Natural Rubber
Description
Natural rubber is a sap obtained from some trees, better known as latex. Latex is actually the original form of rubber, which is later processed by various methods to get the rubbers that we are so well acquainted with. Latex is a white milky sap, with a high viscosity and density. When we speak about natural rubber, we refer to the latex that is directly collected from the trees.
Chemically, natural rubber is a hydrocarbon polymer. It contains several units of isoprene polymerically united to form the stringy form of rubber. In its natural form, rubber is much highly elastic, soft and sticky. There are processes to make this rubber hard and tough, one of the most common of which is vulcanization. When vulcanized, rubber loses most of its elastomer properties and becomes almost inelastic.
Sources And Availability
There are many sources from which natural rubber is obtained. The tree that has the biological name of Hevea brasiliensis is the most notable source of natural rubber, but rubber can also be extracted from other trees of the Euphorbiaceae family, and also the fig tree. However scarpe nike, these sources are not tapped much in the world, and the most prominent supply does come from Hevea brasiliensis.
Actually, Hevea brasiliensis is a native Brazilian plant, as its name indicates. But in the later part of the nineteenth century, this tree was implanted to the Far East, where it showed a much better propensity for growth. Countries like Indonesia, Malaysia, Thailand, Sri Lanka, Singapore and India showed a great crop of the tree in a very short time. Today, Malaysia ranks as the number one producer of rubber in the world, and about three fourths of all the natural rubber used in the world comes from the three countries of Malaysia, Indonesia and Thailand. In India, the state of Kerala is also a major producer of natural rubber in the world, along with the southern country of Sri Lanka. Some rubber production is also obtained from the two African countries of Nigeria and Liberia, but that is about all the African production of rubber that there is.
Natural rubber itself forms a great share of the rubber requirement of the world. Today there are methods of preparing the rubber isomer with synthetic methods, but due to the abundance of natural rubber sources, synthetic methods are not quite vastly used. For high-end purposes like making tires, almost half of the rubber requirement across the world is obtained from natural sources.
Procurement
Even today, quite traditional methods are used in the procurement of natural rubber. A small incision is made on a rubber tree at the outer bark, from which the inner latex sap starts flowing. This is collected in a small receptacle that is connected below the incision. The positioning of the receptacle is adjusted expertly so that the sap completely flows into it, without any wastage. In most areas, natural objects such as half shells of coconuts are used to collect the sap, and these are either tied or nailed to the region below the incision.
In ordinary practice, the incision is made somewhere in the afternoon and the latex is allowed to flow into the receptacle. By the next morning, a cupful of latex is usually obtained. This is all collected into a vat and mixed with formic acid, which gives it some of its hardness. From there on, the natural rubber is sent to the factories for further processing.
Once an incision is made, the latex in the tree is allowed to build up for a period of time before an incision can be made on the tree again. A new incision will always be made at a new place on the tree. Typically, rubber trees will show multiple incisions indicating that latex has been extracted several times from them.
Vulcanization
Vulcanization of rubber, the method perfected by Charles Goodyear, is a method to transform the soft scarpe nike, sticky natural rubber mass into a hard tough substance that is suitable for commercial use. Depending on the requirement, the procedure can be adjusted. Generally scarpe nike, a mass of natural rubber is mixed with some amount of sulfur and then heated for a specific time and a specific temperature according to the requirement. This makes the polymer chains shorter (due to the incorporation of the disulfide units in them) and the rubber becomes harder.
Vulcanization is needed for preparing almost all products of rubber that we use today, including tires, sports equipment, cookware, insulating and shock-absorbing devices, plugs, etc. Related：
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