R. Meyer J. Köhler A. Homburg Explosives

Stability
similar in appearance to a detonator, but loaded with low explosive, so
that its output is primarily heat (flash). Usually electrically initiated and
provided to initiate the action of pyrotechnic devices and rocket propellants.
An electric squib is a tube containing a flammable material
and a-mall charge of powder compressed around a fine resistance
wire connected to electrical leads or terminal (W Initiator, W Bullet Hit
Squib).
Stability
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Stabilität; stabilité
A distinction must be made between chemical and physical stability.
While physical stability is important, particularly in the evaluation of
solid propellants, the chemical stability is of prime importance in the
estimation of the course of decomposition of nitrate esters. The nitrate
esters which are processed for use as propellants – unlike nitro
compounds, which are relatively stable under these conditions – undergo
a steady decomposition, which is due to imperfect purification of
the starting materials and to the effect of other parameters such as
temperature and air humidity. The rate of this decomposition is autocatalyzed
by the acidic decomposition products and may in certain
cases produce spontaneous ignition. In order to reduce the decomposition
rate as much as possible, suitable stabilizers are added to the
powders, which are capable of accepting the acid cleavage products
with formation of the corresponding nitro compounds (W Stabilizers).
The stability is controlled by means of several tests (W Hot Storage
Tests).
A distinction must be made between tests of short duration, in which
the possible decomposition reactions are accelerated by a considerable
rise in temperature, and the so-called service-life tests or surveillance
tests, which take place over several months and may sometimes
take more than a year. Short-duration tests alone do not suffice for a
reliable estimate of the stability, at least where imperfectly known
products are concerned.
An estimation of the probable W Shelf Life of aged propellants can be
made by chromatography*). If e.g. diphenylamine is used as a stabilizer,
the transformation into the nitro derivatives up to hexanitrodiphenylamine
can be analysed; if this stage is reached, decomposition of
the powder occurs.
* Volk, F., Determination of the Shelf Life of Solid Propellants, Propellants and
Explosives 1, 59–65 (1976).
Volk, F., Determination of the Lifetime of Gun-propellants using Thin layer
Chromatography, Propellants and Explosives 1, 90–97 (1976).