Propellants, Explosives, Pyrotechnics 23, 237Ä…239 (1998) 237
Prediction of Explosives Impact Sensitivity
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Maryse Vaullerin and Andre Espagnacq
GIAT Industries, Centre de Bourges, 7 route de Guerry, F-18023 Bourges Cedex (France)
Luc Morin-Allory
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Institut de Chimie Organique et Analytique, URA CNRS 499, Universite d'Orleans, F-45067 Orleans Cedex 2 (France)
  Á
Voraussage der Schlagemp®ndlichkeit von Explosivstoffen Prediction de la sensibilite a l'impact des explosifs
  Á
Die Bestimmung der Schlagemp®ndlichkeit von Hochleistungs- La determination de sensibilite a l'impact des explosifs est une des
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sprengstoffen (HE) ist die am meisten angewandte Methode zur voies les plus communement employees pour evaluer le risque pyro-
È Â Â
Bewertung einer Gefahrdung durch Sprengstoffe. Aufgrund unter- technique. A cause de la diversite des conditions experimentales
schiedlicher Voraussetzungen in der Praxis fur eine mogliche Explo- conduisant a une reaction, beaucoup de methodes experimentales pour
È È Á Â Â Â
 Á    Â
sion, wurden viele experimentelle Methoden zur Messung der la mesure de la sensibilite a l'impact ont ete developpees. Donc la
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Emp®ndlichkeit entwickelt. Daher ist eine Voraussage der Schlag- prediction de cette sensibilite a l'impact des materiaux energetiques est
emp®ndlichkeit energetischer Materialien wichtig. Die vorliegende essentielle.
 Á Â
Arbeit diskutiert ein Kriterium als Hilfsmittel zur Ausleuchtung aller Ce travail presente le critere de sensibilite CS pour effectuer un tel
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energetischen Substanzfamilien. Dieses Kriterium basiert auf der decriptage pour toutes les familles d'explosifs reunies. Il se base sur la
È Â Á Â Â
maximalen Reaktionswarme. Die Ergebnisse unserer Untersuchungen prediction a partir de l'enthalpie maximale de reaction. Les resultats de
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zeigen eine zufriedenstellende gegenseitige interfamiliare Beziehung notre recherche revelent une correlation interfamilles satisfaisante
È Á Â Â
zwischen dem theoretischen Kriterium der Sensibilitat (CS) und den entre ce critere de sensibilite CS et les valeurs experimentales.
experimentellen Werten.
Summary this predictive model doesn't allow the reasons for this
sensitivity to be explained.
The determination of impact sensitivity of high explosives (HE) is
the most commonly used way of evaluating an explosive hazard.
Because of the diversity of practical conditions that make an explosion
2. Prediction of Impact Sensitivity
possible, many experimental methods for measuring sensitivity have
been developed. Therefore, the prediction of sensitivity to impact of
energetic materials is essential.
2.1 Object of the Calculation
This work discusses a criterion that aids in such screening for all
families of energetic substances. This criterion is based on the max-
In fact, there is no correct interfamily theory to connect
imum heat of reaction. The results of our research reveal a satisfactory
mutual interfamily relation between both the theoretical criterion of impact sensitivity to the chemical structures of the com-
sensitivity (CS) and experimental values.
pounds studied.
In this work, we have ®rstly used the C4 criterion pro-
vided by the CHETAH code(9) to classify some explosives
1. Introduction
according to their decomposition mode on impact.
Further to this study, as the CHETAH database allows
All previous works about impact sensitivity of explosives
neither the drawing of all explosives such that NTO nor the
have revealed the existence of several series of correlations
calculation of the C4 criterion for mixtures, we have de®ned
between this property and different physicochemical para-
a reaction model applicable to the sensitivity criterion CS
meters such as the oxygen balance(1Ä…4), the molecular
so as to predict impact sensitivity not only for energetic
electronegativity(5), the dissymmetry of charges around the
molecules but also for carbon, hydrogen, oxygen and
speci®c linkage to the fundamental state and to the excited
nitrogen explosive formulations.
state(6), the heat of explosion(7). These different relation-
ships have been studied according to the nature of the
explosophore linkage, that is to say, by separating the dif-
2.3 CHETAH: Application to Impact Sensitivity
ferent families of explosives (nitramines, nitroaromatics,
nitric esters . . .).
Application
Another study has been led by H. Nefati(8). Contrary to
methods described previously, this statistical and neural CHETAH is software, developed by the American
study regroups the different chemical explosives families. Society for Testing and Materials (A.S.T.M)(9,10) which
Nevertheless, the quantity of parameters implemented in allows the thermal stability, the energy hazard potential and
# WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998 0721-3115/98/0306Ä…0155 $17.50‡:50=0
238 M. Vaullerin, A. Espagnacq, and L. Morin-Allory Propellants, Explosives, Pyrotechnics 23, 237Ä…239 (1998)
DHmax c b
the maximum heat of reaction of a compound to be esti-
CaHbNcOd ! N2 ‡ H2O
2 2
mated.
d b d b
R. D. Coffee(10) referred to the Benson theory of groups(11)
‡ CO2 ‡ a ‡ C
to create the thermochemical calculation code, CHETAH.
2 4 2 4
This code deduces from four criteria including the C4
criterion to thermodynamic data for compounds and pro- 10DH2 M
max
CS ˆ
ducts of reaction.
n
DHmax: Maximum reaction heat (kcalyg)
M: molecular weight (g)
C4 Criterion
n: number of atomsygram
This criterion is represented by the empirical equation:
10DH2 M
max
C4 ˆ
n
3. Results and Interpretation
DHmax: Maximum reaction heat (kcalyg)
Table 1 and Figure 1 show the results of the sensitivity
M: molecular weight (g)
criterion CS as a function of the impact sensitivity coef®-
n: number of atomsygram
cient (ISI) whose experimental values are given in Refer-
ences 11Ä…14.
In the case of impact sensitivity for classical organic
2.3 Criterion of Sensitivity for Molecules and Explosive
explosives, the criterion CS varies between 70 kcal2ymol
Formulations
and 320 kcal2ymol.
With reference to Figure 1, we can see not only three
The prediction of impact sensitivity of molecules and
areas of sensitivity (high, medium, low) but also, con-
explosive formulations is based on the criterion CS for
sidering the diversity of experimental data, the existence of
Criterion of Sensitivity which is the same as that of C4
a thermochemical criterion CS for interfamily classi®cation
because the parameters are de®ned in relation to the gross
of explosives.
formula CaHbNcOd and to the reaction equation as follows:
Table 1. Interfamily Explosive Classification
Acronym Chemical Name Ref. Impact Sensitivity
Sensitivity Criterion
CSI CS
N m kcal2 mol 1
NGl Nitroglycerin 11 0.2 289.1
EGDN Nitroglycol 11 0.2 284.3
Sorguyl 1,3,4,4-Tetranitroglycoluril 11 1.5Ä…2 295.9
PETN Pentaerythritol tetranitrate 11 3.0 251.1
Tetryl Tetryl 11 3.0 232.5
NC (14.14% N) Nitrocellulose 11 3.0 199.4
HNS Hexanitrostilbene 11 5.0 218.6
TetNA 2,3,4,6-Tetranitroaniline 11 6.0 242.1
TNPy Trinitropyridine 11 4.5 268.0
Picric Acid 2,4,6-Trinitrophenol 11 7.4 199.5
Styrhnic Acid Trinitroresorcinol 11 7.4 170.6
HMX Cyclotetramethylene tetramine 11 7.4 231.4
RDX Cyclotrimethylene trinitramine 11 7.5 233.2
DINGU Dinitroglycoluril 11 5Ä…6 199.4
0 0 0
Hexanitrodiphenyloxid 2,4,6,2 ,4 ,6 -Hexanitrodiphenyloxide 11 8.0 280.4
TNB Ac. Trinitrobenzoic Acid 11 10.0 191.7
TNC 2,4,6-Trinitrocresol 11 12.0 163.4
TNT 2,4,6-Trinitrotoluene 11 15.0 180.8
TNA Trinitroaniline 11 15.0 179.9
Trinal Trinitronaphthalene 11 19.0 160.5
Trinitroanisole Trinitroanisole 11 20.0 163.1
TNMA 2,4,6-Trinitro-N-methylaniline 11 21.2 165.1
NTO 3-Nitro-1,2,4-triazole-5-one 12 25.0 132.8
Picramic Acid Dinitroaminophenol 11 34.0 109.2
DNB Metadinitrobenzene 11 39.0 154.5
ClDNB Dinitrochlorobenzene 11 49.0 143.3
DNT Dinitrotoluene 11 50.0 127.9
TATB 1,3,5-Triamino-2,4,6-trinitrobenzene 11 50.0 125.0
ANTA 3-Amino-5-nitro-1,2,4-triazole 12 50.0 111.5
NQ Nitroguanidine 11 50.0 76.6
Propellants, Explosives, Pyrotechnics 23, 237Ä…239 (1998) Prediction of Explosives Impact Sensitivity 239
Figure 1. Diagram of interfamily explosive classi®cation.
4. Conclusion 5. References
(1) M. J. Kamlet, ``The Relationship of Impact Sensitivity with
In conclusion, we can say that impact sensitivity for
Structure of Organic High Explosives: I. Polynitroaliphatic
energetic materials is an athermal phenomenon, that is to
Explosives'', Proceedings 6th Symposium (International) on
say, the sensitivity criterion CS is based on the most stable
Detonation, San Diego, August 1976, ONR Report ACR 221,
products taken at 298 K. 312Ä…322.
(2) M. J. Kamlet and H. G. Adolph, ``The Relationship of Impact
A parallel can be established with the potential of
Sensitivity with Structure of Organic High Explosives: II. Poly-
ionization and the oxygen balance. The athermal process
nitroaromatic Explosives'', Propellants Explos. 4, 30Ä…34 (1979).
of impact sensitivity has only been taken into account
(3) W. S. Wilson, D. E. Bliss, S. L. Christian, and D. J. Knight,
with the potential of ionization. We have found that ``Explosive Properties of Polynitroaromatics'', Naval Weapons
Center, NWC TP 7073.
the concept of the most stable reaction products is linked
(4) D. E. Bliss, S. L. Christian, and W. S. Wilson, ``Impact Sensitivity
to the oxygen balance. On the other hand the relationship
of Polynitroaromatics'', J. Energ. Mater. 9, 319Ä…344 (1991).
that exists with the number of atoms per gram is found
(5) J. Mullay, (a) ``A Relationship Between Impact Sensitivity and
in the oxygen balance and in the potential of ioni- Molecular Electronegativity'', Propellants Explos. 12, 60Ä…63
(1987). (b) ``A Relationship between Impact Sensitivity and
zation.
Electronic Structure'', Propellants Explos. 12, 121Ä…124 (1987).
This comparison with the potential of ionization and the
 Â
(6) A. Delpuech, ``Relation entre la structure electronique molecu-
oxygen balance shows that this new criterion of sensitivity
 Á
laire et la sensibilite au choc des explosifs secondaires'', These de
Á Â
Doctorat es Sciences, Universite de Bordeaux (1980).
CS simultaneously unites the three factors: athermal phe-
(7) I. Fukuyama, T. Ogawa, and A. Miyake, ``Sensitivity and
nomenon, the most stable products of reaction and the
Evaluation of Explosive Substances'', Propellants Explos. 11,
number of atoms per gram, contrary to the notions of
140Ä…143 (1986).
oxygen balance and potential of ionization which elude one  Â
(8) H. Nefati, ``Prediction de la sensibilite au choc des substances
Á
explosives ou non: approches statistique et neuronale'', These de
of these three relationships.
Á Â
Doctorat es Sciences, Universite Paris VI (1994).
Furthermore, results show the superiority of this
(9) W. H. Seaton, E. Freedman, and D. N. Treweek, `` CHETAH, The
approach in comparison with previous works since they
ASTM Chemical Thermodynamic and Energy Release Evaluation
allow the explosives to be classi®ed in interfamilies rather Program'', ASTM Data Published Series, Publication DS 51,
American Society for Testing and Materials, Philadelphia (1974).
than intrafamilies. This same criterion can be used for
(10) CHETAH, version 7.0, ``The Computer Program for Chemical
energetic aluminized, chlorinated . . . formulations. In these
Thermodynamic and Energy Release Evaluation (NIST Special
last cases, a hypothetical molecule CaHbOcAldCle . . . has to
Database 16)'', 3rd edition, American Society for Testing and
be de®ned and the equation of reaction is written with the Materials, 1916 Rase Street, Philadelphia, PA 19103 (1994).
È
(11) J. Kohler, and R. Meyer, ``Explosives'', VCH, Weinheim (1993).
most stable products of reaction.
(12) K. Y. Lee, C. B. Storm, M. A. Hiskey, and M. D. Coburn, ``An
It is obvious that the experimental measures of impact
Improved Synthesis of 5-Amino-3-Nitro-1H-1,2,4-Triazole
sensitivity should be carried out the same conditions so as to
(ANTA), a Useful Intermediate for the Preparation of Insensitive
High Explosives'', J. Energ. Mater. 9, 415Ä…428 (1991).
establish a homogeneous database because the available
scienti®c literature proposes a mosaic of measures which
are often dif®cult to compare. (Received May 7, 1997; Ms 27y97)