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|  MIL-C-48868E (AR)
4 .5.1.3.3 Nitrocellulose.
To provide good heat conduction
to the solvent, place a sufficient quantity of glycerin on the
flask bottom and on the surface of the heat source to produce a
continuous film. Add 10 ml. of ethyl alcohol to the thimble and
residue from 4.5.1.3.1 and extract with acetone using the method
in 4.5.1.3.1. After extraction dry the residue remain-
ing at 100 2C for one hour. Cool in a desiccator (1/2 hr.
min.), weigh to the nearest 0.2 mg. (Weight D) and save for the
acrylic determination in 4.5.1.3.4. Evaporate the acetone
extract to dryness and add 25 ml. of n-butyl acetate and 45 ml
of glacial acetic acid. Replace the air with a stream of inert
gas
or
Maintain the inert atmosphere through
out this test. Reflux the solution for five minutes. Add to
the flask, via the condenser, 25 ml of 0.7N ferrous ammonium
sulfate (prepared per MIL-STD-286, Method 604.1.1) and 10 ml.
concentrated hydrochloric acid. Reflux for thirty minutes more
to obtain a yellow liquid in which the specimen is completely
disintegrated.
With the inert gas still running, cool in water
bath to room temperature. Add 5 ml. of 20% ammonium thiocyanate
solution (MIL-STD-286, Method 706.1). Titrate with a 0.2N
titanous chloride solution (MIL-STD-286, Method 601.1). Perform
a blank titration on the reagents. Calculate percent NC as
follows:
Percent (%) NC =
Where:
V = Volume titanous chloride used for sample, ml.
B
=
Volume titanous chloride used for blank, ml.
W
=
Weight of dried sample, gm.
N
=
Normality of titanous chloride
=
Percent nitrogen in the nitrocellulose
E
4.5.1.3.3.1 Alternate method. Schulze - Tiemann method for
nitrocellulose (NC) determinations.
Assemble the 250 ml Kjeldahl flask, gas evolution apparatus
eudio meter/condenser tube, NaOH bath, lead band, heating
mantle, transformer and protective shield as shown in Figure 1.
Calibrate the apparatus with dry standard A.C.S. grade
Weigh 0.5 - 0.7 g standard samples to 0.1 mg and
analyze using the following procedure. The factor is determined
using the following equation:
20
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