design guide

Acrylonitrile / Butadiene (NBR)

NBR, Buna-N, and nitrile all represent the same elastomer based on a butadiene and acrylonitrile copolymer. Nitrile is inherently resistant to hydraulic fluids, lubricating oils, transmission fluids and other non-polar petroleum based products due to the polar structure of this elastomer. Nitriles are also resistant to air and water environments.

Utilizing the variety of nitrile polymers and compounding ingredients, Minnesota Rubber and Plastics has derived nitrile compounds to withstand environments that require low compression set, abrasion resistance, low temperature flex, gas permeation resistance, ozone resistance and/or stress-stain properties.

By hydrogenation, carboxylic acid addition, or PVC blending, the nitrile polymer can meet a broader range of physical or chemical requirements.

Compound 366Y

  • Excellent petroleum fluid and water resistance
  • Outstanding oil resistance to aniline point oils of 130° F to 255° F (55° C to 124° C)
  • Good compression set resistance

Compound 372FX

  • Good oil and water resistance
  • Good compression set resistance
  • Low durometer and modulus
  • Low temperature resistance

Compound 431 T

  • Low swell to petroleum oils and fuels
  • Outstanding oil resistance - aniline point oils below 130°F (55°C)
  • Low temperature properties to -30°F (-34°C)
  • High tensile strength and good abrasion resistance
  • Good heat aging

Compound 523HW

  • Excellent low temperature performance at -70°F (-57°C)

Compound 525K

  • Excellent abrasion and wear resistance
  • Good heat resistance and compression set resistance
  • Frequently used for ground ball applications
  • Excellent contact compatibility properties with plastics
    Tensile Elongation Oil Aging
Volume Swell (Change %)
70hr at 100°C/212°F
Compound Hardness
Shore A
MPa psi (%) ASTM #1 IRM 903
366Y 70 14.1 2050 320 -4 +10
525K 70 17.2 2500 330 -1 +16
431T 70 14.6 2100 340 -13 -5
523HW 70 13.8 2000 330 -9 +19
372FX 50 10.0 1450 400 -10 +20