NITRILE (NBR, Buna-N) Acrylonitrile-butadiene
Advantages:
Very good resistance to oil and gasoline; superior resistance to
petroleum-based hydraulic fluids; wide range of service temperatures
(-65 to 300F); good resistance to hydrocarbon solvents; very good
resistance to alkalis and acids.
Limitations: Inferior resistance to ozone, sunlight, and natural aging; poor resistance to oxygenated solvents.
Comment:
Nitrile and neoprene are the highest volume oil resistant elastomers.
Nitrile is superior to neoprene in resistance to oil, gasoline, and
aromatic solvents. However, it does not perform as well as neoprene in
applications requiring exposure to weather, ozone, and sunlight.
Furthermore, it has no inherent flame resistance.
The properties
of nitrile vary considerably with the ratio of acrylonitrile and
butadiene. In general, as the acrylonitrile content of the elastomer
increases, oil and sovent resistance and abrasion resistance improve.
When the acrylonitrile content decreases, these properties deteriorate,
and low temperature flexibility and resilience improve.
When
nitrile is modified by polyvinyl chloride (PVC) resins, its resistance
to weather, ozone, and sunlight improves considerably without
significant sacrifice in oil resisting properties. PVC/nitrile is
similar to neoprene, in general, however, it is much inferior to
neoprene in adhesion to fabrics and metals.
Carboxylated nitrile
is generally tougher and more resistant to tear and abrasion than
conventional nitrile, but it is less resilient and flexible at low
temperatures.
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