After beavering away with his assistant Carl Coutelle and a research team in their employer’s laboratory in Elberfeld, western Germany, Hofmann produced the flexible substance methyl-isoprene, and in doing so laid the cornerstone for the development of a viable alternative to natural rubber. To honour this invention, Lanxess has established “World Rubber Day,” an occasion that will be celebrated for the first time on Sept. 12.
Attracted by the desire to end his country’s dependence upon British and Belgian held natural rubber plantations and perhaps further spurred on by a prize of 20,000 marks (a sum that could buy many, many sausages a century ago) offered by his employer, Hofmann began his quest to develop a synthetic rubber in 1906. During the course of his experiments Hofmann discovered that when methylisoprene was heated in an autoclave at various temperatures, the resultant substance was sometimes hard and sometimes soft – but always elastic. Following a period of refinement the patent for the world’s first synthetic rubber was issued on Sept. 12, 1909.
“As the head of various research laboratories I was constantly on the lookout for promising areas of work for my staff,” commented Hofmann much later. “Here [in the manufacture of synthetic rubber] I saw the opportunity to create something that was lacking in my own country and, at the same time, would free it from having to import an expensive product from foreign countries that were naturally blessed with it.”
Hoffmann was well rewarded for his efforts, receiving amongst other kudos the Gold Fischer Medal from the Society of German Chemists, an Honorary Plaque from the German Rubber Society and the gilded Buna medal at the World Exhibition in Paris. His employer, Elberfelder Farbenfabriken, was later incorporated into Lanxess AG.
The significance of this 1909 discovery, and the opportunities it created, is today widely acknowledged. “Hofmann’s 1909 innovation equalled a quantum leap for the rubber industry,” noted Lanxess’s Christoph Kalla during an address at a trade association convention. “Yet, just as important from today’s point of view are the developments that took place after this discovery. And these developments brought many innovations, even if they essentially proceeded without quantum leaps.”
The tyre manufacturer Continental moulded the first car tyres out of the new material as early as 1910, and Hofmann’s boss, Carl Duisberg, drove 4,000 kilometres on the new tyres “without a puncture.” The product even gained the attention of Germany’s Kaiser Wilhelm II, who had his car equipped with the new tyres and sent a telegram saying he was "extremely pleased." Yet declining natural rubber prices in the years after World War One diminished the profitability of synthetic rubber, and production was halted. Despite this setback, as Kalla points out, “the cornerstone for success had been laid. Hofmann not only produced the first technically useful synthetic rubber. With his reach to methyl-isoprene he opened up an important door for technology. He had shown that you can also make useful elastomers out of non-natural raw materials.”
It was the Nazis and their efforts to achieve national self-sufficiency that led to resurgence in synthetic rubber’s popularity. Buna-S, a styrene rubber, became the primary rubber product utilised by Germany in the Second World War. By 1942, with 90 per cent of natural rubber supplies in Japanese hands, allied countries had also developed an interest in synthetic rubbers. By 1944 an estimated 50 synthetic rubber factories were in operation worldwide, producing an output double that of global pre-war natural rubber production.
The synthetic rubber industry never looked back. In the decades that followed, more and more new synthetic rubbers were developed. In 2007, some 13.6 million tonnes of synthetic rubber were used worldwide, compared with roughly 9.7 million tonnes of natural rubber.
Experts expect that demand for synthetic rubber will continue to outpace that of natural rubber as a result of its useful properties. Synthetic rubber is employed today as the basis for a wide range of high-performance rubber products. Three of the four business in Lanxess’s Performance Polymers segment – Butyl Rubber, Technical Rubber Products and Performance Butadiene Rubbers – are dedicated to the substance. Happy birthday, synthetic rubber. (Tyres & Accessories/Staffordshire, U.K.)
