In what circumstances was it discovered? In 1863, a previously unknown hydrocarbon was isolated from the pyrolysis of amyl alcohol by the French chemist E. Caventou. 23 years later, this hydrocarbon was identified as butadiene by Henry Edward Armstrong after isolating it during a pyrolysis of petroleum.
However, the butadiene will only begin its journey as the best ingredient for synthetic rubber in 1910, when the Russian chemist Sergei Lebedev (picture on the right) makes one of the first synthetic rubbers out of it, and in 1928 develops an industrial method to produce it.In the beginning, the first synthetic rubber was too soft to replace natural rubber but being able to synthesize such material means that you are also able to modify its properties by changing the ingredients. Moreover, in the middle of the 20th century, because of the war, not all countries could have access to natural rubber, which was an essential component to determine whether they’ll win or lose the war.
#pictureHow is it synthesized? During the World War II butadiene was produced from ethanol:This process was developed by Sergei Lebedev, the one who discovered its uses and was the basis for the Soviet Union’s synthetic rubber industry. It is based on conversion from ethanol to butadiene, hydrogen, and water at 400 °C over a metal oxide catalyst.It was also used in South America, Eastern Europe, China, and India, for lower capital costs. As of 2017, butadiene is no more produced using this method.Today, there are two main methods to produce it.· The first one is based on extraction from C4 hydrocarbons: Essentially as a byproduct of the steam cracking process used to produce ethylene, it is produced after aliphatic hydrocarbons give up hydrogen when mixed with steam and briefly heated to temperatures near 900°.
· The second is from catalytic dehydrogenation of n-butane: What are its uses? Every year, two million tons of polybutadiene are produced, and 70% of this quantity goes towards tire manufacturing. But since, pure polybutadiene is too soft and elastic for tires, different catalysts are used to alter the properties of the polymer. We can hence distinguish several types of polymers:· The polymer with trans double bonds, forming straight rigid rods, which make the material stiffer, harder, and with a sharp melting point. · The polymer with cis double bonds which forms bends in the chain, making it impossible to be aligned, and thus results in a more amorphous material. i.e. making it more flexible and elastic. · Vinyl polybutadienes, which is produced when the polymerization happens only on the first double bond of the monomer.
The remaining C2 group is thus left as a vinyl group.This polymer makes the product flexible also. Composition of polybutadiene based on the catalyst used: Cis (%) Trans (%) Vinyl (%) Neodymium 98 1 1 Cobalt 96 2 2 Nickel 96 3 1 Titanium 93 3 4 Lithium 10 to 30 20 to 60 10to 70 Hence, by varying the temperature or using a suitable catalyst during the polymerization, chemists can control the ratio of trans to cis double bonds in the polymer. Which make different uses of butadiene polymers possible.
Indeed, stiff but hard-wearing high-trans polybutadiene is used for the outer layer of golf balls, whereas flexible high-cis polybutadiene is used to make truck tires, which helps to improve fatigue to failure life. Butadiene can also be mixed with other ingredients to make other polymers such as Styrene and/or Acrylonitrile to make respectively SBS (styrene-butadiene-rubber), used also in tire manufacturing, and ABS (Acrylonitrile-butadiene-styrene), which has high impact resistance and is thermoplastic and is used to make Lego bricks, computer keyboard keys, or luggage cases.What the challenges concerning Butadiene?The most significant concerns about butadiene are its effects on human’s health.Indeed, this molecule can cause blurred vision, fatigue, headache, and vertigo. Also, when exposed to skin it can lead to frostbite.
Moreover, Long term-exposure has lead to cardiovascular disease, leukemia, and has been associated with cancers. In fact, it is listed a known carcinogen by the Agency for Toxic Substances Disease Registry and the US EPA. Sourceshttps://www.wikipedia.orghttp://www.
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