The Buna^® SE product group comprises the general purpose emulsion styrene-butadiene rubbers (E-SBR) which is one of the most important types of synthetic rubber. Emulsion Styrene Butadiene Rubber is the most widely used rubber in the world, representing about 40% of the synthetic rubber market, which is a result of its excellent balance of properties and cost performance.
A typical E-SBR has 23,5% styrene with random distribution of the monomers in the polymer chain. Increasing the styrene content the processability is improved, as also is the tensile strength, but the resistance to low temperature and wear deteriorates. E-SBR presents a broad molecular weight distribution and a high degree of branching, so it processes easier than solution SBR.
Buna^® SE is produced by a cold (5 to 10°C) free radical polymerization mechanism, in which the monomers are emulsified in an aqueous medium with rosin and/or fatty acids. The monomers react and form a latex, which is then coagulated to generate the solid rubber. The products are available in clear or oil extended grades, with staining or non staining antioxidant.