Friday, August 26, 2016

Natural Rubber Summary

Natural rubber, also called India rubber or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds plus water. Malaysia is one of the leading producers of rubber. Forms of polyisoprene that are used as natural rubbers are classified as elastomers. Natural rubber is used by many manufacturing companies for the production of rubber products. Currently, rubber is harvested mainly in the form of the latex from the para rubber tree or others. The latex is a sticky, milky colloid drawn off by making incisions into the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into rubber ready for commercial processing. Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In major areas latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for marketing. In most of its useful forms, it has a large stretch ratio and high resilience, and is extremely waterproof.

Current Sources

Close to 28 million tons of rubber were produced in 2013, of which approximately 44% was natural. Since the bulk of the rubber produced is of the synthetic variety, which is derived from petroleum, the price of natural rubber is determined, to a large extent, by the prevailing global price of crude oil. Today, Asia is the main source of natural rubber, accounting for about 94% of output in 2005. The three largest producing countries, Thailand, Indonesia (2.4 million tons) and Malaysia, together account for around 72% of all natural rubber production. Natural rubber is not cultivated widely in its native continent of South America due to the existence of South American leaf blight, and other natural predators of the rubber tree.

Cultivation

Rubber latex is extracted from rubber trees. The economic life period of rubber trees in plantations is around 32 years — up to 7 years of immature phase and about 25 years of productive phase.

The soil requirement of the plant is generally well-drained, weathered soil consisting of laterite, lateritic types, sedimentary types, nonlateritic red, or alluvial soils.

The climatic conditions for optimum growth of rubber trees are:

  • Rainfall of around 250 cm evenly distributed without any marked dry season and with at least 100 rainy days per year
  • Temperature range of about 20 to 34 °C, with a monthly mean of 25 to 28 °C
  • High atmospheric humidity of around 80%
  • Bright sunshine, amounting to about 2000 hours per year at the rate of six hours per day throughout the year
  • Absence of strong winds

Many high-yielding clones have been developed for commercial planting. These clones yield more than 2,000 kg of dry rubber per hectare per year, when grown under ideal conditions.

Vulcanization

Natural rubber is often vulcanized, a process by which the rubber is heated and sulfur, peroxide or bisphenol are added to improve resistance and elasticity, and to prevent it from perishing. The development of vulcanization is most closely associated with Charles Goodyear in 1839. Before World War II era manufacturing, carbon black was often used as an additive to rubber to improve its strength, especially in vehicle tires.

Alternative Sources

Dandelion milk has long been known to contain latex. The latex exhibits the same quality as the natural rubber from rubber trees. Yet in the wild types of dandelion, the latex content is low and varies greatly.

In Nazi Germany, research projects tried to use dandelions as a base for rubber production, but failed.

In 2013, by inhibiting one key enzyme and using modern cultivation methods and optimization techniques, scientists in the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) in Germany developed a cultivar that is suitable for commercial production of natural rubber. In collaboration with Continental Tires, IME is building a pilot facility. The first prototype test tires made with blends from dandelion-rubber are scheduled to be tested on public roads over the next few years.


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Why Is an Aircraft Tire Mostly Natural Rubber?

How does One Maintain a Tire?      

By Tieux Kiocchio

Natural rubber has better specs, for heat dispertion for instance.
That's why it's preferred on aircraft.


For maintenance, a tire is a bit like having a solid core and rubber around.
So as long as the core isn't damaged, it's possible to put rubber back on the core to go against wear and minor damages.

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