Nitrile Rubber ( NBR )

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13 Nov 2022

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NBR

Nitrile Rubber ( NBR )

Nitrile rubber, also known as NBR or Buna ® N, is one of the most commonly used sealing elastomers due to its resistance to petroleum based fuels and lubricants and its relatively low price. Nitrile elastomers are copolymers of acrylonitrile and butadiene.There are a number of common variations of nitrile compounds.

Acrylonitrile Content

The acrylonitrile ( CAN ) content of the polymer chains can be varied from 18% to 50%. Lower ACN content gives better low temperature properties but poorer fuels and polar lubricants. Higher ACN content gives poorer low temperature properties but improved fuels and polar lubricants resistance.Standard NBRs typically have 34% ACN content.

Cure system-Sulfur-Cured vs. Peroxide-Cured

Standard Nitriles are usually sulfur – cured. Sulfur – cured compounds offer better low temperature properties but are more prone to hardening with high temperatures. Peroxide -cured nitriles have better heat resistance and lower compression sets but are more expensive and are more difficult to process.

Other Common Variations:

►Nitriles are often internally lubricated to improve ease of installation or reduce friction for dynamic applications.

►Nitriles can be formulated with only “white list” ingredients as specified in 21.CFR 177.2600 for use in applications where the elastomer will be in contact with food or beverages.

►Nitriles can be submitted for approval by the National Sanitation Foundation (NSF) for use in drinking water applications.

►Nitriles can also be submitted for approval to Underwriters Laboratories (UL) for use in applications as prescribed in UL157.

►Nitrile rubber can be combined with polyvinyl chloride (PVC) to create fuel, ozone and weathering resistance NBR-PVC blends.

Performs Well In…

►Petroleum based oils & fuels

►Aliphatic hydrocarbons

►Vegetable oils

►Silicone oils & greases

►Ethylene glycol

►Dilute acids

►Water to below 100°C ( 212°F)

Doesn’t Perform Well In…

►Aromatic hydrocarbons

►Automotive brake fluid

►Chlorinated hydrocarbons

►Ketones

►Ether

►Esters

►Phosphate ester hydraulic fluids

►Strong acids

►Ozone / weathering / sunlight

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admin_ilkhani

14 Nov 2022

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Carboxylated Nitrile ( XNBR )

XNBR Carboxylated Nitrile ( XNBR ) Cabboxylated Nitrile is similar to Nitrile rubber, but the polymer backbone has been chemically modified with Carboxylic Acid containing group. This result is XNBR with more excellent abrasion and tear resistance than traditional NBR. For this reason, XNBR based parts are usually applied in dynamic assembly such as seals and rod wipers. Cure system - Sulfur - Cured Standard XNBR compounds are sulfur-cured Performs Well In… ►Aliphatic hydrocarbon ►Vegetable and mineral oils and greases ►Diesel ►Water Dilute acids, alkali and salt solutions Doesn't Perform Well ...

admin_ilkhani

14 Nov 2022

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Silicone Rubber ( MQ, VMQ, PVMQ )

VMQ Silicone Rubber ( MQ, VMQ, PVMQ ) Physically, silicones are based on silicon, an element derived from quartz. To create this class of synthetic elastomers, pendant organic groups such as methyl, phenyl and vinyl are attached to silicon atoms. The different addition of side chains can achieve significant variations in properties. Silicones have excellent heat, ozone and corona resistance, very well dielectric stability, and resistance to many oils, chemicals, and solvents. And for all elastomers, silicones possess the best flexible property ...