SBR: Styrene Butadiene Rubber
A co-polymer of styrene and butadiene with elastomeric
properties. A general purpose synthetic rubber, first synthesied by Dr. Walter Bock and Eduard Tschunkur in Germany 1933, under the name, Buna-S. Recent reports suggest that some Russian scientists had produced similar
materials as early as 1929, but these reports remain confused.
Buna-S was developed in response to Germany’s
inability to gain supplies of natural rubber from south-east Asia during the
Great War of 1914-18. There was no rubber to fit to the wheels of its trucks, tanks and other vehicles, and the country’s logistical effort was severely hampered by the lack of rubber.
During the second world war (1939-45), the US faced a
similar situation immediately following the bombing of Pearl Harbor, as the
Japanese controlled most of the shipping routes between SE Asia and the US West coast.
Fortunately President Roosevelt had foreseen the possibility
and had set up the Rubber Reserve Company, which had stockpiled sufficient material to keep the country going in the medium term.
In 1942, the US government initiated the American Synthetic Rubber Research Program. This project took priority over all other scientific endeavours in the USA except one: the Manhattan Project to build a nuclear weapon. By the end of 1943, 15 Buna-S plants were in operation in North America, and the country became self-sufficient in the material.
Since that time, the USA has become the principal producer of SBR, as Buna-S came to be known.
Global production in 1996 was around 6.5 million metric tonnes (6500 kt), approximately half the world’s total annual output of synthetic rubber.
The main types of production are
Solid SBR 4400 kt
Latex SBR 620 kt
Carboxylated latex SBR 1535 kt
In the same year, production was divided by region as follows (data in thousand tonnes):
North America 1735 kt
West Europe 1450 kt
Asia / Oceania 1414 kt
Latin America 505 kt
Rest of world 1400 kt
The production process can be one of two types, mainly
distinguished by the type of material in the reaction vessel. The original
process relied on reactants brought together in the emulsion phase, while the modern process depends on solution polymerisation.
Although solution polymers (S-SBR) are the materials of
choice for modern, high-performance car tyres, demand for emulsion polymers,(E-SBR) continues at a high level in Asia, excluding Japan and in other, less-developed parts of the world.