BR: Butadiene rubber

General Properties

Short Name:

Name:

Butadiene rubber

BR stands for “butadiene rubber” and designates, along with SBR (styrene butadiene rubber), the most Adiabatic temperature riseThe adiabatic temperature rise (delta Tad) is the observed temperature rise (delta Tobs) of a self-heating decomposition reaction under adiabatic conditions in consideration of the PHI-factor.commonly used synthetic rubber. BR is produced from 1,3-butadiene. The monomers can be connected on both ends (1,4 bonding) or only on one end (1,2 bonding, vinyl group in the side chain) producing diff erent BR types with different properties. The 1,4 bonding can further be classified into 1,4 cis and 1,4 trans, where “cis“ means that the substituents are on the same side of the double bond; “trans” means they are on the opposite side of the double bond.

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	-106 to -95 (1.4 cis), -107 to -83 (1,4 trans), -15 (1,2)°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	-25 to 12 (1,4 cis), 97 / 145 (1,4 trans), 126 (1,2)°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	46/170 (1,4 cis), 70 to 140 (1,4 trans) J/g
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature	370 to 385 / 460 to 475°C
Young's Modulus	-
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	-
Specific Heat Capacity	1.76 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	0.25 W/(m*K)
DensityThe mass density is defined as the ratio between mass and volume. Density	0.9 to 1.0 g/cm³
Morphology	Elastomer with hard and soft segments
General properties	High elasticity. High stability. High abrasion resistance
Processing	Extrusion, calendering, injection molding, vulcanization
Applications	Tire industry (blends with NR or SBR). Mechanical engineering. Technical rubber goods (e.g., band conveyors). Golf balls, shoe soles

NETZSCH Measurement

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	12.29 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phase	8 min / 3 min / 8 min
Heating/Colling Rates	10 K/min
Crucible	Al, pierced lid
Atmosphere	N₂ (40 ml/min)

Evaluation

Polybutadiene or butadiene rubber has both soft and hard segments. For this reason, the above graphic shows a 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 -101°C (midpoint) in both heatings with a step height (Δc_p) of approx. 0.27 J/(g.K) from the soft segments and a melting endotherm with a peak temperature of -5°C from the hard segments. It can be concluded that the sample is mainly a 1,4 cis type.