ZZ-R-768 Rubber For Mountings Unbonded-Spool And Compression TypesThis specification covers uncured rubber compound or finished cured resilient components to be used in unbonded-spool and compression typed mountings, as specified.

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Properties

First Article

Testing Required

Conformance

Testing Required

Requirement

Test Method

Paragraph

Initial properties

Tensile strength, psi, minimum

x

x

1,800

4.5.1

Ultimate elongation, percent, minimum

x

x

300

4.5.1

Tensile stress (modulus) psi at 100%

elongation

x

x

As determined

4.5.1

Hardness, Type A durometer

x

x

55±5

4.5.2

Specific gravity

x

x

1.25±0.10

4.5.3

Tear resistance, pounds per inch, minimum

x

130

4.5.4

Properties after oven aging for 96±½ hour at 194±2 °F (90±1.1 °C)

Tensile strength, percent of initial, minimum

x

80

4.5.5

Ultimate elongation, percent of initial, minimum

x

75

4.5.5

Tensile stress (modulus) psi at 100%

elongation

x

As determined

4.5.5

Hot compression set, percent, maximum

x

45

4.5.6

After immersion in medium No. 3 oil for 96±½ hour at 122±2 °F (50±1.1 °C)

Volume change, percent

x

±10

4.5.7

Properties at 73.4±2 °F (23±1.1 °C)

Deformation, percent

x

19±2

4.5.8

Resilience, percent, maximum

x

70

4.5.8

Frequency, Hz

x

4.1±0.3

4.5.8

Absorbed energy, inch-pounds per cubic inch

x

29±3

4.5.8

Properties at 32±2 °F (0±1.1 °C)

Deformation, percent of value at

73.4±2 °F (23±1.1 °C), minimum

x

75

4.5.8

Resilience, percent, maximum

x

70

4.5.8

Frequency, Hz, minimum

x

3.6

4.5.8

Absorbed energy, percent of value at

73.4±2 °F (23±1.1 °C), minimum

x

45

4.5.8

Cold compression set, percent, maximum

x

15

4.5.9