MIL-DTL-25988C
TABLE III. Physical properties, type II (molded parts (other than o-rings), sheets, strips, and extruded shapes).
Class 1
Class 2
Class 3
Grade 40
Grade 50
Grade 60
Grade 70
Grade 80
Grade 50
Grade 75
Specific gravity
As determined 1/
As determined 1/
As determined 1/
As determined 1/
As determined 1/
As determined 1/
As determined 1/
Hardness, points
40 ±5
50 ±5
60 ±5
70 ±5
80 ±5
50 ±5
75 ±5
Tensile strength, psi, min.
800 (5.52 kPa)
900 (6.20 kPa)
900 (6.20 kPa)
950 (6.55 kPa)
750 (5.17 kPa)
1150 (7.93 kPa)
800 (5.52 kPa)
Elongation, %, min.
225
200
175
150
70
350
100
Tensile stress @ 100% elongation, psi,
700
min.
Tear strength, psi, min.
40 (276 Pa)
40 (276 Pa)
40 (276 Pa)
75 (517 Pa)
40 (276 Pa)
150 (1034 Pa)
40 (276 Pa)
Temperature retraction, °F, max.
70 (56.6 °C)
70 (56.6 °C)
70 (56.6 °C)
70 (56.6 °C)
70 (56.6 °C)
70 (56.6 °C)
70 (56.6 °C)
After air aging 70 hrs.
@ the 75 ±5 °F (23.9 ±2.8 °C)
Compression set, %, max.
15
15
15
15
15
15
15
After air aging 70 hrs. @ the
392 ±5 °F
392 ±5 °F
392 ±5 °F
392 ±5 °F
392 ±5 °F
392 ±5 °F
437 ±5 °F
temperatures indicated:
(200 ±2.8 °C)
(200 ±2.8 °C)
(200 ±2.8 °C)
(200 ±2.8 °C)
(200 ±2.8 °C)
(200 ±2.8 °C)
(250 ±2.8 °C)
Hardness change, points, max.
±10, 5
±10, 5
±10, 5
±10, 5
±10, 5
±10, 5
±10, 5
Tensile strength decrease, %, max.
30
25
25
20
20
30
35
Elongation decrease, %, max.
25
25
25
25
20
30
45
Weight loss, %, max.
2
2
2
2
2
2
2
After air aging 22 hrs.
@ 347 ±5 °F (175 ±2.8 °C)
Compression set, %, max.
25
35
40
25
45
40
35
9
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