Acrylonitrile-butadiene rubber heat resistance

Acrylonitrile-butadiene rubber (also called nitrile or nitrile butadiene rubber) was commercially available in 1936 under the name Buna-N. It was obtained by emulsion polymerization of acrylonitrile and butadiene. During World War II, NBR was used to replace natural rubber. After World War II, NBR was still used due to its excellent properties, such as high oil and plasticizer resistance, excellent heat resistance, good adhesion to metallic substrates, and good compatibility with several compounding ingredients. 

Nitrile mbber finds broad application in industry because of its excellent resistance to oil and chemicals, its good flexibility at low temperatures, high abrasion and heat resistance (up to 120°C), and good mechanical properties. Nitrile mbber consists of butadiene—acrylonitrile copolymers with an acrylonitrile content ranging from 15 to 45% (see Elastomers, SYNTHETIC, NITRILE RUBBER). In addition to the traditional applications of nitrile mbber for hoses, gaskets, seals, and oil well equipment, new applications have emerged with the development of nitrile mbber blends with poly(vinyl chloride) (PVC). These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile mbber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile mbber in outdoor applications for hoses, belts, and cable jackets, where ozone resistance is necessary. 

Since ABS is composed of a hard material and a soft material, it combines the rigidity of acrylonitrile and styrene polymers with the toughness of butadiene rubbers. Most advantageous is its impact resistance and toughness. ABS can be tailored to improve the impact resistance, toughness, and heat resistance. Selected properties of an ABS type are shown in Table 8.8. 

Acrylonitrile-styrene-acrylate (ASA) copolymers is another family of graft-copolymer-based materials in which the rubber phase is really a copolymer of butyl acrylate (BuA) and butadiene (at least in some recipes) [47, 48], and the matrix is made of a SAN copolymer. Originally, butadiene was not present in the rubber phase [49] and perhaps those were not really graft-copolymer-based materials. The main advantage of ASA over ABS is its increased UV stability and long-term heat resistance due to the lack of residual double bonds in the acrylate part of the rubber. 

Nitrile rubber (acrylonitrile-butadiene copolymer) is a unique elastomer. The acrylonitrile content of the commercial elastomers ranges from 25% to 50% with 34% being a typical value. This nonhydrocarbon monomer imparts to the copolymer very good hydrocarbon oil and gasoline resistance. The oil resistance increases with increasing amounts of acrylonitrile in the copolymer. Nitrile rubber is also noted for its high strength and excellent resistance to abrasion, water, alcohols, and heat. Its drawbacks are poor dielectric properties and poor resistance to ozone. 

First made commercially available in Germany in 1936, this elastomer is officially known as acrylonitrile butadiene, and is usually the product of an emulsion polymerization process that combines the two monomers acrylonitrile and butadiene. However, the polymer can also be made in a solution process, and with a variety of monomers. As a specialty polymer, and even though several commercial brands were available, Buna N (as it was first known) was little used until World War II, when the polymer s unique oil and plasticizer resistance and high heat resistance became very important for transportation products. Nitrile rubber also exhibits exceptional adhesion to metallic surfaces and is compatible with a wide range of additives and compounding ingredients. 

Nitrile Rubber Rubbers prepared by free-radical polymerization of acrylonitrile with butadiene. Has good resistance to petroleum products, heat, and abrasion. Used in fuel hoses, shoe soles, gaskets, oil seals, and adhesives. 

Nitrile rubber, also known as nitrile-butadiene rubber (NBR), is a copolymer of acrylonitrile and butadiene (Fig. 1). As a base polymer for Rubber-based adhesives, it provides a number of specialized properties, which supplement those summarized in the article Rubber-based adhesives typical characteristics. NBR adhesives comprise a range of materials that may differ in proportion of comonomer or may be compounded with other resins. NBR adhesives are characterized by high oil and plasticizer resistance, excellent heat resistance and high adhesion to metallic substrates. 

Polystyrene (PS) (Table 5.3.12) is produced almost exclusively in-substance, for example, by using a production tower (see Topic 5.3.7 for details). The polymer is transparent and readily processable in molding techniques. However, pure PS is somewhat brittle and not very resistant to organic solvents. Therefore, copolymers with substantial shares of PS are of great industrial relevance. Examples are PS-acrylonitrile (SAN), PS-butadiene rubber (SBR), and PS-butadiene-acrylonitrile (ABS) copolymers. Another important apphcation form of PS is PS foams (Styropor ). The latter are used for the thermal insulation of buildings as the air enclosed in the foam reduces the heat conductivity of the material to very small values. 

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