Explosive Performance Properties of Erythritol Tetranitrate (ETN)

3 Pages·2015·0.63 MB·English

by  Virginia W. Manner et al.

SShhoorrtt CCoommmmuunniiccaattiioonn
DOI:10.1002/prep.201500066
Explosive Performance Properties of Erythritol Tetranitrate
(ETN)
VirginiaW. Manner,*[a] DanielN. Preston,*[a] BryceC. Tappan,[a] V.Eric Sanders,[a] GeoffW. Brown,[a]
Ernie Hartline,[a] and Brian Jensen[a]
Abstract: Erythritol tetranitrate (ETN) is a melt-castable ex- PETN. We discuss detonation and wall expansion velocity,
plosive with impressive performance, similar to the well- along with diameter effect information in unconfined rate
known related nitrate ester, pentaerythritol tetranitrate stick tests. The detonation velocity of ETN is 99% that of
(PETN).ThoughETNhasbeenknownsince1849,itsproper- PETN in the same test setup, showing that performance
ties have notbeen thoroughly investigated. Wereport here propertiesareverysimilarforthetwonitrateesters.
the first 1=’’ copper cylinder tests of ETN, compared with
2
Keywords: ETN·Erythritoltetranitrate·Explosive·Performance·Cylindertest
1 Introduction 2 Results and Discussion
2.1 CylinderTests
Erythritol tetranitrate (ETN) (Figure1) is an explosive first
preparedin1849[1]withsimilarpropertiestopentaerythri- ETN has greater sensitivity than PETN, so it was important
tol tetranitrate (PETN). ETN is melt-castable, has impressive to evaluate its safety relative to the cylinder loading pro-
performance, and is not difficult to prepare, which increas- cess. In addition to the standard small-scale safety testing
es the necessity for understanding its properties from [4], ETN was tested for friction sensitivity using a copper
a homemade explosive threat determination perspective plate, and did notundergo any visible reaction at the high-
[2]. Due to its handling sensitivity, ETN has been involved estinputlevel.
in recent accidents [3] and should not be handled outside Pressed pellets were prepared of recently purified ETN at
ofadedicatedexplosivesfacility.Wehaverecentlyreported an average density of 1.74(cid:156)0.01gcm¢3 (98% TMD). How-
the first X-ray crystal structure of ETN [4], and discussed ever, over the course of approximately 20d, the pellets ex-
the influence of crystal packing on the sensitivity of the panded to an average density of 1.69(cid:156)0.03gcm¢3 (95%
material, relative to PETN [5]. Another recent publication TMD). Copper 12.90mm (1=’’) cylinder tests were per-
2
alsodiscussesbasiccharacterizationofETN[6]. formed with the expanded pellets (the cylinders were
We describe herein the first analysis of copper cylinder honed from 12.70mm to account for pellet expansion).
expansion tests with pressed ETN. We discuss the detona- Shorting switches and PDV (Photonic Doppler Velocimetry)
tion behavior for the material, along with wall velocity and measurements were used in a configuration that has been
diameter effect information. All data is compared to PETN described in detail elsewhere [7]. Two cylinder tests were
testedundersimilarconditions. performed using ETN at slightly different densities, and one
control cylinder test was performed with PETN. The data
are summarized in Table1. The ETN detonation velocity
(Figure2a) is 99% that of PETN when corrected for density.
Wallvelocities arecomparable between ETNandPETN(Fig-
ure2bandTable1).
[a] V.W.Manner,D.N.Preston,B.C.Tappan,V.E.Sanders,
G.W.Brown,E.Hartline,B.Jensen
ExplosiveScienceandShockPhysics
LosAlamosNationalLaboratory
LosAlamos,NM87545,USA
*e-mail:[email protected]
Figure1. Erythritoltetranitrate(ETN). [email protected]
460 (cid:211)2015Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim PropellantsExplos.Pyrotech.2015,40,460–462
ExplosivePerformancePropertiesofErythritolTetranitrate(ETN)
Table1. ETNandPETNcylinderperformancedata.
Material Density[gcm¢3][TMD/%]a) Detonationvelocityb)/mmms¢1 Wallvelocityc)[ms¢1] Adjusteddetonationvelocityd)[mmms¢1]
ETN1 1.682(cid:156)0.019[94.9] 7.887(cid:156)0.007 1775(cid:156)12 7.95(cid:156)0.02
ETN2 1.704(cid:156)0.010[96.1] 7.994(cid:156)0.022 1807(cid:156)5 7.99(cid:156)0.02
PETN 1.663(cid:156)0.006[94.0] 7.926(cid:156)0.033 1794(cid:156)12 8.04(cid:156)0.03
a)ETNTMD=1.773gcm¢3,PETNTMD=1.770gcm¢3(ref.[4]). b)Theuncertaintiesarethetwicethestandarddeviationof thevelocity.c)
Averageandtwicethestandarddeviationofthevelocityvaluesat20mscollectedfrom4PDVprobes(allwithin10ms¢1ofaveragefinal
observedvalues).d)Detonationvelocityafteradjustingeachshotdensityto96%TMDusingD1=D2+3(11¢12)(Ref.[8]).
2.3 CheetahThermochemicalCode
Cheetah 6.0 thermochemical code calculations were per-
formed on ETN at 96% TMD [10], and give a detonation ve-
locity of 8.113mmms¢1. This is in good agreement with the
average experimental detonation velocity of
7.97(cid:156)0.02mmms¢1(at96%TMD),1.7%belowthecalculated
value. In comparison, Cheetah calculates a PETN detonation
velocity of 8.270mmms¢1 at 96% TMD, which overestimates
our experimental value by 2.8%. Cheetah predicts that ETN
forms (in mole fractions) predominantly CO (0.415), HO
2 2
(0.314), and N (0.168) gaseous products, along with smaller
2
amounts of NO (0.0782) and O (0.0138). The PETN products
2
are mostly CO (0.362), HO (0.340), N (0.145), and CHNO
2 2 2
(0.103), with some CO (0.0388).Overall, thepredicteddetona-
tionvelocitiesandproductgasesareverysimilarbetweenthe
twonitrateesters.CheetahJWLfitresultsgivetotalenergyof
detonationof¢10.11kJcm¢3and¢10.05kJcm¢3 forETNand
PETN,respectively,inverygoodagreement.
3 Experimental Section
CAUTION: Erythritol tetranitrate is a very sensitive and dan-
gerousexplosivethathasbeeninvolvedinseveralrecentex-
plosives accidents [3]. It should only be prepared and han-
dledinanexplosivesfacility.ETNshouldneverbeburned,as
a small amount of confinement of even a small sample (ca.
Figure2. (a) Shorting switch data used to determine detonation
10mg)cansometimesleadtoaviolentexplosion.
velocities. (b) PDV wall velocities for ETN and PETN cylinder shots.
ETN was prepared from nitric acid, sulfuric acid, and er-
Eachlineisanaveragefrom4PDVprobes.
ythritol using literature procedures [4]. Batches were syn-
thesized on a(cid:139)30g scale, and the solid product was dis-
solved in ethanol (ca. 700mL), precipitated with water (ca.
1300mL), and characterized by NMR spectroscopy [4]. ETN
2.2 SmallDiameterDetonationTests
pellets were pressed at ambient temperature using a 15
Small scale, unconfined detonation rate sticks were tested ton pneumatic using an applied pressure of 3.9(cid:213)108Pa,
at 3.00(cid:156)0.03mm and 6.35(cid:156)0.03mm pellet diameters. with two intensifications of three minutes with a one
The ETN pellets were pressed to an initial average density minute rest between intensifications. Pressing was done
of 1.74(cid:156)0.01gcm¢3 (98% TMD), and pellet expansion was slowly due to friction sensitivity. Expansion on diameters
notmeasuredthereafter.Thesemeasurementsgaveadeto- averaged 0.05mm and height expansions averaged
nation velocity of 7.90(cid:156)0.13 and 8.03(cid:156)0.04mmms¢1 at 0.20mmduringa20dmeasurementperiod(halfoftheob-
3.00and6.35mmrespectively,whicharewithinuncertainty served expansion occurred in the first 4d, and then
of the adjusted detonation velocities observed in the cylin- slowed). During further pressing, material amounts were
der tests, given in Table1. These velocity measurements slightly decreased and pellets pressed shorter to allow for
demonstrate a critical diameter for ETN of<3mm, which is the pellet expansion to reach the final average size of
consistentwiththePETNcriticaldiameterof<1mm[9]. 12.86(cid:156)0.29mm (height)(cid:213)12.82(cid:156)0.03mm (diameter). Re-
PropellantsExplos.Pyrotech.2015,40,460–462 (cid:211)2015Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim www.pep.wiley-vch.de 461
SShhoorrtt CCoommmmuunniiccaattiioonn
V.W.Manneretal.
explosives are within 1%, and wall expansion velocities are
within uncertainty of each other. Initial measurements indi-
cate the critical diameter of ETN is <3mm, and is poten-
tially well under 1mm as with PETN. The predicted behav-
ior from Cheetah 6.0 calculations also show close agree-
ment between the two nitrate esters, with very similar pre-
dictedproductgasesandenergiesofdetonation.
Figure3. (a)FrictiontestingofETNonacoppersurface,executed Acknowledgments
beforeloadingthecylinderwithETNpellets.UnreactedETNisvisi-
bleattheedgeofthedistressedarea.(b)Crosssectionofcylinder
Los Alamos National Laboratory is operated by LANS, LLC, for the
testsetupshowingETNpellets.
U.S.DepartmentofEnergyundercontractDE-AC52–06NA25396.
sults showed that lower initial pressing pressures of 3.6(cid:213)
108Pa resulted in larger expansion than the higher pres- References
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4 Conclusions
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ed the detonation behavior of ETN using cylinder tests and
small diameter unconfined rate sticks. Similar performance Received:March25,2015
properties were observed between ETN and the closely re- Revised:April27,2015
lated nitrate ester, PETN: detonation velocities for the two Publishedonline:June5,2015
462 www.pep.wiley-vch.de (cid:211)2015Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim PropellantsExplos.Pyrotech.2015,40,460–462