Synthetic Rubber Plants
By spring of 1942 the War Production Board had taken control of rubber production, sale, and use, and the annual capacity minimum for U.S. plants was raised to 600,000 tons. But there were the delays of plant production. To build a plant or new structures and equipment within an existing plant, large amounts of metal were necessary. Since all metal was rationed during the war, any time a new plant or machine needed to be built, the companies had to apply to the War Production Board for material, slowing the building process and causing headaches for everyone involved. A. Donald Green, a chemical engineer, described the rubber plant he helped build in Baton Rouge in 1941, while working for Standard Oil of New Jersey. Originally designed as a demonstration of the process on a small scale,
A trial, June, 1942, on a laboratory scale at a pilot plant was encouraging, and plans were made to demonstrate on a full pilot plant scale by installing a suitable vibrating screen and auxiliaries. But before this equipment could be built and tried out, I was shocked to learn that the company management, assuming success for the new development, had informed the government that plant capacities could be tripled with minor expense for additional reactors and polymer finishing equipment. Rubber Reserve immediately authorized increasing the butyl capacity to a total of 132,000 long tons per year, permitting elimination of the large, fourth unit at Baton Rouge. Although I was directly involved in the process development and was in charge of the design of the six plants, no one told me beforehand of the recommendation or had discussed it with me. This management recommendation, intended to help the war effort by saving critical construction materials, was based on very skimpy experimental data and had most unpleasant repercussions later. (Asbury and Green, 16)
Building the plant as a demonstration of manufacturing capability coincided with government reorganization of the rubber program when it was decided that rubber supply needed to be greatly increased. There was a demand for rubber and a need to convert trial demonstration plants into large-scale production plants. The scientific and engineering expertise required to build the plants was enormous. Between 1941 and 1942 Green and his fellow SO engineers worked frantically to build the plants for “butyl rubber, as it came to be called,” which “had superior properties from the standpoint of resistance to tear, flexing, aging, and mineral acids, as well as having good electrical properties and being much less permeable to air than natural rubber or Buna-S” (Asbury and Green, 15). Despite plant construction already under way, the butyl-rubber process continued to be modified, from the early steps to the finishing steps. Green explains:
While my group was designing the plant, further research indicated that using 2 percent isoprene as the di-olefin [co-monomer] instead of [100 percent] butadiene [polymer] gave an improved product quality and simplified the process. Neither pure isobutylene or isoprene were then being made by commercial economic methods, and alternatives were needed quickly for supply of feed materials to the new plant. Lab work showed that a sulfuric acid method for separating isobutylene from refinery butylenes could be modified to produce pure isobutylene. Recovery of isoprene from the Baton Rouge steam cracker was complicated by the multiplicity of chemical compounds present. A relatively new technique called extractive distillation using acetone as solvent was devised. [...] These were busy days for the company's chemists and engineers. (Asbury and Green, 15)
Synthetic rubber comes from the drier and is fed to an automatic weighing machine at the plant operated by United States Rubber Company at Institute, West Virginia. Library of Congress, Prints & Photographs Division, FSA/OWI Collection, LC-USW33-028402-C (b&w film neg.).
The reaction process was not easy. “As I mentioned, the reaction takes place at minus 140 degrees Fahrenheit...to my knowledge the only large, commercial, chemical operation ever conducted at such a low temperature. The reaction is practically instantaneous. If the temperature rises even a few degrees, mutual solubility of the polymer and the solvent causes the polymer to become sticky and tend to agglomerate” (16). There were also unanticipated problems in the process, including the formation of carbon black. “The Germans hadn't told us about that...that was rather a surprise. Well, we just put in a couple of towers and washed the stuff out. And we went to reciprocating compressors, I remember, reciprocating compressors which have valves which can get plugged up with carbon black, but it wasn't too bad” (Asbury and Green, 8-9). With little time to waste and a complicated process for building plants, engineers had to proceed at a faster pace than ever before.