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close this bookThe Fight Against Antipersonnel Mines (EC, 1997, 108 p.)
close this folderAppendix
View the documentAppendix I - The explosives
View the documentAppendix II - The main types of firing devices
View the documentAppendix III - General development of mines
View the documentAppendix IV - Mines trade circuits
View the documentAppendix V - Sub-munitions
View the documentAppendix VI - The limits of magnetic detection
View the documentAppendix VII - The example of Afghanistan
View the documentAppendix VIII - Research and development and mine clearance
View the documentAppendix IX - Localisation and identification of antipersonnel mines

Appendix I - The explosives

· Study of nitro-compound explosives: nitration

Many substances contain hydrogen atoms (H), which are particularly sensitive to the action of nitric acid. If we write 'RH' for one such element, then the SALSIFICATION reaction of nitric acid can be described as follows:

RH + HNO3 ® R-NO2 + H2O + ENERGY.

This reaction (explosion) thus results from the substitution of a combustive (NO2) for a combustible agent (H). Given that the reaction produces water (H2O), it will necessarily be facilitated by the presence of a water-absorptive substance (sulfo-nitric mixture).

This operation- fixation on to a combustible molecule of combustive elements supplied by the nitric acid- is called «nitration»: it is characteristic of the production of explosives. Nitro-compound explosives belong to three families:

· Aromatic derivatives

- T.N.T. (Trinitrotoluene or Tolite) is produced, as its name suggests, by a triple nitration of toluene (a derivative of benzene) and comes in the form of pale yellow flakes. It is water-insoluble. It burns at 290ut can spontaneously combust as of 240°C. When it is in thin layers (of less than 5 cm) and is unconfined, it burns slowly. Its low fusion temperature allows it to be melted. T.N.T. is not highly sensitive to mechanical effects. T.N.T. comes into the composition of many explosives:

- Amatol (British):

T.N.T + Ammonium nitrate

- Ammonal:

T.N.T. + Ammonium nitrate + Aluminium

- Tritonal (American):

T.N.T. + Aluminium, etc.

· Nitric esthers

- Pentrite (Pentaerythrite tetranitrate), also known as Nitropentaerythrite or P.T.N. and as Nitropenta or N.P, is produced by nitration of a formol derivative and acetic aldehyde. It comes in the form of white, water-insoluble crystals. Pentrite is stable up to 100°C, but begins to decompose as of 120°C- preventing melted use; it burns at 220°C. In thin layers (of less than 5 cm) and unconfined, pentrite burns slowly, but can detonate when its mass exceeds a few tens of kilogrammes or if it is confined. It is highly sensitive to mechanical effects and to fusing, and, if dry, electrifies easily. It is more sensitive to friction than are most other commonly used explosives. The above characteristics make pentrite an ideally suitable ingredient in the production of detonators and fazes. Pentrite is an active hypotensor, but is not toxic. It goes into the composition of the following:

- plastic explosives (Plastic): Pentrite (87%) + transformer oil + gelatine;
- leaf explosives (Formex): Pentrite (80%) + natural rubber.

· Nitramines

- Hexogen (Cyclotrimethylene-trinitramine) is also known, in Great Britain, as R.D.X., and, in Italy, as T 4. Produced by the reaction of nitric acid on hexamine (hexamethylene tetramine), hexogen comes in the form of white crystals which have low solubility in water. Easily destroyed under heat by soda and bases, hexogen is stable up to 100°C and decomposes as of around 160°C, preventing melted use. Its combustion (at 260°C) is strong and fast, easily giving detonation. Highly sensitive to mechanical effects and to fusing, it is less reactive to electric sparks than are the other common explosives. Its high sensitivity makes it suitable for use in relay/boosters and in fuzes. Water reduces its sensitivity. It is toxic.

- Hexogen often comes into the composition of the new PLASTIC EXPLOSIVES.

- Tetryl (Tetranitromethylaniline) is produced by nitration of methylaniline. It comes in the form of pale yallow crystals which are virtually insoluble in water. Water, on the other hand, gives rise to a hydrolysis resulting in melanite (picric acid), which attacks metals (with possible production of picrates). Tetryl is stable up to 100°C, whereafter decomposition begins. Its fusion temperature is 128°C and its combustion temperature 240°C. Tetryl burns violently, which can result in detonation in case of confinement or of critical mass. It is toxic (irritation of skin, mucosa and upper airways, and digestive disorders).

- Tetryl is used in the production of detonators (Tetryl + Lead nitride) and of relay/boosters. It is often employed in tablet or in powder form, or mixed with T.N.T. It is possible to graphite it 1% and so to enhance its mechanical sensitivity and electrical conductivity.

- Ammonium nitrate, although not used alone, does come into the composition of explosives such as dynamite, Amatol and ammonal, where it plays the part of an oxydant. It comes in the form of colourless, water-insoiluble crystals. Stable up to 150°C, it melts at 169.6°C and is insensitive to friction or fusing. In a damp evironment, it will attack metals- and in particular copper, forming copper nitrate, a highly sensitive explosive; it does not attack aluminium; it is not toxic.