Faraday had shown in 1829 that rubber had the empirical formula
C5H8. In 1860, Greville Williams obtained a
liquid with the same formula by distilling rubber; he called it "isoprene".
Synthetic rubber technology started in 1879, when Gustave Bouchardat
found that heating isoprene with hydrochloric acid produced a rubberlike
polymer. However, Bouchardat had obtained isoprene from natural rubber;
the first truly synthetic rubber was made by William Tilden three
years later. Tilden obtained isoprene by cracking turpentine, but
the process of converting it to rubber took several weeks. In 1911
Francis Matthews and Carl Harries discovered, independently, that
isoprene could be polymerized more rapidly by sodium.
1906 scientists at the Bayer Company in Germany embarked on a program
to make synthetic rubber. By 1912, they were producing methyl rubber,
made by polymerizing methylisoprene. Methyl rubber was manufactured
on a large scale during World War I, when a blockade halted the
import of natural rubber to Germany. Because methyl rubber was an
expensive and inferior imitation, production was abandoned at the
the 1920s, synthetic rubber research was influenced by fluctuations
of the price of natural rubber. Prices were generally low, but export
restrictions of natural rubber from British Malaya introduced by
the British in 1922, coupled with the resultant price increase,
sparked the establishment of modest synthetic rubber research programs
in the Soviet Union, Germany, and the United States between 1925
at I. G. Farben, a German conglomerate that included Bayer, focused
on the sodium polymerization of the monomer butadiene to produce
a synthetic rubber called "Buna" ("bu" for butadiene
and "na" for natrium, the chemical symbol for sodium).
They discovered in 1929 that Buna S (butadiene and styrene polymerized
in an emulsion), when compounded with carbon black, was significantly
more durable than natural rubber.