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Excerpt from one of the papers below. Can someone explain what ecombn kcal/mol is?

DubaiAmateurRocketry - 7-11-2013 at 10:39

Excerpt from one of the papers below. Can someone explain what ecombn kcal/mol is?

Although im not sure what is the ecombn, maybe it shows how much heat is given off when it is completely burned ? or decompose ? I am not sure.

Any ways, what do you guys think are most promising ? The Nitrated HTPB is also miscible with all polar liquids, which means, finally, these energetic plasticizers can be mixed into NHTPB which i think is not hard to produce on industrial scale.

Ethyleneglycol bis(idoacetate) (EGBAA)
Density 1.34
HOF –167.36
HOC 796.26
OB –84.15
Tg –70.8

Tg -71 is amazing, and it has a good density, however the more traditional DTTN, although with higher Tg, is more cheap to produce, and ... it has a much higher density 1.5(in paper) or a lower density 1.2(wikipedia). If its 1.5, I think DTTN would need no replacement. I think the wikipedia one is wrong.

malford - 7-11-2013 at 11:19

Dany, perhaps I worded my statement in a confusing manner. I meant, below was an excerpt from one of the papers in the original post. I selected those compounds because they had the highest kcal/mol from one of the charts in the paper to which I linked. That chart has two columns, one for kcal/mol and another for ecombn kcal/mol. I don't know what ecombn kcal/mol is and was hoping someone could tell me.

DubaiAmateurRocketry, EGBAA has a high HOF, but DEGBAA is significantly higher. Compare -167 to -329. If I had more free time right now, I'd find more information about these compounds and build a chart which shows kJ/cm³. I believe comparison based on volume is more beneficial because rocket motors and their igniters will be limited by volume not weight.

DubaiAmateurRocketry - 7-11-2013 at 11:24

DubaiAmateurRocketry, EGBAA has a high HOF, but DEGBAA is significantly higher. Compare -167 to -329. If I had more free time right now, I'd find more information about these compounds and build a chart which shows kJ/cm³. I believe comparison based on volume is more beneficial because rocket motors and their igniters will be limited by volume not weight.

Umm, do you mean lower ? Its negative so the smaller the number the larger.

So EGBAA > DEGBAA in HOF, Density, and Tg.

Dany - 7-11-2013 at 12:00

Dany, perhaps I worded my statement in a confusing manner. I meant, below was an excerpt from one of the papers in the original post. I selected those compounds because they had the highest kcal/mol from one of the charts in the paper to which I linked. That chart has two columns, one for kcal/mol and another for ecombn kcal/mol. I don't know what ecombn kcal/mol is and was hoping someone could tell me.

well, first it is E_combn and not ecombn. What the authors mean by that is the Energy or heat of combustion. So the heat of combustion of nitroglycerine is E_combn= 368.4 kcal/mol.

Dany.

malford - 7-11-2013 at 12:39

Quote: Originally posted by Dany

well, first it is E_combn and not ecombn. What the authors mean by that is the Energy or heat of combustion. So the heat of combustion of nitroglycerine is E_combn= 368.4 kcal/mol.

Dany.

Thank you, Dany, for pointing that out. Since heat of combustion is defined as the difference between the heat of formation of the products and reactants, and since these compounds consist of homogenous molecules rather than mixtures of fuel and oxidizer, how, then, is the heat of combustion not the same as the inverse of the heat of formation? I am strictly referring to the compounds in the chart in the aforementioned paper.

Also, Dany, I'd like to return the critical favor. The beginning of your post should be capitalized. You should have used "Well" instead of "well". Also, you are missing a comma after "So". It should look like "So, the heat...". Lastly, your signature, currently "Dany." aspires to be what is known as a sentence in the body of rules called English grammar by displaying the period. It, sadly, falls short. "Dany" would be more appropriate.

Have a nice day.

Dany - 7-11-2013 at 13:15

with or without capitalization, with or without comma, at least you are understanding what is written. However, we will spend all the day to understand ecombn. Here, we are on a science forum so the most important thing is the scientific language. Grammar and poetry is secondary. Sadly, a lazy person put ecombn instead of E_combn...

Back to your question: heat of formation and heat of combustion are different.

"Heat of formation is the is the heat of reaction or enthalpy change involved in making a particular compound, or molecule, from its elements where both the elements and compound are at standard-state condition" for more information see Explosive engineering for Paul W.Cooper.

"The heat of combustion of a specified substance is the heat
evolved when it is converted to the standard oxidation products
by means of molecular oxygen" see M.H. Keshavarz et al. / Journal of Hazardous Materials 185 (2011) 1086–1106 (and reference therein).

Dany.

[Edited on 7-11-2013 by Dany]

woelen - 8-11-2013 at 01:15

I moved some offtopic drivel to detritus. Please stay on topic and stop derailing the thread.

malford - 8-11-2013 at 04:46

woelen, I appreciate your fervor for keeping the information on the forum relevant and useful. I actually took the time to go to detritus and see what was moved and found only the image I had posted. You may not have read the image and understood the purpose of it. The point of the image is not made out of the context of this thread. For your convenience, I will show it again in this post which is now on topic and contains further contribution below to the thread's OP. Also, if you'd like to clean up off-topic bickering, all of the posts regarding AN are entirely unrelated.

Dany, I understand the definitions of the combustion enthalpy and formation enthalpy, but my question was specific to this list of compound which are not mixtures. How can combustion occur with homogenous compounds? Logically, I see the only route for combustion would be once the molecule decomposes, the decomposition products combust. If this is the case, I still don't see how the absolute value of enthalpy change of some decomposition products combusting would be larger than the total enthalpy change of the formation from elements.

[Edited on 8-11-2013 by malford]

[Edited on 8-11-2013 by malford]

Fantasma4500 - 8-11-2013 at 08:05

well, DubaiAmateurRocketry .. sorry for late reply..
the product you get from nitration is a mix of nitrates, which is somewhat oily and sticky, meaning you can stick this to a solid without making it worse as in properties..
ratios can be fixed..
if you want to have a rocketfuel thats OB and you dont wanna mess more with the OB you can make EGDN which has a PERFECT OB meaning you dont need to regulate oxidizer / fuel in the rocketfuel and can just add until you think its enough

Dany - 8-11-2013 at 15:51

As i explained above the "Heat of formation is the is the heat of reaction or enthalpy change involved in making a particular compound, or molecule, from its elements" since the heat of formation of the element is zero (e.g., carbon, Oxygen, fluorine, O₂, F₂...) so the heat of formation is the energy content of the molecule just formed, whereas the heat of combustion (when a molecule burn with O₂ to form CO₂, H₂O...) is the heat difference between heat of formation of the products (CO₂, H₂O...which is not equal to zero) and the heat of formation of the compound which undergoes the combustion (e.g, TNT, a propellant...). This mean you can calculate the heat of formation if you know the heat of combustion (heat of formation and heat of combustion are not equal!). An example is illustrated in [1] page 644 where the authors determine the heat of formation of TNT from the known heat of combustion of TNT with oxygen, a reaction that yield CO₂, H₂O and N₂. The heat of formation of CO₂ and H₂O are well known from thermochemical tables (see, http://webbook.nist.gov/chemistry/name-ser.html). Since we know the heat of combustion of the reaction (which is measured in a bomb calorimeter) the heat of formation of TNT= heat of combustion (of the reaction) minus heat of formation of reaction products. As you can see, heat of formation and heat of combustion are not equal.

a case where the heat of formation equal the heat of combustion [2] is the combustion of elements (e.g., C+O₂----> CO₂) since the heat of formation of carbon and oxygen (or other element like for example aluminum etc...) is equal to zero so here the heat of combustion is equal to the heat of formation of the products (in this case it is CO₂)

[1] Chemistry and Physics of Energetic Materials, editor Surya N. Bulusu.
[2] Propellants and Explosives, Thermochemical Aspects of Combustion, Naminosuke Kubota (see page 280 under Heats of Combustion of Elements)

Dany.

DubaiAmateurRocketry - 17-11-2013 at 07:23

A method of curing azido-polymers where the amount of interlinked bonds can be controled.

This method of curing is also iso-cyanate free. It seems very interesting.

open file with adobe reader
Attachment: phpy4Z0DR (259kB)
This file has been downloaded 1968 times

[Edited on 17-11-2013 by DubaiAmateurRocketry]

DubaiAmateurRocketry - 10-12-2013 at 19:54

Interested by the reaction on page 68

https://smartech.gatech.edu/bitstream/handle/1853/7597/arons...

I think we can graft ''energetic'' tetrazoles onto GAP. This seems interesting !

Im not sure about if the mix acid will kick the tetrazole out and form Poly-GLYN or perform nitration on the COOH. and sorry for my bad drawing of polymers.

However this compound seems like it have a melting point at around room temperature with high viscousity and might not serve good as a ''binder'', however partial reactions still can be done to increase the density and oxygen balance.

If nitration fails, I really do think Trinitro-acetonenitrile can make the above compound. or polymer.

I have found little information about Trinitro-acetonenitrile however if it is a liquid and not a solid, and is compatible with some oxidizers and metal powders, it can be used to Cure GAP while giving oxygen balance during mixing ! making GAP propellant manufacturing crafting easier.

references for the above reaction.

Ralf Haiges * and Karl O. Christe Inorg. Chem., 2013, 52 May 31, 2013

and the paper i already posted.

[Edited on 11-12-2013 by DubaiAmateurRocketry]

[Edited on 11-12-2013 by DubaiAmateurRocketry]

[Edited on 11-12-2013 by DubaiAmateurRocketry]

roXefeller - 1-2-2014 at 07:33

Has any thought ever been given to a partial polymerization of glycerol, and then forming a nitrate ester with the remaining hydroxyl groups? Or would the nitrating split the oligomers apart to form NG?

DubaiAmateurRocketry - 1-2-2014 at 08:04

Has any thought ever been given to a partial polymerization of glycerol, and then forming a nitrate ester with the remaining hydroxyl groups? Or would the nitrating split the oligomers apart to form NG?

Good thought however what will we link glycerol with ?

I think it is ok to call Poly-GLYN(poly-glycidol nitrate), poly-glycerol-nitrate, Nitration of glycidol and glycerol both give nitroglycerin, however, glycidol could be linked together in the reaction of the 2nd picture on this post.

http://www.sciencemadness.org/talk/viewthread.php?tid=28450

poly GLYN is just glycerin connected similar to how diethyleneglycol, tri-tetra, etc, is, however since it have an extra hydroxyl group, it could be nitrated, which is GLYN. And this is why i find poly-GLYN most potential, except its instability when cured with urethane linkages. My proposal on that post to solve the instability with urethane linkage also gives the problem of limited plasticizers since the curing is done with azido groups, any plasticizer containing the azido group most probably could not be used.

polyGLYN have a lot of advantages over GAP, such as significantly higher OB and density, and insensitive at the same time(Impact sensitivity >20J)

[Edited on 1-2-2014 by DubaiAmateurRocketry]

roXefeller - 1-2-2014 at 19:10

The polymerization with phthalic anhydride seems to be a common college-level reaction to form a polyester.

DubaiAmateurRocketry - 3-2-2014 at 10:20

The polymerization with phthalic anhydride seems to be a common college-level reaction to form a polyester.

I dont think its more efficient than Poly-GLYN, would it even be a liquid ?

Edit: forgot to add ''dont'' in the sentence.

[Edited on 4-2-2014 by DubaiAmateurRocketry]

roXefeller - 3-2-2014 at 14:02

It does set up to a thermoset, but that's why I'm conjecturing about the partial polymerization. Since it uses equimolar amounts of phthalic anhydride and glycerol and it's not a catalyzed homopolymer, backing off the phthalic anhydride should keep it as soft oligomers.

franklyn - 6-2-2014 at 01:55

Modern high-energetic polymers

www.chemikinternational.com/pdf/2010/01_2010/chemik_01_2010_018_020.pdf

.

DubaiAmateurRocketry - 9-2-2014 at 10:35

I believe Poly glycidyl nitrate (aka PGN or poly-GLYN or GNP) Should be the future binder. This patent's method for preparing it is much more cost effective than methods used before and synthesizing GAP.

US patent 6362311
https://docs.google.com/viewer?url=patentimages.storage.goog...

Synthesis of GNP, and DTGNP.

This tells why Glycidyl nitrate polymer is better than GAP.

[Edited on 10-2-2014 by DubaiAmateurRocketry]

roXefeller - 9-2-2014 at 17:51

The butane diol was chosen because it forms a preinitiator complex with the BF3. But it was only one of many diols possible. Will ethylene glycol do similar? It was presented to cocatalyze oligomers in this patent (http://www.freepatentsonline.com/4409415.html). That substitution is also useful as it increases the nitrogen percent by reducing the size of the R group.

DubaiAmateurRocketry - 10-2-2014 at 05:10

Roxefeller, Theoretically yes, I am not sure why butane diol is used, but maybe it is more reactive on the terminal hydroxyl groups.

On your question on the increase in energy since the R is smaller for ethylene diol than butane diol, for a molecular weight of 2000 GAP, Ethylene diol GAP contains 41.15% Nitrogen, meanwhile butane diol GAP have 40.6% N. Small improvement but why not. Glyerol which forms trifunctional GAP is even more favorable since if makes more elastic and crosslinked binder.

btw i drew the polymer wrong and its fixed now

roXefeller - 10-2-2014 at 14:05

I thought we were talking about Poly GLYN...

The description paragraphs of the patent discuss polymerization in the diol/BF3 etherate as you detailed. The examples also use CaH2, examples 8&9. Have you eliminated this as unnecessary?

[Edited on 11-2-2014 by roXefeller]

DubaiAmateurRocketry - 11-2-2014 at 09:01

I thought we were talking about Poly GLYN...

The description paragraphs of the patent discuss polymerization in the diol/BF3 etherate as you detailed. The examples also use CaH2, examples 8&9. Have you eliminated this as unnecessary?

[Edited on 11-2-2014 by roXefeller]

Oh, I thought you meant GAP since GAP's energy has to do with the nitrogen content, GLYN is the amount of oxygen.

Umm for the CaH2, they mentioned its use to stop the reaction, im pretty sure it is not a necessary step. Cold water can stop the reaction easily, when water is added, water is miscible with CH2Cl2 and the polymer or glycidyl nitrate is kicked out from the solution (Im pretty sure glycidyl nitrate have a very bad solubility in cold water).

Dany - 11-2-2014 at 13:08

water is miscible with CH2Cl2

Just a little correction, dichloromethane CH₂Cl₂ is not miscible in water. In fact CH₂Cl₂ is a common solvent for aqueous phase extraction in organic chemistry lab.

Dany.

DubaiAmateurRocketry - 11-2-2014 at 13:35

Quote: Originally posted by Dany

water is miscible with CH2Cl2

Just a little correction, dichloromethane CH₂Cl₂ is not miscible in water. In fact CH₂Cl₂ is a common solvent for aqueous phase extraction in organic chemistry lab.

Dany.

Ah, i didnt know that!

Is it possible to have Poly glycidyl nitrate(PGN), the one I drew, to have GAP section terminated polymer? Maybe by polymerizing the glycidyl nitrate first, and then when the reaction is done, add glycidyl azide? How can we make sure most of the polymer's end have a GAP section?

roXefeller - 11-2-2014 at 14:54

Oh, I thought you meant GAP since GAP's energy has to do with the nitrogen content, GLYN is the amount of oxygen.

Yeah, that's where I was going (percent oxygen fixed to nitrogen), but I should've said it better.

The CaH2 is a dessicant, so it probably dehydrates the polymerization process since water forms by way of terminating hydrogens reacting with the hydroxyls of the diol's. It may in fact be necessary as a catalyst. Further it is one of the first additions in the examples, so it cannot logically be used to stop the reaction according to the patent description. However, it may be that its absence stops the process, e.g. by selecting a certain molar quantity, the MW of the oligomers can be planned from the beginning when the CaH2 plays out. Further I suspect that given the choice of dessicant (one that chemically reacts with vigor), one of similar scavenging qualities is needed (Ac2O vice H2SO4 or CaCl2 or other anyhydrous compounds) if CaH2 is not chosen.

Do you know what sort of viscosity the PGN has prior to curing? It's novel enough that I'm having a hard time finding numbers, only 'viscous liquid' as descriptor. Possibly the incorporation of a small fraction of glycerol with the diol could be used to tweak the viscosity by adding a third functional group to increase the branching polymerization.

[Edited on 12-2-2014 by roXefeller]

roXefeller - 24-2-2014 at 17:49

I had this wrong. I'm suprised I wasn't corrected. There isn't water being produced during polymerization, and it is purely a matter of Lewis acid catalysis of epoxide/hydroxyl additions. It does appear that water present would reduce the glycidyl nitrate to glycerol mononitrate, perhaps the reason for the CaH2 dessication. Ac2O would be damaging, reacting with the epoxide groups to form acetates. Somehow I thought that alternating units of epoxide and diol monomers were linked, so the use of glycerol is also mostly wrong. The polyol was just present to initiate the chain and provide hydroxyl for the first epoxide addition.

[Edited on 25-2-2014 by roXefeller]

DubaiAmateurRocketry - 25-2-2014 at 09:48

I had this wrong. I'm suprised I wasn't corrected. There isn't water being produced during polymerization, and it is purely a matter of Lewis acid catalysis of epoxide/hydroxyl additions. It does appear that water present would reduce the glycidyl nitrate to glycerol mononitrate, perhaps the reason for the CaH2 dessication. Ac2O would be damaging, reacting with the epoxide groups to form acetates. Somehow I thought that alternating units of epoxide and diol monomers were linked, so the use of glycerol is also mostly wrong. The polyol was just present to initiate the chain and provide hydroxyl for the first epoxide addition.

[Edited on 25-2-2014 by roXefeller]

I dont think glycidyl nitrate + Ac2O = glycidyl acetate and nitric acid ? Will nitric acid really form?

I dont think glycidyl nitrate will not reduce glycidyl nitrate into glycidyl mononitrate because if you read examples of the patent on the synthesis of glycidyl nitrate, NaOH, CH2Cl2, and nitric acid, all are in solution. NaOH was a dilute 30%, and HNO3 was 90%.

So it means it shouldnt react with water.

If CaH2 is used for dehydration, they will put more than 1 gram on a 1.5 kg batch for example9.

roXefeller - 25-2-2014 at 15:04

I think the acetate doesn't form with the nitrate, but on the group formed when the epoxide opens. Wikipedia mentioned it in the oxirane article for reactions with anhyrides.

But the glycidyl nitrate was separated from the aqueous phase in the CH2Cl2. Then dried with MgSO4, filtered and evaporated. It is then mixed with new CH2Cl2 and CaH2 added. It should be anhydrous by that point. But given its reactivity with water to form glycerol mononitrate it will do its own water scavenging and then provide initiator sites after such. The process of glycidyl nitrate going to glycerol mononitrate looks like the same process as when ethylene oxide reacts with water to form ethylene glycol, and its a industrial process for such.

DubaiAmateurRocketry - 26-2-2014 at 11:27

Oh, I forgot that the NaOH in the solution will keep glycidyl nitrate's oxirane ring from opening, therefore it was alright for HNO3, CH2Cl2 to contain water. What you said should be right, however I still kind of disagree about the desiccant part. I have read a handful of papers about GAP and so on, and none of them used any desiccant? Even if CaH2 was used as desiccant, why 1 gram for such a big batch? GAP's synthesis is very similar except it is glycidyl azide.

Any ways, Ill try these one day. I am wondering how do I get chemicals when I move to the US...

[Edited on 26-2-2014 by DubaiAmateurRocketry]

roXefeller - 26-2-2014 at 12:18

These are very readily available in the states, at least for the nitrate version. The biggest hurdle will be nitric acid, BF3 etherate, and methylene chloride. But these can be managed. One thing that startled me today was browsing the nitromethane on Amazon. The 'also purchased by' list included ice packs, stirring rods, methanol, sulfuric acid, hexamine, aluminum powder, methylene chloride, etc. I can't believe the amount of data logging that is being done by merchants. It's dangerous.

DubaiAmateurRocketry - 3-4-2014 at 13:46

Just wow, This new paper published just last year has shortened the N2O5 synthesis of Nitro-HTPB into a single step NaNO2-I2 1 step synthesis with cheapest chemicals possible.

Unfortunately, the amount of nitro groups hanged onto the polymer backbone is not given, however the ease of synthesis is remarkable! NHTPB's important characteristic is low glass transition temperature(not much difference with HTPB), around 10-20% higher density, and finally the most important - miscibility with other energetic plasticizers which can help with the OB.

The paper is in the uploads.

https://docs.google.com/viewer?url=patentimages.storage.goog...

This patent shows another plasticizer found in this century, It's claimed to have a TC impact sensitivity of 117cm, and ABL impact sensitivity of 11cm. (I have no idea what is those 2 impact sensitivity measurements are.)

Judging from the structure, I feel this plasticizer should not be impact sensitive. It has yet to report its glass transition temperature but it require no more oxygen to burn it self, with an amazing density of 1.47. Its melting point is lower than -60 degree Celsius which is a good sign of a very good plasticizer.

Attachment: phpGT2PHo (703kB)
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[Edited on 3-4-2014 by DubaiAmateurRocketry]

DubaiAmateurRocketry - 2-3-2017 at 13:13

interesting paper published the energetic materials journal in china.

This paper is about epoxy terminated - GYN, removing the initial problem of Glycidyl nitrate polymer's instability.

http://www.energetic-materials.org.cn/hncl/ch/reader/view_ab...

"The reaction between the end hydroxyl of poly(glycidyl nitrate)(PGN) and isocyanates is easily affected by ambient moisture, and the curing stability is poor. Aiming at these problems, epoxy-terminated poly(glycidyl nitrate) (e-PGN) was synthesized. Its structure was characterized by infrared spectroscopy(IR), nuclear magnetic resonance(NMR) and gel permeation chromotagraph(GPC), and its major physiochemical properties were tested. The main physical properties of e-PGN, such as glass transition temperature, viscosity, density, thermal decomposition temperature, were close to those of PGN. The curing reactions of e-PGN with epoxy curing agents, such as imidazole(IMD), o-phthalic anhydride(PA), n-ethylethylenediamine(NEED) and isophorone diamine (IPDA) were studied. Results show that the curing reaction of e-PGN with IMD, PA, NEED and IPDA at 60 ℃/70 ℃ can be performed. When PA is used as curing agent, the mechanical properties of the cured material outperformed; the tensile strength is 0.912 MPa, and the elongation at break is 354%. In addition, the mechanical properties of the cured samples stored at room temperature for 8 months remained almost unchanged."

PHILOU Zrealone - 7-3-2017 at 00:44

I believe Poly glycidyl nitrate (aka PGN or poly-GLYN or GNP) Should be the future binder. This patent's method for preparing it is much more cost effective than methods used before and synthesizing GAP.

US patent 6362311
https://docs.google.com/viewer?url=patentimages.storage.goog...

Synthesis of GNP, and DTGNP.

This tells why Glycidyl nitrate polymer is better than GAP.

[Edited on 10-2-2014 by DubaiAmateurRocketry]

There is a problem with the reaction after the 4th Arrow...the butylen moeity R is lost...I don't see how the epoxide may form without splitting off the "polymer"...here it is no more an epoxide but an acetal because one carbon holds 2 oxygen (ether linkage), a H atom and a link to another C...

[Edited on 7-3-2017 by PHILOU Zrealone]

PHILOU Zrealone - 7-3-2017 at 00:56

Even aluminum does not combust with ammonium nitrate without energetic binders.

Belive me it does burn with dry ammonium nitrate especially when hyper-reactive ultrafine dendritic Al powder with low oxyd layer is used...

I have experimented with it--> It burns bright spreading star sparks all arround like a sparkler but fiercely and this from the simple flame of a cigaret lighter .

Laboratory of Liptakov - 7-3-2017 at 01:08

After reading this thread it seems, respectively I estimate, that will the miracle, if we sometime see only one gram the modern active binder - plasticizer. From preparations in amateur conditions........ :cool:

...Dr.

PHILOU Zrealone - 7-3-2017 at 01:18