XSBR

XSBR stands for carboxylated styrene-butadiene rubber, a class of functionalized styrene-butadiene rubbers. It is produced by introducing carboxyl groups into the SBR backbone, either by copolymerizing styrene and butadiene with a small amount of carboxyl-containing monomer (for example acrylic acid or methacrylic acid) or by post-polymerization modification of conventional SBR. The carboxyl functionality provides polar sites along the polymer chain, which improves interaction with polar fillers and crosslinking systems.

Production and composition are typically achieved through emulsion polymerization in aqueous media. The degree of carboxylation is controlled during synthesis and influences cure chemistry, filler compatibility, and mechanical properties. Carboxyl groups can be neutralized with bases, affecting processability and performance.

Properties and performance: Compared with conventional SBR, XSBR exhibits higher polarity, improved dispersion of silica fillers, and enhanced filler–rubber interaction, leading to lower hysteresis and improved wet traction in silica-filled compounds, as well as increased tensile strength in many formulations. It can modify cure kinetics and may require adjustments to sulfur, resin systems, and silane coupling agents to optimize performance.

Applications: The primary use is in tire treads and other rubber compounds that use silica fillers, where XSBR can improve wet grip and abrasion resistance while maintaining processing characteristics. It is also used in specialty seals, hoses, and damping components where enhanced filler bonding is beneficial.

See also: Styrene-butadiene rubber; Silica reinforcement; Tire tread compounds; Carboxylated polymers.