples were hot-rolled to form strands and kept on a table overnight.
Original state they were left in: hard, candy like
Condition in the morning: moist to outright wet. It was proven that the longer the sample was heated the mohe humidity it gained. I could try weighting methods next time.
- The first sample was still solid, original texture, burned well
- The second sample was bendable, formable, it was plastic like when hot, burned well
- The third sample was really moist, like... burned well
- Fourth sample was wet like bread in water, it left largest stain on the table. Burned well.

Conclusion on chemical processes:

1) saccharose hydrolysis releases water (either during caramelisation or by other means below)
2) acidic environment promotes hydrolysis (SO2 and H2SO3 and NO3-)
3) fructose has low melting point of 103°C compared to saccharose (186°C), or even sulphur (115°C)
4) fructose is highly hygroscopic, candymakers are scared of 0.5% fructose content in saccharose
5) H2SO3 is hygroscopic too (but less than H2SO4)


I wasn't able to confirm any nitrating of the sugars, which would be really, really nice ;-), but the surprise that it burned in 2mm thick, wet strand was really surprising!

B1 mix (batch 1, bake 1)

The idea was to create a molecular mixture or to make a molecular complex.
Not entirely succesfull. I will not publish the idea behind it yet.

The content by weight:
KNO3 - 400g
saccharose - 225.6g
Fe2O3 (TD202 type) - 10g
dextrose (D-glucose) - teaspoon (2-3g)
<0.5g other inert material ~300ml solvent water preparation method undisclosed for now, still improving it. I processed the sugar in two batches by accident anyway. The resultant solid material is suspected to be microporous, the resulting burnspeed in open air is about 1-2 inches per second at most, 1cm/s the least for a wet 'stone'. After careful observation I saw long, microscopic crystals of KNO3, this is the result of quick drying process (QDP). QDP also requires equal heat distribution and high, controlled temperature. Under certain conditions the surface area of the KNO3 will be the highest possible.

Not useable as such as it is rock solid because it hardened and dried as I was preparing it. I was able to stir it and model it, but when removed from the soutce of heat the material solidified and dried. It was possible to crumble the material when hot, but as it is cold and solid now, it is very hard to crush it. * about 10-15g of crushed B1 spread in lenght of 7cm burned on thin paper (slightly weaker than office paper ~70g/m2) in about 0.5s generating large plum of smoke and leaving the paper INTACT. Well the paper catched smoldering on few places after the B1 burned out, but not under where the B1 was, but all over. * I'm keeping the 'stones' of B1 fuel dry, when I tried to light up one of 8mm in size (0.3") it burns so fast you will not have time to retract your hand as it flies away. Waiting for my camera to return home. * to further decrease viscosity of the molten mix - add sulphur. Plasticity of the heated mix dramatically improved from hard marmelade like to strawberry jelly jam like. So soft it could be injection molded. Burn rates are also higher and the tested strands became airborne soon after igniting. Melting point of sulphur is 115°C and it does not dissolve in the sugar, therefore we can expect the mix to melt in low temperatures.

* the flame from added sulphur is not as straight and jet-like like from pure mix. The sulphur tainted B1 has sideflames, like if more rocket engines of different angles were burning there. [note: not all mixes with sulphur did that, but all burned with less dust smoke (Fe2O3) and more flame]

Wetted, softened mix.

new composition.

With very high water content - orange flame, no visible boil zone, the boil zone glows yellowish-red. 30mm sample strand is almost liquid when heated, like a hot petroleum modelling clay, but solidifies to a very hard, glassy substance. (sign of lots of intercrystalline water).
A 30mm strand burned in 7.6 seconds - that would be 6.4 seconds per inch. This is a bit faster than standard J.Y. RCANDY, and I did it with higher water content. This sample was prepared from the BAKE1 - BATCH1 (B1 in text). I took 20 grams of B1, added 1.6g of dextrin.

Back to the yesterday: The mix experiment preparation: 20g of B1, 1.6g dextrin. Added little water, mided by a spoon in a mug. I tried drying in kitchen oven with temp. set to 120°C, but the sample was heated on a paper not with hot air but by radiation from below, so overheating is more than likely since the paper it was drying on got yellow around the mix. The mix itself bubbled and foamed, and was something between softie and crispy, and rather crisp after cooling (but still compressible without crumbling all over!). Burn rate after baking? Enormous. I hammered some of it together in form of a 3x3cm patch (~1x1 inch) and lighed on a side. After catching fire on the paper (~0.5s) it burned whole in ~0.3-0.4 seconds in a large plum of standard smoke. As the smoke plume raised to the sky it looked like a nuclear blast mushroom.
* Some sugar modification is likely to have taken place in the oven because the mix is higly hygroscopic, it went all wet and marmelade-like in one day being left in open air in a room.

Today: However I put in on a iron, set to "** WOOL" and dried it somewhat after long time to get the result mentioned in the beginning. One note: it doesn't have a texture. It resembles clay with some dirt in it.

Temperatures in the heated soft mix:
145°C on the bottom near the iron
130°C in the middle of the mix
108°C 1mm under the top (still very formable like a paste)

I will have my camera again in two weeks so only cameraless tests for now.

Did I mention the dextrin molecule absorbs moisture very effectively? The dextrin is used as a glue for post stamps and such. It has a characteristic smell, etc. See the wiki entry. DEXTRIN

Moderate results after careless redrying:
* The next test strand is 7mm thick and one inch long. The burn speed slowed down to 7.5 seconds and left a carbon residue in the middle. Probably a result of bad mixing together with the overdrying.
* I used another smaller piece of what has left (3mm dia, 1cm lenght) to check the flame size - it is 5cm long now. (2") Unequality of this last small chunk of the mix becomes apparent.
* I made thinner strand of the last remaining stuff, one inch long, 5mm thick. After two seconds it started burning faster and louser. The flame lenght was 7-9cm (2.7"-3.5") and the 1 inch burn time was 6.7s

Second experiment today:
In a similar wetty plastic mix I made with similar method as above the test strand from material that did not even pass the "snap test" about one inch of the mix burned in 4 seconds. The difference was in preparation:

* I tried to make dextrin-KNO3 mix, but it did not burn well, the flame always went out after a split of a second. The mixture was: 6g dextrin, 9g KNO3 and 0.5g Fe2O3. Added water and boiled, etc. The problem was: bad burn - I think the dextrin initially generates too much gas and prevents the rest of the mix from being heated.
* When I saw it does not burn, I put there about two to theree teaspoons of B1 and poured with water (10-20 grams of B1 perharps?). Again boiled and got it to a mushy state and sampled... when too wet the flame went out the same as with totally dry dextrin mix. But as it got drier it became very serious. I made few test strands of approximate lenght and all burns were very intensive. As mentioned above a ~1" long sample (umm, honestly, it was closer to 3cm) burned in about four seconds, the diameter was ~7mm. Mechanical properties when dry: stronger than sugar candy.
* As I tried to scrape the remains of the overdried mix from the steel pan - it was very hard so I was chiseling it out with a knife - I got only chips of ~8mm in size, I collected it and made a small pile. After catching fire the pile burned with speed similar to flashpowder, quickly generating plum od smoke rising to the sky.

***waiting for my camera to come back...

Oxidizer eutectics

MIX 1:

So, KNO3 and KClO3 is one possible mix, 70-30 alloy should have melting temperature of 556K - 283°C. Even 1% AgNO3 would lower it much more. Not sure if it is KClO3 compatible. Two methods of preparation are possible: crystallize from solution and then finely ground to powder. What would be faster is to finely ground both, add little water, heat up, mix, dry. Grind finely, add little water, mix, heat, dry, grind to powder. Should give similar results. *CAUTION* dry KClO3 *CAN* self-decompose under certain circumstances, always process with care and precaution.

What we would appreciate is micrometric Fe2O3 at 2% concentration in this mix. I am not sure whether it is compatible with KClO3 in solution. If it woul be possible to include it in the mix and during controlled crystallization (stirring) it would be nice. We want long crystals as this is the primary oxidizer.

MIX 2:

This is not a good idea, but it is complementary to the one above. KNO3 and KMnO4. The point behind this is that KMnO4 decomposes to MnO2 which is a strong catalyst to anything, including the decomposition of KClO3. Only little of KMnO4 would be needed. We also want this mix with Fe2O3 puder. KNO3 can react with it during decomposition when in areas with abundance of energy, forming KFeO4 or K2Fe2O4 or something, which is one extremely strong oxidizer. This mix2 should be finer powder than mix1 and should be indirectly mixed into the final propellant (accelerates decomposition of mix1) for maximum safety.


Let's look at possible implementation, under a 65/35 rule, in absolute weights

mix1: KN:KC:FO - 32:13:1
mix2: KN:KMn:FO - 16:4:1 (15:5:3 etc)

(sum = 67 grams)

Fuel:
The glue to be mixed in 2.5:1 (Polyols:UBase)

glue:DX:urea:cellulose
(sum = 35 grams)
20:9:2:4 (or 20:8:2:5 is the same)

In proper oxidiser particle size this would be also doable:
12:16:5:2

The dextrose and urea may be prepared from a recrystallized mix.
The microcellulose is added to the whole propelland after proper stirring to prevent setting of the powder particles in the glue. This is important to maintain homogenity. It will also absorb any redundant glue.

Second test of a raw fertilizer mix - polyurethane binder..

AN fertilizer as before: 69g or 68g
1.2g KMnO4
~0.7g CeO2
14.8g polyols
8g urethane base - DFMDIC as before (4,4'-diphenylmethanediisocyanate)

a little of fine cellulose powder (~0.3-0.8g ?)

total = 92.7g (+ cellulose)
organic = 24.6% (+ cellulose)
AN approx. 52g -> 56.1%

The AN fertilizer in this case was kept in rather crude powder, particles up to 0.5mm in size. Hard to ignite, very inert. Burns surprisingly well for the ill composition that it is. What can be observed are the gases that are formed from the AN decomposition driving out vapours from the plastic and burning outside. The dolomite from the fertilizer seriously harms the performance.

Next time, time to try KN: mix FINELY ground KMnO4 into the glue with some urea too. Add a little ferric oxide too. Much more ferric oxide goes into the KN and some KMnO4 too. Also, add microcellulose into the KN. - - Possibly add a low-temp melting sugar too, no.. better would be mixing such sugar into a complete mix, it should have the longest crystals possible. This will cause cavities which will increase the surface area and help gas flow and surface layer separation too. Well, instead of sugar powder, using recrystallized KN/Sugar/Sulphur mix would be more adequate. But you would need to grind this with carbon dioxide (solid) at very low temperatures to get long, thin fragments of powder. Too much complication probably.