Synthetic Rubber Production
Synthetic Rubber Program first described in 1928. Export restrictions of natural rubber sparked interest in finding ways to synthesize the material.
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.
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.
Visit National Historic Chemical Landmarks to read more about efforts to synthesize rubber.
Excerpted with permission, National Historic Chemical Landmarks Program