MIL-DTL-45444C
In the development of a calibration curve using the three HMX/RDX
standards, upon establishing the linearity of the HPLC method
response across the concentration range being studied, a single-
point calibration using the standard which provided a peak area
closest to the area obtained for the sample can be used to
determine the HMX and RDX concentrations in the HMX product.
4.7.2 Melting point. A Fisher-Johns or equivalent hot
state melting point apparatus shall be used to determine the
melting point of HMX. The thermometer of this apparatus shall be
calibrated using appropriate melting point standards. A portion
of the sample shall be ground in small agate mortar and a very
small quantity (approximately 0.05 gram) of the finely pulverized
sample placed between two clean 18 millimeters (mm) diameter
cover glasses. These shall be gently but firmly pressed together
and placed in the circular depression on the stage. The
powerstat shall be turned up and the unit allowed to heat. The
heating rate may be very rapid to within 15 degrees C of the
melting point. Thereafter a heating rate of approximately 1
degree C per minute shall be used. When the sample begins to
melt, the thermometer shall be read and the temperature reading
adjusted to reflect the thermometer calibration correction shall
be reported as the melting point.
4.7.3 Insoluble particles. Weigh three samples of 17 + 0.1
grams each (dry weight) from the prepared HMX sample. Transfer
each sample into a 1000 ml beaker and add 500 ml of acetone to
each beaker. Heat the contents of the beakers until the
explosives are in solution. Combine the solutions and filter
through USSS 40 and USSS 60 sieves. The filtrate shall be
retained and used for testing acetone and inorganic insolubles.
The screens shall be dried. Any particles remaining on the
screens will be counted and reported as insoluble particles.
4.7.4 Acetone insoluble. Use the residue and filtrate from
4.7.3 or weigh an approximately 10 gram portion of the dried
sample accurately to the nearest 0.01 gram, place the sample in a
600 ml beaker and add 400 ml of filtered acetone. Place the
beaker and contents on a steam bath (cover with a watch glass if
necessary) and stir occasionally until all of the HMX has
dissolved. Filter the HMX solution through a 25 ml medium
porosity porcelain filtering crucible, which has been ignited at
700 + 20 degrees C, and tared to the nearest 0.1 milligram.
Transfer any remaining insoluble material from the beaker to the
crucible with the aid of a stream of acetone from a wash bottle.
Wash the material remaining in the crucible three times with 20
ml portions of acetone and aspirate until the odor of acetone is
no longer noticeable. Dry the crucible in an oven at 105 + 5
degrees C for thirty minutes, cool in a desiccator and weigh to
the nearest 0.1 milligram. Reserve the crucible and contents for
determination of inorganic insoluble materials given in 4.7.5.
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