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MIL-P-47099A
3.2 Material. The polyurethane foam compound shall consist of a polyether
type base resin and a separate isocyanate-type base resin and a separate isocyanate-
type curing agent, so formulated as to produce, upon mixing, a polyurethane foam of a
specified density certified by the manufacturer (see 6.2).
3.3 Storage life. The foam shall conform to the requirements of this
specification after a storage period which shall be not less than 6 months for type I and
III and 24 months for type II when stored in the original unopened container at a
temperature between 16 and 32 Celsius (C) [60 and 90 Fahrenheit (F)]. The storage
life shall be certified by the manufacturer (see 6.2).
3.4 Physical properties. The physical properties of the cured material shall be
in accordance with table I (see 4.7).
TABLE I. Physical properties
Property
Type I
Type II
Type III
Density, lb/ft3 ------------------------
2 10%
2 to 3
4 10%
Tensile strength, psi, lb/in2)
minimum ----------------------------
-
10 @ 25C 1(77F 2)
-
Compressive strength, psi, (lb)
minimum ----------------------------
-
3
-
Shear strength, psi, (lb) minimum -
15
6
15
Dielectric constant, maximum at
25C(77F) and 9375 MHz -------
1.25
-
1.25
Dielectric strength, V/mil,
minimum ----------------------------
-
45
-
Dimensional stability, % increase
in volume between -54C(-65F)
and 68C(155F) ------------------
1.5
-
1.5
Flammability -------------------------
-
self extinguishing
-
Temperature resistance, 1 hour at
86.9 3C(190 5F) (loss of
properties) -------------------------
-
None
-
Humidity growth, % increase in
volume, % loss of physical
10%
property values ---------------------
-
60%
-
Fungus resistance --------------------
-
no fungus growth
-
3.5 Workmanship. The polyurethane foam shall meet all requirements of this
specification. The materials shall be clean and free of foreign matter, gel particles and
4

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