1. Silicone Rubber (Q)
Silicone rubber is divided into heat-cured and room temperature-cured types. The heat-cured type is further divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the most used and branded), and methyl vinyl phenyl silicone rubber (PVMQ, resistant to low temperatures and radiation). Other types include clear silicone rubber and fluorosilicone rubber. MQ is a colorless, transparent, high-viscosity, plastic linear polymer compound, with a main chain composed of silicon and oxygen atoms, and side groups connected to silicon are methyl groups, with a molecular weight between 500,000 and 800,000. VMQ is also a colorless, transparent, high-viscosity, plastic linear polymer compound, with a main chain composed of silicon and oxygen atoms, and side groups connected to silicon are methyl and vinyl groups, with a molecular weight between 500,000 and 800,000. PVMQ is obtained by introducing diphenyl siloxane segments or methyl phenyl siloxane segments into the molecular chain of vinyl silicone rubber.
Temperature range: -60℃ (special to -115℃) to 204℃ (special to 260℃)
2. Chloroprene Rubber (CR)
Chloroprene rubber is polymerized from chloroprene monomers and is a polar rubber that lies between saturated and unsaturated. The vulcanized rubber has relatively good ozone resistance (better than NR, SBR, NBR, but worse than EPDM and IIR), weather resistance, chemical corrosion resistance, and aging resistance. It also has good mechanical properties, flame retardancy, good wear resistance, low-temperature elasticity, good torsion resistance, and is resistant to refrigerants such as dichlorodifluoromethane and ammonia, as well as dilute acids and silicone-based lubricants. However, it is not resistant to phosphate-based hydraulic oils, is prone to crystallization and hardening at low temperatures, has poor storage stability, and expands significantly in mineral oils with low aniline points.
3. Polyurethane Rubber
It is polymerized from polyesters (or polyethers) and diisocyanate compounds.
Temperature range: -40℃ to 100℃, can reach 120℃ for a short time
4. Acrylate Rubber (ACM)
Acrylate rubber is an elastomer obtained by copolymerizing acrylate as the main monomer, with a main chain of saturated carbon chains and side groups of polar ester groups. Its special structure endows it with many excellent properties, such as heat resistance, aging resistance, oil resistance, ozone resistance, and UV resistance. Its mechanical and processing properties are superior to those of fluororubber and silicone rubber, and its heat resistance, aging resistance, and oil resistance are better than those of nitrile rubber. ACM is widely used in various high-temperature and oil-resistant environments and has become a sealing material that the automotive industry has focused on developing and promoting in recent years, mainly used for various heat-resistant and oil-resistant seals, gaskets, and oil seals in automobiles and locomotives.
Temperature range: -30℃ to 150℃, can reach 175℃ for a short time
Advantages:
· Good airtightness
· Good ozone resistance
· Excellent oil resistance
· Good UV discoloration resistance
· Good heat aging resistance
· Used for high-temperature oil seals, crankshafts, valve stems, cylinder gaskets, hydraulic oil pipes in automobiles
Disadvantages:
· Poor processing performance, the rubber material easily sticks to rollers
· Poor cold resistance
· Not resistant to water, water vapor, acids, bases, salt solutions, and organic polar solvents
· Poor elasticity, wear resistance, and electrical performance at room temperature
Applicable media:
· Mineral oils (engine oil, gear oil, ATF oil)
Inapplicable media:
· Aromatic hydrocarbons, chlorinated hydrocarbons
· Hot water, water vapor
· Acids, bases, amines
· Ethylene glycol-based brake fluid
