Cooperative
Efforts Solve the Rubber Crisis
The
technology chosen for synthetic rubber production was based on Buna
S research because Buna S could be mixed with natural rubber and milled
on the same machines, and because the raw materials (the monomers)
were available. This rubber was particularly suited for tire treads
because it resisted abrasive wear; and it retained sharper impressions
in molds, calender rolls, and extruders than natural rubber. However,
the synthetic rubber was more difficult to make, had less tackiness,
and required more adhesive in making a tire than natural rubber. These
problems had to be overcome to produce a reliable general purpose
rubber.
"We
would be blind if we did not see the efforts now in progress on
the part of many companies to have a part in the development of
a large new industry with vast postwar possiblities."
Report
of the Baruch Rubber Survey Committee,
September 10, 1942
On
March 26, 1942, the representatives of the companies and the U.S.
government agreed upon a "mutual recipe" to produce the
GR-S rubber. The recipe consisted of monomers butadiene (75%) and
styrene (25%), potassium persulfate as a catalyst or initiator, soap
as an emulsifier, water, and a modifier, dodecyl mercaptan. Because
GR-S required different compounding conditions, accelerators, antioxidants,
and types and amounts of carbon black than natural rubber, the program's
leaders realized that a research and development program would be
necessary to solve the existing and potential problems of GR-S manufacture.
Robert
R. Williams of Bell Telephone Laboratories organized and coordinated
the rubber industry research effort, which included participation
by the National Bureau of Standards, Bell Labs, and such major research
universities as the University of Illinois, University of Minnesota,
and University of Chicago. The first of many Copolymer Research
Committee meetings was held December 29, 1942, in Akron, Ohio, to
share the latest information among the organizations working on
the various aspects of synthetic rubber research. In addition to
representatives from the government, the major companies, and universities,
there were contributors from Columbian Carbon Company, Case
School of Applied Science (now Case Western Reserve University),
Princeton University, and The University of Akron. The affiliations
of the attendees at this meeting demonstrate the wide participation
in the program. Phillips Petroleum, General Tire, the Polymer Corporation,
and Cornell University delegates were at later meetings.
During
the combined effort, the companies shared the findings of more than
200 patents. Participating U.S. scientists and engineers improved
the polymerization process, produced modifiers that allowed existing
processing equipment to equal natural rubber production rates, specified
carbon black grades for specific applications, and modified butadiene
production to improve efficiency. University laboratories developed
better analytical methods to achieve better quality control and
performed fundamental research on the mechanism of GR-S polymerization
and the chemical structure of rubber. Academic and industrial contributors
clarified the factors that influenced the polymerization rate, polymer
molecular weight, and weight distribution.
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