NBR Testing Services

Polyhedron Laboratories performs testing on NBR raw material and products.  Our lab offers a complete range of tests on any of the properties of NBR. In addition, Polyhedron tests can:

  • Perform quality assurance
  • Determine environmental aging and chemical resistance
  • Run product analysis to determine why a product or material did not meet failure requirements.

Polyhedron's tests meet ASTM testing standards.

What is NBR?

NBR is a family of unsaturated copolymers of acrylonitrile and butadiene rubber.  By varying the ratio of acrylonitrile content in the compound, the manufacturer can create a custom product to meet application requirements that require fuel, oil or chemical resistance.  NBR products are used for fuel, oil and hydraulic hoses, seals, grommets, belting and roll covers in the automotive, plumbing and appliance industries.

There are five general types of NBR.

  • Cold NBR is polymerized at temperatures from 5° to 15°C, yielding more-linear polymer chains.
  • Hot NBR is manufactured at temperatures ranging from 30° to 40°C, which yields highly branched polymers.  The branching supports a strong bond and improved hot tear strength compared to cold NBR.  Hot NBR is excellent for compression molded products, extruded shapes and sponge products.
  • Crosslinked Hot NBR has an added di-functional monomer that provides the rubber with increased strength for molding and shape retention for extruded products.  These NBR's are used as additives to PVC's to increase impact resistance and flexibility.
  • Carboxylated Nitrile (XNBR) is used when increased strength is required for an application.  It is manufactured by the addition of carboxylic acid groups to the NBR polymers' backbone.
  • Bound Antioxidant NBR has antioxidants polymerized into the polymer chain.  The addition of antioxidants protects the rubber during prolonged fluid exposure or in mixed fluid and air exposure in demanding environments.

Major Properties of NBR

The table below contains the key properties of NBR as well as the ASTM test methods that Polyhedron Laboratories adheres to.

PROPERTIES ASTM TEST METHOD 41% ACRYLONITRILE 21% ACRYLONITRILE
Density (g/cm3)

ASTM D 790

 

 


0.92

Tensile strength, psi

D412

3200

3055

% Elongation

D412

380

390

100% Modulus, psi

D412

300

355

300% Modulus, psi

D412

1750

2130

Tear Strength, Die C (lb/in)

D624

 

 


209

Hardness, Shore A

D2240

66

 

62

Glass Transition Temperature °C

D5026

-18

-60

Compression Set (%), 70 hrs./125°C

D395B

 

34

38

Brittleness Temperature °C

D746

-20

 

-45

Water Resistance (%), 70 hrs/ 23°C, % Volume Change

D471

+11

 

+5

Oil Resistance, 70 hr/ 100°C , % Volume Change

No. 3

-10

+49

Click here to view a list of some of the other types of rubber we commonly test.

Request Testing Quote today from Polyhedron Laboratories
or call us at 281.879.8600