Encyclopedia entry for nitrile rubber
Release Date:
2022-04-30
【SUMMARY】A synthetic rubber produced by the copolymerization of butadiene and acrylonitrile. It exhibits excellent oil resistance—particularly to aliphatic hydrocarbons—and good aging resistance. Nitrile rubber is classified according to its acrylonitrile content (%), which can range from 42–46, 36–41, 31–35, 25–30, to 18–24. The higher the acrylonitrile content, the better the oil resistance; however, the low-temperature performance decreases accordingly. It can be used continuously in air at 120°C or in oil at 150°C.
Introduction
A synthetic rubber produced by the copolymerization of butadiene and acrylonitrile. It exhibits excellent oil resistance—particularly to aliphatic hydrocarbons—and superior aging resistance. Nitrile rubber is classified according to its acrylonitrile content (%), which can range from 42–46, 36–41, 31–35, 25–30, to 18–24. The higher the acrylonitrile content, the better the oil resistance; however, the low-temperature flexibility decreases accordingly. It can be used continuously in air at 120°C or in oil at 150°C. In addition, it boasts good water resistance, gas tightness, and outstanding adhesion properties. It is widely employed in the manufacture of various oil-resistant rubber products, including oil-resistant gaskets, washers, sleeves, flexible packaging, flexible hoses, printing and dyeing rubber rollers, and cable insulation compounds, making it an indispensable elastomeric material in industries such as automotive, aerospace, petroleum, and photocopying.
Basic Performance
Nitrile rubber exhibits excellent oil resistance, second only to polysulfide rubber and fluororubber, and also boasts good abrasion resistance and gas tightness. However, its drawbacks include poor resistance to ozone, as well as to aromatic hydrocarbons, halogenated hydrocarbons, ketones, and esters; therefore, it is not suitable for use as an insulating material.
Main Uses
Nitrile rubber is primarily used to manufacture oil-resistant products, such as oil-resistant hoses, adhesive tapes, rubber diaphragms, and large oil bladders. It is also commonly employed in the production of various oil-resistant molded articles, including O-rings, oil seals, lip seals, diaphragms, check valves, and bellows, as well as rubber sheets and wear-resistant components.
Blending of nitrile rubber
Nitrile rubber exhibits very strong polarity and generally shows poor compatibility with other polymers; however, it demonstrates good compatibility with highly polar polymers such as chloroprene rubber, modified phenolic resins, and polyvinyl chloride—particularly with chlorine-containing polymers—and is therefore often blended with these materials. In addition, to enhance processability and service performance, nitrile rubber is frequently compounded with nonpolar rubbers such as natural rubber, styrene–butadiene rubber, and cis‑1,4‑polybutadiene rubber. It should be noted, however, that while nitrile rubber is renowned for its excellent oil resistance, blending it with other polymers (with the exception of polyvinyl chloride) tends to reduce its oil resistance.
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