NBR: Acrylonitrile-butadiene rubber

General Properties

Short Name:

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NBR

Acrylonitrile-butadiene rubber

Acrylonitrile butadiene rubber (NBR) is obtained by copolymerization of acrylonitrile (ACN, the content varies between approx. 20 to 50% in commercial products) and 1,3 butadiene. The ACN content significantly influences the properties of the NBR vulca- nizate. Carbon black is often used as fi ller material. Just like NR, CR or SBR, NBR belongs to the R group of rubbers, i.e., to the group with an unsaturated hydrogen carbon chain (classification in accordance with ISO 1629 or ASTM D1418).

Structural Formula

Properties

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 Temperature	-44 to 5°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	-
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	-
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature	450 to 475°C
Young's Modulus	2 to 5 MPa
Coefficient of Linear Thermal Expansion (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	150 to 180 *10^-6/K
Specific Heat Capacity	1.93 to 1.96 J/(g*K)
Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.Thermal Conductivity	-
DensityThe mass density is defined as the ratio between mass and volume. Density	1.00 g/cm³
Morphology	Amorphous rubber
General properties	Good abrasion resistance. Good temperature resistance. Very good resistance to fuels, mineral oils, lubricating greases, vegetable and animal fats and oils
Processing	Cross-linking by means of sulfur (with accelerator)
Applications	Apparatus engineering (e.g., seals, O-rings). Automobile industry (e.g., brake pads, clutches). Packaging industry. Rubber gloves

NETZSCH Measurement

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	11.47 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phase	7 min
Heating/Colling Rates	10 K/min
Crucible	Al, pierced lid
Atmosphere	N₂ (40 ml/min)

Evaluation

In this case, NBR has a slightly lower 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 temperature (-29°C, midpoint, 2^nd heating, red) and a slightly lower Δc_p (0.29 J/(g.K)) than in the HNBR (T_g -23°C, Δc_p 0.38 J/(g.K)) example on the previous pages. 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 is overlapped by a slight RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation.