Cultivation of microorganisms pdf
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Rubber” and “India rubber” redirect cultivation of microorganisms pdf. This article is about the polymeric material “natural rubber”.
For man-made rubber materials, see Synthetic rubber. This article needs additional citations for verification. 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. Currently, rubber is harvested mainly in the form of the latex from the rubber tree or others. The latex is a sticky, milky colloid drawn off by making incisions in 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 most of its useful forms, it has a large stretch ratio and high resilience, and is extremely waterproof. This species is preferred because it grows well under cultivation. The latex exhibits the same quality as the natural rubber from rubber trees. In the wild types of dandelion, latex content is low and varies greatly.
In Nazi Germany, research projects tried to use dandelions as a base for rubber production, but failed. Many other plants produce forms of latex rich in isoprene polymers, though not all produce usable forms of polymer as easily as the Pará. Some of them require more elaborate processing to produce anything like usable rubber, and most are more difficult to tap. The first use of rubber was by the indigenous cultures of Mesoamerica. The Pará rubber tree is indigenous to South America. South America remained the main source of the limited amounts of latex rubber used during much of the 19th century. The trade was heavily protected and exporting seeds from Brazil was a capital offense, although no law prohibited it.
In India , commercial cultivation was introduced by British planters, although the experimental efforts to grow rubber on a commercial scale were initiated as early as 1873 at the Calcutta Botanical Gardens. The first commercial Hevea plantations were established at Thattekadu in Kerala in 1902. In Singapore and Malaya, commercial production was heavily promoted by Sir Henry Nicholas Ridley, who served as the first Scientific Director of the Singapore Botanic Gardens from 1888 to 1911. He distributed rubber seeds to many planters and developed the first technique for tapping trees for latex without causing serious harm to the tree. Charles Goodyear developed vulcanization in 1839, although Mesoamericans used stabilized rubber for balls and other objects as early as 1600 BC.
Rubber produced as a fiber, sometimes called ‘elastic’, had significant value to the textile industry because of its excellent elongation and recovery properties. For these purposes, manufactured rubber fiber was made as either an extruded round fiber or rectangular fibers cut into strips from extruded film. Because of its low dye acceptance, feel and appearance, the rubber fiber was either covered by yarn of another fiber or directly woven with other yarns into the fabric. While rubber is still used in textile manufacturing, its low tenacity limits its use in lightweight garments because latex lacks resistance to oxidizing agents and is damaged by aging, sunlight, oil and perspiration. Rubber exhibits unique physical and chemical properties. Mullins effect and the Payne effect and is often modeled as hyperelastic. Due to the presence of a double bond in each repeat unit, natural rubber is susceptible to vulcanisation and sensitive to ozone cracking.