EPDM: Ethylene-propylene-diene rubber

General Properties

Short Name:

Name: 

EPDM

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 (classifi cation 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 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

Glass Transition Temperature-55 to -30°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Temperature-20 to 60°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Enthalpy5 to 20 J/g
Decomposition Temperature470 to 487°C
Young's Modulus2 to 10 MPa
Coefficient of Linear Thermal Expansion180 *10-6/K
Specific Heat Capacity1.80 to 2.00 J/(g*K)
Thermal Conductivity0.26 W/(m*K)
Density0.86 g/cm³
MorphologyRubber, sometimes with soft and hard segments
General propertiesVery good electrical insulating properties. Very good ozone and sunlight resistance. Good aging resistance. Good resistance to heat, chemicals, hot water and water vapor
ProcessingCross-linking by means of sulfur (with accelerators) or peroxides
ApplicationsSeals and profiles. Cable sheathings and insulations. Cool water hoses. Components of household appliance. Construction sealing strips. Blend partners in PP-EPDM blends (TPV) to improve the impact strength of PP (application in the automobile industry as underbody or bumper material)

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass13.83 mg
Isothermal Phase7 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (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 Temperatura di transizione vetrosaLa transizione vetrosa è una delle più importanti proprietà chimico-fisiche dei materiali amorfi e semi-cristallini, come, ad esempio, vetri, metalli (amorfi), polimeri, ingredienti farmaceutici e alimentari e definisce l’intervallo di temperatura in cui le proprietà meccaniche die materiali variano da duro e fragile a più morbido, malleabile o gommoso.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).