NR: Natural rubber

General Properties

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NR

Natural rubber


NR is a natural product and is produced from the white milky juice (latex) of the rubber tree. The artificially manufactured kind is designated isoprene rubber (IR) and is made up of isoprene (2-methyl-1,3-butadiene) as a monomer. NR is an entirely 1,4 cis isomer. The 1,4 polyisoprene is also a natural product called gutta-percha. For more on cis-trans isomerism. Carbon black is often added in order to increase the tensile strength and abrasion resistance of the material, as well as for coloring.

Structural Formula


Properties

Glass Transition Temperature-72 to -55°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 Temperature25 to 40°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 Enthalpy67 J/g
Decomposition Temperature375 to 400°C
Young's Modulus1 to 5 MPa
Coefficient of Linear Thermal Expansion180 to 260 *10-6/K
Specific Heat Capacity1.91 to 2.08 J/(g*K)
Thermal Conductivity0.13 to 0.15 W/(m*K)
Density0.91 to 0.93 g/cm³
MorphologyAmorphous rubber, partly with hard segments
General propertiesHigh stability and high elasticity. High elongation at break. Good abrasion resistance
ProcessingCross-linking by means of sulfur incl. accelerator (e.g., mercaptobenzothiazole or sulfenamide) and activator (zinc oxide and stearic acid)
ApplicationsTire industry. Technical rubber goods (e.g., rubber springs, band conveyors). Medical engineering. Toys. Shoe soles

NETZSCH Measurement

InstrumentDSC 204 F1 Phoenix®
Sample Mass13.00 mg
Isothermal Phase7 min
Heating/Colling Rates10 K/min
CrucibleAl, pierced lid
AtmosphereN2 (40 ml/min)