General Properties
Short Name: EPDM
Name: Ethylene-propylene-diene rubber
EPDM is a terpolymer with a diene component, such as cyclopentadiene. E stands for ethylene, P for propylene, D for diene and M for the class of saturated carbon molecules in the main macro-molecule-chain (classification in accordance with ISO 1629 or ASTM D1418). Commercial EPDM rubbers have an ethylene content of approx. 45–75 weight%. Polymers with a low ethylene content (45–55 weight%) are amorphous and very flexible at low temperatures. With an increasing ethylene content, the degree of Crystallinity / Degree of CrystallinityCrystallinity refers to the degree of structural order of a solid. In a crystal, the arrangement of atoms or molecules is consistent and repetitive. Many materials such as glass ceramics and some polymers can be prepared in such a way as to produce a mixture of crystalline and amorphous regions.crystallinity rises. EPDM with a mean ethylene content of approx. 55–65 weight% is semi-crystalline. With ethylene contents >65 weight%, EPDM features larger crystalline regions and behaves as a thermoplastic elastomer.
Structural Formula
Properties
NETZSCH Measurement
| Sample Mass | 13.83 mg |
| Heating Rates | 10 K/min |
| Crucible | Al, pierced lid |
| Atmosphere | N2 (40 ml/min) |
Evaluation
This EPDM sample is not purely amorphous since it exhibits a small melting transition at 6°C (peak temperature, 2nd heating, red) with an enthalpy of 0.8 J/g, indicating a small amount of crystalline content. The Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition at -54°C (midpoint, both heatings) is from the amorphous content. The endothermal effect with peak temperatures of 43°C and 52°C (2nd heating, red) is probably due to the melting of additives. This appears as a single peak in the 1st heating (blue).