Page 341 - Carrahers_Polymer_Chemistry,_Eighth_Edition

304 Carraher’s Polymer Chemistry

During this time other materials were found that gave rubber-like materials. In 1901 I. Kondakov, a
Russian, discovered that dimethyl butadiene when heated with potash formed a rubber-like material. In
1910 S. V. Lebedev, another Russian, reacted butadiene forming a rubber-like material (Equation 9.33).

H C=CH–CH=CH → Rubber-like product (9.33)
2 2
During World War I, Germany was cut off from the Far East sources of NR and so developed
their own alternative rubbers. They focused on the Kondakov process making two rubber-like mate-
rials-dubbed methyl “H,” which was a hard rubber and methyl “W,” which was a softer rubber.
Before large-scale production started, the war ended and Germany returned to natural sources of
NR. Even so, Germany continued some research toward the production of rubber. By the 1930s,
they produced three “buna” rubbers. The name “buna” comes from the first two letters of the main

ingredients, butadiene and natrium (sodium), the catalyst. They also discovered another of today’s
rubbers, buna-S, the “S” standing for styrene. Buna-S is derived from butadiene and styrene. The
British referred to buna-S as SBR (styrene–butadiene rubber), while the United States referred to
this as GR–S (Government rubber–styrene). Many of these SRs when vulcanized were superior to
earlier synthesized rubbers and often to NR for some applications.
R
R m n

(9.34)

In 1937, Germany also developed buna-N (N = nitrile; 9.35) which offered good resistance to oil.
Most of these rubbers are still in use today with small modifi cations.

R
R m n

(9.35)

N

The USSR was producing SRs during this time using potatoes and limestone as starting materi-
als. Thus, the move toward natural materials is not new.
As World War II approached, Germany and USSR worked frantically to be free from outside
need of rubber. The United States by comparison were conducting research in a number of areas
that would eventually prove useful, but had made no real push for self-reliance in the issue of rub-
ber. U.S. experiments with SR before 1939 lead to the discovery of neoprene, Thiokol, and butyl
rubber.
As noted above, chemists learned about the structure of rubber by degrading it through heating

and analyzing the evolved products. One of the evolved products was isoprene, a five carbon hydro-
carbon containing a double bond. Isoprene is a basic building block in nature serving as the “repeat”
unit in rubber and also the building block of steroids such as cholesterol.

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