Sciencemadness Discussion Board

microcrystalline cellulose

ecos - 2-12-2015 at 02:34

Hi All,

I am planning to create some microcrystalline cellulose "MCC" to make NC and blasting gel (NG/NC) for some tests.
I think microcrystalline cellulose is better than normal cellulose fibers in nitration. I also think it will give minor air bubbles when mixed with NG.

I started to search on how to make it and found two routes :

1- mixing cellulose with 10% HCL solution and boil it for an hour
I am afraid that HCL would have effect on MMC and decrease its quality, change its structure or even add risk while nitration or final product
effect of acids on MCC :

2- milling of cellulose
I found different machines which don't look like traditional ball mill. I am not sure if traditional bill mill will work or not. any idea?
in this site , there is a study on the effect of milling :

I would prefer to have very fine MCC powder free of acids.

any suggestions ?

[Edited on 2-12-2015 by ecos]

kecskesajt - 2-12-2015 at 07:24

I made MCC by adding cotton to 30% HCl,worked but filtering was terrible pain in the ass. Better to buy.

ecos - 2-12-2015 at 13:10

What was the prob in filteration?

NeonPulse - 2-12-2015 at 15:52

I bought mine, it is used in pressing tablets as a filler and came as a very fine powder of high purity check eBay it's cheap if you can't be bothered making it.

ecos - 3-12-2015 at 01:42

I checked ebay. 1 Lb costs $15 !
I think it would cost me less if I make it my self plus i prefer to explore the science :)

Microtek - 3-12-2015 at 06:26

What is it you are worried will happen during the acid treatment of cotton wool? The article you linked to mention a decreasing degree of polymerisation, but that is what you are after in the first place (hydrolysing amorphic regions while leaving crystalline regions).

ecos - 3-12-2015 at 06:43

I am afraid the acid change any property of cellulose which might add hazards when it become NC !
Think about higher sensitivity or even remaining acids in the final product. this would be high risk when you mix NC with NG.

PHILOU Zrealone - 6-12-2015 at 10:47

Change of property, maybe...

See Nitrocellulose vs Nitrostarch...
NS has lower density than NC --> lower VOD
NS is less stable and harder to stabilize than NC
Same should apply to MCNC vs normal NC

ecos - 8-12-2015 at 02:52

I think with MCNC you will have minor air gaps than NC and this would be higher density and higher VoD.

but why MCNC would be harder to stabilize. i think it would have the same stability as NC.

Hennig Brand - 8-12-2015 at 09:37

The following was taken from this webpage:

Not sure I appreciate the bigshot scientist comments, but they seem to have outlined the basics pretty well describing the main difference between the two polymers.

Cellulose - The Difference Between Cellulose and Starch

Starch and cellulose are two very similar polymers. In fact, they are both made from the same monomer, glucose, and have the same glucose-based repeat units.

There is only one difference. In starch, all the glucose repeat units are oriented in the same direction. But in cellulose, each successive glucose unit is rotated 180 degrees around the axis of the polymer backbone chain, relative to the last repeat unit.

When bigshot scientists are talking bigshot scientist talk they say that the glucose units in starch are connected by alpha linkages, and that the glucose units in cellulose are connected by beta linkages.

Does this make any difference? It makes a lot of difference! The most important difference in the way the two polymers behave is this: You can eat starch, but you can't digest cellulose. Your body contains enzymes that will break starch down into glucose to fuel your body. But we humans don't have enzymes that can break down cellulose. Some animals do, like termites, who eat wood, or cattle, who eat grass, and break down cellulose in their four-chambered stomachs. So unless you're a termite or a cow, don't try to nourish yourself on woodchips.

Cellulose is a lot stronger than starch. Starch is practically useless as a material, but cellulose is strong enough to make fibers from, and hence rope, clothing, etc. Cellulose doesn't dissolve in water the way starch will, and doesn't break down as easily. Breaking down or dissolving in water just would be a little too inconvenient for something we use to make clothes. Not to mention, a good soaking rain would wash away all the wooden houses, park benches, and playground equipment if cellulose were soluble in water."

From what I understand, cellulose is actually a very stable polymer relative to starch. MCNC should be much more stable than NS, everything else being equal. The main reason for NC instability is the great difficulty, or impossibility even, of removing all contaminants which are mostly to blame for decomposition in storage. These contaminants are much more easily removed from MCNC, making it much easier to produce a more stable and consistent energetic material.

I still have some of the propellant made from MCNC and NG described in the "bullet propellants" thread and it looks unaltered for the most part (possibly slight yellowing). It has been stored at room temperature, but not in an airtight container. I am not at that location at the moment or I would post a picture. A couple months ago the same propellant was used for 410 shotgun target practice and at least appeared, without testing equipment, to function as it had when first made.

Bert - 8-12-2015 at 09:55

Did you use any stabilizer in the stored MCNC based propellant- Diphenylamine, centralites, urea, etc.?

Hennig Brand - 8-12-2015 at 10:08

Always meant to start doing some stability testing and getting into experiments involving stabilizers, but so far I haven't done so. No stabilizers were used.

PHILOU Zrealone - 10-12-2015 at 13:15

The main difference between starch and cellulose is the average molecular weight or other said the lenght of the polymeric chain...the lenght of the cellulose chain explains its insolubility in water despite its great hydroxyl group (hydrophilic) content.

Starch may be soluble or not in water depending on its molecular weight... soluble starch is used in clothes ironing to stiffen clothes up and leave them wrinkleless or wrinkle resistant; unsoluble starch is found when you submit flour to a minor water quantity on a cotton fabric; you kneed it and starch passes through the fabric while gluten remains on the fabric; after a while you get a sticky yellow proteic gluten "chewing-gum" and water solution with a white precipitate of unsoluble starch.

If starch had a higher polymeric level; it would be kind of cellulose.

Wood also contains lignin protein aside with cellulose that explain its resistance and use as a material.

The digestibility of starch vs cellulose comes from its form and solubility and from specific enzymes (amylases, maltases, ...); cellulose has also its specific enzymes found in cow tract bacterias, saprophyte mushrooms, in some insects (thermites)...
As glucose polymers they are basic food for the base of the food chain.

[Edited on 11-12-2015 by PHILOU Zrealone]

PHILOU Zrealone - 10-12-2015 at 13:39

Quoted from Explosives, 4th, revised and extended edition by Josef Köhler and Rudolf Meyer:

d= 1,6 g/cm³
(Max density by pressing 1,1 g/cm³)
Lead block test for 10g = 356 cm³
Deflagration point: 183°C or 361°F
Impact sensitivity: 11 Nm

NS is insoluble in water and ether, but is soluble in ether-alcohol mixtures and in acetone.
NS with various N contents (12-13.3%) is prepared by nitration of starch with HNO3 or nitrating mixtures.
The resulting crude product is washed in cold water and then dried at 30-40°C (95-100°F).
NS resembles NC in several respects, but owing to its poor stability, difficulty in preparation and hygroscopicity, it is not used anywhere outside the USA.

Theorically up to 3 NO3 units per glucose unit --> 14.14% N but practically only up to 13.4% N
NC can be found with N% from 11.0 to 13.3

for 13.3%N
d = 1.67 g/cm³
(Max density by pressing: 1.3 g/cm³)
Lead block test for 10g = 370 cm³
Impact sensitivity: 3 Nm

[Edited on 11-12-2015 by PHILOU Zrealone]

Hennig Brand - 11-12-2015 at 06:08

It has been a while since I have read anything much about it, but everything I remember indicates the big reason cellulose is so much harder to break down in most cases is that each monomer is rotated 180 degrees with respect to the last while for starch they are all lined up with no rotation. From what I remember this makes cellulose much tougher in general. However, I may have been in error and extrapolated way to much by assuming this same difference would be observed for the nitrates as well. MCNC does appear to be very easy to stabilize relative to regular NC that much seems clear.

ecos - 11-12-2015 at 08:38

it seems i need to read more about NC and MCNC.

the max density by pressing is 1.3 g/cm3 , i think this would increase if MCNC was used , right?

@Hennig, why you say MCNC does appear to be very easy to stabilize relative to regular NC ? what kind of stability you are talking about ?

PHILOU Zrealone - 11-12-2015 at 10:48

Instead of pressing, one could aswel dissolve the NC or MCNC into a solvent like aceton to get a denser material ;)

I suppose Hennig Brand refers to the fact MC is granular while C is fibrous...washing fluid spreads easier through granules than through intricated fibers...agitation is also easier.

But again Nitrosuggar << Nitrostarch < Nitrocellulose on the storage stability I guess MCNC will be between NS and NC because the storage stability seems to follow molecular weight and polymer lenght...

Hennig Brand - 11-12-2015 at 11:59

I understand more what you mean now, you have explained it well. Though you have made a good case correlating stability to molecular weight other factors could still be involved or even of greater significance in some cases (correlation doesn't necessarily equal causation). Yeah, the thing of most significance for the amateur is that removing residual acidity, etc, from MCNC is a mere tiny fraction of the difficulty involved as is experienced with fibrous NC. For the amateur especially, the practical differences involved in removing impurities and handling are more important by a factor of 10 or 100 even in my opinion.

The amorphous sections of cellulose are what are removed during hydrolysis, if done correctly, from what I understand. Could this result in at least some of the greater stability observed not considering the greater ease and likely extent of purification with these sections removed? Also, during industrial processing the fibrous NC is cut into very short lengths (have to go back and check notes for length), although still probably much longer than MCNC sections for the most part.

Better to buy it

Katie - 7-5-2020 at 12:32

As others have mentioned, MCC is cheap, easily available online, and not a “suspicious” chemical. Amazon and eBay sell high purity MCC as do many “supplement” companies.

If you want to make it for the chemistry of it, I’d still recommend a small test batch using commercial pure MCC for your first batch so you have something to compare the homemade stuff to.

I’ve made NC with my makeup pads (torn apart) and it worked very well. I’d be interested to see if pure MCC gives a better product or more controllable synth.