Rubber, abrasion resistance Butadiene

Polychloroprene and acrylonitrile-butadiene rubber compounds have satisfactory chemical resistance but, except for phosphoric acid, are not suitable for mineral acids at higher concentrations. However, they have good resistance to oils, acrylonitrile-butadiene rubber being the better, and so are often used in oil-contaminated aqueous environments. Generally, abrasion resistance is only fair. Normal maximum working temperature is about 100°C. Acrylonitrile-butadiene rubber ebonites are sometimes used especially where solvent contamination occurs, but are normally very brittle and so should be used with care. 

Butyl Rubber. A synthetic rubber produced by copolymerization of isobutene(98%) with a small proportion(ca 2%) of isoprene or butadiene. Polymerization is conducted at-50 to 100° in a liquid hydrocarbon, with A1C13 as catalyst. Its outstanding property compared with other rubbers is impermeability to gases. The uncured rubber is tacky, but it may be compounded like natural rubber and vulcanized. Butyl rubber has good resistance to chemical attack and to aging even at high temps. It has superior vibration insulation characteristics and abrasion resistance, but relatively low tensile strength and poor flame resistance... 

Styrene butadiene rubber (SBR) is, quantitatively, the most important synthetic rubber. It is a copolymer of styrene and butadiene in such a ratio that its rubbery nature predominates, vulcanization is carried out with sulphur, reinforcement with carbon black. It is used at a very large scale in tyres for passenger cars, thanks to its excellent combination of abrasion resistance and friction on the road. In large tyres it can not replace natural rubber because of its heat development (hysteresis losses). 

Butadiene rubber (BR) or Polybutadiene has an excellent abrasion resistance and a very low damping, but is, undiluted, too jumpy for use in tyres. In blends with SBR or natural rubber a good compromise of properties can be obtained. 

Nitrile rubber 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 rubber 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 rubber for hoses, gaskets, seals, and oil well equipment, new applications have emerged with the development of nitrile rubber blends with poly(vinyl cliloride) (PVC). These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile lubber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile rubber in outdoor applications for hoses, belts, and cable jackets, where ozone resistance is necessary. 

Polyurethane rubbers are a special type of PU elastomer. The PU rubbers are highly resistant to oil and fuel and have high abrasion resistance and tensile strength similar to PU elastomers. Polyurethane rubbers maintain their flexibility even at a temperature as low as -40° C and are thermally stable up to 125°C. Polyurethane rubbers have better mechanical strength and resist abrasion, ozone, and oil better than other specialty rubbers such as acrylates and nitrile butadiene. ... 

Despite the introduction of synthetic elastomers, ceramics and other abrasion resisting metals such as manganese, natural rubber holds a dominant position in this field of application and is the primary choice for abrasion resistance. Synthetic rubbers (particularly styrene-butadiene rubber which is dominant in the tyre industry sector) are used in dry abrasion application such as general purpose abrasion resistant sheets and conveyor belt covers, since the rubber can be reinforced with fine particles of carbon blacks to achieve dry abrasion resistance close to that of natural rubber. It should be noted that styrene-butadiene rubber is inferior to natural rubber in cutting and chipping resistance. 

With the outbreak of war in 1939 and the consequent shortage of natural rubber in the industrial West, the introduction of the copolymer of butadiene and styrene, then known as Buna or GR-S, as an almost total replacement for natural rubber, would not have been possible without carbon black. It may be stated, with little likelihood of contradiction, that no other product exists which contributes as much strength and abrasion resistance to noncrystallizing rubbers, while maintaining to a large extent their desirable elastic properties, as does carbon black. 

The industrial uses of tellurium are limited. In metallurgy, tellurium is used as an additive to improve alloys. The addition of tellurium improves the creep strength of tin and the mechanical properties of lead. Powdered tellurium is used as a secondary vulcanizing agent in various types of rubbers (natural rubber and styrene-butadiene rubbers) as it reduces the time of curing and endows the rubbers with increased resistance to heat and abrasion. In addition, tellurium and its compounds have been used as oxidation catalysts in organic syntheses. Due to its photoelectric properties, tellurium and its compounds are also employed in the semiconductor and electronics industry. In much smaller quantities, tellurium is used in pottery glazes. For further details, see Fishbein (1991). 

Styrene-Butadiene Rubber (SBR). The homopolymer of styrene is relatively brittle and has a low resistance to impact and solvents. The addition of butadiene significantly increases the abrasion resistance resulting in a copolymer that is most widely used as tire... 

Styrene-butadiene rubber is the largest volume synthetic elastomer commercially available. It ean be produced by free-radical emulsion polymerization of styrene and butadiene either at 50 to 60°C (hot emulsion SBR) or at about 5°C (cold emulsion SBR). The two kinds of SBR have sigmfieantly different properties. The hot emulsion SBR process, which was developed st, leads to a more branehed polymer than the cold emulsion process. Cold SBR has a better abrasion resistance and, eonsequently, provides better tread wear and dynamic properties. 

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