Rubber has been used for thousands of years. Europeans only saw it for the first time in the 16th century. Spanish Explorer Hernan Cortes landed on the East Coast of Mexico in April 1519, near the modern city of Veracruz.
Travelling inland, the Conquistadors quickly discovered the first team-sport in Human history – The meso-American Ballgame.
The Spanish were fascinated by the game, but above all they were fascinated by the ball which bounced like nothing they had ever seen before. The balls used by the Aztecs were made from rubber.
Small amounts of rubber found their way back to Europe. One of the first records from a shop in London, dated 15 April 1770 shows that Joseph Priestley, the discover of oxygen, paid three shillings for a half-inch cube. That works out at about £11 or euro 12 in today’s money for around 2 grammes – or euro 6000 per kg.
He used it to erase – or rub out – pencil marks, hence the name in English of rubber. Most other nations use a word derived from Caucho, the word for rubber in the original language spoken in South America.
The material remained something of a curiosity until the middle 1800s. In 1842 Charles Goodyear patented the process known as Vulcanisation.
Before then rubber was used as an eraser or as a waterproofing agent. The specialists in that business were the MacIntosh company in Scotland. But the coated material started to smell and became sticky in sunshine.
Goodyear re-discovered the secret of the Aztecs: how to make rubber hard and durable. The ancient South Americans used the sap of a local vine to convert the rubber from soft and squishy to robust and durable.
Charles Goodyear used sulphur. He mixed rubber with sulphur and then cooked it on a stove. One part was still soft; some of it was charred and burned. But a thin strip in the middle was hard and durable.
That discovery triggered a rubber boom.
By the mid-1880s the city of Manaus in Brazil was at the centre of this boom. One type of local tree – Hevea Brasiliensis – had become the source of unimaginable wealth.
As the industrial revolution accelerated across Europe and engineers needed a material to seal steam cylinders and manufacture tires, shoes and other products, demand for rubber became almost insatiable. Profit margins were very attractive.
So attractive that it was only a matter of time before the Amazonian monopoly would be broken.
In 1876 Sir Henry Wickham, a young British adventurer sailed out of the Amazonian port of Santarem in the ship Amazonas with 70,000 seeds of the Hevea Brasiliensis tree. He arrived back in the UK and under the care of specialists at London’s Kew Botanical Gardens some seeds germinated and grew to maturity. Rubber trees were then shipped to Sri Lanka.
At least, that’s the story. There are a lot of question marks over the historical detail, but the end result was that the British Empire got hold of viable trees and planted them in Sri Lanka and Singapore.
There is a disease common in South America called South American Leaf Blight. It passes from tree to tree. Because of this, dense rubber plantations cannot survive in the Amazon. SALB is not present in Asia, so the trees could be planted close together and this led to the development of a thriving rubber industry across the region which persists to this day.
By the time of the European war of 1914-1918, Europe’s armies had come to rely on rubber for vehicles, shoes and other products. The UK controlled the supply of rubber from South America and South-East Asia. As a result, the opposing armies suffered from a lack of the material.
Germany made plans to develop synthetic alternatives.
The first such material was developed in the laboratories in the laboratories of Elberfelder Farbenfabriken vorm. Friedr. Bayer & Co.
In 1909 Fritz Hofmann made an the elastic substance which we now know as methyl-isoprene, or methyl rubber. Although this offered elastic properties it was not a good substitute for natural rubber. Nevertheless, it was better than nothing and the German company Continental AG made tyres and other goods from the new material.
The following year Russian scientist Sergei Vasiljevich Lebedev created the first rubber polymer synthesised from butadiene. Butadiene rubber (BR) is today one of the mainstays of the tyre industry.
Russia’s first synthetic rubber factory opened in 1932.
In the 1930s, the addition of styrene created a new form of synthetic rubber which we now call styrene-butadiene rubber (SBR). This is the second of the mainstream elastomers used in the modern rubber industry.
Development of these materials accelerated in parallel in Germany and Russia. The United States was less advanced as the world war of 1939-45 opened in Europe.
When Japan invaded the Malayan peninsula and arrived in Singapore in July 1942, the supply of rubber to the UK and US dried up.
The United States quickly realised that rubber was a strategic resource. It began an intensive research programme to develop the chemistry and construct factories to make synthetic rubber. The only project to take precedence over the synthetic rubber project was the Manhattan Project to build the atomic bomb.
The materials developed in these intense wartime programmes were focused on materials to make tyres: SBR, and BR.
However, rubber is used in more than tyres. In 1930 a scientist at DuPont, Wallace Carothers developed chloroprene rubber. Carothers was later to develop Nylon, or polyamide.
In 1934 scientists tried replacing the styrene in SBR with acrylonitrile to make a highly oil-resistant elastomer which they christened Buna-N and is now termed nitrile rubber or NBR.
In 1937 Exxon (now ExxonMobil Chemical) developed butyl rubber, which is especially good at air-retention.
In 1961 Exxon set up the first factory for a rubber made from ethylene and propylene. That was in Baton Rouge, Louisiana. The original material EPM or EPR was subsequently modified with a third monomer to make EPDM or ethylene-Propylene diene monomer. EPDM is especially good at resisting ozone and ultra-violet light.
In the following years a wide range of elastomers were developed. Some have good resistance to ozone while others have superb temperature properties or excellent resistance to oil.
Whatever properties you need, let SPC compounders develop your ideal material to deliver the right combination of in-service properties, ease of processing and, of course, cost.