EXPLOSIVES 383CHIMIA 2004, 58, No. 6

Chimia 58 (2004) 383�389© Schweizerische Chemische Gesellschaft

ISSN 0009�4293

Military High Explosives

Jörg Mathieu* and Hans Stucki

Abstract: Military high explosives are safe to handle, have a long shelf life, their energy density is high and thepropagation of the explosion (detonation reaction) is very fast. The energetic compounds are combined withpolymers and other substances to match the properties as required. To initiate a detonation, a shock wave isneeded. This is accomplished with a small quantity of a primary explosive. Modern, extremely insensitive formu-lations have been developed in most countries to eliminate accidents with ammunition. Apart from insensitiveenergetic compounds, new inert or energetic binder systems will be introduced to improve the vulnerability. Thesearch for new energetic materials with highest performance characteristics is a never-ending task.

Keywords: Energetic binder · Explosives chemistry · Performance · Safety · Vulnerability

1. Development of Military HighExplosives

1.1. General AspectsThe properties of the first known explo-

sives like black powder and dynamite couldnot fulfill the requirements of use in muni-tions. Reliability in use and handling, un-predictability and the risk of unwanted ex-plosions as well as the low performance ofthe detonation was not sufficient.

The ideal military explosive is power-ful, safe and easy to handle, can be stock-piled for long periods of time in any climateand is hard to detonate except under pre-cisely specified conditions. It also has to beloaded into shells, bombs and other objectswithout any difficulties. The energetic com-pound is normally mixed with binders andadditives, so that a suitable productionprocess can deliver the required explosiveobjects. Primary explosives are responsiblethat the propagation of an explosion is ini-tiated. Primary explosives are also ex-plained in this article.

*Correspondence: J. MathieuarmasuisseScience and TechnologyFeuerwerkerstrasse 39CH-3602 ThunTel.: +41 33 228 44 64Fax: +41 33 228 46 01E-Mail: joerg.mathieu@armasuisse.ch

1.2. Traditional Military ExplosivesThe first high explosive to be put into

service was 2,4,6-trinitrophenol, called�picric acid�. It was first demonstrated inFrance in 1885 and it was widely used in thetime of World War I. Unfavorable are thehigh melting point, making the process offilling shells difficult, its reaction withheavy metals and formation of toxic com-pounds and its sensitivity.

The first explosive to fulfill the expecta-tions of producers and users was 2,4,6-trini-trotoluene (TNT). This compound was firstsynthesized in the 1860s, was produced inlarge quantities during World Wars I and IIand is still used today in explosive mixtures.It is cheap and relatively insensitive, can bemelted at low temperatures and poured inbombs and shells easily.

For higher performance the nitraminecompounds hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and later octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrocine (HMX) were in-troduced. In the pure state these compoundsare too sensitive and can only be used withinsensitive additives or in mixtures withTNT. In Switzerland, the nitrate ester 2,2-bis[(nitroxy)methyl]-1,3-propanediol, di-nitrate (PETN) was often used for specialapplications.

1.3. Trends and New ProductsThe search for new energetic com-

pounds with increased performance is pro-gressing rather slowly. The design of newmolecules with a high energy level is fasci-nating, but the demanded stability is hard toachieve. Manufacturing of blended andpolymer-bonded explosives meeting the de-sired demands such as easy processing andhandling together with keeping a high se-

curity level is the state-of-the-art. The latestdevelopments try to increase the safety ofthe explosive products while handling andin case of fire or other unwanted external in-fluences like impact, falling and being firedon.

2. Primary Explosives and Detonators

2.1. General AspectsThe start of a detonation is normally

performed by a primary explosive whichproduces a detonation wave when decom-posed. These compounds have low activa-tion energy. Impact, friction, electric sparksor sudden heating can initiate the decompo-sition. The deflagration to detonation tran-sition occurs within a very short distanceand the detonation wave is sufficient to ini-tiate a secondary explosive in the neighbor-hood. Because of their sensitivity, primaryexplosives are manufactured under specialconditions to avoid any shock, mechanicalload or electric spark. In igniters and deto-nators only small quantities of primary ex-plosives in the range of 20�100 mg areused.

2.2. Primary Explosives and TheirProperties

For many years mercury fulminate,Hg(ONC)2, was the compound mainly em-ployed for initiation, either by itself ormixed with other substances such as potas-sium chlorate. It is easy to prepare by the re-action of mercury with nitric acid andethanol. Mercury fulminate is toxic, lacksstability when stored for a long time and re-acts with metals in a moist atmosphere. Itsuse has been abandoned in most countries.

EXPLOSIVES 384CHIMIA 2004, 58, No. 6

Lead azide, Pb(N3)2, was developed af-ter World War I and is now the most com-monly used material for detonators. It isproduced by the reaction of lead nitrate oracetate with sodium azide in a basic envi-ronment, to avoid formation of hydrazoicacid, which is instable. The addition ofthickeners like dextrin to the solution, leadsto aggregates with purities of only 92�97 %, but with good stability and handlingsafety.

Lead trinitroresorcinate or lead styph-nate (Fig. 1) is prepared by the reaction ofthe magnesium salt of 2,4,6-trinitroresorci-nol with lead nitrate. The precipitated leadstyphnate is a primary explosive. This com-pound has good stability, is compatible withmost metals, is easy to initiate by impact orheat and is especially sensitive to sparks. Itis widely used in combination with leadazide in detonators, in electric igniters andin primary compositions to ignite burning.

The main sensitivity and performanceproperties of widely used primary explo-sives are listed in Table 1. The correspon-ding test methods are described by Köhlerand Meyer [1]. The figures listed are pub-lished data [1] and experimentally deter-mined in our laboratories.

Other compounds used as primary ex-plosives or as a component in primary mix-tures are silver azide, tetrazolyl-guanyl-tetrazene-hydrate (tetrazene) and 2-diazo-4,6-dinitrophenol (DDNP).

2.3. Trends Unpredicted explosions, corrosion and

erosion of gun barrels and materials, andtoxic pollution are the reasons for new im-provements in this field. Igniters containingmercury fulminate and chlorates had corro-sive as well as toxic properties. The devel-opments in this field led to the primer com-position SINOXID containing lead styph-nate, tetrazene and inorganic nitrates. Thiscomposition has conquered the wholeworld, it guarantees almost no corrosionand no erosion in the gun, it has excellentstability and storability and ensures preciseinflammation of the propellant [2].

With modern target practice in indoorrifle ranges, the lead dust in the air reachedintolerably high levels. To eliminate leadand other toxic metals, the SINTOX pri-mary composition without any toxic metalswas developed. The primary explosives are2-diazo-4,6-dinitrophenol and tetrazenecombined with the pyrosystem zinc perox-ide and titanium.

There is also a trend to develop detona-tors without primary explosives. The ex-ploding bridge wire initiation delivers an al-ternative possibility to start a detonation. Ametal wire embedded in secondary high ex-plosive material is charged with a very highelectrical current. The sudden evaporationof the wire and the resulting shock-wave issufficient to initiate the surrounding sec-ondary explosive.

An other new method is the direct initia-tion of secondary explosives by a laser beam.

3. Secondary Explosives

3.1. Energetic Compounds3.1.1. General Aspects

Energetic compounds for use as highexplosives have to be powerful becausetheir energy is mainly responsible for theperformance of an explosive charge. Com-patibility and misciability with other explo-sives, polymers, and additives must be pos-sible, also processes like pressing, melting,cast cure, and extruding are required in themanufacturing process. Compatibility withother materials and long-term stability is

expected for safety in handling and storageof the products.

3.1.2. Production and ChemicalAspects

Most of the substances used belong tothe family of the aromatic nitro compounds,the aliphatic nitramines and the nitrate es-ters. They are produced by liquid-phase ni-tration with acid, a classical chemical pro-cedure. For special compounds, used onlyin small quantities, syntheses in severalsteps and nitration with nitrous oxides areapplied too. Byproducts, isomeric com-pounds and acid residues have to be re-moved to obtain a pure, stable and constantproduct. One example is crude 2,4,6-trini-trotoluene, which contains 2�5% of iso-meric trinitro and dinitro compounds,whereas the demanded TNT purities in mu-nitions production are in the range of99�99.7%. The technical conditions for thesynthesis, cleaning, and refining proce-dures of the classical compounds are wide-ly published [1][3]. In Table 2 the chemicaldata and impact sensitivity of commonlyused energetic compounds are shown and inFig. 2 the corresponding structures are pre-sented.

For special applications a lot of other energetic compounds are used,e.g. 1,3,5-trinitrobenzene (TNB), 3,3-bis(2,2�,4,4�,6,6�-hexanitrostilbene) (HNS),1,3,5-triamino-2,4,6-trinitrobenzene(TATB).

3.1.3. Physical PropertiesThe knowledge of the energetic and

physical properties is important for the de-velopment of explosive charges with a de-fined performance. Table 3 shows the ener-getic data of commonly used energeticcompounds. The optimization of the maingoals, high performance when detonating,safety and low vulnerability are almost con-tradictory. The common practice of addingwaxes and polymers to increase the stabili-ty reduces the performance of the energeticcomponents.

3.1.4. Trends and New EnergeticCompounds

Several known and many new energeticmolecules were tested in regard of their po-tential for the new generation of insensitivehigh explosives (IHE). One of them is 3-ni-tro-1,2,4-triazol-5-one (NTO) (Fig. 3).

NTO is easy to prepare: In a first stepthe condensation of semicarbazid hy-drochloride with formic acid leads to tria-zole and the second step is a conventionalnitration. The resulting NTO is very insen-sitive and hard to set on fire. After initiationit has a high detonation velocity (8590 m/s).Disadvantages are the high solubility in wa-ter, the acid reaction by hydrolysis and the

Fig. 1. Lead styphnate

Table 1. Properties of primary explosives. The lead block test measures the expansion of a definedcavity, caused by detonation of a substance.

Substance Friction Impact Electrostatic Performance Minimal sensitivity sensitivity sensitivity lead block test quantity to

[N] [Nm] [mJ] [cm3/10 g] initiate PETN

Mercury fulminate 8 1–2 10 130 0.17 g

Lead azide 0.1–1 (pure) 2.5–4 0.4 110 0.02 g

Lead styphnate 8 2.5–5 1–10 130 0.55 g

Tetrazene 7 1 180 155 difficult

EXPLOSIVES 385CHIMIA 2004, 58, No. 6

large critical diameter needed for the con-tinuation of the detonation.

1,3,3-trinitroazetine (TNAZ) (Fig. 4) isanother new energetic and insensitive mol-ecule. TNAZ has potential properties as aninsensitive explosive. The low meltingpoint allows its processing by melting. Forits preparation seven steps are necessaryand therefore production is very expensive.

Another compound with potential prop-erties as an IHE is ammoniumdinitramideNH4N(NO2)2 (ADN). This new substancehas a good oxygen balance and containsmuch energy, but it is difficult to produce ina pure quality.

3.1.5. Hexanitrohexaazaisowurtzitaneas a Newcomer

The new molecule 2,4,6,8,10,12-(hexa-nitro-hexaaza)-tetracyclododecane (HNIWor CL-20) is a nitramine compound, similarto RDX and HMX. HNIW has a high den-sity (2.04 g/cm3, ε-modification) and there-fore a calculated [4] theoretical detonationvelocity of 9400 m/s which cannot bereached by any other organic explosive atthe present time. Scheme 1 shows the syn-thesis of HNIW.

CL-20 was invented and synthesized byA.T. Nielsen [5] in 1989 at the US Navy testcenter China Lake, which is why the name�CL� was selected. The synthesis needsthree steps, as described in the patent ofNielsen [6]. In the first step the cage struc-ture is formed by condensation of benzyl-amine with glyoxal. Then a partial deben-zylation and an acylation are followed byreductive acylation in acetic anhydride. Inthe third step the debenzylation is complet-

Fig. 2. Structures of commonly used high explosives

Table 2. Chemical properties and impact sensitivity of high explosives

Name of explosive Melting point Deflagration point Impact Density[ºC] with 20 ºC/min [ºC] sensitivity [Nm] [g/cm3]

TNT: 2,4,6-trinitrotoluene 80.8 300 > 20 1.654

PETN: pentaerythritol 141.3 202–205 2 1.770tetranitrate

RDX, Hexogene: 204 decompos. 230 4 1.820Cyclotrimethylenetrinitramine

HMX, Octogen: 282 decompos. 287 3 1.907Cyclotetramethylenetetramine

Tetryl: 129.4 185–195 2 1.730N,2,4,6-tetranitroaniline

Table 3. Energetic data from the armasuisse explosives database. The lead block test measures theexpansion of a defined cavity, caused by detonation of a substance.

Name Heat of explosion Detonation velocity Max. detonation Lead block test[kJ/kg] [m/s] pressure [GPa] [cm3/10 g]

TNT 3.72 6900 22.3 300

PETN 6.31 8400 33.5 523

RDX 5.62 8750 34.1 480

HMX 5.60 9100 39.0 480

Tetryl 4.25 7850 26.9 410

Fig. 3. Nitrotriazolone (NTO)

Fig. 4. Trinitroazetine (TNAZ)

EXPLOSIVES 386CHIMIA 2004, 58, No. 6

ed and a mild nitration by nitrosonium andnitronium tetrafluoroborate forms thenitramine groups.

In the industrial synthesis slightly mod-ified processes have been established, inparticular for the hydrogenolysis, describedin the patent of R.B. Wardle [7]. A uncom-plicated synthesis procedure, to producelarge quantities of CL-20 at an acceptableprice, is not available today.

Pure CL-20 is too sensitive for safe pro-cessing, handling, and storage. Mixtureswith insensitive materials only or a surfacecoating of the CL-20 particles results in ac-ceptable safety data. But the addition of in-sensitive substances reduces the perform-ance of this material.

Another problem in using CL-20 is thepolymorphism: the crystalline CL-20 canform six different modifications. NormallyCL-20 exists in the ε-modification, which isthermodynamically stable at room temper-ature. Processing this material at elevatedtemperatures and high pressures facilitatesa transformation to the less stable γ- or oth-er modifications. The polymer binder used,which is in contact with the surface of theCL-20 crystals, influences these transfor-mations. A process control is necessary tobe certain that no unstable modificationsare formed. Using IR spectroscopy, the dif-ferent modifications can be distinguishedby the control of the peaks in the fingerprint region in the spectra [8].

CL-20 has the potential to be used in thefuture for explosive charges for highest per-formance and as an energetic additive inrocket propellants, but the material is stilltoo expensive for common use.

3.2. Binder SystemsBasically, the selection of the binder

system determines the processing technolo-gy of an explosive. By coating or mixing

the crystalline energetic compound with abinder system, the formulation is desensi-tized. During processing, in the curingstage, the formation of a solid binder matrixis achieved. The type of binder significant-ly influences the mechanical properties andconsequently the vulnerability of the explo-sive charges. A possible further addition ofbonding agents and plasticizers allows asystematic modification of the characteris-tics of the binder. The development of new,less sensitive explosive formulations ismainly achieved by technical innovations inpolymeric binder systems. Below anoverview of the different binder types andof current trends in this area is given.

3.2.1. Energetic Compounds with aLow Melting-point

For castable explosives energetic com-pounds with low melting points (70 to 110°C) are used directly as binders. The condi-tion for the use of an energetic compoundfor this purpose is a sufficient separationbetween melting point and start of thechemical decomposition reaction. PureTNT melts at 80.8 °C; however the thermaldecomposition does not start before 290 °C.In charges consisting of homogeneous TNTonly, TNT acts as an energetic compoundand as a binder. In addition, e.g. in mixtureswith up to 80% insoluble energetic com-pounds of high performance like hexogen(hextro formulations) and octogen (octolformulations), TNT has the function of abinder.

Cast charges based on TNT as binder donot meet today�s criteria for insensitive am-munition. Alternatives for TNT weresought. These alternative substances mustallow the production of charges with con-ventional casting facilities and also meetthe criteria for active components in insen-sitive ammunition. The development of a

new series of explosives by the US Army isworth watching closely. It is based on thebinder 2,4 dinitroanisol (DNAN) [9] whichis a yellow crystalline substance at roomtemperature and has a melting point of 94.5°C.

3.2.2. PlasticsUntil the 1960s mainly waxes and

paraffins were used as classic binder sys-tems for pressed explosive formulations. Inmodern pressed and diecast formulations,particularly in the field of insensitive highexplosives (IHE), mainly polymers are useddue to their wide range of properties. Thedevelopment goes back to the 1950s, whenin the formulation of pressed explosivesmainly thermoplastics were used, whichwere known from civilian applications (e.g.nylon, Teflon, polyisobutylene). However,the mechanical properties of most of the re-spective formulations showed undesirablehardness, which has a negative effect on thesensitivity. Therefore elastomers (rubber),with hardness from soft to stiff and elonga-tion of up to 400%, are being increasinglyused in modern formulations. From the1960s onwards, the development and avail-ability of tailored resin/hardener systemsled to the introduction of the �cast-cure�technology. Today the used polymers areoften matched to their specific applicationin the formulation of explosives. A novelenergetic binder system containing nitro oracido groups is now available. The me-chanical properties of this binder systemcan be controlled by means of the selectivearrangement of hard and soft block seg-ments.

3.2.2.1. Plastic Binders for PressedFormulations

Mainly thermoplastics and elastomersare used as binders for pressed formula-tions. The granulates used to manufacturethe pressed charges consist of surface-coat-ed (each crystal is individually coated witha thin polymer film) crystalline energeticcompounds.

The distinction between thermoplasticsand elastomers is not totally clear in everycase. In the field of pressed explosives al-most exclusively non-branched polymersare used, which are defined as thermoplas-tics. However, there are a number of poly-mers which are partly hardened or originatefrom the family of block-co-polymers andtherefore show very high molecularweights or very long chains. In this case themobility of the chains is limited and the be-havior corresponds more to that of an elas-tomer. We will subsequently define the typeof binder polymer based on the behaviorand not on the degree of cross linking.

As the following examples will show,polymers with very different chemical ori-gins are used in explosive formulations.

Scheme 1. The synthesis of HNIW/CL-20 in three steps

EXPLOSIVES 387CHIMIA 2004, 58, No. 6

ESTANE (Fig. 5), for example, is apolyester with an OH group on the end ofthe chain, whose free alcohol functionalityis cross-linked to a polyurethane with anisocyanate (4,4�-diisocyanatdiphenyl-methan). ESTANE is a classical binderwhich is commercially used in the formula-tion LX-14. Based on the distinct thermo-plastic behavior of ESTANE (softeningstarts at 50 °C) the respective formulationsare processed under elevated temperatureconditions (90�110°C). Depending on thechain structure, such polyurethanes showvery different mechanical properties. Theesterification with tri- and tetra-alcoholscan be used to achieve additional cross link-ing. In hot water or water vapor atmos-phere, the polymer decomposes throughhydrolysis.

HYTEMP (Fig. 6) is another binderbased on an ethyl-/butylacryl-co-polymer.It contains a small percentage of chloricmonomers, mostly 2-chlor-ethylvinylether,which are used for cross linking. The

acrylic elastomer is resistant to ageing, heatand fatigue. Moreover HYTEMP is resist-ant to oxygen, ozone, oil and UV light; itsstability in hot water and water vapor is un-der certain conditions only just sufficient.Most formulations based on HYTEMPcontain the softening agent dioctyladipat(DOA), which is added in a ratio of 1:3(w/w). Particularly if the percentage ofbinder is high, the explosive has a soft andcrumbling consistency. This makes the me-chanical processing of the respectivecharges very difficult.

In addition fluorinated co-polymers andsilicone rubbers are also used as binders.

3.2.2.2. Plastic Binders for ‘Cast-cure’Formulations

Plastics which are used as binders forthe cast-cure technology of explosives arebased on resin/hardener systems. The for-mulation is homogenized in a mixer, filledinto a mould or case and then cured at ele-vated temperature. The main group of

�cast-cure� binders includes cureablepolyurethanes. The basis for the crosslink-age reaction are hydroxyl terminated poly-mers, which can be cross linked with iso-cyanates. Scheme 2 shows the schematicdescription of the crosslinkage process.

Depending on the functionality of thealcohol and isocyanate used (di-, tri-, tetra-functional) the degree of crosslinking andhence the mechanical properties can becontrolled. This fact, together with the mul-titude of basic substances (polyols), makesit possible to create �made-to-measurebinder systems�.

Among the so-called crosslinkablepolyether prepolymers there are both inertand energetic representatives. While in to-day�s classical formulations mainly poly-ethylene glycol or polypropylene glycol isused, polymers used in the future will bemodified with energetic groups in the mol-ecule. The filling capacity of diecast explo-sives is limited by the viscosity of the ex-plosive mass to be processed. The relative-ly high percentage of binder material(>10%) leads to a reduced performance. Inorder to partially compensate for this, ener-getic prepolymers were developed. Due totheir OH groups on the end of the chain,they can be crosslinked to polyurethans bymeans of isocyanates too. Moreover, thereis the possibility of producing energeticblock-co-polymers from such prepolymers,consisting of hard and soft segments, reach-ing comparable mechanical properties tothe thermoplastic elastomers (TPE).

The type of the soft segment influencesthe glass transition temperature of the poly-mer, the hard segment influences the melt-ing temperature. By combining hard andsoft segments (type, distribution of molec-ular weight, arrangement of segments) theproperties of these binder systems can becontrolled and adjusted to the specificneeds [11].

Thermoplastic elastomers are processedat higher temperature than crosslinkedpolymers (pressed, extruded etc.). Duringprocessing at higher temperatures the ther-moplastic elastomer forms a liquid filmwhich embeds the energetic compounds.After cooling down, a solid energeticcharge is obtained. The mechanical proper-ties are comparable to a product manufac-tured with a crosslinked polymer. The bestknown energetic thermoplastic elastomersused today are based on a block-co-polymer consisting of 3-azidomethyl-3-methyloxetan (AMMO) and poly[3,3-bis(azidomethyl)oxetan) (BAMO) seg-ments (Fig. 7) [12].

In the field of crosslinked polymersGAP (glicidyl-acid polymer) (Fig. 8) is be-coming increasingly important for manyapplications.

Hydroxyl terminated polybutadienes(HTPB) (Fig. 9) cannot be fitted into the

Fig. 5. Structure of ESTANE [10]

Scheme 2. Crosslinking of polyurethanes

Fig. 6. Structure of HYTEMP

dialcohol

EXPLOSIVES 388CHIMIA 2004, 58, No. 6

system of cross-linkable polyesters andpolyethers. Due to the outstanding mechan-ical properties of HTPBs, they have beenused in the field of explosives since 1989 ascrosslinkable prepolymers. Several com-mercial available explosives are qualifiedwith HTPB in the formulation.

The very high elasticity has a shock-ab-sorbing effect which drastically reduces thesensitivity of the respective explosive. A highpercentage of 1,4-crosslinkages with cis-dou-ble bonds has a positive effect on elasticityand lowers the glass transition temperature.1,2-crosslinkages have the opposite effect.The use of a HTPB is also foreseen for mod-ern diecast explosives on the basis of CL-20.

The curing agents used for crosslinkinghydroxyl terminated polymers are di- or tri-isocyanates. The degree of crosslinkage canbe controlled by means of the functionality.The isocyanates used most frequently inexplosives are isophorondiisocyanate (IPDI) and 4,4�-diisocyanatdiphenyl-methane (MDI) (Fig. 10).

In order to accelerate the crosslinking ofresin and curing agent systems, cure cata-lysts are used. For polyurethanes primarilymetallo-organic tin compounds are used forthis purpose.

3.3. Additives3.3.1. Addition of Plasticizers

By adding plasticizers, the mechanicalproperties of binder systems can be adjust-

ed within a wide range. Plasticizers reducethe auxiliary valency forces between thepolymer chains of a rigid crystallite struc-ture and thereby soften it. The miscibility,compatibility, and migration stability of aplasticizer within a polymer matrix is an ab-solute prerequisite for its applicability.

Typical representatives of low viscositymonomer plasticizers are dioctyl adipate inHYTEMP and isodecyl pelargonat inHTPB-polyurethane. But there are also en-ergetic plasticizers such as bis(2-fluor-2,2-dinitroethyl)formal (FEFO) or bis(2,2-dini-tropropyl)acetal/formal (BDNPA/F) (Fig.11).

3.3.2. Other AdditivesTo meet requirements, the properties of

an explosive formulation can be modifiedby adding different additives.

To improve the adhesion between thecrystals of the energetic compound and thesurrounding binder, metal-organic com-pounds based on titanium are used as�bonding agent� in several explosives. N,N2-Hydroxyethyl-dimethyl-hydantion (Dan-tocol) is also widely used as a bondingagent.

Polymers, elastomers, thermoplasticelastomers and in particular energetic poly-mers and plasticizers have to be protectedfrom ageing and degradation with adequatestabilizers as e.g. strongly sterically hin-dered bisphenyl.

3.4. PerformanceThe performance of an explosive formu-

lation largely depends on the type and fillingcapacity of the energetic compound and, ifenergetic binders are used, on the energy theycontribute to the conversion reaction. Sincethe performance depends directly on the en-ergy density, there is a linear increase of det-onation velocity and detonation pressure asthe density of the formulation increases.

The main parameters used to determinethe performance of military explosives are:detonation velocity, detonation pressure andthe resulting capability to accelerate metals.These parameters can be determined experi-mentally or calculated by means of suitablecomputer codes. In Table 4 the performancedata of some common military explosive for-mulations are listed.

At the moment formulations based on oc-togen offer the highest performance potential(see Table 4). By developing formulationscontaining the new energetic compound CL-20, the performance of future explosivecharges can be increased by 10�15%. For thefirst time the extraordinarily high detonationvelocity of 9280 m/s was measured in a for-mulation consisting of 98% CL-20 and 2% ofthe energetic polymer GAP [14]. Fig. 12shows the detonation velocity versus densitycurve of new high explosive formulationscontaining the energetic polymer GAP.

Received: March 30, 2004

Fig. 7. Example of typical prepolymers which are used as hard and soft seg-ments

Fig. 9. Hydroxyl-terminated poly-butadien (HTPB) type R45M [13]

Fig. 8. Glicidyl-acid-polymer Fig. 10. Typical diisocyanate curing agents for the ‘cast-cure’ process of hydroxyl terminated pre-polymers

Isophorondiisocyanate 4,4�-Diisocynatdiphenylmethane

EXPLOSIVES 389CHIMIA 2004, 58, No. 6

Fig. 12. Calculated and measured detonation velocity of CL-20/GAP 98/2 compared to HMX/GAP98/2

Table 4. Performance data of military explosive formulations

Name

Comp A3

LX-14

PBXW-11

PAX 21

Composition B

Octol

PBXN-109

PBXN-110

Composition[% by weight]

Hexogen/Wax91/9

Octogen/Estane95.5/4.5

Octogen/Hytemp/DOA96/1/3

DNAN/Ammonium perchlorate/Hexogen

34/30/36

original blend TNT/Hexogen/Wax

39.5/59.5/1

original blend TNT/Octogen 75/25

Hexogen/Al/HTPB64/20/16

Octogen/HTPB88/12

Density[g/ccm]

1.67

1.81

1.79

1.73

1.72

1.76

1.70

1.68

Detonation[m/s]

8520

8830

8690

8120

7920

8300

7480

8390

Pressure[GPa]

26.0

37.0

29.1

29.1

29.2

31.6

23.4

29.1

Processing

Pre

ssed

Cas

tD

ie-

cast

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Fig. 11. Energetic plasticizers