The Chemistry of Powder and Explosives - Sciencemadness Dot Org

MANUFACTURE OF SINGLE-BASE POWDER 299
while a flashless ballistite of class II b c is made by incorporating
centralite and DNX oil with nitroglycerin and nitrocellulose, and
one of class II b e by mixing centralite and nitroguanidine with
nitroglycerin and nitrocellulose. The nitroguanidine does not dissolve
in the colloid but is distributed through it in a state of fine
subdivision. Ten or 15 parts of nitroguanidine incorporated with
90 or 85 parts of pyrocellulose colloided with ether-alcohol gives
a mixture which may be extruded through dies and yields a
powder (I a e) which is flashless. PETN is another substance,
insoluble in nitrocellulose colloids, which in the state of a fine
powder may be incorporated in single-base or in double-base
mixtures to yield powders (I a e and II a e) which are hotter
and more powerful than otherwise.
Manufacture of Single-Base Powder
The operations in the manufacture of smokeless powder from
pyrocellulose, briefly, are as follows.
1. Dehydrating. The pulped pyrocellulose contains about 25%
moisture when it arrives at the smokeless powder plant. Most of
this is squeezed out by pressing with a moderate pressure, say
250 pounds per square inch, for a few moments. The pressure is
then released, alcohol in an amount at least equal to the dry
weight of the pyrocellulose is forced into the mass by means of a
pump, and the pressure is increased to about 3500 pounds per
square inch. The process is managed in such fashion that the
resulting cylindrical block consists of pyrocellulose moistened
with exactly the amount of alcohol which is needed for the
formation of the colloid. The requisite amount of ether is added
later. The solvent consists altogether of 1 part by weight of
alcohol and 2 parts of ether, 105 pounds of the mixed solvent for
every 100 pounds of pyrocellulose if the colloid is to be made into
0.30-caliber powder, 100 parts if into powder of which the web
thickness is approximately 0.025 inch, and 85 parts for powder
having a web thickness of 0.185 inch. The block is received in a
cannister of vulcanized fiber and is covered over in order that
loss of solvent-by evaporation may be reduced to a minimum.
From this point on, in fact, the material is kept and is moved
from one operation to another in covered cannisters at all times
except when it is being worked.