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Page Title:
Cured PBXN-109, analytical procedure |
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| MIL-E-82886(OS)
where:
V = Volume of gas, (mL)
All other characteristics are identified in 4.11 of MIL-STD-650, Method 503.1.1. The sample shall be cut
into small cubes with a maximum size of 3 mm before being placed in the vacuum stability test tube. Two
samples, one from each section of the batch shall be used.
4.6.4.3 Alternate method #2. A second alternate method which may be used is MIL-STD-286,
Method 403.1.2.
4.6.5 Composition analysis.
4.6.5.1 Cured PBXN-109, analytical procedure. Analyze, in duplicate, each sample of PBXN-109
received for analysis. This shall consist of a sample from the top and a sample from the bottom of the
batch. Weigh a 0.5-g sample to the nearest 0.1 mg into a 100-mL beaker. Add 20 mL of acetone, boil and
break up with a flat tipped stirring rod. Filter the solution through a weighed, medium porosity, sintered-
glass crucible. Repeat the acetone extraction twice (total 60 mL acetone), then quantitatively transfer the
residue to the crucible with acetone. Dry the crucible plus the residue at 100C for 1 hour. Dilute the
acetone solution to 100 mL in a 100-mL volumetric flask.
a.
Weigh the crucible plus residue, then add 1 mL of 6N hydrochloric acid to the residue. Wait
for the initial reaction with the aluminum to begin and subside, then add 5 mL more of the 6N
hydrochloric acid. Let the reaction go overnight (about 15 hours). Dilute the acid with 10 mL
of water and remove by suction. Rinse the resulting polymer at least 10 times with 10 mL of
water, then with 10 mL acetone. Dry the crucible plus polymer at 100C for 1 hour, cool, and
weigh. The difference in weight after acetone extraction and after hydrochloric acid treatment
is the weight of aluminum. The residue on the crucible after treatment with the hydrochloric
acid is the polymer.
b.
Weigh 0.5 g of di-n-butylphthalate into a 100-mL volumetric flask, dissolve in acetone, and
dilute to volume with acetone. Mix 1 mL of this solution with 9 mL of the acetone solution
from 4.6.5.1 above. Inject an aliquot of the mixture into a gas chromatography column
containing SE-30 (2.5% on Chromosorb W HP 100/120 mesh, 4 feet x 1/4 inch) at 230C
(injection port 240C; helium, 70 mL/minute) using flame ionization detector. Compare this
chromatogram with a standard solution containing known amounts of di-n-butylphthalate and
DOA.
c.
Weigh 1.5 mg of TNT into a 10-mL volumetric flask, dissolve in methanol, and dilute to
volume with methanol. Pipette 100 microliters of the acetone solution from 4.6.5.1 above into
a 10-mL volumetric flask, and remove the acetone by heating in a boiling water bath. Add 1
mL of the TNT solution to the residue, dissolve by heating in the water bath, and dilute to
volume with methanol. Prepare a standard methanol solution containing 6 parts per million
(ppm) HMX, 30 ppm RDX, and 15 ppm TNT. Inject aliquots of the standard mixture and the
unknown containing TNT onto an RP-8 HPLC column, elute with 40% methanol in water (2
mL/minute), and detect with 240 nanometers radiation.
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