309-4 Carboxylated Acrylonitrile Butadiene Rubber (XNBR)

Temperature Range:

-25°C to +125°C (-15°F to +260°F)

Intermittent High 140°C (Int 285°F)

Properties

Acrylonitrile or Nitrile as it’s more commonly referred to, is a copolymer of Acrylonitrile and Butadiene. The Nitrile content varies in commercial products from 18% to 50%, the higher the Nitrile content the better the resistance to petroleum oils and hydrocarbon fuels, but low temperature flexibility decreases.

As Nitrile has an excellent resistance to petroleum products, and an ability to be compounded for service over a wide temperature range, Nitrile is the most widely used elastomer in the seal industry today. Nitrile compounds are superior to most elastomers with regard to compression set, tear, and abrasion resistance but have limited resistance to ozone, sunlight, or weather. To obtain good resistance to lower temperatures, it is often necessary to sacrifice some high temperature resistance. Nitrile should not be kept near electric motors or other ozone generating equipment and should not be kept in direct sunlight.

By Introducing carboxylic acid groups to the polymer backbone of NBR (nitrile butadiene rubber) significantly alters the rubber’s properties – extra crosslinks in the polymer – creating a polymer matrix with significantly increased strength, tear, modulus and abrasion resistance at the expense of reduced compression set, water resistance, resilience and some low-temperature properties.