MIL-DTL-25988 Rubber, Fluorosilicone Elastomer, Oil-And-Fuel Resistant, Sheets, Strips, Molded Parts, And Extruded ShapesThis specification covers oil- and -fuel-resistant fluorosilicone elastomer rubber sheets, strips, molded parts, and extruded shapes for aeronautical and aerospace applications.

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MIL-DTL-25988C

4.5 Test methods

4.5.1 Physical properties

Unless otherwise specified herein, physical properties shall be determined in accordance with

ASTM test methods for rubber products as follows:

Property

ASTM method

Hardness

D 2240

Tensile strength and elongation

Type I

D 1414

Type II

D 412, (use die C for oil aging)

Tensile stress

Type I

D 1414

Type II

D 412

Tear strength

D 624, die B

Volume change

D 471

Specific gravity

D 297, hydrostatic method

4.5.2 Temperature retraction (TR-10)

The temperature retraction test shall be conducted in accordance with ASTM D 1329. Three

O-ring specimens as specified in 4.2.1 shall be used for type I and shall be elongated 50

percent in accordance with the rod markings. The temperature retraction test for type II shall be

conducted on three 2-inch (50.8 mm) specimens. Elongation of type II materials shall be 50

percent of the ultimate elongation. The test shall be conducted at a heating rate of 1 �C per

minute.

4.5.3 Air aging

Air aging shall be conducted in accordance with ASTM D 573, except that the aging time and

temperature shall be in accordance with TABLE II or TABLE III as applicable. Tensile strength,

elongation, and hardness changes shall be determined as specified in 4.5.1.

4.5.3.1 Weight loss

The weight loss test shall be conducted on samples air aged in accordance with 4.5.3. Test

specimens shall be conditioned for 24 hours in a desiccator before and after air aging. The

specimens shall be weighed immediately after the desiccation period before and after aging.

The percentage weight loss shall be calculated as follows: