Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
Cyclodextrin monomer and polymer as a new energetic materials
In a paper presented to the 29th International Annual Conference of ICT Held in Karlsruhe (1998), J. P. CONSAGA and R. C. GILL form the Naval Surface
Warfare Center, synthesize and characterize new energetic materials derived from cyclodextrin. Cyclodextrin molecule (CD) are small oligomers formed
by the association of saccharides unit (glucose). What is special about this oligomer is that the association of glucopyranoside unit form a cyclic
(torus shape) structure rather than a linear one (e.g, cellulose). Typical cyclodextrin oligomers contain between 6 to 8 glucopyranoside molecule and
thus are designated by alpha, beta and gamma (6, 7 and 8 glucopyranoside unit, respectively). What is more interesting, is that the torus shape
molecule possess a hydrophilic surface while the cavity is hydrophobic.
What the authors have done in this study is to nitrate the free hydroxyl group of the gamma-CD (forming a cyclodextrin nitrate, CDN) by various mean
of nitrating agent. Complete nitration of all hydroxyl group is achieved using P2O5 and 98% fuming nitric acid in
dichloromethane. As already mentioned above, cyclodextrin possess hydrophobic cavity so the authors tried to introduce other energetic molecule that
fit inside the cavity of CDN, forming a guest-host complex. If the size of the cavity is suitable, the molecule can enter the cavity and stay there
thanks to dipole-dipole interaction. Trimethylolethane trinitrate (TMETN), 1,2,4-butanetriol trinitrate (BTTN) and nitroglycerine (NG) fit the cavity
forming a 1/1 complex with CDN. Shock sensitivity test shows that the inclusion of energetic material inside the CDN cavity, decreases the shock
sensitivity of the materials relative to pure compound. Polymers from cyclodextrin are also synthesized by various mean (forming for example urethane
linkage between each CD molecule) and nitrated by super critical fluid nitration with N205 in liquid carbon dioxide.
In the paper, the authors give some physiochemical properties of a nitrated gamma-cyclodextrin molecule (in this material 21 out of 24 hydroxyl groups
are nitrated):
Molecular formula : C40H52N21O82
Heat of formation : +1124.34 kcal/mol
density : 1.654 g/cm3
Unfortunately, the authors didn't give any detonation performance, only specific impulse is given which is 240 lb.-sec/lb, so i calculate the
detonation performance based on reported density and heat of formation using the Kamlet-Jacobs method [1]. The calculated Dcj,
Pcj, Qdetonation and oxygen balance OB are presented below:
Dcj= 7.33 km/s
Pcj= 226 kbar
Qdetonation= 1873 cal/g
OB% = -27.2
An important thing to note: the heat of formation reported in the article seems wrong. In general , Nitrated sugars and aliphatic polyols have
negative heat of formation so i think the authors committed a mistake in typing the value of heat of formation, it should be negative.
if we take -1124.34 instead of +1124.34 and calculating detonation performance we get:
Dcj= 6.33 km/s
Pcj= 169 kbar
Qdetonation= 1348 cal/g
OB% = -27.2
P.S: a useful empirical relationship for calculating heat of formation of nitrocellulose as a function of %Nitrogen (%N) is
[2]:
DH0(NC)= - 413,0+62,00 N (kcal/kg)
this equation is applicable to NC with %N from 10 to 14%.
Anyway, the authors published a patent in 2002 (see attached file) where they synthesized and nitrated different CD-polymer. These polymer will serve
as a propellant and as an encapsulating materials for energetic materials for enhancing safety.
[1] Kamlet M.J., Jacobs S.J., Chemistry of Detonation. I.A Simple Method for Calculating Detonation Properties of C,H,N,O Explosives, J. Chem. Phys.,
1968, 48, 23-35.
[2] To the question on the enthalpy of formation for the nitrocellulose, Yuriy N. Matyushin, Tatjana S. Konkova, Lidiya I. Korchatova, 29th
International Annual Conference of ICT Held in Karlsruhe (1998).
Dany.
Attachment: Polymeric cyclodextrin nitrate esters.pdf (118kB)
This file has been downloaded 658 times
[Edited on 24-8-2013 by Dany]
|
|
|
doktor x
Harmless
Posts: 4
Registered: 30-8-2013
Member Is Offline
Mood: No Mood
|
|
can be sintezed cyclodextrines without enzimes?
|
|
|
Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
According to the book "Cyclodextrins and Their Complexes: Chemistry, Analytical Methods, Applications"
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-3527608443...
cyclodextrins can be obtained by enzymatic (biochemical) degradation of starch. Also, organic synthesis can be achieved. for alpha-cyclodextrin the
synthesis via 21 steps with 0.3% total yield and 0.02% yield for gamma-CD's.
-reference article for alpha-CD synthesis:
Takahashi, Y.; Ogawa, T. Carbohydr.Res. 1987, 164, 277.
-reference article for gamma-CD synthesis:
Takahashi, Y.; Ogawa, T. Carbohydr.Res. 1987, 169, 127.
Dany.
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
Dany do you research in energetic materials ?
I read all your posts and all of them are interesting!
|
|
|
Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
Thanks for being interested in what i post.
yes, i do theoretical research on HEDM.
Dany.
[Edited on 6-9-2013 by Dany]
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
Is this compound a liquid or solid ? They mentioned ''the product is dried in vacuum'' and ''10g of the product'' and that the cyclodextrin nitrate
was ''mixed with RDX in acetone'' So I suppose it is a solid ?
I personally think liquid nitrate esters have much better use because they can be used as a energetic high density plasticizer in plastic bonded
explosives or rocket fuels. You also mentioned TMETN, a compound I am also very interested in. TMETN is attracting because it have a very high density
considering it from the CH2:ONO2 ratio. TMETN have more fuel and higher density than EGDN, which makes it more effecient when burned and less
sensitive. It is also a very good plasticizer. Do you know where I can find a synthesis of this compound ? I have found one published last century,
but I really want to repeat its synthesis on a more modern-improvised method if there is any ?
|
|
|
Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
DAR,
the nitrated cyclodextrine polymer is a solid as well as the polymer encapsulating the RDX. The importance of this polymer is that you can encapsulate
sensitive explosive in cyclodextrine cavity which as the result shows decrease the sensitivity. Also, no big loss in performance of the new explosive
formulation since the polymer is an energetic one.
now for your Metriol trinitrate or TMETN, actually i don't see that this compound is intersting over let say nitroglycerine (NG) for example. it's
less dense than nitroglycerine (ρTMETN=1.47 g/cm3 vs 1.59 g/cm3 for NG) the value of ρTMETN is
from [1]. You request a modern synthesis for TMETN. actually there is nothing special in the synthesis of this compound so old patent (the old patent
is for the ethyl analogue of TMETN) is enough, however, i attached to you a synthesis from an old patent (year 1933) and a new one (for TMETN) from
Klapotke (year 2010). In fact i found an alternative synthesis of TMETN which is more complicated. the TMETN is obtained by the nitration of an
oxetane derivative with N2O5, see [2].
Regarding detonation properties, i managed to calculate the detonation performance using FORTRAN BKW thermochemical code. The FORTRAN BKW is a code
written in 1967 by Charles MADER and other at the Los Alamos National Laboratory. FORTRAN BKW uses the Becker-Kistiakowsky-Wilson equation of state
(BKW EOS) for gaseous detonation product and the Cowan Equation of State for solid detonation products. The parameter used are those of RDX (best
fit). the RDX parameter used are:
beta= 0.16
kappa= 10.91
alpha= 0.5
theta= 400
there is another possibility of parameter set called TNT parameter which is used in explosive that generate too many mole of carbon in there
detonation products (e.g., TNT, DATB...). for more information see [3].
the data needed to perform the calculation:
1-ρTMETN=1.47 g/cm3
2-heat of formation at 0°K (and not at 298°K, calculated with data from NIST-JANNAF thermochemical tables)= -84.7 kcal/mol
3-molecular formula: C5H9N3O9
the results:
Dcj= 7.33 km/s
Pcj= 207 kbar
Tcj= 2937 °K
Vcj= 0.5 cm3/g
gamma or adiabatic coefficient= 2.81
OB%= -34.5
the experimental Dcj for nitroglycerine from MADER is 7.58 km/s and the calculated Pcj= 246 kbar.
so also NG outperformed TMETN in detonation performance.
References
[1] Military Explosives (TM 9-1300-214)
[2] Golding; Millar; Paul; Richards, Tetrahedron, 1993 , 49, 32 p. 7051 - 7062
[3] Numerical modeling of explosive and propellants, Charles L. MADER, CRC press, 3rd edition.
Dany. .
http://www55.zippyshare.com/v/11477282/file.html (for Klapotke article)
Attachment: 1933 patent.pdf (101kB)
This file has been downloaded 501 times
[Edited on 29-12-2013 by Dany]
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
Yes NG is amazing except its sensitivity. I spoke about TMETN as a good additive compared to butanetriol triniate(BTTN) due to its extra methyl group
that took up less space than it normally does and beats BTTN in gas production and average molecular weight of gas production. Which is favorable for
propellants. TMETN have a very good sensitivity suitable for up-scaling and it have a good glass transition temperature that could serve as an
plasticizer.
the encapsuling of RDX seems interest, however explosives can be generally de-sensitisezed in polymers. I think this might be more useful for azido
compounds.
Thanks for the paper, so nearly a 1:1 mixed acid.. seems okay. Why did the auther say its melting point is over room temperature though?It seems the
1933 patent did a nitration of Trimethylolpropane and not Trimethylolethane Where the author called Trimethylolpropane trimethylolethyl-methyl. Any ways, I expect it to have a similar synthesis.
Im looking for a liquid nitrate ester with very low Tg and viscosity and preferbly having density over 1.3 g/cm cubed.
[Edited on 29-12-2013 by DubaiAmateurRocketry]
|
|
|
Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
according to reference [1] TMETN is as sensitive as nitroglycerin, with a drop height of four centimeters for a two kilogram
weight (taken on The Bureau of Mines impact apparatus) so be careful from where you get your information and do not attempt the synthesis on a big
scale...
the melting point of TMETN is -3°C.
Dany.
[Edited on 29-12-2013 by Dany]
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
i think that reference have a mitake. Coppethead chemical company says 47cm for 2KG which is aroubd 10J so its insensitive.
|
|
|
Dany
Hazard to Others
Posts: 482
Registered: 3-8-2013
Member Is Offline
Mood: No Mood
|
|
The COPPERHEAD CHEMICAL COMPANY says that the 47 cm for TMETN is obtained on a 20" (PA apparatus) which is different from the one that i cited (The
Bureau of Mines impact apparatus) proving that for a single compounds, many sensitivity value can be obtained on different apparatus. It is not
necessarily that on of them is wrong. maybe the two are wright or wrong, the most important is as conflicting values are present, you should take care
from what are you doing...try sensitivity test on small quantity of TMETN. Personally, i would not take the risk of working with ten or hundred grams
of TMETN only if this is done by remotely.
Dany.
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
yeah thanks, and if i ever do try to synthesize i obviously will not do anything near 10 grams. TMETN is used in most US missiles along with some
others so its sensitivity might not be that high. as the 1 reference said, as sensitive as nitroglycerin.
|
|
|
DubaiAmateurRocketry
National Hazard
Posts: 841
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline
Mood: In research
|
|
Alright, so I checked out more TMETN's sensitivity along with few others. It seems the answer lies closer to your reference. TMETN has a impact
sensitivity with a drop high twice less than Butanetriol Trinitrate. Around 2.1 Joules. Which is a little bit higher than ETN, safer than
nitroglycerin. Do you know is there is any way to calculate the impact sensitivity of mixtures? Such as a 1:1 mixture of TMETN and diethyleneglycol
dinitrate.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
