Natural Rubber
Made from latex collected from rubber trees, it is a polymer of isoprene. It possesses excellent abrasion resistance, high elasticity, tensile strength, and elongation. It ages easily in air, becomes sticky when heated, and readily swells and dissolves in mineral oil or gasoline. It is alkali-resistant but not strong acid-resistant. Advantages: Good elasticity, acid and alkali resistance.
Styrene-Butadiene Rubber
A copolymer of butadiene and styrene. Compared to natural rubber, it has more uniform quality, fewer impurities, and better abrasion resistance and aging resistance, but its mechanical strength is weaker. It can be blended with natural rubber.
Butyl Rubber
It is a polymer of isobutylene and a small amount of isoprene. Due to the steric hindrance of the methyl group, the molecular motion is less than in other polymers, resulting in lower gas permeability. It exhibits high resistance to heat, sunlight, and ozone, and excellent electrical insulation. It also has high resistance to polar solvents. The typical operating temperature range is -54 to 110 °C. Advantages: Impermeable to most common gases, good resistance to sunlight and odors, and can be exposed to animal or vegetable oils or vaporizable chemicals.
Hydrogenated Nitrile Rubber
Hydrogenated nitrile rubber is nitrile rubber that has undergone hydrogenation to remove some of the double chains. After hydrogenation, its temperature resistance and weather resistance are significantly improved compared to ordinary nitrile rubber, while its oil resistance is similar. The typical operating temperature range is -25 to 150 °C. Advantages: It has better abrasion resistance than ordinary nitrile rubber and excellent resistance to corrosion, tension, tearing, and compression.
Ethylene-propylene rubber (EPDM)
Made by copolymerization of ethylene and propylene, it exhibits excellent heat resistance, aging resistance, ozone resistance, and stability. However, it cannot be sulfurized. To address this issue, a small amount of a third component with double chains is introduced into the EP main chain, allowing for sulfurization and thus creating EPDM. Its typical operating temperature is -50~150℃. It has excellent resistance to polar solvents such as alcohols and ketones. Advantages: Good weather resistance and ozone resistance; excellent water and chemical resistance; can be used with alcohols and ketones; resistant to high-temperature vapors; and excellent impermeability to gases.
Nitrile rubber (Nubryl butadiene rubber)
Made by copolymerization of acrylonitrile and butadiene, with an acrylonitrile content ranging from 18% to 50%. Higher acrylonitrile content results in better resistance to petrochemical oils and hydrocarbon fuel oils, but lower low-temperature performance. Its typical operating temperature range is -25~100℃. Nitrile rubber is one of the most commonly used rubbers for oil seals and O-rings. Advantages: Excellent resistance to oil, water, solvents, and high-pressure oil. Good compressibility, abrasion resistance, and elongation.
Cycloprene rubber
Made from chloroprene monomers. After vulcanization, the rubber has good elasticity and abrasion resistance, is not afraid of direct sunlight, has excellent weather resistance, is not afraid of severe torsion, is not afraid of refrigerants, and is resistant to dilute acids and silicone ester lubricants, but not resistant to phosphate ester hydraulic oils. It easily crystallizes and hardens at low temperatures, has poor storage stability, and expands significantly in mineral oils with low aniline points. The general operating temperature range is -50~150℃. Advantages: Good elasticity and compression set; sulfur-free formulation makes it very easy to manufacture; resistant to animal and vegetable oils, and its properties are not affected by neutral chemicals, fats, greases, various oils, and solvents; flame-retardant properties.
Composition of Synthetic Rubber
Synthetic rubber is a polymer made by polymerizing petroleum and natural gas as raw materials and dienes and olefins as monomers.