StyreneButadiene

Styrenebutadiene, commonly known as styrene-butadiene rubber (SBR), is a synthetic elastomer produced by copolymerizing styrene and butadiene. It is the most widely used synthetic rubber and serves as a primary replacement for natural rubber in tires, as well as in seals, belts, footwear, and various molded or extruded goods. SBR can be prepared by emulsion polymerization (ESBR) or by solution polymerization (SSBR). The styrene content typically ranges from about 20 to 40 percent by weight, with higher styrene making the material harder and more heat resistant.

In ESBR, polymerization occurs in an aqueous latex with surfactants, yielding inexpensive, high-volume material commonly used in standard tires. SSBR, produced in hydrocarbon solvents, offers tighter molecular control and finer microstructure, contributing to improved performance in high-end tires and specialty applications. The microstructure of SBR is influenced by the ratio and arrangement of 1,4- and 1,2-additions of butadiene units, which affect glass transition temperature, elasticity, and processing.

Properties of SBR include good abrasion resistance, aging stability, and versatile processability, making it suitable for dynamic elastomer applications. Heat resistance is lower than that of natural rubber, and mechanical properties are tuned by styrene content, molecular weight, and vulcanization conditions. Vulcanization with sulfur and accelerators forms a crosslinked network that balances resilience and durability.

Applications are dominated by tires, where SBR provides wear resistance and cost efficiency, especially in tread compounds. It is also used in belts, hoses, gaskets, footwear, adhesives, and various molded parts. Environmental considerations include dependence on fossil fuels, tire end-of-life management, and ongoing research into recycling and devulcanization to reduce waste.

---