Nitrile butadiene rubbers (NBR) are copolymers of butadiene and acrylonitrile that are produced by emulsion polymerization. They were discovered in 1930 in Germany, as described by Hofmaan, and underwent initial commercialization in 1937.2 Acrylonitrile imparts a good resistance to oils or solvents,...
Nitrile butadiene rubbers (NBR) are copolymers of butadiene and acrylonitrile that are produced by emulsion polymerization. They were discovered in 1930 in Germany, as described by Hofmaan, and underwent initial commercialization in 1937.2 Acrylonitrile imparts a good resistance to oils or solvents, having a high strength and low gas permeability. Butadiene affects elasticity and low-temperature elasticity. Because of the unsaturated main chain, nitriles require protection against oxygen, ozone, and ultraviolet light. They have good resistance to oil, aliphatic and aromatic hydrocarbons, and vegetable oils but they are swollen by polar solvents such as ketones because of the polarity of acrylonitrile. Owing to its oil resistance, NBR is widely used in sealing applications, hose lines, roll coverings, conveyor belts, shoe soles, and plat linings. Low temperature properties of an elastomer depend on type of rubber, the content of plasticizer, and also type of filler. Choice of rubber and compounding additives are a prime factor to have good low temperature properties. Among the additives, plasticizers, and softeners have a leading role. Plasticizers are low molecular weight nonvolatile substances added to a polymer to improve the flexibility and process-ability. They are added to rubbers primarily to aid in processing operations such as mixing, calendaring, and extruding. Small quantities of plasticizer markedly reduce the glass transition temperature (Tg)ofthepolymer. This effect is due to the reduction in cohesive forces between polymer chains. Plasticizer molecules penetrate into the polymer matrix and act as a lubricant between polymer chains, thereby reducing the Tg. In this study, NBR compounds were manufactured with different raw rubbers and different types of plasticizers with different contents. We examined the mechanical properties, oil resistance, and low-temperature elasticity of the compounds. Then, we investigated the effects of the plasticizers on the physical properties and low temperature resistance of the compounds. The mechanical properties (hardness, tensile strength and elongation at break) of NBR were improved at higher ACN contents. And oil resistance was improved at higher ACN contents according to degree of volume change and change of mechanical properties. glass transition temperature that was measured by DSC had lower value at low ACN contents. Also TR test and gehman stiffness test value were similar to glass transition temperature. The mechanical properties (hardness, tensile strength, and elongation at breakage) of the NBR were better with plasticizers having a high molecular weight. The oil resistance differed according to the type of plasticizer according to the ratio of the volume change and the change in the mechanical properties. At this time, DOA with the lowest molecular weight showed excellent oil resistance. The Tg measured by the DSC had a lower value with a low-molecular-weight plasticizer. The TR test and Gehman stiffness test values were similar to the Tg. By way of exception, RS735 had a good TR-10 value that was compared to the previous tendency.
Nitrile butadiene rubbers (NBR) are copolymers of butadiene and acrylonitrile that are produced by emulsion polymerization. They were discovered in 1930 in Germany, as described by Hofmaan, and underwent initial commercialization in 1937.2 Acrylonitrile imparts a good resistance to oils or solvents, having a high strength and low gas permeability. Butadiene affects elasticity and low-temperature elasticity. Because of the unsaturated main chain, nitriles require protection against oxygen, ozone, and ultraviolet light. They have good resistance to oil, aliphatic and aromatic hydrocarbons, and vegetable oils but they are swollen by polar solvents such as ketones because of the polarity of acrylonitrile. Owing to its oil resistance, NBR is widely used in sealing applications, hose lines, roll coverings, conveyor belts, shoe soles, and plat linings. Low temperature properties of an elastomer depend on type of rubber, the content of plasticizer, and also type of filler. Choice of rubber and compounding additives are a prime factor to have good low temperature properties. Among the additives, plasticizers, and softeners have a leading role. Plasticizers are low molecular weight nonvolatile substances added to a polymer to improve the flexibility and process-ability. They are added to rubbers primarily to aid in processing operations such as mixing, calendaring, and extruding. Small quantities of plasticizer markedly reduce the glass transition temperature (Tg)ofthepolymer. This effect is due to the reduction in cohesive forces between polymer chains. Plasticizer molecules penetrate into the polymer matrix and act as a lubricant between polymer chains, thereby reducing the Tg. In this study, NBR compounds were manufactured with different raw rubbers and different types of plasticizers with different contents. We examined the mechanical properties, oil resistance, and low-temperature elasticity of the compounds. Then, we investigated the effects of the plasticizers on the physical properties and low temperature resistance of the compounds. The mechanical properties (hardness, tensile strength and elongation at break) of NBR were improved at higher ACN contents. And oil resistance was improved at higher ACN contents according to degree of volume change and change of mechanical properties. glass transition temperature that was measured by DSC had lower value at low ACN contents. Also TR test and gehman stiffness test value were similar to glass transition temperature. The mechanical properties (hardness, tensile strength, and elongation at breakage) of the NBR were better with plasticizers having a high molecular weight. The oil resistance differed according to the type of plasticizer according to the ratio of the volume change and the change in the mechanical properties. At this time, DOA with the lowest molecular weight showed excellent oil resistance. The Tg measured by the DSC had a lower value with a low-molecular-weight plasticizer. The TR test and Gehman stiffness test values were similar to the Tg. By way of exception, RS735 had a good TR-10 value that was compared to the previous tendency.
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