Mandrel Research Papers - Academia.edu (original) (raw)

Composite propellant mainly consists of two
parts, binder matrix (prepolymer, plasticizer, cross linker,
antioxidant and curative etc.) and solid ingredients (oxidizer,
metal fuel, burn rate modifier, combustion stabilizer etc.). Its
processing involves several stages like ingredient preparation
(grinding, 1.1 Hazard Division – 1.1 HD), mixing (1.1 HD),
casting (1.1 HD), curing (1.3 HD) and extraction (1.3 HD).
Each and every process is very hazardous. Removal of any
of the mentioned step will be a great achievement for solid
rocket motor processing. Mandrel is used to give proper
grain geometry. But for metal mandrel, its extraction process
(1.3 HD) is very dangerous. Proper safety precaution should
be taken to perform the said operation. Also, for a metal
mandrel, it is very difficult to develop intricate grain geometry
due to extraction problem. This paper mainly deals with
casting techniques of propellants (case bonded or cartridge
loaded) with a chemically collapsible mandrel. This mandrel is
collapsed in presence of suitable chemicals, hence extraction
step (1.3 HD) becomes simpler. As the extraction process
is very easy, intricate grain geometry can be developed in
solid rocket motor. The mandrel is cheap, recycleable and
relatively lightweight compared to the metal mandrel, thus
handling becomes very easy. The mandrel material and the
dissolution solvent have no effect on the propellant, which
will be confirmed by evaluation of physicochemical as well as
ballistic properties measurement.