The History of Synthetic Rubber ②

In the past few thousand years, people have been using wooden wheels, or around wheels, with metal rims.In 1845, after Goodyear invented the practical vulcanized rubber, British engineer R.W.Thomson around the wheel set on an inflatable rubber hose, and obtained a patent for the device, in 1890, was officially used on bicycle tyre, in 1895, has been used in all kinds of antique cars.Although rubber is a soft and fragile substance, it is more wearable than wood or metal.The durability, cushioning and other properties of rubber, plus the clever design of the pneumatic tyre, make riders feel more comfortable than ever.As the number of cars increased, so did the demand for rubber for tires.Such a wide range of applications make natural rubber in short supply.Facing the serious situation of rubber production, Countries compete to develop synthetic rubber.

The first thing that comes to mind is the use of the natural rubber structure, isoprene, to make synthetic rubber.As early as 1880, chemists discovered that isoprene had been used for a long time to become soft, and acidified it became a rubbery substance.Kaiser Wilhelm ii had used this material to make a royal car's tire, to show off German chemical prowess.However, using isoprene as the raw material for synthetic rubber, there are two difficulties. One is that the main source of isoprene is the natural rubber itself.The second is in the natural rubber long chain, all isoprene units are oriented in the same direction;In solid tower slope of the long chain, they are strictly in accordance with the a is a reverse direction, and artificial aggregate isoprene units are often no together regularly, get is a kind of slope is not a rubber or a solid tower adhesive material.The substance, which lacks the elasticity and flexibility of rubber, will soon become sticky, so it can't be used to make car tires (the royal car for state events is certainly an exception).

During the first world war, the German adopted dimethylbutadiene to form methyl rubber, which can be mass-produced and cheap.During world war I, Germany produced about 2,500 tons of methyl rubber.Although the rubber was not ideal to withstand pressure, it was eliminated after the war, but it was the first practical synthetic rubber.

Around 1930, Germany and the Soviet union used butadiene as a monomer, as a catalyst, to synthesize a type of sodium butadiene rubber.As a synthetic rubber, the sodium butyl rubber is satisfactory for the rubber plaques.Copolymerization with other monomers can improve the performance of sodium rubber.For example, buna-s are common with styrene, and its properties are very similar to natural rubber.In fact, during world war ii, the German army was because of styrene butadiene rubber, and there was no serious shortage of rubber supplies.The Soviet union used the same method to provide rubber to its troops.

The United States studied synthetic rubber after the war.First, it synthesizes chloroprene rubber, which has some anti-corrosion properties that natural rubber does not have.For example, it has a high corrosion resistance to organic solvents such as gasoline, far from softening and expanding like natural rubber.As a result, the chloroprene rubber is actually more suitable than natural rubber.Neoprene, for the first time made it clear that, as in many other fields, in the field of synthetic rubber, in a test tube products must not only ACTS as a substitute of natural substances, its performance can be better than natural substances.

In 1955, the americans used the catalyst that ziegler used in polyethylene (also known as ziegler, the natta catalyst) to polymerize isoprene.Synthetic natural rubber, which is basically the same as natural rubber, was synthesized by artificial method for the first time.It was not long before the two simplest monomers, ethylene and propylene, were also successful.There are also various types of rubber with special properties.The total production of synthetic rubber now exceeds that of natural rubber.

The History of Synthetic Rubber ①

Humans have been using natural rubber for centuries.Columbus discovered on the voyage of the new world that a ball of native American play was made with a hardened plant SAP.Columbus and later explorers were all amazed at this bouncy ball.Some samples were taken back to Europe as curiosities.It was later discovered that the elastic ball could erase the marks of the pencil and gave it a common name, "rubber."This is still the name of the substance at the moment.This substance is rubber.

But it wasn't until 1839, when Charles Goodyear, an American, succeeded in vulcanization of natural rubber, that rubber became a useful material.The crosslinking of rubber chain is achieved by heating with sulfur, which makes the rubber have good elasticity.Why is rubber elastic?Let's analyze the molecular structure of rubber.The chain monomer of natural rubber molecule is isoprene.We know that the molecular force between the chain and the chain determines its physical properties.In rubber, the interaction between the molecules is weak, because it is not easy to interact with other chains.It's like two friends trying to shake hands, but everyone has a lot of things on their hands, so it's hard to shake hands.The force between rubber molecules determines the flexibility of the rubber.The molecules of rubber are easy to rotate and have ample space for movement, and the arrangement of molecules presents an irregular and random natural state.When subjected to external influences such as bending and elongation, the molecules are forced to show certain regularity.When the outside force is removed, the rubber molecules return to their original irregular state.This is why rubber is elastic.Because of the weak intermolecular force, the molecules can rotate freely, and there is not enough coupling between the molecular chains. Therefore, the molecules will slide between each other and the elastic will not show up.This slip is reduced by intermolecular entanglement.However, the intermolecular entanglement is unstable, and as the temperature increases or the winding of the time is loosened, it is necessary to establish a stronger connection between the molecular chains.This is the cure that Goodyear invented.The vulcanization process usually takes place at a temperature of 140 to 150 degrees Celsius.Goodyear's little stove was heating up.The main effect of vulcanization is simply to form a crosslink between the molecular chain and the molecular chain, thereby enhancing the interaction between the molecular chains.


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