These test methods can be used for determining which EPDM polymers are evaluated in the different compounds in Test Methods D3568.

Differences in ethylene sequence distribution cause differences in crystallinity and green strength at the same ethylene content. Since these are important variables in EPM and EPDM processability and end-use properties, the ethylene content of the rubber should not be used as the sole measurement to determine the suitability of a particular rubber for an intended purpose.

1.1 These test methods cover the determination of the proportion of ethylene and propylene units in ethylene-propylene copolymers (EPM) and ethylene-propylenediene terpolymers (EPDM) over the range from 35 to 85 mass % ethylene. Four test methods are needed to encompass the variety of commercial polymers that contain additives or polymerized diene units that interfere with the various infrared peaks. Except when interferences are present, all four test methods should give similar results. The test methods appear in the following order: