1.0 Nitrile Butadiene Rubber (NBR)
23 Mar 2024
Elastomers are polymeric materials that can be stretched at room temperature to at least twice their original length and return almost to their original state when the force is removed. Rubbers are polymers that are not crosslinked but can be crosslinked, i.e., vulcanized. At high temperatures and under deforming forces, they show viscous, liquid-like flow, so they can be shaped under optimum conditions. Shaped elastomer materials display both viscous and elastic (spring-like) behavior.
The ability to crosslink is explained by vulcanization. Vulcanization changes the rubber's chemical structure (crosslinking reaction) and irreversibly converts it into an elastic state.
Nitrile Butadiene Rubber (NBR)
NBR is a very widely used rubber and is recommended for most sealing elements in industrial applications. It was first produced in Germany in 1934. Nitrile rubber (NBR) is a polymer of butadiene and acrylonitrile (ACN). It offers very good resistance to aliphatic hydrocarbons (propane, butane, petroleum), mineral oils (lubricating oils; Group H, HL and HLP oils), fire-resistant hydraulic fluids and greases (HFA, HFB, HFC), vegetable and animal greases, and light heating oil and diesel fuels. Its properties depend on the ACN content, which ranges from 18% to 50%. As the acrylonitrile content increases, these properties increase:
Resistance to oils, fuels and solvents,
Density and hardness,
Cure rate,
Gas impermeability,
Abrasion resistance,
Heat resistance,
Processability.
These properties decrease:
Low-temperature resistance,
Gas permeability,
Compression set,
Elasticity.
As the ACN content decreases, rebound resilience and low-temperature flexibility increase. The glass transition temperature (Tg) is -38 °C at 18% ACN and -2 °C at 50% ACN.
KİMHEX® can produce NBR compounds tailored to different applications and property requirements. The ACN content of the nitrile compounds we use ranges from 30% to 50%.
Standard nitrile compounds are recommended for -30 °C to +105 °C, and for short periods up to +120 °C.