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 Cristalinidad / Grado de CristalinidadCrystallinity 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

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 Enthalpy	5 to 20 J/g
Decomposition Temperature	470 to 487°C
Young's Modulus	2 to 10 MPa
Coeficiente lineal de expansión térmica (CLTE/CTE)The coefficient of linear thermal expansion (CLTE) describes the length change of a material as a function of the temperature.Coefficient of Linear Thermal Expansion	180 *10^-6/K
Specific Heat Capacity	1.80 to 2.00 J/(g*K)
Thermal Conductivity	0.26 W/(m*K)
Density	0.86 g/cm³
Morphology	Rubber, sometimes with soft and hard segments
General properties	Very good electrical insulating properties. Very good ozone and sunlight resistance. Good aging resistance. Good resistance to heat, chemicals, hot water and water vapor
Processing	Cross-linking by means of sulfur (with accelerators) or peroxides
Applications	Seals 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

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	13.83 mg
Isothermal Phase	7 min
Heating/Colling 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, 2^nd heating, red) with an enthalpy of 0.8 J/g, indicating a small amount of crystalline content. The Temperatura de Transición VítreaThe 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 (2^nd heating, red) is probably due to the melting of additives. This appears as a single peak in the 1^st heating (blue).