AS IS WELL KNOWN, natural rubber was the only polymer from which rubber products could be made until the first synthetic rubber, Neoprene, was invented and became commercialized in the 1930s. Natural rubber was the only polymer used in large ticket items such as tires until the Second World War. When the natural rubber supply was cut off in the early 1940s, the mainstay synthetic, SBR (Styrene Butadiene Rubber) was developed and commercialized.