Unit
- Natural rubber (NR): harvested from Hevea brasiliensis latex, offers high tensile strength, elasticity, and good abrasion resistance. Its crystallizing behavior gives superior green strength but limits oil and heat resistance.
- Styrene-butadiene rubber (SBR): a synthetic copolymer used extensively in tire treads and industrial goods. It provides good wear resistance and aging stability but lower tensile strength and higher heat buildup than NR.
- Butadiene rubber (BR): known for excellent low-temperature flexibility, high resilience, and abrasion resistance. It is often blended with NR or SBR to improve wear properties in tire sidewalls and conveyor belts.
- Ethylene-propylene-diene monomer (EPDM): offers outstanding resistance to ozone, weathering, and heat, making it ideal for automotive weatherstripping, roofing membranes, and radiator hoses.
- Nitrile rubber (NBR): a copolymer of acrylonitrile and butadiene, provides excellent oil and fuel resistance. Higher acrylonitrile content increases oil resistance but reduces low-temperature flexibility.
- Chloroprene rubber (CR): also known as Neoprene, combines good mechanical properties with moderate oil and flame resistance. Used in gaskets, hoses, and protective coatings.
- Silicone rubber (VMQ): offers extreme temperature resistance (from -60 to 230 degrees Celsius) and biocompatibility, commonly used in medical devices, seals, and electrical insulation.
- Fluoroelastomers (FKM): provide highest chemical and heat resistance among rubbers, used in demanding applications such as O-rings, shaft seals, and fuel system components.
- Butyl rubber (IIR): a copolymer of isobutylene and isoprene, offers extremely low gas permeability, making it ideal for inner tubes, tire inners, and pharmaceutical stoppers. It also exhibits good vibration damping and resistance to ozone and chemicals, though it has poor oil resistance.
- Polyurethane rubber (AU/EU): known for outstanding abrasion resistance, high tensile strength, and resistance to oils and fuels. Used in solid tires, rollers, and high-durability seals. However, it has poor resistance to hydrolysis and elevated temperatures above 100°C.
- Acrylic rubber (ACM): provides excellent resistance to high temperatures (up to 175°C) and oils, especially sulfur-containing oils. It is commonly used in automotive transmission seals and gaskets, but has poor low-temperature flexibility and water resistance.
- Epichlorohydrin rubber (ECO): offers a unique combination of oil resistance, low-temperature flexibility, and ozone resistance. Used in fuel hoses, gaskets, and diaphragms. It also has good resistance to gas permeation and heat aging, though processing can be challenging.
Safety Consideration
Hazard: Dust from synthetic rubber bales and compounding ingredients can cause respiratory irritation and create fire/explosion risks when airborne in high concentrations.
Mitigation: Ensure local exhaust ventilation at receiving and weighing areas. Use dustless forms of fillers (e.g., polymer-bound pellets) and implement good housekeeping to minimize dust accumulation on surfaces.
Quick Revision
- Natural rubber offers high strength and elasticity but limited thermal and oil resistance.
- Synthetic rubbers (SBR, BR, EPDM, NBR, CR, VMQ, FKM) fill specific performance gaps such as oil, heat, or ozone resistance.
- Blending different rubbers allows compound designers to balance properties for cost and performance.
- Proper handling of raw materials is essential to avoid dust hazards and ensure consistent quality.