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Professor Hanington's Speaking of Science: The history of synthetic … – Elko Daily Free Press

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A World War II tire information poster.
A residue that had settled to the bottom of a bottle became the basis for several developmental programs at Du Pont in 1930 in the quest for a latex substitute. The chemist who made the discovery, Dr. Arnold M. Collins, annotated his laboratory notebook with the words “the mixture had stood from some weeks and solidified to white, somewhat rubber-like masses,” thus beginning the mechanism that would eventually help America win WWII.
It was named “chloroprene” because it was monovinylacetylene polymerized with hydrochloric acid. By 1936, Du Pont introduced a spin off called “Neoprene,” from a group headed by Wallace Carothers, the famed inventor of nylon. Because Neoprene was impervious to oil and water, it was immediately put to use as electrical wire insulation for use in harsh environments, replacing the fabric cellulose material invented by Thomas Edison in 1892 and still in use. As you can see, synthetic rubber was a product waiting to happen, if only you could make it.
Natural rubber had been around for centuries. The French explorer Charles-Marie de la Condamine discovered in 1745 that South American Indians used the latex from the rubber tree (Hevea brasiliensis), a poly-cis-isoprene, to form a modern day flip-flop by coating their feet with it. The name “rubber” originated because the dried latex could be used to erase pencil marks on paper. Michael Faraday had shown in 1829 that rubber had the empirical formula C5H8 and the chemist Williams obtained a liquid with the same formula by distilling latex and called it “isoprene.”

But natural rubber had many disadvantages. It cracked in the winter and oozed in the hot summer, making it unsuitable for most applications. When Charles Goodyear invented vulcanization in 1839 by mixing in sulfur, a stabilized material was available that founded the rubber industry. By 1910, Asian rubber plantations, started from seeds brought from the Amazon Basin, displaced latex from the wild trees of South America and became the primary source for the world’s growing market. With the advent of the motor car and the need for tires, belts and hoses, the demand increased so much there didn’t seem to be enough trees to tap in all the world.
As with all raw materials, synthetic rubber research was influenced by fluctuations of the price and availability of natural rubber. When a blockade closed down the importation of natural rubber into Germany during WWI, scientists at the Bayer Company perfected a way of producing methyl rubber, made by polymerizing methylisoprene and it was manufactured on a large scale for the war effort. When British Malaya introduced natural rubber export restrictions in 1922 and the price headed higher, synthetic rubber research programs began in earnest in the Soviet Union, Germany and the United States. By 1929, the discovery that butadiene could be polymerized using sodium metal resulted in a synthetic rubber called “Buna” (“bu” and “na” for sodium). When Buna was mixed with styrene and carbon black, a good tire material could be obtained that was far more durable than natural rubber.
With the world arming towards war in the late 1930s, President Franklin Roosevelt, well aware of United States vulnerability because of its total dependence on threatened supplies of natural rubber (especially those from the Far East within the sphere of Japan), formed the Rubber Reserve Company in 1940 with the goal of stockpiling rubber and conserving its use. As you would expect, the start of WWII abruptly cut off all supply of natural rubber from that side of the world, causing grave concern and great impetus for the development of a man-made material. As learned in WWI, you can’t win a war without ample supply of raw materials and that included rubber as well. Thankfully, America had a stockpile of over a million tons of natural rubber under her belt but a utilization rate of 600,000 tons per year would leave the cupboard bare within two years. With no practical commercial process to fill the gap, the situation looked bleak because no amount of conserving, reclaiming or stockpiling could solve the problem.
Within two weeks of the attack on Pearl Harbor, Roosevelt’s RRC began a program to produce 400,000 tons of synthetic rubber and awarded contracts to four large rubber companies, Firestone, Goodrich, Goodyear and United States Rubber Company. As the need for rubber increased and present stocks sank, a committee that included scientists James B. Conant, president of Harvard University, and Karl T. Compton, president of Massachusetts Institute of Technology, decided the best technical methods to proceed along. With everyone working together, 51 synthetic rubber plants were quickly built that turned out a variation of Buna called GR-S rubber containing 75 percent butadiene, 25 percent styrene and potassium persulfate as a catalyst or cross-linking agent. Firestone produced the program’s first bale of synthetic rubber on April 26, 1942. By 1945, the United States was producing about 920,000 tons per year of synthetic rubber, 85 percent of which was GR-S rubber, a majority going towards vehicle tires.
In 2015, the total US tire shipments are projected to exceed 311 million units — almost one for each citizen — and world production amounts to more than 12 million tons, about half going to China.
Gary Hanington is a professor of physical science at Great Basin College and chief scientist at AHV. He can be reached at: gary.hanington@gbcnv.edu.
To make whole numbers from a combination of 4’s using the usual mathematical symbols can be a wonderful brain expander. Consider the task of making the number 1 using four 4’s: (44/44).
The number 2 is: (4/4 + 4/4). Can you make the number 64 by just using four 4’s? You can only use: + – / ^ (power) SQRT and ! (factorial) symbols. Here is 64 from five 4’s: 4(4+4+4+4).
(4 + 4)(4 + 4)

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A World War II tire information poster.
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