Elastomer Properties - Abrasion/Coefficient of Friction/Electrical Properties

Abrasion: Resistance to wear may be a very important property in many applications. Standard test methods use a uniform abrading material and application. Abrasion is a measure of the amount of material lost in these tests.

Test Methods:

ISO 4649 (ISO), 5470 (Taber)

ASTM D394 (Du Pont), D1630 (NBS),

D2228 (Pico), D3389 (Taber)

Coefficient of Friction: The coefficient of friction is the ratio of the frictional force between two bodies, parallel to the contact surface, to that of the force normal to the contact surface. Breakaway friction is the threshold friction coefficient as motion begins, and running friction is the steady-state friction coefficient as motion continues.

Volume Resistivity: The measure of electrical resistance through a volume of elastomer. This property is useful in predicting conductive or antistatic behavior.

ASTM D991

abrasion rate vs. tear resistance of various sealing elastomers

Dielectric Constant (Permittivity): The ratio of the capacitance of a capacitor filled with the elastomer to that of the same capacitor having only vacuum as the dielectric.

ASTM D150

Dielectric Strength: The measure of the ability of an elastomer to resist current flow when a voltage is applied.

ASTM D149

coefficient of friction of a typical elastomer

Electrical Properties of Various Sealing Elastomers

	Volume Resistivity (Ohm-cm)	Dielectric Constant (23C, 1kHz)	Dielectric Breakdown (kV/0.15mm)
EPDM	1.0 x 10¹⁵ to 1.0 x 10¹³	2.3–2.8	-
FKM	5.8 x 10¹⁰ to 3.5 x 10¹⁵	8.8–10.7	-
AEGIS	1.4x 10¹⁷	2.4	7.0

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